{"id":8742,"date":"2026-04-29T10:45:25","date_gmt":"2026-04-29T02:45:25","guid":{"rendered":"https:\/\/www.flywing-tech.com\/blog\/?p=8742"},"modified":"2026-04-29T10:45:25","modified_gmt":"2026-04-29T02:45:25","slug":"capacitor-selection-power-supply-design","status":"publish","type":"post","link":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/","title":{"rendered":"How to Choose the Right Capacitor for Power Supply Design"},"content":{"rendered":"<div class=\"fsc_text\">\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"introduction\"><\/span>Introduction<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Capacitors hold an essential role in any power supply design. Although they are smaller and cheaper than semiconductors and transformers, inappropriate choice of capacitor leads to overheating, ripple voltage, electromagnetic interference (EMI), reduced efficiency, and circuit failure.<\/p>\n\n\n\n<p>Capacitors are widely used in DC-DC converters, motor controllers, linear regulators, and industrial power supplies. Therefore, to ensure long-term reliability and stable performance in such applications, it is critical to understand how to select the right capacitor for a specific application.<\/p>\n\n\n\n<p>This article explains an engineering methodology for the Capacitor Selection of power supply design. This guide mainly focuses on voltage ratings, capacitance value, ripple current, temperature, lifetime, type of dielectric material, and proper placement. In addition, case studies based on real-world applications are also covered to help designers make better decisions.<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_76 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\r\n<div class=\"ez-toc-title-container\">\r\n<h2 class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/h2>\r\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #023a85;color:#023a85\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #023a85;color:#023a85\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\r\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#introduction\" >Introduction<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#why_capacitor_selection_is_important_in_power_supplies\" >Why Capacitor Selection is Important in Power Supplies?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#role_of_different_capacitors_in_power_supply_design\" >Role of Different Capacitors in Power Supply Design<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#important_key_parameters_for_capacitor_selection\" >Important Key Parameters for Capacitor Selection<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#type_of_capacitors_and_where_to_use_them\" >Type of Capacitors and Where to Use Them<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#capacitor_selection_parasitic_issues_esr_and_esl\" >Capacitor Selection: Parasitic Issues (ESR and ESL)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#important_parameters_in_capacitor_datasheet\" >Important Parameters in Capacitor Datasheet<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#output_filter_design_for_buck_converter_a_case_study\" >Output Filter Design for Buck Converter: A Case Study<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#pcb_layout_and_capacitor_placement\" >PCB Layout and Capacitor Placement<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#modern_trends_in_power_supply_capacitors\" >Modern Trends in Power Supply Capacitors<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#capacitor_selection_checklist\" >Capacitor Selection Checklist<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#conclusions\" >Conclusions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#frequently_asked_questions_faqs\" >Frequently Asked Questions (FAQs)<\/a><\/li><\/ul><\/nav><\/div>\r\n\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"why_capacitor_selection_is_important_in_power_supplies\"><\/span><strong>Why Capacitor Selection is Important in Power Supplies?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>When designing a power supply, designers mainly focus on controllers, MOSFETs and magnetics (<a href=\"https:\/\/www.flywing-tech.com\/blog\/mosfet-selection-guide\/\" target=\"_blank\" rel=\"noreferrer noopener\">check <\/a><a href=\"https:\/\/www.flywing-tech.com\/blog\/wp-admin\/post.php?post=8281&amp;action=edit\" target=\"_blank\" rel=\"noreferrer noopener\">our MOSFET selection guide<\/a>). However, capacitor selection is equally important because it directly impacts several system parameters.<\/p>\n\n\n\n<p>Depending on the capacitor placement, choice of capacitor is directly related to output ripple voltage, input voltage stability, load transient response, thermal reliability, EMI performance, and lifetime of the device.<\/p>\n\n\n\n<p>Therefore, a poor capacitor selection can lead to unstable regulation, excessive ripple, noise, and lower lifetime. &nbsp;&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"role_of_different_capacitors_in_power_supply_design\"><\/span><strong>Role of Different Capacitors in Power Supply Design<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Before selecting a capacitor, it is essential to identify where it is used in the system. Based on the circuit placement, capacitors can serve different roles. Such as input capacitor is used to filter out transients coming from input supply, while decoupling capacitors are placed close to the IC pins to avoid high-frequency noise (see Fig-1).<\/p>\n\n\n\n<p>&nbsp;The table below summarizes type of capacitors and their specific role in the power supply design.<\/p>\n\n\n\n<figure class=\"wp-block-table aligncenter is-style-stripes\"><table class=\"has-fixed-layout\"><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Type of Capacitor<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\"><strong>Role<\/strong><\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Input capacitor<\/td><td class=\"has-text-align-center\" data-align=\"center\">It is placed near the input source and reduces input voltage dips<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Output capacitor<\/td><td class=\"has-text-align-center\" data-align=\"center\">Located at load\/output side and helps in reducing load transients<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Decoupling capacitor<\/td><td class=\"has-text-align-center\" data-align=\"center\">This is used as close as possible to IC pins and suppress high-frequency noise<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">Bulk capacitors<\/td><td class=\"has-text-align-center\" data-align=\"center\">Although there is no fix position, this provides stored energy for sudden load demand or startup.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1408\" height=\"768\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/Fig-2-1.png\" alt=\"Capacitor Selection:  buck converter capacitor placement\" class=\"wp-image-8768\" style=\"aspect-ratio:1.8333731200763905;width:696px;height:auto\" \/><figcaption class=\"wp-element-caption\">Fig-1:Role of different capacitors<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"important_key_parameters_for_capacitor_selection\"><\/span><strong>Important Key Parameters for Capacitor Selection<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Capacitance Value<\/strong><\/h3>\n\n\n\n<p>One of the most important and basic parameters is capacitance. This refers to amount of energy a capacitor can store and typically measured in \u00b5F, nF, pF. Higher capacitance value result in lower ripple voltage and better transient support (<a href=\"https:\/\/www.flywing-tech.com\/product-detail\/ceramic-capacitors-samsung-electro-mechanics-cl10a476mq8qrnc-811f5e01\" target=\"_blank\" rel=\"noreferrer noopener\">for example, see Samsung 47 \u00b5F MLCC<\/a>).<\/p>\n\n\n\n<p>Output ripple in many switching power supplies can be approximated by the equation given below:<\/p>\n\n\n<p>\\[\\Delta V=\\frac{I}{fC}\\]<\/p>\n\n\n\n<p>Where:<\/p>\n\n\n\n<p>\u0394V= Ripple voltage<\/p>\n\n\n\n<p>I= Ripple current components<\/p>\n\n\n\n<p>f= Switching frequency<\/p>\n\n\n\n<p>C= Capacitance<\/p>\n\n\n\n<p>According to given equation, ripple decreases as the capacitance value increases. However, excessive capacitance leads to higher startup inrush current, size and cost (<a href=\"https:\/\/community.infineon.com\/t5\/Knowledge-Base-Articles\/DC-Bias-characteristics-of-Multilayer-Ceramic-Capacitor-MLCC\/ta-p\/250035?utm_\" target=\"_blank\" rel=\"noreferrer noopener\">Infineon\u2019s MLCC DC bias guide<\/a>).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Voltage Rating<\/h3>\n\n\n\n<p>It is the maximum voltage a capacitor can sustain. Rule of thumb is to always apply safety margin such that capacitors should be rated at least 1.25 times the operating voltage. Mathematically:<\/p>\n\n\n<p>\\[V_{rated}\\ge1.25\\times V_{operating}\\]<\/p>\n\n\n\n<p>For example: For a 12V rail, using a 16V capacitor is safer than using exact 12V capacitor.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Equivalent Series Resistance (ESR)<\/strong><\/h3>\n\n\n\n<p>ESR represents the internal resistance of a capacitor. The materials like electrolytes, foils, leads create a small amount of resistance that acts in series with capacitance.<\/p>\n\n\n\n<p>Higher ESR results in higher ripple voltage, heat generation (P=I<sup>2<\/sup>R), reduced efficiency, and poor transient response.&nbsp; The ripple caused by ESR is estimated as:<\/p>\n\n\n<p>\\[V_{ESR}=I_{ripple}\\times ESR\\]<\/p>\n\n\n\n<p>Therefore, low-ESR capacitors are preferred in power supply applications (<a href=\"https:\/\/article.murata.com\/en-eu\/series\/capacitor-knowledge\" target=\"_blank\" rel=\"noreferrer noopener\">For additional discussion check this guide<\/a>).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Ripple Current<\/h3>\n\n\n\n<p>The ripple current for a capacitor is the maximum RMS alternating current it can handle without overheating or failure. It arises from AC voltage fluctuations on a DC line, such as in switching power supplies or input\/output filters. <\/p>\n\n\n\n<p>Datasheets generally provide maximum ripple current rating for every capacitor. If ripple current exceeds that value, internal heating increases leading to device failure (<a href=\"https:\/\/www.avnet.com\/wcm\/connect\/bc2e0047-96d0-4904-8b2b-63739f197c9f\/tech-topic-basic-principles-of-ripple-current-and-mlcc.pdf?CACHE=NONE&amp;CVID=oqtRGoe&amp;ContentCache=NONE&amp;MOD=AJPERES&amp;utm_source=chatgpt.com\" target=\"_blank\" rel=\"noreferrer noopener\">check ripple fundamentals here<\/a>).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Temperature Rating<\/h3>\n\n\n\n<p>Like MOSFETs or other electronic components, temperature rating strongly affects capacitor lifetime. Common temperature ratings for capacitors are from 85\u00b0C-125\u00b0C (<a href=\"https:\/\/www.flywing-tech.com\/blog\/mosfet-failure-power-circuits\/\" target=\"_blank\" rel=\"noreferrer noopener\">See why MOSFET fails in power circuits<\/a>).<\/p>\n\n\n\n<p>Choice of capacitor depends on environment they are going to be used. In hot environments such as motor drives, LED power supplies, and automotive electronics, higher temperature capacitors are used.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Capacitor Lifetime<\/h3>\n\n\n\n<p>Although not always explicitly mentioned in datasheet, Capacitor lifetime is critical parameter especially in products expected to operate continuously. Applications such as telecom systems, industrial power supplies, solar inverters, EV and auxiliary systems place strong emphasis on reliability. &nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"type_of_capacitors_and_where_to_use_them\"><\/span><strong>Type of Capacitors and Where to Use Them<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-table aligncenter is-style-stripes\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Capacitor type<\/strong><\/td><td><strong>Where to use<\/strong><\/td><td><strong>Advantages<\/strong><\/td><td><strong>Limitations<\/strong><\/td><\/tr><tr><td>Ceramic capacitor<\/td><td>-High-frequency decoupling &nbsp; <br>-Output filters &nbsp; <br>-Compact designs<\/td><td>-Very low ESR <br>-Small size <br>-High reliability<\/td><td>-Capacitance drops with DC bias <br>-Creates audible noise in some converters<\/td><\/tr><tr><td>Electrolytic capacitors<\/td><td>&#8211;<a href=\"https:\/\/www.flywing-tech.com\/product-detail\/aluminum-electrolytic-capacitors-nichicon-uhe1e470mdd1td-c77672cd\" target=\"_blank\" rel=\"noreferrer noopener\">Energy storage<\/a> <br>-Input filters <br>-Low-cost power supplies<\/td><td>-High capacitance <br>-Economical<\/td><td>-Higher ESR than ceramic capacitors <br>-Lower lifetime<\/td><\/tr><tr><td>Film capacitors<\/td><td>-High voltage applications <br>-Snubber circuits <br>-AC filtering<\/td><td>-Excellent stability <br>-Longer lifetime <br>-Lower loss<\/td><td>-High cost <br>-Lower capacitance<\/td><\/tr><tr><td>Polymer capacitors<\/td><td>-Low ESR applications <br>-Fast transient loads<\/td><td>-Low ESR <br>-Better ripple handling<\/td><td>-Higher cost compared to electrolytic capacitors <br>-Lower voltage ratings in some cases<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1408\" height=\"768\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/Fig-1-1.png\" alt=\"Capacitor Selection: Types and role of capacitors\" class=\"wp-image-8769\" style=\"aspect-ratio:1.8333731200763905;width:774px;height:auto\" \/><figcaption class=\"wp-element-caption\">Fig-2:Type of capacitors used in power supplies<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"capacitor_selection_parasitic_issues_esr_and_esl\"><\/span><strong>Capacitor Selection: Parasitic Issues (ESR and ESL)<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Parasitic parameters, ESR and Equivalent Series Inductance (ESL) are as important as datasheet parameters. In real applications, the impedance (Z) of capacitor is defined by parasitic parameters:<\/p>\n\n\n\n<p>ESR= The resistance of dielectric material, plates, and internal connections.<\/p>\n\n\n\n<p>ESL= The inductance formed by leads and physical geometry of the component.<\/p>\n\n\n\n<p>The impedance of capacitor at given frequency is given by:<\/p>\n\n\n<p>\\[Z=\\sqrt{ESR^2+\\left(X_C-X_L\\right)^2}\\]<\/p>\n\n\n\n<p>Where:<\/p>\n\n\n<p>\\[X_C=\\frac{1}{2\\pi f C}\\]<\/p>\n\n\n<p>\\[X_L=2\\pi f \\, L\\]<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>WHY ESL and ESR Matter<\/strong><\/h3>\n\n\n\n<p>These parasitic parameters significantly affect capacitor performance particularly in high-frequency switching applications (see Fig-3).&nbsp;<\/p>\n\n\n\n<p>As shown in equation above, during the lower frequency operation, capacitive reactance (X<sub>C<\/sub>) dominates the capacitor behaviour. While as frequency increases, the capacitor approaches its self-Resonant Frequency (SRF).&nbsp; In this case, X<sub>C<\/sub> and X<sub>L<\/sub> cancel each other and impedance of capacitor is determined by its ESR.<\/p>\n\n\n\n<p>Beyond SRF, the capacitor starts exhibiting inductive behaviour due to ESL.&nbsp; This becomes very critical in power converters where transient currents (di\/dt) are present. If capacitor with high ESL is used, transient currents generate significant voltage spikes across the parasitic inductance resulting in degradation in capacitor performance.<\/p>\n\n\n\n<p>Therefore, ESR and ESL are considered when selecting capacitors for power supply design.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1408\" height=\"768\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/Fig-3.png\" alt=\"Capacitor Selection: capacitor Equivalent model\" class=\"wp-image-8770\" style=\"aspect-ratio:1.8333731200763905;width:744px;height:auto\" \/><figcaption class=\"wp-element-caption\">Fig-3: Equivalent circuit model showing ESR and ESL<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"important_parameters_in_capacitor_datasheet\"><\/span><strong>Important Parameters in Capacitor Datasheet<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Capacitance<\/li>\n\n\n\n<li>Voltage ratings<\/li>\n\n\n\n<li>ESR\/impedance curve<\/li>\n\n\n\n<li>Ripple current rating<\/li>\n\n\n\n<li>Temperature range<\/li>\n\n\n\n<li>Mounting style<\/li>\n\n\n\n<li>Dimensions<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"output_filter_design_for_buck_converter_a_case_study\"><\/span><strong>Output Filter Design for Buck Converter: A Case Study<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>To identify how capacitor selection affects real power supply performance, a buck converter design example is explained in this section.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Design Scenario<\/h3>\n\n\n\n<p>A designer needs to develop a synchronous buck converter with following requirements:<\/p>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table class=\"has-fixed-layout\"><tbody><tr><td>Voltages levels (V<sub>in<\/sub> and V<sub>out<\/sub>)<\/td><td>12V-3.3V<\/td><\/tr><tr><td>Load Current (I<sub>load<\/sub>)<\/td><td>10A<\/td><\/tr><tr><td>Type of Load<\/td><td>FPGA<\/td><\/tr><tr><td>Converter switching frequency<\/td><td>500kHz<\/td><\/tr><tr><td>Allowable ripple (\u0394V)<\/td><td>30mV peak-to-peak<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>In this type of application, choice of output capacitor is critical for voltage stability and noise performance.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Design Approach<\/h3>\n\n\n\n<p>To select an appropriate capacitor for a buck converter, several parameters need to be understood.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Step-1: Calculating required capacitance<\/strong><\/h4>\n\n\n\n<p>Using the ripple approximation formula, (Assuming \u0394I<sub>L<\/sub>=2A)<\/p>\n\n\n<p>\\[\\Delta V=\\frac{\\Delta I_L}{8f_sC}\\]<\/p>\n\n\n<p>\\[C=\\frac{\\Delta I_L}{8f_s\\Delta V}\\]<\/p>\n\n\n\n<p>Substituting values:<\/p>\n\n\n<p>\\[C=\\frac{2}{8(500\\times10^3)(30\\times10^{-3})}\\]<\/p>\n\n\n<p>\\[C\\approx16.7\\mu F\\]<\/p>\n\n\n\n<p>This gives a theoretical value, however in real designs a capacitor with higher capacitance is usually selected to account for load transients.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Step-2: Voltage rating<\/h4>\n\n\n\n<p>The output voltage is 3.3V, however, designers always apply safety margin.<\/p>\n\n\n<p>\\[V_{rated}\\ge1.25\\times V_{operating}\\]<\/p>\n\n\n\n<p>Hence, capacitor should sustain minimum voltage of<\/p>\n\n\n<p>\\[V_{rated}\\ge4.125V\\]<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Step-3: Understand ESR requirements<\/h4>\n\n\n\n<p>It is highly recommended to make sure that ripple due to ESR remain below specification.<\/p>\n\n\n<p>\\[\\Delta V_{ESR}=\\Delta I_L\\times ESR\\]<\/p>\n\n\n\n<p>For the ripple below 20mV (keeping the safety margin), allowable ESR becomes<\/p>\n\n\n<p>\\[ESR\\le\\frac{20mV}{2A}=10m\\Omega\\]<\/p>\n\n\n\n<p>(See Fig-4 to understand effects of ESR on ripple)<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Step-4: Ripple current capability<\/strong><\/h4>\n\n\n\n<p>Assuming ripple current stress is I<sub>ripple<\/sub>=2A, the selected capacitor should have higher ripple current rating.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><strong>Step-5: Consider ESL due to high frequency operation<\/strong><\/h4>\n\n\n\n<p>Since the converter switching frequency is higher (500kHz), high transient suppression is also important.&nbsp;<\/p>\n\n\n\n<p>This suggests that low ESL capacitor can be a suitable choice for this application.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Capacitor selection<\/strong><\/h3>\n\n\n\n<figure class=\"wp-block-table aligncenter is-style-stripes\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Parameter<\/strong><\/td><td><strong>Calculated Requirement<\/strong><\/td><td><strong>Potential Choice<\/strong><\/td><\/tr><tr><td>Capacitance<\/td><td>16.7\u00b5F minimum<\/td><td>22\u201347 \u00b5F low-ESR capacitor<\/td><\/tr><tr><td>Voltage Rating<\/td><td>4.125V<\/td><td>6.3 V rated capacitor<\/td><\/tr><tr><td>ESR<\/td><td>10m\u03a9<\/td><td>Low-ESR capacitor meeting requirement<\/td><\/tr><tr><td>Ripple Current<\/td><td>3A<\/td><td>Capacitor rated above 3 A<\/td><\/tr><tr><td>High-Frequency Filtering<\/td><td>Low ESL preferred<\/td><td>Optional ceramic bypass capacitor<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>A practical solution for this design should be a <a href=\"https:\/\/www.flywing-tech.com\/product-detail\/ceramic-capacitors-murata-electronics-grm31cr60j476me19l-3df07960\">22-47uF capacitor<\/a> with low ESR. An optional ceramic capacitor can be used to decouple high-frequency noise.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1408\" height=\"768\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/Fig-4.png\" alt=\"Capacitor Selection: ESR effect on ripple\" class=\"wp-image-8771\" style=\"aspect-ratio:1.8333731200763905;width:702px;height:auto\" \/><figcaption class=\"wp-element-caption\">Fig-4: Effect of capacitor ESR on output ripple<\/figcaption><\/figure>\n<\/div>\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.flywing-tech.com\/category\/capacitors\/ceramic-capacitors-0b51bc1f\" target=\"_blank\" rel=\" noreferrer noopener\"><img loading=\"lazy\" decoding=\"async\" width=\"2160\" height=\"270\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/grm31cr60j476me19l.png\" alt=\"Murata GRM31CR60J476ME19L ceramic capacitor \u2013 47 \u00b5F 6.3 V X5R 1206 specifications and technical support at Flywing\" class=\"wp-image-8919\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"pcb_layout_and_capacitor_placement\"><\/span><strong>PCB Layout and Capacitor Placement<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Proper PCB placement is equally important as selecting the right capacitor. The parasitics introduced by poor PCB layout can degrade capacitor performance (See Fig-5). The following practices help minimize these effects and improve power supply performance.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Capacitor placement near switching nodes:<\/strong> Capacitors are placed as near as possible to switching devices to reduce parasitic inductance.<\/li>\n\n\n\n<li>&nbsp;<strong>Shorten loop area:<\/strong> Keep high di\/dt current loop between input capacitor, switching device, and ground as small as possible to avoid voltage spikes, ringing, and EMI.<\/li>\n\n\n\n<li><strong>Use vias carefully:<\/strong> Vias can add unwanted inductances. If vias are necessary, use multiple in parallel to lower net inductance.<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1408\" height=\"768\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/Fig-5.png\" alt=\"Example of good and bad PCB layout\" class=\"wp-image-8772\" style=\"aspect-ratio:1.8333731200763905;width:719px;height:auto\" \/><figcaption class=\"wp-element-caption\">Fig-5: Good and poor capacitor placement practices<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"modern_trends_in_power_supply_capacitors\"><\/span><strong>Modern Trends in Power Supply Capacitors<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Technologies continue to improve over time. Recent trends in capacitor technology include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Conductive polymer capacitors with very low ESR<\/li>\n\n\n\n<li>Hybrid capacitors combining advantages of multiple technologies<\/li>\n\n\n\n<li>High temperature capacitors<\/li>\n\n\n\n<li>High-capacitance MLCC capacitors in smaller packages<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"capacitor_selection_checklist\"><\/span><strong>Capacitor Selection Checklist<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Before making a final choice, multiple questions should be answered.<\/p>\n\n\n\n<p>Q1: What is purpose of this capacitor?<\/p>\n\n\n\n<p>Q2: What is operating voltage of system?<\/p>\n\n\n\n<p>Q3: What ripple voltage does the system allow?<\/p>\n\n\n\n<p>Q4: What maximum temperature must it withstand?<\/p>\n\n\n\n<p>Q5: How big\/small ESR is?<br><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"conclusions\"><\/span><strong>Conclusions<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>An appropriate choice of capacitor for power supply design requires more than selecting a capacitance value. Designers also need to consider voltage derating, ripple current, ESR, temperature, lifetime, PCB placement, and different operating conditions. <\/p>\n\n\n\n<p>Whether designing a simple DC supply or advanced converters, capacitor selection has a direct impact on final system performance. Because a properly selected capacitor results in improved efficiency, lower ripple, enhanced stability and extended lifetime of product.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"frequently_asked_questions_faqs\"><\/span><strong>Frequently Asked Questions (FAQs)<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1777118215191\"><strong class=\"schema-faq-question\"><strong>Q1: Why do power supplies often use multiple capacitors of different values in parallel?<\/strong><\/strong> <p class=\"schema-faq-answer\">Large value capacitors such as electrolytic capacitors often have higher ESL, which means they are not suitable for functioning at higher frequency. In contrast, capacitors with smaller capacitance (ceramic capacitors) have lower ESL but cannot store bulk energy.<br \/><br \/>Designers use multiple capacitors (with different capacitances) in parallel to create composite impedance curve that remains extremely low across a higher frequency range, suppressing high frequency noise. This phenomenon is often called broadband decoupling.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1777118324013\"><strong class=\"schema-faq-question\"><strong>Q2: What is the difference between X7R, X5R, and Y5V ceramic capacitors?<\/strong><\/strong> <p class=\"schema-faq-answer\">\u00a0These codes refer to temperature range and maximum capacitance drift. X7R capacitors can operate between -55\u00b0C to 125\u00b0C with a capacitance drift of 15%. While X5R goes upto 85\u00b0C with the same capacitance drift.<br \/><br \/>Y5V operates under the range of -30\u00b0C to 85\u00b0C, however they can lose 22% to -82% of their capacitance across this range. From power supply perspective, X7R and X5R are strongly recommended.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1777118348244\"><strong class=\"schema-faq-question\"><strong>Q3: Can I replace a failed electrolytic capacitor with a ceramic one of the same value?<\/strong><\/strong> <p class=\"schema-faq-answer\">Short answer is no. Replacing electrolytic blindly with a ceramic capacitor can lead to system instability. Switching regulators and linear regulators (LDOs) are carefully compensated for a specific range of ESR. Electrolytic capacitors inherently provide a &#8220;zero&#8221; in the control loop due to their high ESR, which aids in stability. Replacing it with an ultra-low ESR ceramic capacitor removes this zero, often causing the power supply to oscillate strongly.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1777118378527\"><strong class=\"schema-faq-question\">Q4: Why do capacitors fail early in power supplies?<\/strong> <p class=\"schema-faq-answer\">Common reasons include overheating, excessive ripple current, overvoltage, poor quality parts, and aging.<\/p> <\/div> <\/div>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.flywing-tech.com\/category\/capacitors\/ceramic-capacitors-0b51bc1f\" target=\"_blank\" rel=\" noreferrer noopener\"><img loading=\"lazy\" decoding=\"async\" width=\"2160\" height=\"798\" src=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/ceramic-capacitors-for-stable-signal-filtering.png\" alt=\"ceramic capacitors used for decoupling, filtering, and noise suppression in embedded, analog, and high-frequency electronic systems.\" class=\"wp-image-8920\" \/><\/a><\/figure>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Introduction Capacitors hold an essential role in any power supply design. Although they are smaller and cheaper than semiconductors and transformers, inappropriate choice of capacitor leads to overheating, ripple voltage, electromagnetic interference (EMI), reduced efficiency, and circuit failure. Capacitors are widely used in DC-DC converters, motor controllers, linear regulators, and industrial power supplies. Therefore, to [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":8918,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1217,377,380],"tags":[1221,1220,1218,1226,1223,1225,1219,1222,1224,219],"class_list":["post-8742","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-capacitor-selection","category-experience-sharing","category-technical-tutorial","tag-buck-converter-capacitor","tag-capacitor-for-power-supply","tag-capacitor-selection","tag-ceramic-capacitor-selection","tag-electrolytic-capacitor","tag-esr-ripple-current","tag-low-esr-capacitor","tag-mlcc-capacitor","tag-output-capacitor-selection","tag-power-supply-design"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\r\n<title>Capacitor Selection for Power Supply Design: A Practical Guide<\/title>\r\n<meta name=\"description\" content=\"Learn capacitor selection for power supply design, including ESR, ripple current, voltage rating, PCB layout, and practical design examples.\" \/>\r\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\r\n<link rel=\"canonical\" href=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\" \/>\r\n<meta property=\"og:locale\" content=\"en_US\" \/>\r\n<meta property=\"og:type\" content=\"article\" \/>\r\n<meta property=\"og:title\" content=\"Capacitor Selection for Power Supply Design: A Practical Guide\" \/>\r\n<meta property=\"og:description\" content=\"Learn capacitor selection for power supply design, including ESR, ripple current, voltage rating, PCB layout, and practical design examples.\" \/>\r\n<meta property=\"og:url\" content=\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\" \/>\r\n<meta property=\"og:site_name\" content=\"Fly-Wing\" \/>\r\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/profile.php?id=100090565081283\" \/>\r\n<meta property=\"article:published_time\" content=\"2026-04-29T02:45:25+00:00\" \/>\r\n<meta property=\"og:image\" content=\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png\" \/>\r\n\t<meta property=\"og:image:width\" content=\"2610\" \/>\r\n\t<meta property=\"og:image:height\" content=\"1200\" \/>\r\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\r\n<meta name=\"author\" content=\"Flywing Tech Blog\" \/>\r\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\r\n<meta name=\"twitter:creator\" content=\"@MIKEBigcoolguy\" \/>\r\n<meta name=\"twitter:site\" content=\"@MIKEBigcoolguy\" \/>\r\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Flywing Tech Blog\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"11 minutes\" \/>\r\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\"},\"author\":{\"name\":\"Flywing Tech Blog\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/person\/5527ee803431e14d91ccce0a6dffe41b\"},\"headline\":\"How to Choose the Right Capacitor for Power Supply Design\",\"datePublished\":\"2026-04-29T02:45:25+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\"},\"wordCount\":2093,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#organization\"},\"image\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png\",\"keywords\":[\"Buck Converter Capacitor\",\"Capacitor for Power Supply\",\"Capacitor Selection\",\"Ceramic Capacitor Selection\",\"Electrolytic Capacitor\",\"ESR Ripple Current\",\"Low ESR Capacitor\",\"MLCC Capacitor\",\"Output Capacitor Selection\",\"Power Supply Design\"],\"articleSection\":[\"Capacitor Selection\",\"Experience Sharing\",\"Tutorials\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#respond\"]}]},{\"@type\":[\"WebPage\",\"FAQPage\"],\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\",\"url\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\",\"name\":\"Capacitor Selection for Power Supply Design: A Practical Guide\",\"isPartOf\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png\",\"datePublished\":\"2026-04-29T02:45:25+00:00\",\"description\":\"Learn capacitor selection for power supply design, including ESR, ripple current, voltage rating, PCB layout, and practical design examples.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#breadcrumb\"},\"mainEntity\":[{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118215191\"},{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118324013\"},{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118348244\"},{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118378527\"}],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage\",\"url\":\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png\",\"contentUrl\":\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png\",\"width\":2610,\"height\":1200,\"caption\":\"How to Choose the Right Capacitor for Power Supply Design\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.flywing-tech.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Tutorials\",\"item\":\"https:\/\/www.flywing-tech.com\/blog\/category\/technical-tutorial\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"How to Choose the Right Capacitor for Power Supply Design\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#website\",\"url\":\"https:\/\/www.flywing-tech.com\/blog\/\",\"name\":\"Fly-Wing\",\"description\":\"Electronic Components Source @Fly-Wing\",\"publisher\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.flywing-tech.com\/blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#organization\",\"name\":\"Fly-wing Technology (HK) Co., Limited\",\"alternateName\":\"Fly-wing Technology\",\"url\":\"https:\/\/www.flywing-tech.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2025\/06\/512_512.png\",\"contentUrl\":\"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2025\/06\/512_512.png\",\"width\":512,\"height\":512,\"caption\":\"Fly-wing Technology (HK) Co., Limited\"},\"image\":{\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/profile.php?id=100090565081283\",\"https:\/\/x.com\/MIKEBigcoolguy\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/person\/5527ee803431e14d91ccce0a6dffe41b\",\"name\":\"Flywing Tech Blog\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/8566db81fcd93340708157c8388c72694690c3e1a2553f9909b7c5af735f8f97?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/8566db81fcd93340708157c8388c72694690c3e1a2553f9909b7c5af735f8f97?s=96&d=mm&r=g\",\"caption\":\"Flywing Tech Blog\"},\"description\":\"This blog is maintained by the editorial team at Fly-Wing Technology. We aim to share valuable insights on electronic components, industry trends, and practical engineering guides to support global developers and buyers.\",\"sameAs\":[\"https:\/\/www.flywing-tech.com\/blog\/\"],\"url\":\"https:\/\/www.flywing-tech.com\/blog\/author\/content_manager_04\/\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118215191\",\"position\":1,\"url\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118215191\",\"name\":\"Q1: Why do power supplies often use multiple capacitors of different values in parallel?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Large value capacitors such as electrolytic capacitors often have higher ESL, which means they are not suitable for functioning at higher frequency. In contrast, capacitors with smaller capacitance (ceramic capacitors) have lower ESL but cannot store bulk energy.<br \/><br \/>Designers use multiple capacitors (with different capacitances) in parallel to create composite impedance curve that remains extremely low across a higher frequency range, suppressing high frequency noise. This phenomenon is often called broadband decoupling.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118324013\",\"position\":2,\"url\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118324013\",\"name\":\"Q2: What is the difference between X7R, X5R, and Y5V ceramic capacitors?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"\u00a0These codes refer to temperature range and maximum capacitance drift. X7R capacitors can operate between -55\u00b0C to 125\u00b0C with a capacitance drift of 15%. While X5R goes upto 85\u00b0C with the same capacitance drift.<br \/><br \/>Y5V operates under the range of -30\u00b0C to 85\u00b0C, however they can lose 22% to -82% of their capacitance across this range. From power supply perspective, X7R and X5R are strongly recommended.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118348244\",\"position\":3,\"url\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118348244\",\"name\":\"Q3: Can I replace a failed electrolytic capacitor with a ceramic one of the same value?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Short answer is no. Replacing electrolytic blindly with a ceramic capacitor can lead to system instability. Switching regulators and linear regulators (LDOs) are carefully compensated for a specific range of ESR. Electrolytic capacitors inherently provide a \\\"zero\\\" in the control loop due to their high ESR, which aids in stability. Replacing it with an ultra-low ESR ceramic capacitor removes this zero, often causing the power supply to oscillate strongly.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118378527\",\"position\":4,\"url\":\"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118378527\",\"name\":\"Q4: Why do capacitors fail early in power supplies?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Common reasons include overheating, excessive ripple current, overvoltage, poor quality parts, and aging.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"}]}<\/script>\r\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Capacitor Selection for Power Supply Design: A Practical Guide","description":"Learn capacitor selection for power supply design, including ESR, ripple current, voltage rating, PCB layout, and practical design examples.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/","og_locale":"en_US","og_type":"article","og_title":"Capacitor Selection for Power Supply Design: A Practical Guide","og_description":"Learn capacitor selection for power supply design, including ESR, ripple current, voltage rating, PCB layout, and practical design examples.","og_url":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/","og_site_name":"Fly-Wing","article_publisher":"https:\/\/www.facebook.com\/profile.php?id=100090565081283","article_published_time":"2026-04-29T02:45:25+00:00","og_image":[{"width":2610,"height":1200,"url":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png","type":"image\/png"}],"author":"Flywing Tech Blog","twitter_card":"summary_large_image","twitter_creator":"@MIKEBigcoolguy","twitter_site":"@MIKEBigcoolguy","twitter_misc":{"Written by":"Flywing Tech Blog","Est. reading time":"11 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#article","isPartOf":{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/"},"author":{"name":"Flywing Tech Blog","@id":"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/person\/5527ee803431e14d91ccce0a6dffe41b"},"headline":"How to Choose the Right Capacitor for Power Supply Design","datePublished":"2026-04-29T02:45:25+00:00","mainEntityOfPage":{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/"},"wordCount":2093,"commentCount":0,"publisher":{"@id":"https:\/\/www.flywing-tech.com\/blog\/#organization"},"image":{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage"},"thumbnailUrl":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png","keywords":["Buck Converter Capacitor","Capacitor for Power Supply","Capacitor Selection","Ceramic Capacitor Selection","Electrolytic Capacitor","ESR Ripple Current","Low ESR Capacitor","MLCC Capacitor","Output Capacitor Selection","Power Supply Design"],"articleSection":["Capacitor Selection","Experience Sharing","Tutorials"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#respond"]}]},{"@type":["WebPage","FAQPage"],"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/","url":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/","name":"Capacitor Selection for Power Supply Design: A Practical Guide","isPartOf":{"@id":"https:\/\/www.flywing-tech.com\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage"},"image":{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage"},"thumbnailUrl":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png","datePublished":"2026-04-29T02:45:25+00:00","description":"Learn capacitor selection for power supply design, including ESR, ripple current, voltage rating, PCB layout, and practical design examples.","breadcrumb":{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#breadcrumb"},"mainEntity":[{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118215191"},{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118324013"},{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118348244"},{"@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118378527"}],"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#primaryimage","url":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png","contentUrl":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2026\/04\/how-to-choose-the-right-capacitor-for-power-supply-design.png","width":2610,"height":1200,"caption":"How to Choose the Right Capacitor for Power Supply Design"},{"@type":"BreadcrumbList","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.flywing-tech.com\/blog\/"},{"@type":"ListItem","position":2,"name":"Tutorials","item":"https:\/\/www.flywing-tech.com\/blog\/category\/technical-tutorial\/"},{"@type":"ListItem","position":3,"name":"How to Choose the Right Capacitor for Power Supply Design"}]},{"@type":"WebSite","@id":"https:\/\/www.flywing-tech.com\/blog\/#website","url":"https:\/\/www.flywing-tech.com\/blog\/","name":"Fly-Wing","description":"Electronic Components Source @Fly-Wing","publisher":{"@id":"https:\/\/www.flywing-tech.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.flywing-tech.com\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.flywing-tech.com\/blog\/#organization","name":"Fly-wing Technology (HK) Co., Limited","alternateName":"Fly-wing Technology","url":"https:\/\/www.flywing-tech.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2025\/06\/512_512.png","contentUrl":"https:\/\/www.flywing-tech.com\/blog\/wp-content\/uploads\/2025\/06\/512_512.png","width":512,"height":512,"caption":"Fly-wing Technology (HK) Co., Limited"},"image":{"@id":"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/profile.php?id=100090565081283","https:\/\/x.com\/MIKEBigcoolguy"]},{"@type":"Person","@id":"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/person\/5527ee803431e14d91ccce0a6dffe41b","name":"Flywing Tech Blog","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.flywing-tech.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/8566db81fcd93340708157c8388c72694690c3e1a2553f9909b7c5af735f8f97?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/8566db81fcd93340708157c8388c72694690c3e1a2553f9909b7c5af735f8f97?s=96&d=mm&r=g","caption":"Flywing Tech Blog"},"description":"This blog is maintained by the editorial team at Fly-Wing Technology. We aim to share valuable insights on electronic components, industry trends, and practical engineering guides to support global developers and buyers.","sameAs":["https:\/\/www.flywing-tech.com\/blog\/"],"url":"https:\/\/www.flywing-tech.com\/blog\/author\/content_manager_04\/"},{"@type":"Question","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118215191","position":1,"url":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118215191","name":"Q1: Why do power supplies often use multiple capacitors of different values in parallel?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Large value capacitors such as electrolytic capacitors often have higher ESL, which means they are not suitable for functioning at higher frequency. In contrast, capacitors with smaller capacitance (ceramic capacitors) have lower ESL but cannot store bulk energy.<br \/><br \/>Designers use multiple capacitors (with different capacitances) in parallel to create composite impedance curve that remains extremely low across a higher frequency range, suppressing high frequency noise. This phenomenon is often called broadband decoupling.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118324013","position":2,"url":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118324013","name":"Q2: What is the difference between X7R, X5R, and Y5V ceramic capacitors?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"\u00a0These codes refer to temperature range and maximum capacitance drift. X7R capacitors can operate between -55\u00b0C to 125\u00b0C with a capacitance drift of 15%. While X5R goes upto 85\u00b0C with the same capacitance drift.<br \/><br \/>Y5V operates under the range of -30\u00b0C to 85\u00b0C, however they can lose 22% to -82% of their capacitance across this range. From power supply perspective, X7R and X5R are strongly recommended.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118348244","position":3,"url":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118348244","name":"Q3: Can I replace a failed electrolytic capacitor with a ceramic one of the same value?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Short answer is no. Replacing electrolytic blindly with a ceramic capacitor can lead to system instability. Switching regulators and linear regulators (LDOs) are carefully compensated for a specific range of ESR. Electrolytic capacitors inherently provide a \"zero\" in the control loop due to their high ESR, which aids in stability. Replacing it with an ultra-low ESR ceramic capacitor removes this zero, often causing the power supply to oscillate strongly.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118378527","position":4,"url":"https:\/\/www.flywing-tech.com\/blog\/capacitor-selection-power-supply-design\/#faq-question-1777118378527","name":"Q4: Why do capacitors fail early in power supplies?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Common reasons include overheating, excessive ripple current, overvoltage, poor quality parts, and aging.","inLanguage":"en-US"},"inLanguage":"en-US"}]}},"_links":{"self":[{"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/posts\/8742","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/comments?post=8742"}],"version-history":[{"count":32,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/posts\/8742\/revisions"}],"predecessor-version":[{"id":8921,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/posts\/8742\/revisions\/8921"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/media\/8918"}],"wp:attachment":[{"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/media?parent=8742"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/categories?post=8742"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.flywing-tech.com\/blog\/wp-json\/wp\/v2\/tags?post=8742"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}