1、電容主要參數(shù)的應(yīng)用課件電容主要參數(shù)的應(yīng)用電容主要參數(shù)的應(yīng)用電容主要參數(shù)的應(yīng)用課件討論目的討論目的1.介紹各參數(shù)代表的意義 2.利用參數(shù)預(yù)估計(jì)算所需值電容主要參數(shù)的應(yīng)用課件討論主題討論主題n電容基本module介紹n電容基本參數(shù)介紹n如何應(yīng)用參數(shù)決定電容n其它現(xiàn)象討論 電容主要參數(shù)的應(yīng)用課件一一.電容基本電容基本Module介紹介紹 1.REAL Module CR21 R21 L電容主要參數(shù)的應(yīng)用課件2.DC Module CR21 R21 L M ohm21 CR21 R21 L M ohm21電容主要參數(shù)的應(yīng)用課件3.AC Module (Z=ESR) CR21 R21 Lm ohm21電

2、容主要參數(shù)的應(yīng)用課件Frequency Vs Impedance電容主要參數(shù)的應(yīng)用課件二二.基本參數(shù)介紹基本參數(shù)介紹 1.LEAKGE CURRENT Leakage current is the residual current which flows through the capacitor after the charging time underrated voltage.電容主要參數(shù)的應(yīng)用課件n2.Dissipation Factor It is a function of the series resistance of the capacitor and the capacit

3、ance at low frequency 電容主要參數(shù)的應(yīng)用課件n3.Impedance=Zn The formula for impedance is: Z=(R2+(L-1/C ) 2)電容主要參數(shù)的應(yīng)用課件n R: equivalent series resistance of the capacitor L: Inductance mainly due to the leads C: capacitance 電容主要參數(shù)的應(yīng)用課件n4.Maximun current ripple & Voltage rippleThe maximum value of the ripple

4、current or ripple voltage which can be applied to the capacitor is only limited by the thermal effect .The ESR and to the square of ripple current (P=ESR lrms2)電容主要參數(shù)的應(yīng)用課件三三.如何應(yīng)用參數(shù)決定電容如何應(yīng)用參數(shù)決定電容n1.Output 波形波形電容主要參數(shù)的應(yīng)用課件將將V-ripple 分為分為 DC & AC電容主要參數(shù)的應(yīng)用課件實(shí)際電路與參數(shù)的關(guān)係實(shí)際電路與參數(shù)的關(guān)係 CR21 R21 L CR21 R21 L

5、LL Lo oa ad dTest pinLeak IZ電容主要參數(shù)的應(yīng)用課件對(duì)對(duì)DC而言而言5m ohm21A AA Au uA Au uA A5 5V V D DC CM ohm21M ohm21L Lo oa ad dTest pin電容主要參數(shù)的應(yīng)用課件可近似為可近似為5m ohm215 5V V D DC CA AA AL Lo oa ad dTest pinVin Vout 5V電容主要參數(shù)的應(yīng)用課件對(duì)對(duì)AC而言而言( 設(shè)設(shè) Z=ESR)n未裝電容時(shí)n 5m ohm21L Lo oa ad dTest pin5 50 0 o oh hm m50mVVin Vout 50mV電容主要

6、參數(shù)的應(yīng)用課件電容並聯(lián)時(shí)電容並聯(lián)時(shí)Voltage ripple:50mvx(RC/Load)/Rc+(RD/Load)=33mV5m ohm21L Lo oa ad dTest pin50mV5 50 0 o oh hm m100 ohm21電容主要參數(shù)的應(yīng)用課件如何選用適合的如何選用適合的CAPVoltageRatingChose Type Frequency Life TempCalculator OutputImpedanceCheck V Ripplein SPECCalculator I Ripple in SPECTest thermal calculatorLife timeDi

7、mensions電容主要參數(shù)的應(yīng)用課件1電容主要參數(shù)的應(yīng)用課件2電容主要參數(shù)的應(yīng)用課件3電容主要參數(shù)的應(yīng)用課件例:Output 5V 20A5/20=0.25=250m選擇小於10倍ESR的兩個(gè)6.3V 58m的CAP電容主要參數(shù)的應(yīng)用課件例:5V V Ripple 為50mV(在C上測(cè)到)則Cape的 I Ripple為50mV/58m=0.862mA電容主要參數(shù)的應(yīng)用課件4代號(hào)意義單位L2實(shí)際使用下電容器預(yù)估壽命值小時(shí)L1廠商保證之壽命值小時(shí)T0電容器之額定最高工作溫度Tx實(shí)際應(yīng)用下的環(huán)境溫度Iuse實(shí)際應(yīng)用下的漣波電流mAIstd型錄上的額定漣波電流(r.m.s)mAK加速因子-KIstdIuseTxTLL2551002