Panasonic EE26 Circuit Design, Expected Life Estimate Quick Reference Guide, Failure rate curve

Aluminum Electrolytic Capacitor

Application Guidelines

1. Circuit Design

E n s u r e t h a t operational and mounting conditions follw the specified conditions detailed in the catalog and specification sheets.

1.1 Operating Temperature and Frequency

Electrolytic capacitor electrical parameters are normally specified at 20°C temperature and 120Hz frequency. These parameters vary with changes in t e m p e ra t u r e a n d f r e q u e n c y. C i r c u i t d e s i g n e r s should take these changes into consideration.

(1)Effects of operating temperature on electrical parameters

a)At higher temperatures, leakage current and capacitance increase while equivalent series resistance(ESR) decreases.

b)At lower temperatures, leakage current and capacitance decrease while equivalent series resistance(ESR) increases.

(2) Effects of frequency on electr ical parameters a ) A t h i g h e r f r e q u e n c i e s , c a p a c i t a n c e a n d impedance decrease while tan δ increases.

b)At lower frequencies, ripple current generated heat will rise due to an increase in equivalent series resistance (ESR).

1.2 Operating Temperature and Life Expectancy

(1)Expected life is affected by operating temperature. Generally, each 10°C reduction in temperature

will double the expected life. Use capacitors at

t h e l owe s t p o s s i b l e t e m p e r a t u r e b e l ow t h e maximum guaranteed temperature.

(2) If operating conditions exceed the maximum g u a r a n t e e d l i m i t , r a p i d e I e c t r i c a l p a ra m e t e r deterioration will occur, and irreversible damage will result.

Check for maximum capacitor operating tempera- tures including ambient temperature, internal capacitor temperature rise caused by ripple current, and the effects of radiated heat from power transistors, IC?s or resistors.

Avoid placing components which could conduct heat to the capacitor from the back side of the circuit board.

(3)The formula for calculating expected Iife at lower operating temperatures is as fllows;

T1-T2

L2 = L1 x 2 10 where,

L1: Guaranteed life (h) at temperature, T1° C

L2: Expected life (h) at temperature,T2°C

T1: Maximum operating temperature (°C)

T2: Actual operating temperature, ambient temperature + temperature rise due to ripple currentheating(°C)

A quick eference capacitor guide for estimating exected life is included for your reference.

■Expected Life Estimate Quick Reference Guide

Temperature	120							1. 85°C2000h
	110	2	3	4				2.105°C1000h
									°
								3.105 C2000h
	100								°
								4.105 C5000h
	90		1
Ambient	80
	70
Capacitor	60
	50
	40
24h	(h)		2000	5000	10,000	20,000	50,000	100,000	200,000

operat-	Years	1	2	3	4 5	7	20
ion
8h/d	Years	3	6	10	15	20	30

■Failure rate curve

	Initial failure period
	Random failure period	Wear failure period
rate	Life Time
Failure
	Time

Design, Specifications are subject to change without notice. Ask factory for technical specifications before purchase and/or use. Whenever a doubt about safety arises from this product, please inform us immediately for technical consulation without fail.

– EE16 –

Mar. 2005