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How to Select an Electric Double Layer Supercapacitor

Series

Maximum Operating (Discharge) Current

0.047 F

0.1 F to 0.33 F

0.47 F to 1.5 F

3.3 F to 4.7 F

10 F to 50 F

SG, SD, NF

200 µA

300 µA

1 mA

–

–

F

200 µA

300 µA

300 µA

–

–

EN

–

10 µA

–

–

–

HW

–

–

100 mA

300 mA

1 A

Estimated initial back-up time

Back-up time for Type EDL Electric Double Layer Supercapacitors decreases with use and over time

especially when the current is large or operating at high temperature. Be sure to specify extra back-up

time initially to allow for product changes.

Select the optimum supercapacitor according to applied current.

The internal resistance of the supercapacitor prevents drawing high discharge currents. Select the

supercapacitor capable of delivering the peak current at switchover to back-up mode using the follow-

ing table.

Back-up Time Example

Back-up time is the time it takes for the applied voltage to decay to the cut-off voltage set by the user

after applying the application’s maximum voltage at application maximum temperature.

Example: An F Type EDL, P/N EDLF105B5R5C (Rated at 5.5 V, 1.0 F) is charged to 5.0 Vdc. The circuit

requirement is such that it must maintain a memory circuit with a current drain of 10 µA in an ambient

temperature of +40 ºC. The memory RTC cut-off voltage is 2.0 Vdc.

Using minimum capacitance, calculate the back-up time as

follows:

t = CΔV ⁄ I = C[V

C = 1.0 F–20% = 0.8 F, R=50 Ω, V

Therefore,

And thus the initial back-up time is 55 hours. After 1000 hours,

t: Back-up time (s)

C: Capacitance of Type EDL (F)

V

V

i: Current during back-up (A)

i

R: Internal resistance (Ω) at 1 kHz

Life Design for Electric Double Layer Supercapacitors

Type EDL supercapacitors have a useful lifetime that decreases with increasing operating temperature,

humidity, applied-voltage, current and backup-time requirements.

Expected lifetime is the product of four factors:

Expected Life = (Lifetime)•(Temperature Factor)•(Voltage Factor)•(Moisture Factor)