bq24074 OUT pin capacitor value

Ed Walker

Hello Forum.

I am designing a battery pack and will not be having a load on OUT, nothing connected to it except the LEDs as shown in the datasheet.

I want to use a 0.1uF on OUT which is much lower cost than a large 4.7uF.

Since OUT is a regulated output I suspect there must be linear regulator control that may prove unstable if a 4.7uF cap is not there.

Can this cap be reduced to reduce cost without risk of instablility?

Thank you.

over 8 years ago

0 Dick Stacey over 8 years ago

TI__Genius 14890 points

Ed,

Since the LDO on OUT is also the power supply for the BAT charging, the larger capacitor is mandatory. With higher charging currents and potential load steps, the system may require higher than 4.7uF at both BAT and OUT.

Regards,

Dick

0 Ed Walker over 8 years ago in reply to Dick Stacey

Prodigy 5 points

In my application I am just using it as a charger.

So there is no external load on OUT, no system being powered.
Does the IN to OUT LDO require a 4.7uF for stability?

0 Dick Stacey over 8 years ago in reply to Ed Walker

TI__Genius 14890 points

Ed,

Yes, the OUT pin does need the 4.7uF capacitor for stability. Even with no load on OUT.

Dick

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bq24074 OUT pin capacitor value