BQ24078: Q2 turn off condition during over discharging

GaryC

Expert 3305 points

Part Number: BQ24078

Tool/software:

May I know what is the Q2 turn off condition?

When the OUT is over discharging, what is the condition to turn off Q2 to protect the system? Thanks

BR,

Gary

over 1 year ago

0 Garrett Kreger over 1 year ago

TI__Mastermind 31810 points

Hi Gary,

SYSOFF pin is used to turn of Q2 between battery and system output. When SYSOFF is pulled high Q2 FET will turn off.

Out short circuit protection works to turn off Q2 if there is an out pin overload. Q2 will turn off if OUT voltage drops typical 250mV below battery voltage. This is described in datasheet section 9.3.4.1.3.

Best Regards,

Garrett

+1 GaryC over 1 year ago in reply to Garrett Kreger

TI__Expert 3305 points

Hi Garrett,

Thanks for your support.

BR,

Gary

0 GaryC over 1 year ago in reply to Garrett Kreger

TI__Expert 3305 points

Hi Garrett,

One more question. If the battery works on discharge mode. May I know how low of the VBAT can disable the Q2 FET?

The purpose is wanted to know how low of the VBAT can protect the battery? Is it the same as V(lowv)?

BR,

Gary

0 Garrett Kreger over 1 year ago in reply to GaryC

TI__Mastermind 31810 points

Hi Gary,

The BQ24078 does not have a built in battery over discharge protection. There is not a falling VBAT threshold to disable Q2 FET. It is recommended customer use a battery protector, which is often already built into a battery pack, to disconnect battery from system at a desired fully discharged voltage.

Best Regards,

Garrett

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BQ24078: Q2 turn off condition during over discharging