BQ24079T: Input path

Koen Ven, van de

Part Number: BQ24079T
Other Parts Discussed in Thread: BQ25606

For an application I would like to use the bq24079T as a charger but without the input path (>1.5A load @ 5V).

The bq24079T is used for charging (parallel), discharging and disconnecting the load using SYSOFF.

Would it be allowed to short IN to OUT? Optionally a low drop schottky to IN can be added. IN circuit is: 24Vdc->Diode->Sync buck->5Vdc.

See the picture below:

Thanks.

over 6 years ago

0 Raheem over 6 years ago

TI__Mastermind 21590 points

Hello Koen,
The BQ4079T regulates the OUT pin to 5.5V so with a 5V input, the OUT pin will not be regulated and will just be equal to IN voltage minus IR drop on the input FET. Is there any reason why this will not be work for you application?

0 Koen Ven, van de over 6 years ago in reply to Raheem

Prodigy 90 points

Hi Raheem,

Thanks for your response. That won't work because the load current is about 2A @ 5V and the maximum input limit for the BQ4079T is 1.5A.

0 Raheem over 6 years ago in reply to Koen Ven, van de

TI__Mastermind 21590 points

Koen,
I would advise you take a look at a switching charger like the BQ25606 with higher input current limits. Shorting the Input to OUTput can cause issues for what is powered by OUT by bypassing the protections in the device.

Power management

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BQ24079T: Input path