BQ77915: Does it have Charger reverse polarity Protection or Do we need to any extra circuit ?

Anil Sudhakaran

Part Number: BQ77915

Hi,

Using 5 cell configuration circuit in Fig 9-13 of datasheet for my new BMS design for which Layout is in progress with below circuit. (same circuit except I have one more set of Mosfets in parallel).

Could you let me know whether this circuit /IC has charger reverse polarity protection ? If not , please please suggest what modification to be provided.

Exact part number planning to use is BQ7791506.

Circuit used is as below (with one more set of mosfet in parallel)

Regards,

Anil

over 4 years ago

0 Shawn Hinkle over 4 years ago

TI__Expert 7465 points

Hi,

The BQ77915 does not protect against a charger being incorrectly connected. The VDD pin could be damaged if the voltage goes below -0.3V.

Maybe this video can help out with modification.

0 Anil Sudhakaran over 4 years ago in reply to Shawn Hinkle

Expert 1125 points

Hi Shawn,

In one of the previous discussions on the same topic, it was mentioned "Reverse polarity is essentially built into the basic circuit structure". Datasheet page fig numbers mentioned in that are not matching with present datasheet.

Could you please go through and comment on that.

Would be good if you can suggest a circuit solution.

SN4 question in thread below

Regards,

Anil

0 Shawn Hinkle over 4 years ago in reply to Anil Sudhakaran

TI__Expert 7465 points

Hi Anil,

I spoke with the author of that post, and I agree with his conclusion. The device should be able to handle reverse polarity if the discharge FET is able to withstand the voltage, the charge FET gate must be protected (zener across it typically), the resistor to CHG must be large enough (or have large resistor across the diode) and the resistor to LD must be large enough to not violate the pin spec.

0 Anil Sudhakaran over 4 years ago in reply to Shawn Hinkle

Expert 1125 points

Thanks Shawn for the clarification.

Closing/resolving this thread.

Regards,

Anil

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BQ77915: Does it have Charger reverse polarity Protection or Do we need to any extra circuit ?