TIDA-010247: Reverse polarity protection

Vladislav Mocluza

Part Number: TIDA-010247

Tool/software:

Hello team,

There is a diode D37 in the reference design TIDA-010247. I think it was placed to avoid voltage spikes during SC events, but I have some questions about how does it influence to reverse polarity protection.

1. Correctly I understand that if Charger does not have a reverse polarity protection then current will flows through D37?

2. Correctly I understand that if charger's current is more than 5A, then D37 will be damaged?

3. Will this diode influence to the reverse polarity protection of Q44? Looks like between PACK- and PACK+ should be 0.9V in case of reverse polarity.

4. Do you have any recommendations or suggestions how to avoid points 1 and 2 in case of using this diode?

Best regards,

Vladislav

4 months ago

+1 Abhijith V Narayan 4 months ago

Intellectual 446 points

Both solutions are aimed at reverse polarity protection and will sort of work in tandem.

D37 will start conducting faster to redirect the current than the circuit based on Q44. However, this will provide enough time for the Q44 circuit to get enabled fully preventing the flow of current.

Of course as you suspected, if the current flow is not stopped quickly, then D37 will get damaged. So depending your use case, please size them accordingly.

Best,
Abhijith.

0 Vladislav Mocluza 4 months ago in reply to Abhijith V Narayan

Prodigy 70 points

Thank you for the answer.

Did I understand correct the purpose of that diode? Or does it have different purpose?

0 Kian Lin 3 months ago in reply to Vladislav Mocluza

TI__Expert 4220 points

Thanks Abhijith.

Hi Vladislav,

I was out last two weeks. Abhijith gave the correct answer to your questions. You can read this app note for more details:https://www.ti.com/lit/an/sluaa09a/sluaa09a.pdf

BRs

Kian

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TIDA-010247: Reverse polarity protection