BQ76925: Cin Value

Big Bill

Expert 1980 points

Part Number: BQ76925

Dear expert:

can i modify the Cin value to 10nf, i don't need the balance function in my application, what happen if I modify the Cin value？ or any suggestion to help cost the Cin？ How much the Cin minimum required value ？ Thanks~

over 7 years ago

0 Matt Sunna over 7 years ago

TI__Guru* 81034 points

Hi Bill,

The minimum recommended value in the datasheet is 100nF. Since TI has not done any characterization of the device at lower Cin values, I would not recommend a value below that. The input filter components are important to protect the device from transients and from unintentional reset in case the battery voltage drops.

Best regards,
Matt

0 Big Bill over 7 years ago in reply to Matt Sunna

Expert 1980 points

Dear matt:

thanks for your reply, I see the minimum recommended value is 100nf in the datasheet. but i don't find anything wrong with 47nf Cin. 100Ω Rin in my application,

1. can you help me explain why use above 100nf instead of below 100nf?
2. can i Increase the Rin value with reduce the Cin value to meet the BQ76925，is there any theoretical basis？

Look forward to your reply. Thanks~

0 Matt Sunna over 7 years ago in reply to Big Bill

TI__Guru* 81034 points

Hi Bill,

I don't see a problem with your idea if you increase the Rin to maintain the filtering. The goal is to protect from transients and unintentional resets, so as long as you can still achieve that goal, it should be okay.

Best regards,
Matt

0 Big Bill over 7 years ago in reply to Matt Sunna

Expert 1980 points

Dear Matt:

Thanks for your relay, as your argument I can reduce the Cin value below 100nf by increasing the Rin , is my understanding correct？

0 Matt Sunna over 7 years ago in reply to Big Bill

TI__Guru* 81034 points

Yes, Bill. Your understanding is correct. However, we have not tested this at TI, so I recommend you evaluate the performance to make sure there are no unforeseen issues.

Thanks,
Matt

0 Big Bill over 7 years ago in reply to Matt Sunna

Expert 1980 points

Dear Matt:
Thanks for your relay, as your argument I can reduce the Cin value below 100nf by increasing the Rin , is my understanding correct？
How much should I choose the Cin rated voltage value ? How about 10V ? thanks

0 Big Bill over 7 years ago in reply to Matt Sunna

Expert 1980 points

Dear Matt:

How much should I choose the Cin rated voltage value ? How about 10V for 6 Cell application ? thanks

0 Matt Sunna over 7 years ago in reply to Big Bill

TI__Guru* 81034 points

Hi Bill,

That's up to you. I don't see an issue assuming you have a 4V cell voltage, but you need to decide based on your system design.

Best regards,
Matt

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BQ76925: Cin Value