BQ76952: OCD Protection parameter

Subhrajit Majumder

Part Number: BQ76952

Hello sir.

We are using BQ76952 for battery management with STM32 using I2C protocol.

Sir we use 1miliohm current sense register.

Sir we set the OCD1 threshold parameter 0x01. So, the OCD1 protection need to trigger at 2 amps. But OCD1 protection trigger at 1.6 amps. Sir we have to set OCD1 protection accurately.

The same problem also happen with OCD2 parameter.

Please help to solve this problem. Looking for positive reply.

Regards,

Subhrajit Majumder.

over 2 years ago

0 Jose Couso over 2 years ago

TI__Mastermind 27321 points

Hello Subhrajit,

Setting the OCD1 to trigger at 2A with a sense resistor of 1mOhm means 2mV range across Rsense. The tolerance of the resistor might be affecting the accuracy causing OCD1 to trigger at 1.6A.

Can you use a bigger Sense Resistor? This will give you more range to work with and tolerance won't be an affecting factor in this case.

Please refer to section 10.3 Coulomb Counter and Digital Filters in datasheet.

Regards,
Jose Couso

0 Subhrajit Majumder over 2 years ago in reply to Jose Couso

Prodigy 110 points

Hello sir..

If I use higher value of sense register, then the accuracy will perfect?

And sir if I want to use 1mohm sense register what is the procedure get accuracy?

0 Jose Couso over 2 years ago in reply to Subhrajit Majumder

TI__Mastermind 27321 points

Hello Subhrajit,

Using a higher value of sense resistor, will definitely make it more accurate. The higher, the more accurate it will be.

If you want to stay with 1mOhm sense resistor, then it will highly depend on the tolerance of the resistor. If you can find a resistor with a very low tolerance, it will help.

Regards,
Jose Couso

0 Subhrajit Majumder over 2 years ago in reply to Jose Couso

Prodigy 110 points

Dear sir,

Sir I have a question.

Using any other value of sense register,is the step size(2mv) remain same ?

0 Jose Couso over 2 years ago in reply to Subhrajit Majumder

TI__Mastermind 27321 points

Hello Subhrajit,

A 5mOhm resistor requires setting the OCD threshold to 10mV across the sense resistor to trigger at 2A.

Regards,
Jose Couso

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BQ76952: OCD Protection parameter