BQ27742-G1: Current protection is triggered before it reach the specified value.

Asael7

Part Number: BQ27742-G1

In charge and discharge current protection is triggered before it reach the specified value. The specified value for Hardware Overcurrent in Charge Configuration is 28 mV and for Hardware Overcurrent in Discharge Configuration is 34 mV. Those values are configured because Rsense = 10 mOhm and maximum current for charge is 2.8 A and maximum current in discharge is 3.4 A.

The current protection is triggering at 3.1 A in discharge and 2.5 A in charge.

Is there other parameter related to current protection that causes the protection to active earlier? or which could be the reason to current protection is triggered before it reach the threshold?

over 5 years ago

0 Onyx Ahiakwo over 5 years ago

TI__Guru* 76230 points

Can you attach your gg file so we verify that is indeed the case. Also, you need to measure the value of your sense resistor and to make sure you aren't having some trace resistance contributing to the voltage drop accross the SRN and SRP pins there by reducing the current threshold you programmed.

thanks
Onyx

0 Asael7 over 5 years ago in reply to Onyx Ahiakwo

Intellectual 270 points

Yes, I can attach the gg file.

I will measure the value of my sense resistor.

1s3p.gg.xlsx

0 Asael7 over 5 years ago in reply to Asael7

Intellectual 270 points

I applied a charge of 1.6 A and I measured the voltage in the sense resistor (15.9 mV). So, the value of the sense resistor (10 mOhm) is OK. Also I measured the voltage in the capacitor (Cdiff) near SRN and SRP pins, and the voltage is 15.9 mV.

0 Onyx Ahiakwo over 5 years ago in reply to Asael7

TI__Guru* 76230 points

Hi Martin,
your setting in your looks fine. Are you certain of the current being applied to be 2.8 and 3.4A? Do you have scope shots? If that you are certain on the currents being applied is correct, then it maybe perhaps the analog comparator of the chip has some error. Does a second IC/board have the same behavior?

thanks
Onyx

0 Asael7 over 5 years ago in reply to Onyx Ahiakwo

Intellectual 270 points

Yes, the maximum current that I want to apply is 2.8 A and 3.4 A but overcurrent protection triggers in 2.5 A and 3.1 A.
I have 3 different battery packs (1s3p, 1s4p and 1s6p), the hardware protection for overcurrent is the same (2.8 A and 3.4 A) and the behavior is similar, the overcurrent protection for charge is trigger between 2.5 and 2.6 A and the overcurrent protection for discharge is trigger between 2.9 and 3.1 A

0 Onyx Ahiakwo over 5 years ago in reply to Asael7

TI__Guru* 76230 points

That means the analog comparator has some level of error. Let me double check with the IC designers if that is the case and get back to you
thanks
Onyx

0 Onyx Ahiakwo over 5 years ago in reply to Onyx Ahiakwo

TI__Guru* 76230 points

Going back to look at the data sheet, i see that was captured in the min and max spec so that error is expected.

thanks

Onyx

0 Asael7 over 5 years ago in reply to Onyx Ahiakwo

Intellectual 270 points

You're right. Thank you to answer my questions.

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BQ27742-G1: Current protection is triggered before it reach the specified value.