BQ76952: DSG Gate Switching Speed and IC Reset Question

JP Alleyne

Prodigy 10 points

Part Number: BQ76952

Tool/software:

Hi TI Team,

2 questions.

What are our circuit options in order to increase the DSG gate switching speed?
What lines on the BQ76952 should I scope to evaluate whether the part is resetting due to switching transients on SRP and SRN?

Thanks,

6 months ago

+1 Alexis_H 6 months ago

TI__Mastermind 18005 points

Hello JP,

1. Section 16.5 FET Driver Turn-Off from the datasheet talks about how to adjust the speed for turn-off. Section 8 DSG Driver and Section 9 DSG Driver Current Paths from the Multiple FETs App Note may also be useful to refer too.
This previous post may help as well: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1402788/bq76952evm-reduce-chg-dsg-fet-turn-on-off-time

2. Observing the voltage between the SRP and SRN pins on a scope would help the best in determining if transients on SRP and SRN are causing the part to reset.

Best Regards,
Alexis

0 JP Alleyne 6 months ago in reply to Alexis_H

Prodigy 10 points

Thanks, Alexis. We are seeing some issues with the SCD. We will open up a new post to do deep diving into this issue.

0 Alexis_H 6 months ago in reply to JP Alleyne

TI__Mastermind 18005 points

Hello JP,

If the device resets, the FET drivers will also reset and turn OFF and then could turn back on shortly depending on what the initialization settings are.

Best Regards,
Alexis

0 JP Alleyne 6 months ago in reply to Alexis_H

Prodigy 10 points

What would that waveform look like? Also, would you be able to see the failure on I2C pins, LD, or REG18?

Can we look at Accum time to see the reset? Or is this only for "normal" resets?

0 Alexis_H 6 months ago in reply to JP Alleyne

TI__Mastermind 18005 points

Hello JP,

JP Alleyne said:
What would that waveform look like? Also, would you be able to see the failure on I2C pins, LD, or REG18?

I unfortunately do not have a waveform on me to show that behavior exactly.
If the part enters SHUTDOWN mode and wakes back up again, this would show up on REG18 (0V back to 1.8V) Further information on SHUTDOWN mode and RESETs can be found in the following FAQs:
1. RESET FAQ
2. SHUTDOWN FAQ
I will double-check regarding the I2C and LD pins.

JP Alleyne said:
Can we look at Accum time to see the reset? Or is this only for "normal" resets?

If the device goes through a partial reset or is reset using the RST_SHUT pin, the subcommand 0x0082 RESET_PASSQ() needs to be used to ensure the charge accumulation is properly initialized, so it could be looked at potentially to see the reset. More information about RESET_PASSQ() can be found in Section 4.3 Coulomb Counter and Digital Filters from the Technical Reference Manual.

Best Regards,
Alexis

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BQ76952: DSG Gate Switching Speed and IC Reset Question