BQ76952: Power-on initialization issue

Cherry Zhou

Part Number: BQ76952

Hi team,

The customer has designed a BMS board and sometimes the initialization is successful and sometimes unsuccessful after a power-on reset. If the initialization is successful, an alert signal is generated and the BQ76952 register is set up for normal read and write. If unsuccessful, no ACK returned after BQ76952 address 0x10 was sent through the MCU's single-step trace debug. The reset signal is generated 100 ms high by the MCU GPIO and is connected to the RST_SHUT pin of the BQ76952.

The customer would like to know what to do with the BQ76952 after power-on initialization or reset. Could you help resolve this case? Thanks.

Best Regards,

Cherry

over 3 years ago

0 Luis H. S. over 3 years ago

TI__Mastermind 42060 points

Hello Cherry,

At what voltages are they trying to power the device? Do they wake the device after power-on?

Best Regards,

Luis Hernandez Salomon

0 Cherry Zhou over 3 years ago in reply to Luis H. S.

TI__Mastermind 22235 points

Hi Luis,

Luis H. S. said:
At what voltages are they trying to power the device?

At 53V.

Luis H. S. said:
Do they wake the device after power-on?

Yes, the customer has tried 2 ways:

1. use MCU to control TS2 to pull down 500 ms.

2. TS2 is connected directly in series with a resistor to ground.

After pulling low on TS2, transmitting 0x10, bq76952 is still no ACK response.

Thanks and Best Regards,

Cherry

0 Luis H. S. over 3 years ago in reply to Cherry Zhou

TI__Mastermind 42060 points

Hello Cherry,

Tell the customer to wait 60-ms after waking the device before configuring the registers. Tell me if work in this case.

Does the REG18 pin show any voltage? Tell them to read this voltage, it can show if the device is actually awake or not.

Best Regards,

Luis Hernandez Salomon

0 Cherry Zhou over 3 years ago in reply to Luis H. S.

TI__Mastermind 22235 points

Hi Luis,

Luis H. S. said:
Tell the customer to wait 60-ms after waking the device before configuring the registers. Tell me if work in this case.

The customer has tried this way, but unfortunately it dose not work.

1. Enter configuration mode, and then configuring. 2. Exit configuration mode. 3. Measure the voltage of the REG18, which is 1.8 V. 4. After the I2C bus sends out 0x10, the ACK signal is still not received.

And some configurations are as follows:

1. low-side MOSFET.

2. I2C/SPI interface compatible.

3. BA76952 only does voltage/current/temperature and fault flags, does not control the MOSFET, Protection control is done by the MCU.

4. SHUNTDOWN MODE/charger detection/load detection is not required, these are done by the MCU. TS2 pulls down 60 ms.

And the customer see this document to do the Low-side MOSFET control.

The schematics has been deleted here.

Thanks and Best Regards,

Cherry

0 Luis H. S. over 3 years ago in reply to Cherry Zhou

TI__Mastermind 42060 points

Hello Cherry,

Could the customer try doing this communication to the IC from an EVM board? Do they encounter the same issue if using the IC from the EVM or is it able to communicate?

Best Regards,

Luis Hernandez Salomon

0 Cherry Zhou over 3 years ago in reply to Luis H. S.

TI__Mastermind 22235 points

Hello Luis,

Thanks!

And the customer has tried to connect EVM through MCU fly-wire, and I2C communication is good.

Thanks and Best Regards,

Cherry

0 Luis H. S. over 3 years ago in reply to Cherry Zhou

TI__Mastermind 42060 points

Hello Cherry,

I see the customer may have opened a new thread with this question (https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1062916/bq76952-sometimes-the-initialization-is-not-work). Correct me if I am wrong.

I will close this thread and answer on the new one.

Best Regards,

Luis Hernandez Salomon

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BQ76952: Power-on initialization issue