BQ76930: The chip AD detection section cannot be enabled

Hi Cherry,

They can check the power pins on the BQ76930003 devices to see if the IC is functioning. They should measure the CAP1, CAP2, REGOUT, VC5x, and BAT pins. The TS1 pin should show a pulse every 2 seconds for the temperature measurement. Is the I2C bus working correctly (are they seeing ACK from the devices and are they using CRC)? 

There is example microcontroller code available in the product folder that might be helpful.

Best regards,

Matt

Hi Matt,

Both chips are capable of output voltages around 3.3 V, CRC8 is used in the program, and the slave ACK response can be detected by the logic analyzer. And can read that the gain of both BQs is gain1 = 0x95 gain2 = 0x83, and the calculated gain is 0x0175. Offset is 0x30 and 0x2F, respectively.

Matt Sunna said:

They should measure the CAP1, CAP2, REGOUT, VC5x, and BAT pins. The TS1 pin should show a pulse every 2 seconds for the temperature measurement.

The voltages at each point are as follows: (Bat_H, 68.4V), (REGOUT_H, 41.73V), (CAP1_H, 41.73V), (VC5x_H, 53.3V), (CAP2_H, 56.5V), TS1_H does not detect pulses with a frequency of 2S. (Bat_L, 38.46V), (REGOUT_L, 3.296V), (CAP1_L, 3.278V), (VC5x_L, 19.16V), (CAP2_L, 22.44V), TS1_L also did not detect pulses with a frequency of 2S.

Thanks and Best Regards,

Cherry

Hi Cherry,

The voltages appear to be okay. Just one question, this is a 20S system, but it seems like there are 19 cells (BAT_H - VC5x_H voltage looks like 4 cells instead of 5). 

The TS1 pulses missing might be because the TEMP_SEL bit is zero by default (uses internal temperature). Setting this bit to '1' will use the external thermistor pins. 

Do you have different I2C bus lines to the top and bottom devices? Do both the top and devices show the issue with the ADC_EN bit?

Thanks,

Matt

Hi Matt,

Matt Sunna said:

BAT_H - VC5x_H voltage looks like 4 cells instead of 5). 

This is because one of the wires connecting the terminals is open. 

Matt Sunna said:

Setting this bit to '1' will use the external thermistor pins. 

Yes, default shutdown requires host to turn on bits such as ADC_EN , TEMP_SEL, CC_EN are all set to 1 in the program and sent to the BQ chip. And get ACK response (logic analyzer monitoring).

Now the customer replace the original BQ chip (after changing, CAP2_H/_L - VC5X_H/_L，REGOUT_H/_L - GND_H/_L，CAP1_H/_L - GND_H/_L, the voltage between them is all around 3.3 V), and the ADC_EN_H、ADC_EN_L ， CC_EN_H、CC_EN_L still cannot be set to 1.

In addition, here's also something strange: when DsgMOS and ChgMOS are turned on, the DSG_H and CHG_H output is 20 V, while DSG_L and CHG_L are only 12 V and 6 V.

The customer has compared the design files to the 20S file on TI's official website, the front-end detection section and the power control section only modified the IIC communication circuit section.

For the detection of the IIC circuit, it is determined that the value written into the protection register is true by reading the value of the protection register after writing.

Could you also help check this? Thanks a lot.

Best Regards,

Cherry

Hi Cherry,

Sorry for the delay, I just returned from the holidays. You mention that one of the wires connecting the cell terminals is open. Can you share a picture of this? The unused cell input pins should be shorted as shown in the datasheet (see the section "Configuring Alternative Cell Counts").

What modifications were made to the I2C circuit from the TI reference design?

Best regards,

Matt