BQ24157: Register 0x06 cannot be written

Hi TI Team,

Our customer using BQ24157 on their new project and encountered a problem that register 0x06 cannot be written. From the datasheet we learned that the 0x06 register can be written only after reset, and it was locked when written to other registers. Now we trying to write 0x8C to this register and found it didn't success. the dump is always 0x40, which is the reset value.

The schematic is as below:

The serial port log output 0x06 register is 0x40;

bq24157_dump_register():  bq24157_dump_register bq24157:[0x0]=0xc0
bq24157_dump_register():  bq24157_dump_register bq24157:[0x0]=0xc0
bq24157_dump_register():  bq24157_dump_register bq24157:[0x1]=0x40
bq24157_dump_register():  bq24157_dump_register bq24157:[0x1]=0x40
bq24157_dump_register():  bq24157_dump_register bq24157:[0x2]=0x8e
bq24157_dump_register():  bq24157_dump_register bq24157:[0x2]=0x8e
bq24157_dump_register():  bq24157_dump_register bq24157:[0x3]=0x51
bq24157_dump_register():  bq24157_dump_register bq24157:[0x3]=0x51
bq24157_dump_register():  bq24157_dump_register bq24157:[0x4]=0x9
bq24157_dump_register():  bq24157_dump_register bq24157:[0x4]=0x9
bq24157_dump_register():  bq24157_dump_register bq24157:[0x5]=0x4
bq24157_dump_register():  bq24157_dump_register bq24157:[0x5]=0x4
bq24157_dump_register():  bq24157_dump_register bq24157:[0x6]=0x40
bq24157_dump_register():  bq24157_dump_register bq24157:[0x6]=0x40

Setting register 0x06 to 0x8C and find write failed:

bq24157_sw_reset();
bq24157_set_value(BQ24157_REG_SAFETY, BQ24157_VSAFE, BQ24157_VSAFE_SHIFT, VSAFE4P44);  // VSAFE = 4.44V
bq24157_set_value(BQ24157_REG_SAFETY, BQ24157_ISAFE, BQ24157_ISAFE_SHIFT, ISAFE1350);
// ISAFE = 1450mA (68mOhm)

Can u help to analyze the cause of this problem?

Thanks,

Best Regards