BQ24725AEVM-710: Charger never starts charging the battery

Philippe O'Sullivan-Dargis

Part Number: BQ24725AEVM-710
Other Parts Discussed in Thread: BQ24725A

Hi,

I have BQ24725AEVM-710 evaluation board connected with a 4S1P smart battery. The evaluation board is also connected to a 20V and 3,3V power supply. When I measure voltages on the test points I get 6V at REGN, 3.3V at ACOK and 6V between ACDRV and CMSRC which should be OK. When I look probe the SMBus, I see a communication between the battery and the charger. The battery sends out current and voltage requests for charging. However, the BQ24725AEVM-710 never starts to charge the battery. The input current limit is at it's default value and should not inhibit the charge. I do not have access to a EV2300 to send commands directly to the charger. Do you have an idea what could prevent the charger from charging?

Thank you

Philippe Dargis

over 5 years ago

0 Wang5577 over 5 years ago

TI__Guru 56650 points

Philippe,

1. Could you also measure the ILIM pin voltage?

2. Could you read out 0x12H, 0x14H and 0x15H register value?

0 Philippe O'Sullivan-Dargis over 5 years ago in reply to Wang5577

Prodigy 60 points

Hi,

1. ILIM voltage is 785mV.

2. On 0x12 I get 0xF912. On 0x14 and 0x15 I get 0x0000 even after the battery sent a command to the charger. This is what prevents the charger from charging. When I send commands from the software, these registers update correctly and the battery starts charging. However, as soon as the battery sends a new command, these resisters are reset to 0x0000. The only difference between the packets sent by the battery and those sent by the sofware is that the battery ends its communication with what seems to be a packet error checking byte. Could this PEC be what causes the 0x14 and 0x15 register to reset to 0x0000?

Thanks a lot.
Philippe

0 Wang5577 over 5 years ago in reply to Philippe O'Sullivan-Dargis

TI__Guru 56650 points

Philippe,

You found it. BQ24725A doesn't accept PEC code. Please disable the PEC in the broadcast mode.

Power management

Power management forum

BQ24725AEVM-710: Charger never starts charging the battery