BQ24735EVM-710: ACFET and RBFET not functioning

Shaithanya Chenniah

Part Number: BQ24735EVM-710
Other Parts Discussed in Thread: BQ24735

we are using BQ24735EVM-710 design as reference for our board when we follow the test summary section 2.4.1 V(TP(ACDRV, CMSRC)) = 6 V ± 0.5 V not showing. is there any programmable settings is required to get 6V. we supplied external 6V to ACFET gate terminal mosfet start conduction showing 5.1V in source terminal. 19.5V given in Drain. anyone can help me to resolve this issue.

over 8 years ago

0 Wang5577 over 8 years ago

TI__Guru 56650 points

Do you add 3.3V reference on the board? What is the ACOK and ACDET voltage?

0 Shaithanya Chenniah over 8 years ago in reply to Wang5577

Intellectual 285 points

yes we added 3.3V reference on the board and ACOK - 3.3V & ACDET - 2.6V.

0 Wang5577 over 8 years ago in reply to Shaithanya Chenniah

TI__Guru 56650 points

"we are using BQ24735EVM-710 design as reference for our board". Would you order an bq24735EVM and compare which pin voltage? And then, we can understand the issue.

0 Shaithanya Chenniah over 8 years ago in reply to Wang5577

Intellectual 285 points

Hello Mr. wang

i will explain the issue clearly with attached documents

bq24735_725A Test summary.pdf Battery charger board schematic.pdfMeasured voltages are marked with yellow. please refer the Test summary attachment at section 2.4.1.

Refer schematic

1. Q1 (ACFET) & Q2(RBFET) Not switching on.

2. since we are not getting 6V gate drive voltage in ACDRV MOSFET not swicthing on.

3. we removed R8 inrush current resistor and supplied 6V from externally to drive ACFET and RBFET even tough not switching on

can you please suggest us any programmable configuration is required

0 Wang5577 over 8 years ago in reply to Shaithanya Chenniah

TI__Guru 56650 points

Except IC damage or board damage, I cannot give other reason right now. Are you add the 6V on Q1's gate and source directly?
If that is the case, the Q1 should be turned on and Vsys should be same as input voltage.

0 Wang5577 over 8 years ago in reply to Wang5577

TI__Guru 56650 points

If the IC or board is damaged, please contact local FAE or sales team to help you submit failure analysis form.

0 Shaithanya Chenniah over 8 years ago in reply to Wang5577

Intellectual 285 points

Mr. Wang

Thanks for your support after replacing the IC now the board is functioning properly. But when we connect SYS, voltage droping from 12V to 3.5V.

Is there any system maximum current we have to enable through programming.?

0 Wang5577 over 8 years ago in reply to Shaithanya Chenniah

TI__Guru 56650 points

bq24735 is a direct power path device which connects the input to system through the input ACFET and RBFET. If voltage dropping from 12V to 3.5V when we connect SYS, I would think the input FETs also get damage. Before you change the input FETs, please double check the ACOK voltage; ACDET voltage and 10ohm VCC series resistor to make sure they are normal.

0 Shaithanya Chenniah over 7 years ago in reply to Wang5577

Intellectual 285 points

Dear Mr. Wang

Do you have any provision in BQ24735EVM-710 for measuring Lithium-ion Battery percentage indication.

Regards

Shaithanya C

0 Wang5577 over 7 years ago in reply to Shaithanya Chenniah

TI__Guru 56650 points

bq24735 is a slave charger and doesn't monitor the battery state-of-charge. Please post the battery charge percentage question to the gauge forum.

Power management

Power management forum

BQ24735EVM-710: ACFET and RBFET not functioning