BQ76942: REG1 output falls to zero within 3 seconds

Richard Cooke

Part Number: BQ76942
Other Parts Discussed in Thread: EV2400

Hi Folks,

I'm bringing up a new board with the BQ7694204 (SPI version). It's not behaving. The REG1 output starts out correctly but then quickly falls to zero. Is this normal? I haven't gotten to the point where I can connect it to the EV2400 module.

Thanks,

Richard

over 4 years ago

0 Matt Sunna over 4 years ago

TI__Guru* 81035 points

Hi Richard,

Is this an EVM or a different board? How is the voltage to REGIN being supplied? REGIN supplies the REG1 / REG2. By default, the BQ7694204 is programmed to use BREG to control a external BJT (REG0_EN = 1).

Best regards,

Matt

0 Richard Cooke over 4 years ago in reply to Matt Sunna

Expert 1530 points

Hi Matt,

This is a new board (not the EVM). The REGIN is being supplied by a NPN BJT (p/n: DXTN26070CY-13). Here's my circuit:

Does this look acceptable?

Thanks,

Richard

+1 Matt Sunna over 4 years ago in reply to Richard Cooke

TI__Guru* 81035 points

Hi Richard,

So it seems your board is correctly configured for the REGIN circuit. However, I did notice in the image that R38 is 10k instead of 10M.

Do you have cells connected to the board or is power supplied to the VCx pins in a different way?

0 Richard Cooke over 4 years ago in reply to Matt Sunna

Expert 1530 points

Hi Matt,

Thanks for catching the R38 error. I wouldn't have found that for quite a while.

Richard

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BQ76942: REG1 output falls to zero within 3 seconds