BQ40Z50-R2: Unable to get circuit power up or communicate...Need Schematic Review please !!

Jess S

Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50, EV2400, BQSTUDIO

We have designed a circuit around TI reference design of bq40z50. We have be40z50evm and ev2400. We can communicate with the evm and ev2400 without any issues however I cannot get any of my board powered up from our own circuit. This is my 2nd prototype batch after I made some changes to first batch which again I could not get to communicate.

Can you guys please take a moment and look at my schematic and try to help me out. It is really discouraging at moment and about to give up on this.

Kindly also let me know if pin 16 PRES can be left floating ??

Also any tips on debugging the circuit. I am not getting any voltage on pack output and can't communicate with bqstudio.

Thanks very much and looking forward to hear back.

over 5 years ago

0 Jess S over 5 years ago

Intellectual 295 points

7356.Schematic.pdf

0 Andy Liu (BMS) over 5 years ago in reply to Jess S

TI__Guru 52115 points

If the [NR] bit is set, the PRES input can be left floating, as it is not monitored.

Andy

0 Jess S over 5 years ago in reply to Andy Liu (BMS)

Intellectual 295 points

I understand, but we are talking about assembling new chip on board and not been successful to communicate with it. So it is not programmed before. Would that prevent the IC to bootup or communicate with bqstudio.

0 Andy Liu (BMS) over 5 years ago in reply to Jess S

TI__Guru 52115 points

Try to pull the /PRES pin to ground through a resistor and see if you can communicate with the device. The resistance must be 20 kΩ or lower.

0 Jess S over 5 years ago in reply to Andy Liu (BMS)

Intellectual 295 points

I Tried and that did not help. Thanks

Can you pls take a look at our schematic and see any other issue

0 Andy Liu (BMS) over 5 years ago in reply to Jess S

TI__Guru 52115 points

Did you ever apply a voltage on the PACK+ to wake up the device before you communicated with the gauge device?

Andy

0 Jess S over 5 years ago in reply to Andy Liu (BMS)

Intellectual 295 points

Yes I did and that did not help start the board.

What is TI recommendation for pin 16 ?? Is leaving floating an issue because I think by default when you buy the chip it is programmed as NR bit not set.

Also I Notice that from gnd to chg test point, there is voltage of 1.5v

0 Kang Kang over 5 years ago in reply to Jess S

TI__Mastermind 24870 points

You need to short top of the cell stack and pack together to wake up the device. Please follow EVM user's guide.

0 Jess S over 5 years ago in reply to Kang Kang

Intellectual 295 points

That was performed the first thing.

0 Kang Kang over 5 years ago in reply to Jess S

TI__Mastermind 24870 points

Hello Jess,

That should have woken up the part. Do you see this on any other EVMs you have? I would measure the PBI pin as well.

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BQ40Z50-R2: Unable to get circuit power up or communicate...Need Schematic Review please !!