BQ40Z50-R2: BQ40Z50-R2 the chip crashes

Hello Star,

I'm not sure what you mean. Please clarify what they process is and what is defined as a "crash"? The BQ40Z50-R2 does not crash unless something is changed incorrectly in data flash or the schematic is not correct.

Please share schematic, .gg file, and their test conditions.

Sincerely,

Wyatt Keller

Hi Wyatt 

Thanks for your reply.

The test process is as follows.

They sent 12 batteries to the customer in shutdown mode. After two months storage, they inserted the battery to their system to wakeup and charge.

6 batteries could not be waked up and exited from shutdown mode. The other 6 batteries were activated normally.

The six inactive batteries needed to disconnect the cell and reconnected the cell then powered on it can work normally.

The following are schematic and gg files.

gg.gg.csv

Please give some suggestions.

Thanks

Star

Hello Star,

If power is supplied to PACK side on the PACK pin above V startup then the gauge will wakeup from shutdown. Did they confirm it work before shipping, was it unresponsive after assembly?

Sincerely,

Wyatt Keller

Hi Wyatt Keller

Thanks for your reply.

The battery can wakeup after assembling, also can wakeup from shutdown mode before shipping.

Is there anything else that may cause wakeup failure(It needed to disconnect the cell and reconnected the cell then powered on it can work normally.)

Waiting for your reply.

Thanks

Star

Hello Star,

As long as there is enough power to keep the gauge active and a voltage is applied on the PACK pin the gauge should wakeup from shutdown. What are the voltages on the gauge pins for PBI, PACK, BAT, and VCC after they try to wakeup the gauge?

Sincerely,

Wyatt Keller

Hi Wyatt Keller

Thanks for your reply.

They try to apply 16.4V on pack pin, the PACK pin voltage is 16.4V, PBI is 16.0V, BAT is 16.25V, VCC is 16.0V, cannot wakeup the gauge.

Thanks

Star

Hello Star,

If PBI is high the gauge is most likely active, it may just not be responding to commands. Can you share a scope capture of the TS1 pin, if it is pulsing at approximately 250ms this means the firmware is executing but the communication is not responding. If it is not pulsing then firmware is not executing.

Sincerely,

Wyatt Keller

Hi Wyatt Keller

Thanks for your patience.

The TS1 waveform as below:

The TS1 keep low,  firmware is not executing. 

Why does the firmware not executing?

Waiting for your reply.

Thanks 

Star

Hello Star,

I am checking with the design team on this. It looks like the gauge is staying stuck in shutdown mode even when voltage is on PACK pin and gauge is properly powered.

Sincerely,

Wyatt Keller

Hello Star,

What is retuned by the gauge when you read word 0x0d?

Does the gauge respond to anything over SMBus?

Sincerely,

Wyatt Keller

Hi Wyatt

There is no response. The battery is inserted into their system, and cannot communication.

When reading with EV2400, also cannot communication.

Thanks

Star

Hello Star,

They tried communicating on both address 0x17 and 0x16 with read word 0x0d and there is no ACK?

Design team is not sure of root cause from the description given. If PMID is powered then the gauge is not in shutdown, but TS pin not pulsing indicates FW is not running. Only other options is it is in ROM mode or the firmware was corrupted, which doesn't seem to be the case if a POR fixes the issue.

Sincerely,

Wyatt Keller

Hi Wyatt

Thanks for your help.

The customer do the ESD test can simulate the same phenomenon. 

They connected the battery at the output port. The air is 15K, and the contact is 8K.

Every time do an electrostatic test, they will discharge the power to the connection port. If the discharge is incomplete or the static electricity is applied for several times continuously, the chip will not active. Then all battery cells need to disconnect and reconnect again it can work normally.

Attached the SREC file

6646.srec.zip

Waiting for your reply.

Thanks

Star

Hello Star,

It sounds like the boards need to be optimized further for ESD mitigation if the ESD event is causing some type of damage or bits to flip in the gauge where only a POR can recover the state.

Can you share the board layout files?

Sincerely,

Wyatt Keller

Hi Wyatt

Attached the layout picture. The layout file is encrypted they can not share. 

Whether the layout issue will cause the chip not active after 2month storage?

Thanks

Star

Hi Wyatt

Thanks for your help.

If it is caused by ESD, How to improve ESD anti-interference ability？

Thanks

Star