BQ78Z100: DSG-FET is always off

Jari Tuikkala

Prodigy 20 points

Part Number: BQ78Z100
Other Parts Discussed in Thread: BQSTUDIO

I have a single cell application and DSG-FET is always off state after:

- testing discharge over current limit

- pack side shorted (intentional test)

- reset from bqstudio command

- device is disconnected from battery cell

I have updated FW to 1100_0_05. Calibration is done, cell chemistry is loaded from bqstudio and golden image has been created according to discharge - relax - charge - relax instructions.

After manufacturing enable I am able to set DSG on.. No problems with seal/unseal/full access control.

For me it seems that device doesn't start executing firmware after reset?

Which issue could prevent FW to execute as PF registers are ok?

over 1 year ago

0 Dominik Hartl11 over 1 year ago

TI__Guru 60826 points

This is usually due to one or more protection (not PF but regular protection) events that affect the DSG FET. Please check the TRM for all protection events that can affect the DSG FET. Check that the gauge is configured for the correct number of cells, not that the protector turns off the DSG FET because of an under-voltage protection event.

The FW is running. Otherwise the gauge would not respond on the bus.

0 Jari Tuikkala over 1 year ago in reply to Dominik Hartl11

Prodigy 20 points

DA configuration is set to 1-series. Manufacturer access register value stays 0x0054 and can't be changed to 0x0022.

0 Jari Tuikkala over 1 year ago in reply to Jari Tuikkala

Prodigy 20 points

Well FET_EN state changes when 0x0022 is written to 3E. CHG-fet and DSG-fet remains inactive.

0 Dominik Hartl11 over 1 year ago in reply to Jari Tuikkala

TI__Guru 60826 points

FET_EN doesn't indicate if the FETs are on or off. XDSG and XCHG do. But neither XDSG nor XCHG indicate why the FETs are on or off. This is indicated by one or more of the protection event bits (SafetyStatus registers and/or PF).

What are all the protection event flags?

Power management

Power management forum

BQ78Z100: DSG-FET is always off