BQ40Z80: bq40z80

Adam

Expert 1215 points

Part Number: BQ40Z80
Other Parts Discussed in Thread: BQSTUDIO

Hello,

I have a question regarding /SHUTDN pin functionality of BQ40z80.

I have pin 17 assigned as /SHUTDN and button to GND connected to it.

The User Guide says:

When a high-to-low transition on the SHUTDN pin is detected with a debounce delay of about 1 s for the low level threshold, the gauge turns off the CHG and DSG FETs immediately

However what I observe on the pin during normal state is low level actually (when the button is not pushed). Does I need to add externall pul-up to VCC?

Regards,

Adam

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Adam,

Let me check with an EVM and get back to you.

Andy

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Adam,

No. You don't need to.

As you see in the bq40z80EVM schematic, you only need to connect a pushbutton to GND.

Andy

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

Expert 1215 points

Thank you for the answer.

But could you check what is the deafoult voltage level of pin 17 when is set to SHUNTDN?

Because when is set to PRES i can observe short 5V pulses

Regards,

Adam

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

TI__Guru 52115 points

Hi Adam,

You should see the 5V short pulses as well when the Pin 17 is configured as /SHUTDN pin. I would suggest you double-check using a scope.

Andy

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

Expert 1215 points

Hi,

I've double checked it.

Have permanent 0V on Pin17 with SHUTDN setting.

I have:

[MFP17_SEL0][MFP17_SEL1][MFP17_SEL2] = 001

and

DA Configuration[NR] = 1 and DA Configuration[EMSHUT_EN] = 1

Are they other settings I need to enable?

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

TI__Guru 52115 points

These should be all the configurations needed. If you are using an EVM, make sure all the necessary jumpers are correctly set.

Andy

0 Vincenzo Pizzolante over 5 years ago in reply to Andy Liu (BMS)

TI__Mastermind 25426 points

hi Andy,

i will send you the schematic via outlook...

Vincenzo

0 Andy Liu (BMS) over 5 years ago in reply to Vincenzo Pizzolante

TI__Guru 52115 points

Are you able to send a bq40z80 EVM to Adam? I have checked the configurations using my bq40z80EVM.

Andy

0 Vincenzo Pizzolante over 5 years ago in reply to Andy Liu (BMS)

TI__Mastermind 25426 points

done :)

Vincenzo

0 Adam over 5 years ago in reply to Vincenzo Pizzolante

Expert 1215 points

Thank you,

I've received the EVM and tested it already.

Still have the same issue that when BQ40z80 Pin17 is configured as SHTDN I can not shunt down the device.

Also when configured as PRES I can observe the pulses on scope, when SHTDN mode is used no pulses observed.

Could you maybe check your EVM with my settings (5S LiPol battery - I've send the *.gg file to Vincenzo)

Regards,

Adam

0 Adam over 5 years ago in reply to Adam

Expert 1215 points

Also (could be some hint for you) The CHG_FET_TOGGLE and DSG_FET_TOGGLE commands does not work with my settings - maybe still I'm missing some setting?

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

TI__Guru 52115 points

Hi Adam,

Check if the Manufacturing Status[FET_EN] is set in the bqStudio. If so, CHG_FET_TOGGLE and DSG_FET_TOGGLE commands will not work because the firmware is controlling the DSG and CHG FETs

Andy

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

Expert 1215 points

Hi, yes, the FET_EN is set.

Could you maybe send me settings that works at your dev board (but for 5 cells) I could compare with mine.

Adam

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

TI__Guru 52115 points

Hi Adam,

If the FET_EN is set, the firmware is controlling the FETs, and therefore CHG_FET_TOGGLE and DSG_FET_TOGGLE commands will not work. You need to send the FET_EN command again and make sure the FET_EN bit clears.

I work from home now and don't have a good power supply to power my EVM. Let me check if I can make my EVM work next week and then share with you my settings.

Andy

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

Expert 1215 points

Thank you Andy!

Regarding CHG_FET_TOGGLE and DSG_FET_TOGGLE it works now after your reply - thanks.

Ip possible please share your settings while you will have the power supply

Regards,

Adam

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

TI__Guru 52115 points

Hi Adam,

I will have access to a power supply this Friday and will share my settings before next Monday.

Andy

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

Expert 1215 points

Thanks

will appreciate that

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

TI__Guru 52115 points

See my gg file below. Most of the configurations are default. I have only made changes to a few settings.

SHUTDN.gg.csv

Basically, if I press the SHUTDOWN button on the EVM, the CHG and DSG FETs are turned immediately. In addition, if I press the button again, the FETs will be turned on again.

Andy

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

Expert 1215 points

Thank you Andy,

SHUTDOWN functionality is working.

I can now see wehere I was wrong..

In the BQ User Manual there is note to set

[MFP17_SEL0][MFP17_SEL1][MFP17_SEL2] = 001,

so I understood that the highest bit should be set..

however the lowest one (SEL0) should be set to 1 and SEL1 and SEL2 to 0. In that configuration everything works.

Regards,

Adam

0 Adam over 5 years ago in reply to Adam

Expert 1215 points

However I've noticed it is not the same SHUTDOWN mode as when I use "SHUTDOWN" command, right?

I can still have communication with battery, can toggle led's etc.

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

TI__Guru 52115 points

That's correct.

The SHUTDOWN command will put the bq40z80 into shutdown mode. However, the Emergency FET Shutdown function will just turn off the CHG and DSG FETs to disable the battery power to the system.

Andy

Power management

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BQ40Z80: bq40z80