BQ28Z610-R1: Wake without press button

Hi Adrian,

Right, but in this worth case the charger is not present. Only voltage battery is available.

My setup is simple:
no charger, I connect the battery but because VPACK is null, the bq28 is in shutdown (or sleep) mode

An other idea ? Do you have an application note with diode and resistor between VBAT and VPACK ?

Best regards

Hello Eric,

Let me take a step back and first verify if the device is in shutdown or sleep mode. Can you currently communicate with the device? Are you able to read any registers from the device?

Regards,

Adrian

Hi Adrian,

I don't know if the device is shutdown or sleep mode because the µP is not supply by battery (VPACK not present !), so I can't read the registers.
I think the BQ28 is not a fuel gauge for removal battery, but my question is : Do you have Application Note (or advice) to wake the bq28 when the battery is reconnected (without adaptater).
My fear is if I add a diode and resistance in serie between BAT+ and VPACK (anode diode in battery side), the battery try from charging itself. Right ? The EVM (SLUUBE3) have a switch to "temporarily" connect BAT+ to PACK+, probably to prevent this potential issue.
Best regards

Hello,

The team is currently out of office today. We will get back to you next week.

Regards,

BMS Apps Team

Hi, i found this nice information:

"To wake-up the gauge from shutdown, a voltage above the VSTARTUP needs to be applied to the PACK pin for a minimum time of 30ms to wake-up the hardware." from https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1106903/faq-how-long-does-the-voltage-on-the-pack-pin-need-to-be-applied-to-wake-up-the-gauge

Do you know the VSTARTUP voltage value ? Do you have schematic or AN to do it ?

Best regards

Eric

Thank Adrian,

Do you have an Application Note to do a temporarily connect BAT+ to PACK+ ?

Best regards

Hello Eric,

We do not have an application note about this.

Regards,

Adrian

Hi Adrien,

What do you think about a "diode + resistor" beetween BAT+ and PACK+ ?

Thank for your advice

Eric

Hello Eric,

This will essentially cause a short over the protections FETs. Thus, I would not recommend this.

Regards,

Adrian

yes, that's a good point.

But how to wake-up the BQ28 chip without press-button ?

Hello Eric,

By applying a voltage on the PACK pin.

Regards,

Adrian

Hi Adrien

I was rather expecting a response with a schematic to help me apply the voltage on the PACK pin with the right characteristics (time and voltage).

Hello Eric,

In your design, how do you plan on charging the battery?

Regards,

Adrian

Hi,

The battery is charging by external power supply adapter but with human intervention (plug and unplug it).

For my application, with battery alone, I need to be sure that a "unexpected" disconnection/reconnection of battery (even transient) wake-up the bq25. Otherwise my device is switch off and inoperational.

In the EVM, the switch S1 is present to temporarily connect BAT+ to PACK+, but it is not possible to add a switch on my device. My question is : how to have the switch S1's functionnality with discret components ?

Hello Eric,

There really is not any way of doing this with discrete components without compromising the functionality of the FETs. Now, to use this gauge, the BQ40z80 should always be connected to the battery pack since this is a pack side gauge. There should not be an instance when the battery will be disconnected from the gauge. If this is a possibility in the design, then a system side gauge will need to be used. If the FETs are turned off then one of the following happened, a protection has tripped on the gauge, the gauge had a PF event occur, the gauge entered shutdown mode. In any of theses instances, there will be the need of a human intervention to recover the device, because it is an indication that something went wrong.

Regards,

Adrian