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BQ76942: Configuring ALERT Pin for overcurrent detection

Part Number: BQ76942

Hi, I want to configure the BQ76942 in my design to trigger an interrupt when the detected current exceeds 8 A. 

I am finding the description of alarm register masking etc (in the technical reference manual) to be quite confusing, and am struggling to understand which registers need to be set.

Would really appreciate it if you could describe which configuration registers to set (and what to set them to) to achieve the following:

ALERT pin (normally high impedance, pulled high by external resistor), drives low when the BQ76942 detects discharge current above 8 A. No other alarms or protections trigger the ALERT pin. 

After reading the TRM, my understanding is that this will involve configuring the alert pin to be active-low, setting up an Overcurrent in Discharge protection, and then configuring this so that it triggers the ALERT pin (and nothing else). But I'm struggling to actually achieve this.

Any help would be appreciated, thanks!

  • Hello Oscar,

    The TRM describes things in detail how ALERT gets configured in Section 6.6 ALERT Pin Operation

    Section 13.3.2.11 Settings:Configuration:ALERT Pin Config describes the different bits for the ALERT pin configurations and what each does. I'd recommend to read this to understand how to configure it to drive low. You can also make it Hi-Z or pull-up to the device's LDO in this case.

    For when do the ALERT pin triggers to go low during a fault, you'd have to configure Settings:Alarm:Default Alarm Mask and Settings:Alarm:SF Alert Mask A–C.

    The Settings:Alarm:Default Alarm Mask register is described in Section 13.3.4.1 Settings:Alarm:Default Alarm Mask. You will want to set the Settings:Alarm:Default Alarm Mask[MSK_SFALERT] bit, so that ALERT triggers when a specified protection triggers.

    Which protection triggers MSK_SFALERT can be chosen in the Settings:Alarm:SF Alert Mask A register.

    Hope that helps Slight smile.

    Best Regards,

    Luis Hernandez Salomon