The BQ25157 has three programmable ADC comparators that may be used to monitor any of the ADC channels as configured through the ADCTRL0 and ADCCTRL1 registers. The comparators will send an interrupt whenever the ADC measurement the comparator is monitoring crosses the thresholds programmed in their respective ADC_ALARM_COMPx registers in the direction indicated by the x_ADCALARM_ABOVE bit. The comparators are only 12 bit compared to the 16 bits reported by the ADC, so only the first 12 bits of the ADC measurements are used to make the comparison. Note that the interrupts are masked by default and must be unmasked by the host to use this function.

When configuring the ADC comparators, it is recommended to first disable the comparator through the ADCCTRLx registers and allow the ADC to complete a measurement on the desired channel before enabling or reconfiguring the comparator by setting the ADC_COMPx_2:0 bits to the desired channel. This would prevent the comparator from sending an interrupt based on an outdated ADC reading when the comparator is enabled or reconfigured, especially in battery only operation where the ADC is not continuously performing measurements in all the channels.