Figure 8-2 and Figure 8-3 show the ALERT pin response to a BUS over voltage fault with a conversion time of 140μs for the bus voltage measurements with averaging set to 1. For these scope shots, persistence was enabled on the ALERT channel to show the variation in the alert response for many sequential fault events. The alert response time can change depending on the value of the current before fault occurs as well as the how much the fault condition exceeds the programmed fault threshold. Figure 8-2 shows the response time for an overcurrent fault when the fault condition greatly exceeds the programmed threshold. While Figure 8-3 shows the over voltage response time when the fault slightly exceeds the programmed threshold. Variation in the alert response exists because the external fault event is not synchronized to the internal ADC conversion start. Also the ADC is constantly sampling to get a result, so the response time for fault events starting from zero are slower than fault events starting from values near the set fault threshold. In applications where the alert timing is critical, the worst-case alert response is equal to 2 × (t_{conv_shunt} + t_{conv_voltage}) × number of channels enabled. When alerting on over power conditions, an additional 60μs needed to allow for background math calculations.

Figure 8-2 Alert Response Time (Sampled Values Significantly Above Threshold)

Figure 8-3 Alert Response Time (Sampled Values Slightly Above Threshold)