The ADS816x has a programmable digital window comparator for every analog input channel. The integrated digital window comparator allows the host to not read ADC data over the serial interface for comparison purposes. In monitoring applications, the ADC compares channel data with the set thresholds and alerts the system host using the ALERT pin. Furthermore, the digital window comparator does not require software high and low comparisons and thus saves processing cycles.

Window comparison is achieved by comparing the channel output code with a programmable high and low digital threshold. As shown in Figure 6-17, each analog input channel has a programmable hysteresis that is applicable to both the high and low thresholds of the corresponding channel. Thus, low threshold, high threshold, and hysteresis configurations are available for each analog input channel.

Figure 6-17 Digital Window Comparator

The thresholds and hysteresis are configured independently for each analog input channel. The ALERT output of the device is a logical OR of all enabled alert outputs corresponding to the analog inputs. The window comparator is selectively enabled for the analog inputs by configuring the ALERT_CFG register.

Read the alert status of an individual analog input channel from the ALERT_STATUS register. See the ALERT_HI_STATUS and ALERT_LO_STATUS registers for further information on the high or low threshold ALERT, respectively. When monitoring only a low threshold, set the high threshold to the ADC positive full-scale code. Similarly, when monitoring only a high threshold, set the low threshold to the negative full-scale code.