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 can compare channel data with the set thresholds and alert 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 49, each analog input channel has a programable 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.
The thresholds and hysteresis can be 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 can be selectively enabled for the analog inputs by configuring the ALERT_CFG register.
The alert status of an individual analog input channel can be read 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, the high threshold can be set to the ADC positive full-scale code. Similarly, when monitoring only a high threshold, the low threshold can be set to the negative full-scale code.