For the system gain management to have a quick response time, a low-latency configurable over-range function is included. The over-range function works by monitoring the converted 12-bit samples at the ADC to quickly detect if the ADC is near saturation or already in an over-range condition. The absolute value of the upper 8 bits of the ADC data are checked against a programmable threshold, OVR_TH. The threshold programmed into OVR_TH is used for all analog inputs.Table 8-1 lists how an ADC sample is converted to an absolute value for a comparison of the thresholds.

Over-range detection is enabled by setting OVR_EN to 1. If the upper 8 bits of the absolute value equal or exceed the OVR_TH threshold during the monitoring period, then the over-range bit associated with the over-ranged ADC channel is set to 1, otherwise the over-range bit is 0. For the Quad channel device, the over-range status can be monitored on the ORA, ORB, ORC or ORD output pins for ADC channels A, B, C and D, respectively. OVR_N can be used to set the output pulse duration from the last over-range event. Table 8-2 lists the over-range pulse lengths for the various OVR_N settings.

Typically, the OVR_TH threshold is set near the 8-bit full-scale value (228 for example). When the threshold is triggered, a typical system turns down the system gain to avoid clipping. The downstream logic device then monitors the output samples to determine when the over-range condition no longer exists and then increases the system gain as desired.