SLAS986D November 2014 – February 2018 AMC7836
The AMC7836 device offers the option of using an external interrupt signal, such as the output of a comparator as an alarm event. The GPIO0/ALARMIN pin is used as the alarm input and must be configured accordingly in the GPIO configuration register (address 0x12). The pin is active low when configured as an alarm input.
A typical application for ALARMIN pin is to use it as a hardware interrupt that is responsible for forcing one or more DACs to a CLEAR state. The DAC is loaded with a zero-code input and the output voltage is set according to the operating output range, however the DAC buffer or active registers do not change (see the Digital-to-Analog Converters (DACs) section for more details). To enable this functionality the ALARMIN pin must be enabled as a DAC clear-alarm source in the DAC clear source 1 register (address 0x1B). Additionally the DAC outputs to be cleared by the ALARMIN pin must be specified in the DAC clear enable registers (address 0x18 through 0x19).
In this application when the ALARMIN pin goes low, all the DACs that are set to clear in response to the ALARMIN alarm in the DAC-clear enable registers enter a CLEAR state. When the ALARMIN pin goes back high the DACs are reloaded with the contents of the DAC active registers which allows the DAC outputs to return to the previous operating point without any additional commands.