SBAS633E February 2016 – August 2022 ADS8681 , ADS8685 , ADS8689
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The device features an active-high alarm output on the ALARM/SDO-1/GPO pin, provided that the pin is configured for alarm functionality. To enable the ALARM output on the multifunction pin, see the SDO1_CONFIG[1:0] bits of the SDO_CTL_REG register to 01b (see the SDO_CTL_REG register).
The device features two types of alarm functions: an input alarm and an AVDD alarm.
When the alarm functionality is turned on, both the input and AVDD alarm functions are enabled by default. These alarm functions can be selectively disabled by programming the IN_AL_DIS and VDD_AL_DIS bits (respectively) of the RST_PWRCTL_REG register.
Each alarm (input alarm or AVDD alarm) has two associated types of alarm flags: the active alarm flag and the tripped alarm flag. All the alarm flags can be read in the ALARM_REG register. Both flags are set when the associated alarm is triggered. However while the active alarm is cleared at the end of the current ADC conversion (and set again if the alarm condition persists), the tripped flag is cleared only after ALARM_REG is read.
The ALARM output flags are updated internally at the end of every conversion. These output flags can be read during any data frame that the user initiates by bringing the CONVST/CS signal to a low level.
The ALARM output flags can be read in three different ways: either via the ALARM output pin, by reading the internal ALARM registers, or by appending the ALARM flags to the data output.
Figure 7-20 depicts a functional block diagram for the device alarm functionality.