The INA4230 has the ability to assert the alert pin on several different fault conditions as described in Alert Configuration Registers. The desired fault condition to assert the alert pin needs to be selected by appropriately programming the ALERT MASK field in the Alert Configuration Register. Fault thresholds are set by programming the desired trip threshold into the Alert Limit Registers.

For example, channel 1 can be configured to alert on an over current condition by setting the ALERT1 register CHANNEL field to channel 1(00b) with the ALERT MASK field set to shunt over voltage (001b). The desired threshold for the over current condition has to be programmed in the Limit1 Register. In this example, the over current threshold is 9.0A and the value of the current sense resistor is 8.0mΩ, which give a shunt voltage limit of 72mV. Once the shunt voltage limit is known, the value for the shunt over voltage limit register is calculated by dividing the shunt voltage limit by the shunt voltage LSB size.

For this case, the calculated value of the alert limit register is 72mV / 2.5μV = 28800d (7080h).

Values stored in the LIMIT1 to LIMIT4 registers are set to the default values when the device is disabled or V_S is power cycled.

Fault limits programmed into the LIMIT registers can be applied to a single channel or distributed to each of the 4 measurement channels. For example, if monitoring of the bus voltage was also required on channel 1, the CHANNEL field of the ALERT2 register can be also set to channel 1(00b) with the ALERT MASK field set to monitor over bus conditions (011b). The value for the over voltage fault can be set as desired in the LIMIT2 register.