7.3.5 Adjustable Overcurrent Threshold

The VOUT voltage is the amplified voltage developed across the current-sensing resistor. The signal developed at the VOUT pin is the input voltage across the IN+ and IN– pins multiplied by the gain of the amplifier. The INA381 has four gain options, as shown in Figure 42: 20 V/V, 50 V/V, 100 V/V, and 200 V/V. If additional hysteresis is not required, directly connect the VOUT pin to the CMPIN pin.

Figure 42. Resistor Divider Voltage

The device determines if an overcurrent event is present by comparing the voltage on the CMPIN pin to the corresponding signal developed at the CMPREF pin. The threshold voltage for the CMPREF pin can be set with a resistive divider, or by connecting an external voltage source (such as a reference generator device). Figure 43 depicts the REF3140 used as an external reference source.

Figure 43. External Reference Voltage