SBOS848B December 2017 – October 2019 INA381
The onboard comparator of the device is designed with a hysteresis of 50 mV. The INA381 is designed for the user to change the hysteresis from a preset value of 50 mV by connecting an external resistor between VOUT and CMPIN. Figure 46 shows a detailed block diagram of adding additional hysteresis.
The default hysteresis is 50 mV. Internal to the comparator, the INA381 has a current source of 4 µA in series with 12.5 kΩ. The internal current source and hysteresis of the comparator is set by the internal hysteresis control circuit that is enabled only after ALERT is asserted low. ALERT is asserted low during an overcurrent condition when the voltage on VOUT exceeds the threshold set on the CMPREF pin. The internal 4-µA hysteresis circuits are triggered only after ALERT is asserted low.
To increase hysteresis to greater than the default 50 mV, the RHYS resistor must be connected between the VOUT and CMPIN pins. Equation 1 describes the internal configuration to set the external hysteresis resistor.
Table 3 lists the external resistors required at the input of the CMPIN pin to set the hysteresis.
|HYSTERESIS VOLTAGE||EXTERNAL RESISTOR AT THE CMPIN PIN|
|50 mV||0 Ω|
|75 mV||6.25 kΩ|
|100 mV||12.5 kΩ|
|125 mV||18.75 kΩ|
|150 mV||25 kΩ|
|200 mV||37.5 kΩ|
|250 mV||50 kΩ|
|300 mV||62.5 kΩ|