INA381 datasheet(21/44 Pages) TI2

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HYS

12500

P u

Internal

Hysteresis

Control

VOUT

RESET

ALERT

IN+

IN±

VS+

GND

CMPIN

CMPREF

10 k:

RPULL-UP

0 V to 26 V

G = 20, 50,

100, 200

5 V

2.7 V to 5.5 V

RSENSE

Load

INA381

12.5 k

RHYS

4 µA

VS+

INA381

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SBOS848B – DECEMBER 2017 – REVISED OCTOBER 2019

Product Folder Links: INA381

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8.1.2 Increase Comparator Hysteresis

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.

Figure 46. Increase Hysteresis to the Comparator

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.

where

•

VHYS is the desired hysteresis voltage

•

RHYS is the external resistor on the input of the CMPIN pin

(1)

Table 3 lists the external resistors required at the input of the CMPIN pin to set the hysteresis.

Table 3. Hysteresis Resistor Selection

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

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