VOUT

VLIMIT1

VLIMIT2 - VHYS

VLIMIT2

ALERT1

ALERT2

VLIMIT1 - VHYS

Critical Threshold

Warning Threshold

VOUT

VLIMIT1

VLIMIT2 + VHYS

VLIMIT2

ALERT1

ALERT2

VLIMIT1 - VHYS

Overcurrent Threshold

Undercurrent

Threshold

SOURCE

TRIP

SENSE

REF

V

I

R

GAIN

V

u

u

20

INA302, INA303

SBOS775C – SEPTEMBER 2016 – REVISED MARCH 2019

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Copyright © 2016–2019, Texas Instruments Incorporated

Feature Description (continued)

7.3.3.1.2

Voltage-Source-Controlled Current Limit

The second method for setting the out-of-range threshold is to directly drive the LIMITx pins with a programmable

DAC or other external voltage source. The benefit of this method is the ability to adjust the current-limit threshold

to account for different threshold voltages used for different system operating conditions. For example, this

method can be used in a system with one current-limit threshold level that must be monitored during a power-up

sequence, but different threshold levels must be monitored during other system operating modes.

The voltage applied at the LIMITx pins sets the threshold voltage for out-of-range detection. The value of the

voltage for a given desired current trip point is calculated using Equation 4:

where

•

ITRIP is the desired out-of-range current threshold.

•

RSENSE is the current-sensing resistor.

•

GAIN is the gain option of the device selected.

•

VREF is the voltage applied to the REF pin.

(4)

NOTE

The maximum voltage that can be applied to the LIMIT2 pin is VS – 0.6 V and the

maximum voltage that can be applied to the LIMIT1 pin must not exceed VS.

7.3.3.2 Hysteresis

The hysteresis included in the comparators of the INA30x reduces the possibility of oscillations in the alert

outputs when the measured signal level is near the overlimit threshold level. For overrange events, the

corresponding ALERTx pin is asserted when the output voltage (VOUT) exceeds the threshold set at either LIMITx

pin. The output voltage must drop to less than the LIMITx pin threshold voltage by the hysteresis value in order

for the ALERTx pin to deassert and return to the nominal high state. Likewise for underrange events, the

corresponding ALERTx pin is also pulled low when the output voltage drops to less than the threshold set by

either LIMITx pin. The ALERTx pin is released when the output voltage of the current-sense amplifier rises to

greater than the set threshold plus hysteresis. Hysteresis functionality for both overrange and underrange events

is shown in Figure 45 and Figure 46 for the INA302 and INA303, respectively.

Figure 45. Comparator Hysteresis Behavior (INA302)

Figure 46. Comparator Hysteresis Behavior (INA303)