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INA300

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SBOS613B – FEBRUARY 2014 – REVISED APRIL 2016

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(1)

Lowering the trigger point results in the device issuing an overcurrent alert prior to reaching the corresponding

effect internal noise has on the threshold voltage.

7.3.2.2 Voltage Source Controlled Current Limit

The second method for setting the limit voltage is to connect the LIMIT terminal to a programmable DAC (digital-

to-analog converter) or other external voltage source. The benefit of this method is the ability to adjust the

current limit to account for different threshold voltages that are used for different system operating conditions. For

example, this method can be used in a system that has one current-limit threshold level that must be monitored

during the power-up sequence but different thresholds must be monitored during other system operating modes.

setting. This value is equal to 500 µV and is used to adjust the operating point for the noise in the delay setting.

delay settings, the NAF term is omitted. See the Noise Adjustment Factor (NAF) section for more details on the

noise adjustment factor.

PARAMETER

EQUATION

Desired current trip value

(1)

Programmed threshold limit voltage

(1)

averaging effect included with the 50-µs and 100-µs delay settings inherently eliminates the effect internal noise

has on the threshold voltage.

7.3.3 Delay Setting

The device response time for overcurrent events is adjustable based on the DELAY terminal setting. Three

response time settings are available, ranging from 10 µs to 100 µs. The primary purpose for the three different

delay settings is to offer a trade-off between a faster alert response and a more precise overcurrent threshold

level detection.

The device has a 10-µs internal comparison window. This single comparison window is the fundamental time unit

used for all three delay settings. For the 10-µs delay setting, the device compares the average of the input signal

during the 10-µs comparison window to the threshold limit programmed at the LIMIT terminal. If the averaged

input signal exceeds the threshold at the end of the 10-µs comparison window, the output alert triggers and pulls

the ALERT terminal low. However, if the averaged input does not exceed the threshold at the end of the 10-µs

comparison window, there is no change in the output alert status, which remains high to indicate that no

overcurrent event is detected.

For the 50-µs delay setting, there must be five consecutive 10-µs comparison windows that result in an average

input signal exceeding the threshold limit in order for the output alert to trigger and pull the ALERT terminal low.

If any single 10-µs comparison window fails to detect an overcurrent condition before reaching five consecutive

overcurrent comparisons, the internal counter is reset and no output alert is issued. With the internal counter

reset, a new group of five consecutive 10-µs comparison windows of overcurrent conditions are required in order

to trigger the alert and pull the ALERT terminal low.

The 100-µs delay setting operates in the same manner as the 50-µs method, but instead requires ten

consecutive 10-µs comparison windows with an input signal exceeding the threshold limit in order to issue an

output alert and pull the ALERT terminal low.