INA381: Fastest overcurrent detection

Hiromu Susami

Part Number: INA381
Other Parts Discussed in Thread: TLV9152, , LM2903, INA180, TLV3231

Tool/software:

Hi team,

I'm looking for op amps and comparators that enable high-speed overcurrent detection for compressor motor. Could you tell me the fastest solution for this?

[Requirements]

Offset voltage: <1,000 UV
Slew rate: >10 V/us
Package: SOIC (2 in 1)
GBW (MHz): >0.5 MHz
Supply voltage: >4.5 V

Short-circuit protection should be done in us.

TLV9152 + compressor is too slow.

My first thought is INA381. Alert is outputted in about 2.3usec in response to a 0.1V shunt voltage rise. Slew rate is not good enough(2V/us).

And I olso thought INA180 + LM2903.

What is the fastest solution to output alert? I hope you will give me multiple options.

Regards,

Hiromu

3 months ago

+1 Mallika Senthil 3 months ago

TI__Intellectual 2140 points

Hi Hiromu,

We don't have any Current-Sense amplifiers with a slew rate greater than 10V/us, our maximum spec is 8V/us. However, we can meet your specs with discrete solutions.
For example, the TLV9152 + TLV3231 can work. Another side note, if you want to operate the op-amp in bi-directional mode, the REF pin can be set to less than Vs/2 e.g. Vs/5 to increase your sensing range and preserve slew rate.

The following links will give you more options from our device catalog:
https://www.ti.com/amplifier-circuit/op-amps/general-purpose/products.html#2954=SOIC&22typ=10%3B70&1261max=5%3B45&23typ=0.5%3B62.5&
https://www.ti.com/amplifier-circuit/comparators/products.html#83=0.005%3B0.099&2954=SOIC&

Best,
Mallika Senthil

0 Hiromu Susami 3 months ago in reply to Mallika Senthil

TI__Prodigy 270 points

Hi mallika,

Thank you for your comment. I have additional question.

1. If I focused on the speed of the alert signal output, what is the best solution? (Allow for insufficient slew rate)
2. This is probably a basic question, but which item of the datasheet should I look at to confirm the time it takes to output the alert signal ?

　Overload recovery time? Propagation delay? The following graph? Or, other things?

Regards,

Hiromu

+1 Mallika Senthil 3 months ago in reply to Hiromu Susami

TI__Intellectual 2140 points

Hi Hiromu,

The red line depicts the propagation delay time of comparator only. The first line in the datasheet is for a smaller step size of 20mV whereas the second line is for a larger step size from 0.5V to 4.5V.

The blue line depicts the propagation delay time from the amplifier to the comparator at small and big step sizes.

If you're concerned only about the speed of the alert signal output, then the propagation delay time of comparator only (red line) should be the parameter of interest.

Best,
Mallika Senthil

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INA381: Fastest overcurrent detection