INA180-Q1: Limit input current

Lothar Kulzer

Part Number: INA180-Q1
Other Parts Discussed in Thread: INA180, , INA4180, INA186, INA4290

Tool/software:

Hello all,

we plan to use the INA180-Q1 as a high side current sense in an 24V design. Due to tolerances of the power supply we can have higher voltages up to 26.4V. This would violate the max. rated common mode range of the INA180. However the data sheet says in note 3: Input voltage at any pin can exceed the voltage shown if the current at that pin is limited to 5 mA. But the input current is mostly limited by the integrated input resistors. So, what is the value of these resistors? If we add further input resistance to limit the current, we will increase gain error, when the resistors on + - are unmatched. Up to what value would You recommend to do so?

Is there another technique to enforce the INA180s input, eg. a virtual ground?

Or, is there another current mirror from TI which has higher common mode range and is available in a quad configuration similar to INA4180?

Thanks in advance for Your help.

Lothar

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 316440 points

The absolute maximum ratings do not help you; to ensure that the device works correctly, you need to stay inside the recommended operating conditions.

The INA4290 supports up to 120 V with four channels. If that is too expensive, the next best choice would be 4× INA186.

0 Joe Vanacore over 1 year ago in reply to Clemens Ladisch

TI__Genius 17070 points

Clemens,

Thank you for your continued support on the Forum :)

Lothar,

Thank you for your post. I agree with Clemens; the ABS max is for no device damage and to meet the warrantied specifications, you need to stay within the recommended operating conditions.

You can limit the impact of these higher voltages using the series resistances you mentioned but this is to protect the device and not ensure performance.

I hope this makes sense,

Joe

0 Lothar Kulzer over 1 year ago in reply to Clemens Ladisch

Prodigy 100 points

Both, abs. Max and recommended common mode voltage is 26V. I understand Your hint in that way, that even if the device would not get damaged it would not operate as expected. Right?

Thanks for the alternatives, i will check that.

+1 Clemens Ladisch over 1 year ago in reply to Lothar Kulzer

Guru 316440 points

The absolute maximum ratings actually are 28 V; there is a 2 V range where the device will not yet be damaged, but where the electrical characteristics are no longer guaranteed.

0 Lothar Kulzer over 1 year ago in reply to Clemens Ladisch

Prodigy 100 points

OK, now i got it. I will go with the alternatives, You recommended. Thanks for Your help.

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INA180-Q1: Limit input current