INA138: INA138 output voltage goes high (~1V) when V+ voltage goes below 1.3V

uday kumar reddy

Other Parts Discussed in Thread: INA138, INA168

We are using below circuit for current measurement, When DC1 voltage goes below 1.3v the voltage across R323 is going to ~1V(As like the wave form), even no current is flowing. Is this the behaviour of the INA138 or any issue with our circuit.

Please help us in resolving this...

For information VM_SW voltage is 18V, DC1 Voltage is 12V.

A138

Thanks & Regards

Uday kumar

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Uday,

can you show a schematic? (Click the "Insert Code, Attach Files and more..." button and then click the "paper clip" button.)

Kai

0 Javier Contreras4 over 5 years ago

TI__Mastermind 28490 points

Hello Uday,

Thank you for reaching out on the E2E forum to get your question answered.

To answer your question you cannnot use the INA138 or INA168 to measure the current if the common mode voltage on Vin+ and Vin- is below 2.7V. This is seen in the Common-Mode input range from 2.7V to 36V on the INA138.

Please let me know if you need assistance in looking for an alternative parts. If so please give me key specifications you require.

0 uday kumar reddy over 5 years ago in reply to Javier Contreras4

Intellectual 540 points

Hi Javier,

Thank you very much for your information,

Regards,

Uday kumar,

Amplifiers

Amplifiers forum

INA138: INA138 output voltage goes high (~1V) when V+ voltage goes below 1.3V