INA240: How much current might INA240A2PWR consume in a 3.3V design when in application of sensing 12V motor current flow?

Hi Chieh Wei,

Thank you for your question! Our engineers will analyze and respond when we return to the office on Monday.

Best regards,

Ian Williams
Applications Manager
Current & Magnetic Sensing

Hello Chieh Wei,

Thank you for using the forum.  I have a question about the inputs/output of the device and its operations. 

During this large current draw is there anything changing at the inputs or is this happening at a static state?

What is the behavior at the output, for good bad setups?  Do both setups behave the same?  Is there an oscillation at the output of the higher current draw devices?

If you see oscillations at the output then please verify what capacitor you have at the output in needs to be under 1nF.  If you do not have an resistor before the capacitor then adding one may help.

Please let me know if the answer to my questions to better help of if you have found your root issue?

Javier Contreras4 said:

Hello Chieh Wei,

Thank you for using the forum.  I have a question about the inputs/output of the device and its operations. 

During this large current draw is there anything changing at the inputs or is this happening at a static state?

What is the behavior at the output, for good bad setups?  Do both setups behave the same?  Is there an oscillation at the output of the higher current draw devices?

If you see oscillations at the output then please verify what capacitor you have at the output in needs to be under 1nF.  If you do not have an resistor before the capacitor then adding one may help.

Please let me know if the answer to my questions to better help of if you have found your root issue?

Hi Javier, 

Thank you for your response. Truly appreciated.

After a few days looking into this issue, we believe that we've found the root cause of it.

But we'd still want to double check since our application due to space limitation is forced to use SOT23-5 package for 3.3V LDO.

So I posted this question hoping to understand if INA240A2PWR could potentially draw higher current than what it is said in the datasheet

which is 2.4mA,  to confirm once again if our design is solid enough.

Could you give us a confirmation on INA240A2PWR power consumption?

For the root cause of this issue, we believe it is caused by the poor quality of LDO which claims to be able to supply up to 16V while our application only draws 5mA theoretically.

Yet it couldn't and the voltage output of the LDO starts to oscillates at input voltage is 12V.

We saw as high as 6-7V peak value in the voltage oscillation which we believe is the cause that damaged the INA240A2PWR.

Therefore the large current was drawn due to the internal logic of INA240A2PWR was already damaged by EOS.

As for the large current draw, it is caused by the devices on the 3.3V rail were broken.

2 IC devices

1. INA240A2PWR

2. MCU (PIC16F18325)

We found it is usually the INA240A2PWR was damaged that drew such large current. Only in a very rare case the MCUs were broken.

But it was caused by poor quality LDO and electrical over stress