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INA180: Part heating when input side left grounded

Part Number: INA180

Hello,

We are testing a part of our larger circuit separately. In the tested section, we have a INA180A2 which is supplied by an LDO at 5V. IN- is connected to GND of the IC and IN+ is connected to a sense resistor but there is NO bus voltage applied or load connected. Once the LDO is turned ON, the INA180 heats upto 100 degrees celcius and the voltage on IN- goes to 3.6V and IN+ goes to 3.85V, the output goes high too (4.2V). Please let us know if this is an incorrect way of testing or what might be the reason behind the part heating and voltage generation at IN pins.

  • Hello,

    I have a couple questions about your concern. Is the IN+ left floating? Is there any voltage difference between the GND pin on the INA and the connection between R39 and BGND? What is the voltage on the VS pin of the INA? Is the LDO only powering the INA?

    Regards,

    Castrense

  • Hello,

    Below is the information as requested:

    1. INA+ is connected to output electrolytic capacitor bank which is currently not being supplied by any source.

    2. There is no voltage difference between GND pin of INA and the connection between R39 and BGND

    3. The voltage on VS pin is 4.93V (Probably because LDO is getting overloaded), the output voltage is coming to be 4V and not 4.2V.

    4. Yes, the LDO is only powering the INA

    IL+ is connected between R38 and R'' (The INA is used as output current sensor for a LLC converter)

  • Hello,

    I am looking into this problem my initial thought was there might have been a voltage difference between gnd' s due to layout. I would like to verify if there is current going into IN+ and IN- pins can you check the voltage on R38 and R39. 

    Regards,

    Castrense

  • Hello,

    The current seems to going out of IN+. IN- pins since the measured voltage on R38, R39 are 3.85V, 3.6V respectively towards the IC being at higher voltage and both ends of Current sense resistors are at IC ground voltage level. We noticed both R38, R39 also getting hot while the IC was getting hot.

    We can personally email you the full schematic or layout if you request along with our current testing strategy.

  • Hello,

    It seems that the schematic view of the INA180A2IDBVT on your first picture has the wrong pinout. Please refer to the picture below with the correct pinout of both the INA180 Pinout A and Pinout B, for the SOT-23. 

    If you have any questions please reply

    Regards,

    Castrense