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PCA9554A: Over current fail

Luis Vidaurreta
Prodigy 20 points
Part Number: PCA9554A
Other Parts Discussed in Thread: PCA9554

Hi,

I am using the PCA9554ADG in 2 project and I have the same problem in both.

A few second after powering on the board, the PCA9554ADG increase the power supply current and fails. After the failure the resistance between VCC and GND is below 25 ohm.

The last  test has been done only with the power supply connected. The I2C and output port had no load connected.

As additional test, I have included a ESD  protection between Vcc and GND with the same outcome.

Any help is welcome

  • 0
    TI__Genius 15345 points

    Hi Luis,

    Are you able to measure the current and if so what was the maximum current reached? There is a limit on the continuous current through VCC and ground:

    Have you been able to isolate the issue to the PCA9554A. This means have you taken it off board and attached it to a regular power supply and seen if it starts to draw a lot of current.

    What other devices are connected to the power supply? If there are other devices can you remove them and see if the issue still persists? If it does, remove the PCA9554 from the circuit and see if the issue still persists.

    The only way I could see this being an issue that has to do with the PCA9554A is one of the down stream devices on the ports is causing a short which is causing this device to draw a lot of current.

    When the board is powered is the PCA9554A automatically programmed and if so what are you programming the output ports to? Are any of them outputs?

    Best,

    Chris

  • 0 in reply to Chris Ayoub
    Prodigy 20 points

    Hi Chris,

    I am using a PCB with the PCA9554A and the outputs are not connected to nothing.

    The external power supply is programmed to 3V@100mA.

    The I2C bus is not programmed and is not connected. I only connect Vcc and GND.

    I2C pull-up 2k7.

    I have measure the impedance before connect power supply.

    Outputs to GND= 170k

    Outputs to Vcc= 68k

    Vcc to Gnd= 160K

    SDA to Vcc= 2k7

    SDA to GND= 150k

    SCL to Vcc= 2k7

    SCL to GND = 150k

    SDA to SCL= 5k

    The first 5-10s the Vcc current is bellow 0.1mA. After that, the current increase to 100mA and the Vcc voltage go to 0V.

    BR

    Luis

  • 0 in reply to Luis Vidaurreta
    TI__Genius 15345 points

    Luis,

    Have you tried using a different power supply? Do other devices work using this same power supply?

    Just to confirm, I know you said that nothing was connected to this device, but is it possible that any of the ports are set as outputs?

    Lastly, all of our devices should come with LOT numbers. Can you send me the LOT number for this batch of devices to my email: c-ayoub@ti.com . I can check if these are genuine TI parts.

    Best,

    Chris

  • 0 in reply to Chris Ayoub
    Prodigy 20 points

    Hi Chris,

    Yes We have done the test with different power supply.

    The output have the default configuration because never has been programmed. 

    It is upsetting because the failure occur several seconds after connect the power supply

    The samples were bought on Mouser. I have sent your email the information available.

  • 0 in reply to Luis Vidaurreta
    TI__Genius 15345 points

    Hi Luis,

    I sent you an email about the Lot number. Hopefully with some more investigation we can find out what is happening here. If it is needed you can have the parts sent to my team and we can further test them.

    Best,

    Chris