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PCA9306 VREF2 Problem

Danny Gale1
Prodigy 10 points
Other Parts Discussed in Thread: PCA9306

I have a problem with the PCA9306. It's hooked up with VREF2 and EN tied together, with a 200kOhm pull up resistor to 3.3V. The voltage at the VREF2 pin is only 0.117V, indicating a sink current of about 16 uA. Reducing the resistor to 20k gives 331mV at VREF2 (or 148 uA sink current). Reducing the resistor further to 2k gives 492mV at VREF1 (1.4 mA of sink current). 

What is the problem here? My PCA9306 is connected as shown in Figure 3 of the datasheet, except VREF1 is pulled to 2.5V

On an aside, this is where I've ended up after 3 business days of waiting for a response to a support ticket. I called TI today to see if I could get through to anybody and was told that I'd be receiving a response by email today. The response I received by email today told me to ask at the E2E forum. Exactly what part of that required 3 days? Very disappointed with TI customer service right now.

  • 0
    TI__Mastermind 30310 points

    I need to see a picture of the schematic to verify how it is connected.

    Your description is correct but obviously something is not matching up.

    Using lower resistor values than 200kOhm should produce a lower voltage on VREF2, but you are claiming the opposite is true.

    Also, I think you have a typo in the last line of the 1st paragraph:

    "Reducing the resistor further to 2k gives 492mV at VREF1 (1.4 mA of sink current)." This should be VREF2, correct?

    Please label your voltages on the schematic and we will be able to resolve this.