AD8232 not outputting any signal

Hello,

Recently I purchased the AD8232 evaluation board and it has been working perfectly.

After seeing that this worked, I purchased some AD8232 IC's from digikey and populated my own PCB that had the exact same schematic as the evaluation board.

I unfortunately see nothing coming from the output of the AD8232.  Just a zero volt signal.

I've tried both 2 lead and 3 lead designs.

I've ordered more AD8232 components in case I received a bad batch of components.

I've tried both reflow and hand soldering.

Even with all these variations, I could not get anything to work.  A couple of times a board would work for a few minutes and then return to outputting a zero volt signal.

At this point I assumed that maybe the component was just extremely sensitive to stray impedance, so I decided to copy the exact layout.

I ordered a different eval board from Spark Fun (SparkFun Single Lead Heart Rate Monitor - AD8232 - SEN-12650 - SparkFun Electronics), tested it to see that it worked, and then copied the layout and made my own PCB using Advanced Circuits (www.4pcb.com).

Unfortunately, this still didn't work.


After reading around the forum it doesn't seem like anyone else is having this problem...

Does anyone have an idea why I can't get this IC to work on my own boards?


Thank you!

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  • Thanks for the advice Gustavo,

    I was very careful with the soldering this time and washed the board and I am now getting an output signal.

    Unfortunately, the output I'm getting is a square wave of 20Hz that goes from ground to 3.3v (this is vdd for me).

    I put a probe on the IAOUT pin and I see heart rate there!

    When I put a probe on the SW pin (this is after the passive hpf that is after IAOUT), I see this 20Hz signal being interjected on the heart rate signal.

    I have a LPF with some gain after this, so my guess is that the 20Hz signal is causing saturation after the amplification so the heart rate is no longer noticeable.

    any thoughts as to why 20Hz noise is coming from the SW pin?  My AC/DC pin is grounded and my FR pin is pulled high.  I've triple checked these connections.

    Thanks,

    James

  • Try to change output amplifier gain, decrease the gain until you see desired signal.

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