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Original question:

TIPD111: Hardware "pace" using slope detection circuit work with Vcc as 3.3v instead of 5v.

TIPD111: Strange signal on the slope detection output

Damien_Effi
Intellectual 515 points
Part Number: TIPD111

Hello,

I did the Pace detection as mentionned in the TIPD111. Instead of 5V, I supplied the circuit to 3.3V.

This circuit is connected the PACE_OUT ADS1294R chipset.

I attached a scope where the channel 1 is ECG+Pace and channel 2 is the voltage at the OPA348.

With the whaletek tool, I can manage the Pace pulse voltage and duration.

Due to the strange singl on the Channel 2, I am not able to detect PACE level below 50mV.

I used exactly the same value mentionned in document.

Do you have an idea about the strange signal seen on channel2?

Due to the starnge signal on the OPA348 output signal, I can't decrease the pace level until 2mV. How to clean this?

Thanks,

Regards

Damien

  • 0
    TI__Genius 10850 points

    Hi Damien,

    Thanks for your post. Please accept delayed response as many of us are on holiday break. We will support you shortly.

    -Tamara

  • 0
    Guru 140200 points

    Hi Damien,

    the output signal of OPA348 looks more like an amplified and inverted copy of the input signal, as if the OPA348 would work as an inverter with a bit of gain.

    Are you sure that your signal generator has a 0R source impedance? Only then the OPA348 will work as true differentiator.

    Also, increase the supply voltage to 5V for a test.

    Kai