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Original question:

MAX3232E: MAX3232E

MAX3232E: DOUT pulses

Naizeng Wang
Expert 5450 points
Part Number: MAX3232E

Tool/software:

Hi team, 

My customer encountered a problem. Power supply is 3.3V, customer uses 0.1uF for C1-C4. The actual capacitance is about 88nF. 

The schematic is shown as below. 

The waveform of DOUT is shown as below. You can see small pulses here. If they increase the capacitance of C3 and C4 to higher than 0.1uF, there is no pulses then.

I think this may be related to unstable power supply. Could you please share your insights? Thanks! 

  • 0
    TI__Guru 72901 points
    Naizeng Wang said:
    I think this may be related to unstable power supply. Could you please share your insights? Thanks! 

    Do those ripples show up on the power supply Vcc as well? Is there a switching regulator on the power line?

    Could you also get scopeshots of the V+ and V- pins?

    Naizeng Wang said:

    I

    Do you have a scopeshot of this with the GND reference and what is the vertical div? (5V/Div???)

    -Bobby