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SN65C3221 - Jaggy DOUT output waveform

Guru 19775 points
Other Parts Discussed in Thread: SN65C3221

Hi Team,

Please help us support SN65C3221. Customer is evaluating the device looking into the waveforms.At DOUT, they observed jaggy waveform. They are using the recommended cap value for each caps, C1 to C4 = 0.1uF @ VCC=3.3V.

Q). What would be the root cause for this jaggy output ?

It seems to be the switching waveform of the charge pumps. Lack of DC bias characteristics of the caps ?

We can share the schematic and the waveform information. Could you please allow us to discuss offline ? Please email me to the following email address.

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Best Regards,

Kawai

  • Kawai-san,

    The waveform is normal and does not affect the data integrity.
    The charge pump is a doubler that would normally generate (upto) 6.6V
    However the output is regulated to +/-5.5V to reduce power consumption.
    This is the case of the jaggy waveform.

    If desired, the magnitude of the jaggy wave can be reduced by increasing V+ and V- capacitor capacitance.
    Do not increase C1 as that will make it worse.

    Will can share files privately through a friendship conversation. I will send the request.
  • Hi Ron-san,

    Thank you for your support.

    Best Regards,
    Kawai