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SN65C3232E: Capacitor Value

Shota Mago
Expert 6580 points
Part Number: SN65C3232E

Hi team, 

My customer provided a question in terms of capacitor value for SN65C3232E.

Datasheet shows VCC vs CAPACITOR VALUES table and it describes C1: 0.047µF/C2-C4 : 0.33 µF respectively under VCC=5 V ± 0.5 V.

The customer thinks these value are relatively large under condition that cable length is <1m and VCC=5V.

Would it be possible to reduce capacitor such as 0.1uF from 0.33uF under condition that cable length is <1m and VCC=5V.?

I'm looking forward to hearing back from you.

Best regards,

Shota Mago

  • 0
    TI__Mastermind 25705 points

    Shota,

    It's possible to use smaller capacitors. But in the meantime, please try to keep the ratio between C1/C3 and C2/C4. The ratio between the flying capacitor and storage capacitor makes sure the output ripple not too large. Please refer to this blog for the details.

    Regards,

    Hao

  • 0
    Guru 244270 points
    Reducing the flying capacitor C2 will increase the charge pump's output impedance. The datasheet values are chosen to support the specified worst-case load; if the actual load is smaller, the flying capacitor could be reduced proportionally.

    Reducing the output capacitors C3/C4 will increase the output ripple.