This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SN75176B: decoupling capacitor

Part Number: SN75176B

Hello E2E community,

The layout example in the datasheet for the SN75176B transceiver shows a capacitor from VCC to GND. The value of 1.5uF is rather large, and there is no other mention of the capacitor in the datasheet. When is this capacitor recommended or even necessary?

Best regards,
Stefan Altstadt

  • Stefan,

    Decoupling capacitance on the VCC rail (to ground) is useful in compensating for the inductance/resistance of a PCB's power routing and ensuring there is no voltage "droop" even as the IC draws current relatively quickly (in order to switch the output state, for instance). I would always recommend including this capacitance, but the relatively large value of 1.5 uF is not always necessary. In most applications 100 nF is suitable. Larger values could be useful if the power supply comes through a cable, if the PCB routing from the power supply to the IC is long/narrow, or if the power supply presents a large ripple voltage that needs to be filtered.

    Regards,
    Max
  • Hi Max,

    Thank you for the clear answer. I already have a 10uF "bulk" capacitor on the board, so I'll try with 100nF at the transceiver.

    Best regards,
    Stefan