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TCA9800: Can TCA9800 be used to switch the clock level?

Hailiang Zhang
Genius 11080 points
Part Number: TCA9800
Other Parts Discussed in Thread: SN74AUP1G17

Hi,

In the customer's barcode scanner, the RTC clock is required. The level of the clock generated by the active clock generator is relatively high (3.3V), while the MCU can only accept 0.85V. Can TCA9800 be used to connect the generator and MCU? I think TCA9800 supports a rate of 400kHz, which is sufficient for the RTC clock signal. Is it right?

Or is there a better solution or device?

Many thanks!

  • +1
    Guru 317060 points

    The TCA9800 translates bidirectional open-drain signals.

    For unidirectional downtranslation, you can simply use a buffer with an overvoltage-tolerant input, such as the SN74AUP1G17.

    Is the I/O voltage of the MCU really that low? Or does it want something like a sine wave with 0.85 V peak-to-peak?

  • 0 in reply to Clemens Ladisch
    TI__Genius 11080 points

    Many thanks.

    The input pin of the SN74AUP1G17  can tolerate a voltage higher than Vcc. Set Vcc to 0.85V, then It can convert the input 3.3V clock signal into 0.85V clock signal. Is that right?

    Does this type of level shift device cause distortion? Especially SN74AUP1G17 adopts Schmitt trigger input.


    In addition, what engineers really need is a single-ended clock signal.

  • 0 in reply to Hailiang Zhang
    Guru 317060 points

    Yes, the SN74AUP1G17 accepts any higher voltage, and outputs a digital signals at its own supply voltage.

    If the input signal is a square wave, the Schmitt trigger does not introduce additional distortion.

    Please specify the MCU that is being used.