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PCA9306: VREF1=VREF2 =EN 5V

cafain
Mastermind 6775 points
Part Number: PCA9306


Hi, Staff

I plan to use PCA9306 with Vcc1 = Vcc2 = 5V.
Data sheet (SCPS113N) page12 Figire8-5 has a connection example of Vcc1 = Vcc2.

This circuit configuration controls the switch by the input to EN.

Question
1. Is there any problem with the method of shorting EN and Vref2 (always switching ON operation)?

2. If VREF2 + Vth is required for the EN signal, is it necessary to apply 5.7V?
* VREF1 = VREF2 = 5V, Vth = 0.7V

best regards
cafain

  • +1
    Guru 319720 points

    1. It is possible to have the same voltage and EN always high. But what would be the purpose of a switch that is always on? You could replace the PCA9306 with two wires.

    2. Figure 8-5 shows that this is not necessary. Having the gate voltage (EN) above VREF1 can speed up switching because a high-level signal on side 1 would not need to completely (discharge) the gate.

  • +1
    TI__Guru* 78111 points

    Hi Cafain,

    Clemen's is correct as usual.

    I'll add some more context though.

    cafain said:
    2. If VREF2 + Vth is required for the EN signal, is it necessary to apply 5.7V?
    * VREF1 = VREF2 = 5V, Vth = 0.7V

    If your enable voltage is lower than your Vref1/Vref2 voltage then the device will still work but the consequence is you're Ron will be weaker (larger) and your footroom (I don't like to use the term ViL but you could imagine this is ViL) is lowered.

    -Bobby

  • +1 in reply to BOBBY
    Mastermind 6775 points

    Hi Clemens-san, BOBBY-san

    Thank you for your prompt comment.
    The existing circuit had a level conversion of 3.3V-5V.

    Since 5V-5V can be used by changing the circuit, the purpose was to check whether the PCA9306 can be used as a wire function.
    However, in reality, we plan to remove PCA9306.

    best regards
    cafain