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SN74LVC16T245-EP: Partial Power Down- VCC Isolation Feature

Eren Erdogan
Intellectual 280 points
Part Number: SN74LVC16T245-EP

Hello TI,

 

I have some question about partial power down and vcc isolation feature

 

Q1: I'm planning to use translator in a system with two different voltage levels.

Vcca will always be active. Vccb will turn on and off from time to time.

I will make the OE pin high before turning off the Vccb

Is it ok to use it such a way?

 

Q2: When Vcca is active-Vccb is turned off, can I leave the Vcca input/output ports floating?

 

Q3: Does using this way for a long time affect the device in terms of reliability?

 

Regards,

Eren

  • +1
    Guru 243090 points

    1. Yes. (If /OE were low, it would be possible to get wrong signals while the supply on one side is too low to make the circuits work correctly.)

    2. The A input buffers are still powered, so they must not float. If the signals are not driven at all times, add pull-up or pull-down resistors (even weak ones).

    3. No; the absolute maximum ratings allow this.