Post Go back to editing

ADG3308 supply & control question

Hi, this looks like a question for FEB!

When using ADG3308 to interface between an MCU on 3V3, and a peripheral with 1V8 logic levels, is it possible to enable and disable the ADG3308 level translator by switching power (1V8) to the VCCA supply pin? I presume removing the VCCA supply would cause the A-side I/O pins to go high impedance, or at least make them go logic low? Would this cause any problems for the level translator, such as increased current consumption?

The reason for wanting to do this is that there is no permanent 1V8 supply available, but whenever the peripheral is enabled, it generates a 1V8 auxiliary output that could power a level translator.

If this is possible, what should be done with the ADG3308's EN input so that switching on the 1V8 supply again caused the level translator to be enabled properly? Would the ADG3308 or ADG3308-1 be better suited to this control method?

Thanks very much,


  • Hi John-

    Sorry for the delay on this.  I moved this question to the Interface and Isolation Community.  Someone here should be able to help you.



    EngineerZone Community Manager

  • Hi johnm,

    I wouldn't recommend powering down the A side supply to disable the device I/O pins as the I/O pins are not designed to go in the high impedance mode when this happens. As long as VCCA <=VCCY, I don't expect high supply currents on the VCCY rail with VCCA powered down.

    Please use the EN pin instead and since you need it to be 1.8V compatible, use the ADG3308-1 which meets this requirement. The EN pin on the ADG3308 is referenced to VCCY, so it will not work with 1.8V logic.