SN74LVC2G66 power off state

Shu-Cheng LIN

Other Parts Discussed in Thread: SN74LVC2G66, SN74CB3Q3305

Hi Sir,

Sorry to bother you.

We used SN74LVC2G66, have some question need to check.
Because we use SN74LVC2G66 to switching I2C at power S5 state, We have pull high 3.3v at I/O. But if SN74LVC2G66 no VCC, the I/O will be pull low to 0.7-0.9v.
It's will make the I2C send wrong signal.

So we would like check what is I/O state of SN74LVC2G66 at power off? Hi-z or???
If possible, could you provide suitable solution for us( Dual SPST and Hi-z at power off)

Thanks for your reply.

over 10 years ago

0 Clemens Ladisch over 10 years ago

Guru 327370 points

The datasheet specifies the maximum switch I/O voltage as V_CC + 0.5 V. If you exceed that, current flows through the protection diode from the output to V_CC.

TI has lots of digital switches with I_OFF feature, but there are probably other solutions.

0 ShreyasRao over 10 years ago in reply to Clemens Ladisch

TI__Guru 64290 points

Hi Shu Cheng ,

The Vcc is required for the I/os to work and unless there is Ioff feature in the device , it could be harmful to have IO voltages .

0 ShreyasRao over 10 years ago in reply to ShreyasRao

TI__Guru 64290 points

You can consider the SN74CB3Q3305 device . This is dual SPST and has Ioff feature and OE for Hi-Z state .

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SN74LVC2G66 power off state