• Resolved

SN74LVC1T45: Backdrive when powered off causes chip to turn on and latch output low

Prodigy 40 points

Replies: 3

Views: 53

Part Number: SN74LVC1T45


Our customer is using a SN74LVC1T45 to drive an input to us which we have pulled up through a 49.9K to 3.3V and goes to a FET gate.  They are concerned that our pull-up can back drive their transceiver when they are powered down and cause it to power up and latch the output low.  I don't believe this is a real concern, but I'm trying to get some confirmation of whether this is a concern or not.  Any help is greatly appreciated.

  • Hey Jeremy,

    This FAQ should clear up the concern here.

    Check out our new AXC family of Voltage Translators! 

    Watch the Introduction to AXC Family to find out more about the family.

  • Dylan,

    This FAQ discusses Ioff for partial power down where only one of the supplies is on and if you backdrive the device.  Does this still apply if both supplies are off?   If both supplies are off and I back drive the output with 3.3V then is the output still high Z with an Ioff maximum current draw of only 2uA?

  • In reply to Jeremy Richardson:

    Hi Jeremy,

    Yes, this applies when both supplies are off. From the datasheet EC table:

    The highlighted values are for the V_CCA and V_CCB columns.

    Looking for a low voltage translator? Check out the AXC family that supports 0.7V to 3.3V translation!

    The Logic Minute training page has videos on many interesting topics that all are kept shorter than 5 minutes.