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SN74LVC244A: Ioff feature

Koshi Ninomiya

Expert 5595 points

Part Number: SN74LVC244A
Other Parts Discussed in Thread: SN74LVC1G125

Dear Team,

The SN74LVC244A datasheet shows the below at features.
- Ioff supports live insertion, partial-power-down mode, and back-drive protection

However, there is no description of Ioff at detailed description.
Vcc recommended operating range is 1.65V to 5.5V.
When Vcc=0V, Ioff feature works and Output becomes Hi-Z, riight?
When Vcc is between 0V and 1.65V during power up/down with /OE=Vcc, does Ioff feature work and Output become Hi-Z too?

Best Regards,

Koshi Ninomiya

0 Malcolm Lyn 6 days ago

TI__Mastermind 27140 points

Hi Koshi,

Your understanding is correct. Ioff is active when VCC=0, and the outputs are then high-impedance. If VCC > 0, Ioff does not work.

Best,

Malcolm

0 Koshi Ninomiya 6 days ago in reply to Malcolm Lyn

TI__Expert 5595 points

Hi Malcolm-san,

In case of the SN74LVC1G125, even if 0V < Vcc < 1.65V, Ioff works with /OE=Vcc.

SN74LVC1G125: Vcc condition for Ioff

The Ioff of the SN74LVC244A does not work when 0V < Vcc < 1.65V with /OE=Vcc, does it?

Best Regards,

Koshi Ninomiya

+1 Malcolm Lyn 5 days ago in reply to Koshi Ninomiya

TI__Mastermind 27140 points

Hi Koshi,

Ioff only applies for VCC=0V. Logic gates and switches with Ioff or powered-off protection: empowering you to po

If you tie the /OE to VCC with a resistor, then the outputs will be guaranteed Hi-Z when 0V < VCC <1.65V.

Best,

Malcolm