Low power voltage translation

Andrey Limonchenko

Other Parts Discussed in Thread: SN74AUP1G34, SN74AUP2G126

I'm looking on the best way to interface 2.2V and 1.8V systems. Direct connection draws ~40uA. I only have 20uA in my budget. I have tried a bus switch solution, but apparently they are optimized more for speed than for power, and all of them contain pullup resistors of 40K or less drawing too much excess current. I need two logic lines down, two logic lines up, and one logic line bi-directional. The speed is not critical to the design. Thanks for any thoughts on this.

over 13 years ago

0 Chris Cockrill over 13 years ago

TI__Mastermind 46480 points

High Audrey

Not sure why you would need t translate since 1.8V is a good high for 2.2V Vcc. and 2.2V should not be too high for 1.8Vcc.

Here is one way to do it. This will require single parts for each line. this will be only about 6ua total.

2 x SN74AUP1G34 for translating down with Vcc set to 1.8V and input can be 2.2V with output equal to Vcc, less than 1ua each

2 x SN74AUP1T34 for translating up with Vcc set to 2.2V and input can be 1.8V with output equal to Vcc or you could use the AUP1G34 again but current might be slightly higher. Less than 1ua each

1x SN74LVC1T45 for bidirectional translation, less than 2ua

0 Andrey Limonchenko over 13 years ago in reply to Chris Cockrill

Prodigy 50 points

Why does Page 5 has Delta Icc rating as 40uA:

ΔICC VI = VCC – 0.6V IO = 0 3.3 V 40uA

This means that when the inputs is not at VCC, then it's is going to draw extra 40uA?

0 Chris Cockrill over 13 years ago in reply to Andrey Limonchenko

TI__Mastermind 46480 points

Hi Andrey

Yes The closer to Vcc or gnd the less current it will draw. Or the closer you get to the switching threshold the more current it will draw.

The AUP family is the lowest supply current parts we have. The AUP1T devices have their threshold lowered so that if you High is not quite Vcc it will stii be farther away from the threshold and draw less current.