Logic Level Shifter for Low Power System

Hello Eric,

I have a few questions to move this request forward.

How many channels?

What data rate?

Any package restrictions such as no QFN packing?

Do the supply rails at 5 and 3 volts already exist such that you could make use of the dual supply shifter?

The key features to look at are the Icc current of the device in the datasheet.

Have you looked through the parametric search tool? I have narrowed do the search a little.

http://www.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=705&uiTemplateId=NODE_STRY_PGE_T#o7=Dual%20Supply%20Translator&p1498=Catalog

Let me know when you have the information to the questions above and you have had a chance to peruse the parametric search tool and a few of the datasheets of the available devices.

Ryan

Thanks for helping out. I only have 2 channels, the data line and the clock line for the keyboard.

Data rate: Enough to not be able to notice a different from whether the keyboard were plugged in to the PS/2 port versus running Bluetooth. Not really sure what that would be but any help calculating this value would be much appreciated.

Not really any package restrictions. 

Both supply rails will exist so I can use a dual supply shifter.

I'll continue looking at the link you sent me. But here is more information as of now, hadn't seen that before.

Eric

Hello Eric,

I would suggest looking at either the TXB0102 or the TXS0102.

Looking through the datasheets the TXB0102 might be a little bit lower power.

Are you using this for I2C? Otherwise I would ask if there is any chance that the keyboard side load is more than a few mA.

Ryan

The keyboard should draw no more than 275mA, modern keyboards draw a sizable amount less. And the PS/2 protocol has 1 data line(bi directional) and a clock line they are used serially with an 11-12bit frame. This link gives a decent explanation of how communication works: http://www.computer-engineering.org/ps2protocol/.

Eric

Hello Eric,

Alright thank you for the information on the application.

I would think that either of those two devices would work fine. Be sure that you configure side A and side B properly for the voltage that they are connected to with side A for the 3 V and side B for the 5V.

Hello Eric,

Thank you for the additional information.

Either of those devices should work fine for you application.