TXS0102: power consumption (supply current) when inputs are toggled

Hey Ting,

You can expect to have greater power savings using the TXB0102 over the TXS0102.

This difference stems from the architecture; the TXS is a switch type translator (TXS) using a pass gate transistor while the TXB uses buffers (TXB). The translator’s active buffer design means that it doesn’t have a constant drain current being dropped across internal resistors like the switch type of the TXS. If you look at the figure 5 in the TXS0102 datasheet it has two resistors, R1 and R2, which are 10k internal to the device.  A constant drop is going to appear and result in approximately 330uA on Vcca and 500uA on Vccb, I suspect this is what you’re seeing.

If you plan on replacing the TXS for the TXB component you should take into consideration your drivers and load impedance. Keep the following in mind:

- TXB is designed exclusively for push-pull while TXS also open-drain.

- TXB should only be used for capacitive loads below 70pF.

- TXB had protocols like SD and SPI in mind during design.

- TXS had protocols like I2C in mind during design.

More information can be found in the following TI documents:

“A Guide to Voltage Translation With TXB-Type Translators” 

"A Guide to Voltage Translation With TXS-Type Transistors"

Let me know if you have any more questions,

Nick