Hi, I have a question about level shifter IC.

Yunsik Chung

Other Parts Discussed in Thread: TXS0108E

Hi,

I was studying about communication between two IC which use different supply voltages.

I started wondering the difference between using pull-up resistor and using level shifter IC(like TXS0108E) to make ICs communicate.

If i understood it correctly, when we use open drain topology, without using level shifter IC, by just using pull-up resistor with proper supply voltage we can make two IC communicate like below.

Then, why do we need level shifter IC(like TXS0108E) between two different supply voltage ICs?

what is the advantages of using level shifter IC compared to using just pull-up resistor?

Thanks,

Yunsik

over 5 years ago

0 Clemens Ladisch over 5 years ago

Guru 316920 points

An open-drain output like this can be use for unidirectional level shifting.

Lever shifter ICs like LSF/TXS allow bidirectional signals and have automatic direction sensing. The TXS also has edge accelerators to allow higher speeds than those that could be reached with passive pullup resistors.