0
\$\begingroup\$

I am trying to understand the block diagram of the TXS0108E bidirectional logic shifter. In the chip's description it says

When the output-enable (OE) input is low, all outputs are placed in the high-impedance (Hi-Z) state.

However at page 18, this block diagram is given:

enter image description here

There are pull ups at both the Va and Vb side pins, so if the gate at the centre is not turned on, shouldn't the Va and Vb side pins have a voltage of Va and Vb respectively?

If I understand correctly, something like this would give a high impedance output when the input level is 0

enter image description here

but the pull ups in the TXS0801E chip should prevent the output from going high impedance. So what does it mean when it says the chip outputs are placed in high impedance when the OE pin is set to low?

\$\endgroup\$

2 Answers 2

1
\$\begingroup\$

Rpua and Rpub are disabled when the OE is driver low.

The block diagram doesn't clearly show that though. Paragraph below the block diagram states the above quoted line.
enter image description here

\$\endgroup\$
1
\$\begingroup\$

The resistors must have a switch in series with each that is not shown. The datasheet says explicitly:

enter image description here

\$\endgroup\$

This site is temporarily in read-only mode and not accepting new answers.

Not the answer you're looking for? Browse other questions tagged .