Other Parts Discussed in Thread: SN74LV541A, SN74LV4066A, TPS22948, UCC27519
Tool/software:
I am trying to use the bus switch to optionally to pull up a bunch of nets to 5 V. The schematic is as shown below. I want to be able to use both the 16811C and 16211C, so I implemented the bias side (B) as the source and the non-biased side (A) as the sink. I doubled up channels 1 and 2 just to reduce the on-state resistance further. With a 1.6 kΩ pull down to GND on the A-side I am seeing the on-state resistance between B and A being about 1.2k (I measure 4.99 V @ B, 3.66 V @ A). With 40 µA of pull-down I'm seeing an on-state resistance of 29.3k between A and B.
I've confirmed when I apply 3V3 to !OE that the pull up through U900 disappears, so this suggests the chip is "ON" but no current is getting through. I measured the same behavior on every channel and two cards, so the result is consistent. What am I doing wrong, and why isn't the switch turning fully on?