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TXB0104: TXB0104

Part Number: TXB0104
Other Parts Discussed in Thread: TXU0104

Tool/software:

Hi,

I am using the TXB0104 in my design (schematic attached.
in my design VCCB is 5V and VCCA is 3.3V

- The input to VCCB is off / 24V fed to the pins via resistor split as shown in attached picture.(i,e:   44.2K and 10K to GND)

The issue is that i expected to get 4.42V and i get 1.5V ( I verified and the reason is the connection to the IC). 

I tried also to alter the circuit and place on the input pin a p.d of 53.6K to GND and then find resistor so the overall divider will give me >3.25V (Vih min per datasheet)

1. I failed to find any combination to meet my needs.

2. my calculations assumed that maybe there is internal resistance in parallel to the 10K....i got ~4K)....and based on that tried to make divider to get correct Vi...but no success

3. why is it not that straight forward. 

4. i also tried to change the device to TXS0104...with external P.U...and no success