TXB0108: TXB0108

The TXB can source up to 0.02 mA. (The TXB outputs are very weak to allow other devices to override the voltage level; this is how the bidirectionality is implemented.)

How many LEDs do you have, and what is the voltage of the control signal? Would it be possible to drive the LED's cathode instead?

Hi,

Thanks for your reply.

I have two LEDs. Both are connected to the B port IOs of TXB01.
VCCB is 5V and LED forward voltage at 10mA is 2.2V.

If we are connecting to cathode, will TXB will be able to Sink 10mA of current in IO pin?

Whether the TXS also source up-to only 0.02mA?

Best Regards,
Shafeeq

The TXB's sink current also is 0.02 mA.

The TXS is a passive switch; it can source 20 µA (through its pull-up resistor), and it can sink as much current as the driving device can sink.

For the LEDs, it would be possible to use SN74LVC2G07 or SN74LVC2G06 as a buffer (the open-drain outputs are overvoltage tolerant). What are you using the other six channels for? Are any of those signals bidirectional? If not, a buffered translator might be a better option.

Hi,

We have tried connecting IO to cathode. The TXS is able to sink the current. But when we try to turn off the LED by making IO high, it is not able to turn it off completely.

What voltage is the anode connected to? If it's 5 V, no current should be able to flow.

Anode is connected to 5V and cathode is connected to TXS. But when IO is low, led is on. But when IO is high, the LED is on the brightness is very less. LED is not turning off completely. 

When the output is set to high, the voltage at led cathode 3.1V

If both ends are at 5 V, no current can flow. Please measure the voltages.