TXS0108E: The drive capability of TXS0108E

Jay Li

Prodigy 110 points

Part Number: TXS0108E
Other Parts Discussed in Thread: TPS55288, TXU0304, TXU0104, TXU0204

Hi，

We found a question in the application of TXS0108E.

In our application , VCCA=1.8V , VCCB=3.3V.

we connect A1 pin to the IO of FPGA 1.8V bank and B1 pin to the EN pin of TPS55288.

There is a 1K pull-down resistor on the EN pin of TPS55288.

The voltage on B1 pin drop from 3.3V to 0.9V in this condition .

We would like to ask why the TXS0108E can't drive the EN of TPS55288 ?

The current on the EN pin of TPS55288 is only 1mA.

The output current of TXS0108E is max 50mA.

Thanks

Best regards

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 284820 points

What the absolute maximum ratings describe are not characteristics of the device, but limits that your circuit must not try to exceed.

The guaranteed output current can be found in the test conditions of the V_OH specifications in section 6.5; it's −20 µA. (The TXS is a passive switch; the output high voltage is created only be the internal 4 kΩ pull-up resistor.)

You need a different level translator. Try the TXU0104/TXU0204/TXU0304.

0 Jay Li over 2 years ago in reply to Clemens Ladisch

Prodigy 110 points

OK，I understood the drive capability of TXS0108.

But we found the other question：

The I2C interface after TXS0108 level shifter can communicate with M24512 , but can not communicate with PCA9655E .

What is the reason ?

PCA9655E-D.PDF M24512-RMN6TP.pdf

+1 Clemens Ladisch over 2 years ago in reply to Jay Li

Guru 284820 points

This is an entirely different question. Please create a new thread, show the schematic, describe what exactly "can not communicate" means, and, if possible, show oscilloscope traces of the I²C signals.

+1 Jay Li over 2 years ago in reply to Clemens Ladisch

Prodigy 110 points

OK, I will create a new thread to ask this question.

Thanks.

Logic

Logic forum

TXS0108E: The drive capability of TXS0108E