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TXB0102: TXB0102 configuration problem

Kun Yuan
Intellectual 945 points
Part Number: TXB0102

Hi!

TXB0102 typical application and our schematic are  as follow:

1 we must use a processor to control the EN of TXB0102.

So the first question is, if there is no processor in the our system, will this chip not be used?

2 we can find the follow description :"OE must be tied to GND through a pulldown resistor to assure the high-impedance state during power up or power down; the minimum value of the resistor is determined by the current-sourcing capability of the driver." 

so the 2rd question is if I pull up the OE to VCC, what will happen?

  • 0
    Guru 297210 points

    You can connecte OE directly to VCC if you do not care about the state of the I/Os during power up.

    A processor would be necessary only if you actually wanted to change the value of OE.

    Please note that the TXB has integrated 4 kΩ series resistors. R1149/R1150 increase the impedance to 4033 Ω, which makes no difference; remove them.

  • 0 in reply to Clemens Ladisch
    Intellectual 945 points

    Thanks for your quickly response. So if I connect OE directly to VCC.

    what will happen? Or what is the worst situation to signal or other.

  • 0 in reply to Kun Yuan
    Guru 297210 points

    If OE is high during power-up, then the I/Os are not in the high-impedance state. And as long as the supply voltage has not yet reached the minimum listed in the recommended operating conditions (1.2 V VCCA, 1.65 V VCCB), anything could happen. In particular, the edge rate accelerators on either side could activate.