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TXS0104E: electric leakage

run Ren
Prodigy 220 points
Part Number: TXS0104E
Other Parts Discussed in Thread: TXB0104, SN74AXC4T245, SN74AVC2T245, SN74AXC1T45, TXB0102

Hi :

I use the level conversion chip of TI. May I ask you some questions? Thank you!

1.TXS0104EPWR level conversion chip, VCCA connect 3.0V, level conversion chip will have leakage of 103uA.If the A1 channel of the level conversion chip is connected with a voltage greater than 3.0V, leakage of 2-3uA will occur,If I choose TXB0104, will there be leakage of electricity?

2.TXS0104 from the internal block diagram is a pull up resistance, VCCA on the power, all channels have voltage;And TXB0104 internal no pull-up resistance, is it true that after VCCA on, the corresponding channel no voltage output?

3.The current TXS0104 module TXD greater than A1 channel voltage, there will be leakage of 3uA, which will affect the PSM consumption of the module,Can you recommend a module TXD voltage will not leakage to level conversion chip IC?

My actual operation principle diagram is as follows, please guide me:

  • 0
    TI__Genius 16735 points

    Hi,

    1.

    Can you clarify what the conditions are when the leakage is occurring and how you are measuring the leakage? Is there leakage when VCCA is 2.8V? What is the input signal range when this leakage is occuring? This is high amount of leakage current and I can't know if changing to TXB will fix this.

    I do notice that your signals are of fixed directions, so the SN74AXC4T245 might be a better.

    2.

    TXS output has a defined state because of its pullup resistors as you have said. TXB device will also have voltage output but it won't be a defined state.

    3.

     How much higher is the TXD voltage to the channel voltage? Again maybe changing to an AXC part might help fix the problems.

    I have informed our translation expert. He should be helping you with this issue.

    Thanks!

    -Karan

  • 0
    TI__Guru 62600 points

    Hi Run Ren,

    You are using only 2 channels with the other 2 IO channels grounded. I would suggest to switch to either the SN74AXC1T45 (x2) or consider using the SN74AVC2T245 which have dual direction pins to allow the UART communication.

    103uA is very high leakage. Is it measured from the Vcca/ Vccb pins or going into or out of IO pins? What is the clamp current on the Vcc supplies? 

    You have the A3,A4, B3, B4 grounded. could this be due to this? You can leave the unused pins IO floating in the TXS devices as they are held internally by the pullup resistors. Also, I would recommend to remove the 120K pulldown to gnd on the OE pins. 

    I believe that the bypass caps are connected to the supply pins and not to the A1, A2 pins. Is the level conversion from 2.8V to 3.3V? Generally, the Vih of the logic devices can accept 2.8V input with 3.3V supply.

    TXB0102 shouldnt have leakage either, similiar to the TXS device. I do not see IO leakage specifications in the datasheet when the device is active. We only specify Ioff ( either Vcc is at 0V) or Ioz (when OE is low).