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TXB0104: multi-channel test is abnormal while single-channel test is correct

Xiaopeng Wen
Prodigy 90 points
Part Number: TXB0104
Other Parts Discussed in Thread: TEST2

Dear team,

Our customer found that errors appeared in some channels of TXB0104 when every channel has input signal. I did some tests shown in below. And VCCA=OE=1.8V, VCCB=3.3V, input signal is f=1kHz, amp=1.8V square wave.

  1. A2B single channel test is operating correctly. For example, A1 is input, and B1 output waveform is correct when A2-A4 is grounded. Attachment1 is test result. The blue line is input, the yellow line is output. 
  2. A2B multi-channel test is abnormal. When IN=A1=A2=A3=A4, B1-B4 are all abnormal. Attachment2 is the test result of B1 and B2 while B3 waveform is close to B2, and B4 waveform is close to B1.
  3. I added 65KΩ pull-up resistor between B1-B4 and VCCB based on test2, and the output waveform became correct.
  4. B2A test is correct whether in single channel or multi-channel test. (In B2A test, input signal is f=1KHz,amp=3.3V square wave, output is amp=1.8V square wave)
  5. I measured ICCA and ICCB when VCCA=OE=1.2V, VCCB=3.3V.ICCA is 0.005uA and ICCB is 0.5uA when VI=GND. And on the other hand, ICCA and ICCB both are 20uA when VI=VCCA. The ICC result is strange enough.

Attachment1：

Attachment2：

This is customer schematic circuit. 

Thanks!

     

  • 0
    TI__Guru 62270 points
    Hi Xiaopeng,

    Thanks for the schematic and scopeshots.
    I will review this and get back to you soon today.
  • 0
    TI__Guru 62270 points
    Hi Xiaopeng,

    Please send the scopeshots with the input and output measured at the same time. and also measure the another output channel.

    what are the connections after the TXB ports?
    from the schematic, i see that there are unconnected IO ports 3 and 4, however, the second experiment connects the inputs to all of the ports? is it being driven from single source?
    A measurement of the Vcca and Vccb on the scope can also be helpful to see how is it acting when the abnormal behavior occurs.
  • 0 in reply to ShreyasRao
    TI__Prodigy 90 points

    Hi Shreyas,

    Thanks for your reply.

    The schematic is customer's application design.And below is my test diagram.The TXB input is connected to signal generator while output is connected to digital oscilloscope.And the 4 channel inputs were  driven by the same signal generator in multi-channel test.  

                                        

    And I measured VCCA, VCCB, INPUT(A1-A4), B1, B2, B3, B4 at the same time, the result is attached below.

    1) INPUT(blue)-VCCA(green)-VCCB(purple) window time=100us

    2) INPUT(blue)-VCCA(green)-VCCB(purple) window time=20ns

    3) B1(blue)-B2(green)-B3(purple) window time=100us

    4) B1(blue)-B2(green)-B3(purple) window time=20ns

    5) B1(blue)-B4(purple) window time=100us

     

    6) INPUT(blue)-B1(green)-B2(purple) window time=100us

    If you want to know more test details, please be free to contact me via email. I'll still post our discussion points here for others' reference.Of course, E2E is OK.

    Best regards,

    Xiaopeng Wen

    e-mail: xiaopeng-wen@ti.com

  • 0 in reply to Xiaopeng Wen
    TI__Guru 62270 points
    Sure, Xiaopeng.
    Will work with you via email and post the resolution here once we have them.