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SCAN15MB200: Is there any part P2P to SCAN15MB200 but lower Vcm?

Jenny Chen
Intellectual 2380 points
Part Number: SCAN15MB200

Tool/software:

Hi team,

The application now requires the Vcm=0.8V according to the IEEE1149.6 IC spec.

However, we now used SCAN15MB200 the Vcm=1.2V.

Is there any part with the P2P but lower Vcm?

Thanks!

Have a nice day, 

Jenny Chen

  • +1
    TI__Guru**** 177141 points

    Jenny

    The SCAN15MB200 is intended for high-speed signaling up to 1.5 Gbps and includes IEEE1149.6 on all differential inputs and outputs. You do not need a different part to support IEEE 1149.6. 

    You would need to use AC coupling caps to isolate the VCC offset from the source that has the VCM of 0.8V and then implements a voltage divider to set the appropriate common-mode voltage across the SCAN15MB200 LVDS receiver (should be around 1.2 V) while also providing a failsafe bias for the LVDS receiver. I recommend using higher value fail-safes (such as R1 (resistor to VCC) = 13 kOhm and R2 (resistor to GND) = 8 kOhm) to further minimize waveform distortion.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Intellectual 2380 points

    Hi David,

    It should be a little bit misleading as I mentioned about common mode voltage capacitance.

    The product test card is designed to detect that our customers have a capacitance on them to catch the common mode voltage on my side.

    One of my concerns is that when the customer's board capacitors are shorted together (the customer's bad pcs), the customer's IC will be broken.

    This is because the original purpose is to see if the capacitance of the board to be tested is good

    Higher value fail-safes:(such as R1 (resistor to VCC) = 13 kOhm and R2 (resistor to GND) = 8 kOhm).

    =>Can you draw me a reference circuit

    Thanks a lot!

    BR,

    Jenny

  • +1 in reply to Jenny Chen
    TI__Guru**** 177141 points

    Jenny

    Please see this app note, https://www.ti.com/lit/ab/slaa840/slaa840.pdf, on AC coupling the LVDS input, in particular Figure 4 of the app note on the R1 and R2 implementation.

    Thanks
    David