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LMK00301: About LMK00301 unused reference

Vera Mao
Expert 5065 points
Part Number: LMK00301
Other Parts Discussed in Thread: LMK00304,

hi dear supporting team,

I have below questions on LMK00301 & LMK00304

1. for LMK00301 & LMK00304 unused ref input and output, could customer float it? 

2. and if  input LVDS signal into 00301 with DC coupling, the Vcm of LVDS  could be inside 0.25~2.2V right? (3.3V supply) 

3. for 00304 unused OSCIN&OSCOUT, could we float it? 

4. customer use below circuit for convert LVPECL output to LVDS to the load,  pls help comment whether it is ok. tks!

  • 0
    TI__Genius 16845 points

    A1. Unused inputs  and outputs can be left floating

    A2. Correct. I would expect the LVDS driver to set the common mode to 1.2V at the receiver for the DC-coupled configuration with 100 ohm differential load termination.

    A3. Correct

    A4. Does the receiver have integrated terminations? Does the reciever have integrated biasing? This will impact the termination network.
    The 182ohm resistors and 47.5ohm series resistor should be placed close to the driver. Use AC-coupling at the receiver before receiver terminations. If there is no integrated receiver termination, replace the 47.5ohm parallel terminations with a 100ohm differential load. If there is an integrated receiver termination, the customer can DNP the 47.5ohm parallel terminations. If the receiver does not have integrated bias, you will need to generate a bias at the receiver using kilohm resistors.

    Kind regards,
    Lane