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LMK05318: LMK05318 input mode configuration

Part Number: LMK05318

Hi team,

My customer is using the LMK05318 now with 50ohm pull down configuration. But the front edge is LVCOMS output, so the system voltage is too low with 50ohm SE configuration.

1. How to deal with the terminator resistors?

2. Whether we can change the 50ohm SE to CMOS? Whether it has risks here with LVCMOS configuration?

3. What are the advantages and disadvantages?

 Thanks.

 

  • Hi Frank,

    If it's 3.3V CMOS, then with 50Ohm internal resistor it is fine because the swing is halved but still higher than the minimum swing in the datasheet (1Vpp). The only problem is that the DC current may be too high and it better be AC-coupled.

    Alternatively, you can select "CMOS" without internal termination. For 3.3V CMOS, add below resistor divider to reduce the swing to <2.6V. For 1.8V CMOS, no extra termination is needed.

    Regards,
    Hao