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LMK04610: About SYSREF Settings

Toshiyuki
Mastermind 7075 points
Part Number: LMK04610


Hi,

I'm confirming SYSREF mode of LMK0461x. Concerning the termination for SYSREF, we need to  adopt DC-Couple because our customer requires a couple of SYSREF Pulses. I understand the LMK0461x Family have much more benefits than LMK048xx. However, LMK0461x has only HCSL and HSDS output interface. Thereby, for LVDS Receivers, I doubt  whether there is a method to DC-Couple, while LMK048xx has LVDS format. Would you provide information about the method of SYSREF design ?

Best Regards,

Toshiyuki

  • 0
    TI__Genius 9920 points

    Hi Toshiyuki,

    What's the requirements (Vod: swing on a single line; Vim: input common mode voltage)for the LVDS receiver ?

    This post also could be referred. Here is the link:

    LMK04616: About output 100 ohm termination.

    Regards,

    Shawn

  • 0 in reply to Shawn Han
    Mastermind 7075 points

    Hi Shawn,

    Thank you for your reply. I've attached LVDS standard spec. We need to generate a couple of pulses for SYSREF steadily.

    Best Regards,

    Toshiyuki

  • 0 in reply to Toshiyuki
    TI__Genius 9920 points

    Hi Toshiyuki,

    Considering Vin range 0~2.4V and Vth typ +100mV, HSDS 4mA could satisfy it.

    HSDS 6mA also is fine.

    This is the HSDC to LVDS AC coupling connection. If LMK04610 output VOH and VOL satisfy the LVDS receiver's VIH and VIL, DC coupling is allowed, just short two AC caps.

    If the 100 Ohm load had been integrated in LVDS receiver, the external 100 Ohm also could be removed.

    Considering SI design, you could place two serial 0 Ohm resistors at HSDS driver side. (AC caps become resistors, and move them at HSDS driver side.)

    Please double check real requirements for your LVDs receiver. Thanks.

    Regards,

    Shawn