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Original question:

LMX2582: LMK04828,LMX2582,HMC987(ADI buffer)- LDO recommendation and single LDO for LMX2582 and HMC987

LDOs for LMX2582 , LMK04828 and Analog Devices clock buffer(HMC987)

LALIT VERMA
Expert 1695 points
Other Parts Discussed in Thread: TPS7A92, TPS7A90, TPS7A91, TPS7A89, TPS7A87, TPS7A88, LMX2582

Hi TI,

Asked this question on Clock and Timing forum. But got recommendation to ask here.

So I just posting the same question here. Please look into this.

We are going to use LMK04828, LMX2582 and HMC987 for clocking ADC12DJ3200. There will be three ADCs on single PCB.

LMK04828 will be used to provide SYSREF to ADC and FPGA.

LMX2582 will generate sampling clock and HMC987 will buffer this clock and provide sampling clock from three of its outputs to three ADC12DJ3200.

We will be using LDOs to power LMK,LMX and HMC987.

We are planning to use single separate LDO for LMK04828 and a single separate LDO for both LMX2582 and HMC987.

Please verify this:

 Can we use signle LDO for both LMX2582 and HMC987 or we need to use separate LDO for LMX2582 and HMC987 so that noise can't couple from LMX to HMC or vice-versa(although LMX and HMC will be running at same frequency i.e., @ 3.2 Ghz)

Also please suggest some LDOs which we can used with LMK and LMX,HMC987, without compromising LMK,LMX and HMC performance.

Thanks,

Lalit 

  • 0
    TI__Expert 4320 points

    Hi Lalit,

    For single-channel LDOs I'd like to recommend the TPS7A9x family: TPS7A90, TPS7A91, TPS7A92 which are are pin-to-pin compatible with each other (500mA/1A/2A variants).

    For dual-channel LDOs I'd like to recommend the TPS7A8x family: TPS7A87, TPS7A88, TPS7A89 which again, are pin-to-pin compatible with each other.

    I would suggest using single channel LDOs if isolation is not required. If isolation is required then I would recommend dual-channel.

    Regards,

    Wilson

  • 0 in reply to Wilson Fwu
    Expert 1695 points

    Hi Wilson,

    Thanks for the suggestion.

    I have a query:

    Is isolation required between power supply of LMX2582 and HMC987 for best performance?

    Thanks,

    Lalit

  • 0 in reply to LALIT VERMA
    TI__Expert 4320 points

    Hi Lalit,

    That depends on your end application and if you require it to be isolated or not. Isolation is usually required for safety. With that in mind, I'm not aware of any performance degradation of isolated vs non-isolated.

    Regards,

    Wilson