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LMK62I0 LDO selection

Gowthamman G
Prodigy 35 points
Other Parts Discussed in Thread: LMK6H

I am using the HCSL 100MHZ 1.8V VIN - OSC -LMK6HA10000ADLET . So I have 5V power supply in my tester and I need to convert them in to 5V ( VIN) to 1.8V (VOUT ) - (1.5 to 2 A - Load Current - Current is more because we have 8 OSC on the board ) with less Voltage ripple to avoid some Jitter issue caused by power.

When I read the data sheet of  LMK6HA10000ADLET has built in LDO with good PSSR. But I am unable to find the on CHIP LDO inside the OSC - Noise immunity !! 

But I selected One voltage regulator with less BOM cost !! the part number is TPS7A9001DSKR by TI webench. Could TI team can help to verify this Voltage regulator  is best for this OSC Power supply ? looks like 11.5mV voltage ripple is there in this part it will accepted by LDO inside the OSC ?  or TI can suggest any power supply for my requirement ?

 I read the  LMK6HA10000ADLET EVAL board also they have used TPS7A9000DSKR but it will supply only 500mA only

  • 0
    TI__Genius 12420 points

    Hi Gowthamman, 

    We have some PSRR specs in the LMK6H datasheet, are you looking for a spec that isn't mentioned there? I believe the voltage ripple LMK6H can tolerate mainly depends on the specific phase noise requirements for your system. 

    I can also forward this thread to another product line for specific voltage regulator recommendations. 

    Regards, 

    Connor 

  • 0 in reply to Connor Lewis
    Prodigy 35 points

    When I read the datasheet They said this OSC has Inbuilt LDO so the Output of LDO goes To the  internal circuitry and input of the LDO which I need to connect the external Voltage regulator - for this I asked the allowed Output ripple spec of my Voltage regulator going to connect with on CHIP LDO input. i am not sure about phase noise requirement .

  • 0 in reply to Gowthamman G
    TI__Genius 9260 points

    Hi Gowthamman,

    You can have that ripple injected on the part. It would just degrade the jitter performance as mentioned in the datasheet. If you have decoupling cap to ground that would also help smooth out this ripple.

    Best.

    Asim

  • 0
    TI__Genius 12420 points

    Hi Gowthamman, 

    I was re-reading through this thread and I noticed that you mentioned LMK6HA10000ADLET. I just wanted to double check because LMK6HA10000ADLET is the 2.5V/3.3V variant, and LMK6HA10000BDLF is the 1.8V variant that I believe you're looking for. Note that we have only released the 1.8V 100 MHz HCSL variant in the DLF (2.5 x 2.0 mm) package for now but the DLE (3.2 mm x 2.5 mm) package will be coming later. 

    Regards, 

    Connor