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AFE5809: Demodulator's DVDD_LDO1/2 sepcification questions

Genius 3105 points

Replies: 14

Views: 637

Part Number: AFE5809

Hi there,

For AFE5809, DVDD_LDO 1/2, it is digital power for modulator. It can be internally generated. also , external higher performance 1.4-V supply can be applied to N4 and N6 for minimizing digital noise emission.

What is the requirement for this power supply if we use external spply? Such as, current it consumes, noise requirement, and so on?

Thanks! 

  • In reply to Chen Kung:

    Hi Yi,
    How are you?
    Please look at AFE5809's EVM schematics shown on the AFE5809 User's Guide (page 38),
    DVDD_LDO1 and DVDD_LDO2 connections from the external supply,
    we are using one TPS79601 LDO to provide all the power
    to DVDD_LDO1 and DVDD_LDO2
    because it can support the output current up to 1A.

    Thank you and best regards,
    Chen
  • In reply to Chen Kung:

    Hi Chen, Thanks for you patient answer !

    We will follow the spec and seperate DVDD_LDO1/2 on PCB. 

    I noticed that on page 15-16 of datadsheet, when demodulator is enabled, the additional power consumption is typ.90mW/CH on the basis of max. 190mW/CH. That is 50% increasement. 

    For 16pcs AFE5809 for our system, no matter internall or external power supply for demodulators, the additional current on D1V8 or on DVDD_LDO1/2 should be : 

    90mW/CH * 128Channel* 130%(margin) / 1.8V = 8320mA. This is a big increase on current. And I think we have to change our power tree structure. 

    Thanks.

  • In reply to yi xiao:

    Hi Yi,
    How are you?
    Our system engineer recommended
    you can find 6A LDO from TI website to support high current consumptions
    for DVDD_LDO1 and DVDD_LDO2 pins when running external mode.

    Thank you!
    Have a nice day!

    Best regards,
    Chen
  • In reply to Chen Kung:

    Hi Chen, that is just what I am planning to do. Thanks.

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