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Original question:

TRF3722: Reference Clock and PFD Feedthrough

TRF3722: getting the VCO to lock

Michael T Schneider
Expert 3790 points
Part Number: TRF3722

Hello Team,

We are having some issue with getting the VCO to lock, could you please see the code below for programming the TRF3722. Could you check to make sure that the registers are correct?

#i=8  <- this is the register address

#i=401b300  <- this is the data

0x10 0x06 0x6c 0x01  <-These are the bits that are sent thru the SPI in order of MSB to LSB  -> reverse of the address bit and data.

 

#i=c

#i=10

0x30 0x40 0x00 0x00

 

#i=a

#i=5578511

0x54 0x45 0x0f 0x55

 

#i=e

#i=88eac

0x71 0xab 0x88 0x80

 

#i=9

#i=1400816

0x93 0x40 0x80 0x14


#i=d

#i=33d5188

0xb0 0x8c 0x55 0xe6

 

#i=b

#i=0

0xd0 0x00 0x00 0x00

  • 0
    TI__Mastermind 18095 points

    Michael:

    Please provide a bit of background.

    • Is this issue on the TI EVM or customer board?
    • Is this integer mode or fractional mode?
    • What is the reference frequency?
    • What is the desired PFD frequency?

    Typical issues when the device does not lock is the reference frequency is not working or is at an unexpected frequency.  That can be checked.  You can use the TI EVM and associated GUI to ensure the programming for equivalent set-up is correct.

    --RJH

  • 0 in reply to RJ Hopper
    TI__Expert 3790 points

    It seems that the customer was sending the bits in reverse. this has been resolved. 

    thanks for the quick response.