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LMK01801: Register Programming

Brenton Yiu
Prodigy 80 points
Part Number: LMK01801

We are experiencing issues programming the LMK01801 and require clarification on information from the datasheet.

In section 9.5.1, "Registers are programmed in numeric order with R0 being the first and R15 being the last register programmed. The recommended programming sequence involves programming R0 with the reset bit (b4) set to 1 to ensure the device is in a default state. Then R0 is programmed again, the reset bit is be cleared to 0 during the re-programming of R0."

Is it required to program all registers every time we would like to enable / disable a clock output or is the following acceptable? We would like to be able to modify only a single clock output without resetting and reprogramming (which would upset other clock outputs we'd like to remain configured). Our preferred approach would be:

  1. On initialization, follow recommended programming sequence programming all preferred register settings (but leaving CLK0 and CLK2 disabled for now)
  2. When deemed necessary, write to only Reg1 to enable / disable CLK0
  3. When deemed necessary, write to only Reg1 to enable / disable CLK2
  • +1
    TI__Guru** 106960 points

    Hi Brenton,

    After a Vcc power up, we need to follow the recommended programming sequence in order to (1) clean the register content with RESET and (2) program all registers once to configure the device.

    After that, we only need to program the necessary register only. For example, if you change the divider value, simply program the related register, no need to program all registers.