lmk03000c National Semiconductor Corporation, lmk03000c Datasheet - Page 11

• Manufacturer Part Number: lmk03000c
• Description: Precision Clock Conditioner With Integrated Vco
• Manufacturer: National Semiconductor Corporation

2.0 General Programming Information
The LMK03000/LMK03000C/LMK03001/LMK03001C devices are programmed using several 32-bit registers which control the
device's operation. The registers consist of a data field and an address field. The last 4 register bits, ADDR[3:0] form the address
field. The remaining 28 bits form the data field DATA[27:0].
During programming, LEuWire is low and serial data is clocked in on the rising edge of CLKuWire (MSB first). When LE goes high,
data is transferred to the register bank selected by the address field. Only registers R0 to R7, R11, and R13 to R15 need to be
programmed for proper device operation.
For the frequency calibration algorithm to work properly OSCin must be driven by a valid signal when R15 is programmed. Any
changes to the PLL R divider or OSCin require R15 to be programmed again to activate the frequency calibration routine.
2.1 RECOMMENDED PROGRAMMING SEQUENCE
The recommended programming sequence involves programming R0 with the reset bit set (RESET = 1) to ensure the device is
in a default state. It is not necessary to program R0 again, but if R0 is programmed again, the reset bit is programmed clear (RESET
= 0). Registers are programmed in order with R15 being the last register programmed. An example programming sequence is
shown below.
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Program R0 with the reset bit set (RESET = 1). This ensures the device is in a default state. When the reset bit is set in R0, the
other R0 bits are ignored.
— If R0 is programmed again, the reset bit is programmed clear (RESET = 0).
Program R0 to R7 as necessary with desired clocks with appropriate enable, mux, divider, and delay settings.
Program R11 with DIV4 setting if necessary.
Program R13 with oscillator input frequency and internal loop filter values
Program R14 with Fout enable bit, global clock output bit, power down setting, PLL mux setting, and PLL R divider.
Program R15 with PLL charge pump gain, VCO divider, and PLL N divider. Also starts frequency calibration routine.
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