Programming Description

3.0 INPUT DATA REGISTER

The descriptions below describe the 24-bit data register loaded through the MICROWIRE Interface. The data register is used to

program the 15-bit IF_R counter register, and the 15-bit RF_R counter register, the 15-bit IF_N counter register, and the 19-bit

RF_N counter register. The data format of the 24-bit data register is shown below. The control bits CTL [1:0] decode the internal

register address. On the rising edge of LE, data stored in the shift register is loaded into one of 4 appropriate latches (selected

by address bits). Data is shifted in MSB first

MSB

LSB

DATA [21:0]

CTL [1:0]

23

2 1

0

3.1 Register Location Truth Table

CTL [1:0]

DATA Location

10

0

0

IF_R register

0

1

IF_N register

1

0

RF_R register

1

1

RF_N register

3.2 Register Content Truth Table

First Bit

REGISTER BIT LOCATION

Last Bit

23

22

21 20 19

18

17

16 15 14 13 12 11 10

9

8

7

6

5

4

3

2

1

c1

0

c2

IF_R

OSC

FRAC_16

FoLD

IF_CP_WORD

IF_R_CNTR

0 0

IF_N

IF_CTL_WORD

CMOS OUTPUTS/

FRAC TEST

IF_NB_CNTR

IF_NA_CNTR 0 1

RF_R DLL_MODE

V2_EN

RF_CP_WORD

RF_R_CNTR

1 0

RF_N

RF_CTL_WORD

C_WORD

B_WORD

A_WORD

FRAC_CNTR

1 1

4.0 PROGRAMMABLE REFERENCE DIVIDERS

4.1 IF_R REGISTER

If the Control Bits (CTL [1:0]) are 0 0, when data is transferred from the 24-bit shift register into a latch when LE is transitioned

high. This register determines the IF R counter value, IF Charge pump current, FoLD pin output, fractonal modulus, and oscillator

mode.

MSB

LSB

OSC

FRAC_16

FoLD [2:0]

IF_CP_WORD [1:0]

IF_R_CNTR [14:0]

0

0

23

22

21

19 18

17 16

2 1

0

4.1.1 OSC

(IF_R[23])

The OSC bit, IF_R [23], selects whether the oscillator inputs OSC

a common input signal path. When OSC=0,the OSC

When the OSC = 1, the OSC

4.1.2 FRAC_16

(IF_R[22])

The FRAC_16 bit, IF_R [22], is used to set the fractional compensation at either 1/16 and 1/15 resolution. When FRAC-16 is set

to one, the fractional modulus is set to 1/16 resolution, and FRAC_16 = 0 corresponds to 1/15 (See section 5.2.3).

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