DATA SHEET • SKY72310 FREQUENCY SYNTHESIZER

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

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July 30, 2008 • Skyworks Proprietary and Confidential information • Products and Product Information are Subject to Change Without Notice • 200705E

Modulation Using the SKY72300, SKY72301, and SKY72302 Dual

Synthesizers/PLLs (document number 101349).

Register Descriptions

Table 1 lists the eight 16-bit registers that are used to program

the SKY72310. All register writes are programmed address first,

followed directly with data. MSBs are entered first. On power up,

all registers are reset to 0x000 except the Divider Register at

address 0x0, which is set to 0x006.

Synthesizer Registers

The Divider Register contains the integer portion closest to the

desired fractional-N (or the integer-N) value minus 32. This

register, in conjunction with the Dividend Registers (which control

precise frequency. As shown in Figure 5, the value to be loaded

is:

• Synthesizer Divider Index = Nine-bit value for the integer

portion of the synthesizer divider. Valid values for this register

are from 6 to 505 (fractional-N) or 0 to 511 (integer-N).

The Dividend MSB and LSB Registers control the fraction part of

to the main integer selected through the Divider Register. As

shown in Figures 6 and 7, values to be loaded are:

• Synthesizer Dividend (MSBs) = Ten-bit value for the MSBs of

the 18-bit dividend for the synthesizer.

• Synthesizer Dividend (LSBs) = Eight-bit value for the LSBs of

the 18-bit dividend for the synthesizer.

The Dividend Register MSB and LSB values are 2's complement

format.

NOTE: When in 10-bit mode, the Dividend LSB Register is not

required.

The reference frequency divider provides the reference frequency

to the phase detector by dividing the crystal oscillator frequency.

Divide ratios from 1 to 32 are possible for the reference frequency

divider (see Table 2).

The Reference Frequency Dividers Register configures the

reference frequency divider for the synthesizer. As shown in

Figure 8, the values to be loaded are:

• Reference Frequency Divider Index = Desired oscillator

signifying that the reference frequency is not divided for the

phase detector.

Table 1. SKY72310 Register Map

Address (Hex)

Register (Note 1)

Length (Bits)

Address (Bits)

0

Divider Register

12

4

1

Dividend MSB Register

12

4

2

Dividend LSB Register

12

4

3

Unused

4

Unused

5

Reference Frequency Dividers Register

12

4

6

Phase Detector/Charge Pump Control Register

12

4

7

Power Down/Multiplexer Output Select Control Register

12

4

8

Modulation Control Register

12

4

9

—

Modulation Data Register

Modulation Data Register (Note 2) — direct input

12

2 ≤ length ≤ 12 bits

4

0

Note 1: All registers are write only.

Note 2: No address bits are required for modulation data. Any serial data between 2 and 12 bits long is considered modulation data.