sa8027 NXP Semiconductors, sa8027 Datasheet - Page 12

• Manufacturer Part Number: sa8027
• Description: 2.5 Ghz Low Voltage, Low Power Rf Fractional-n/if Integer Frequency Synthesizer
• Manufacturer: NXP Semiconductors

Philips Semiconductors
2.0 SERIAL PROGRAMMING BUS
The serial input is a 3-wire input (CLOCK, STROBE, DATA) to
program all counter divide ratios, fractional compensation DAC,
selection and enable bits. The programming data is structured into
24 bit words; each word includes 2 or 3 address bits. Figure 11
shows the timing diagram of the serial input. When the STROBE
goes active HIGH, the clock is disabled and the data in the shift
register remains unchanged. Depending on the address bits, the
data is latched into the selected working registers or temporary
registers. In order to fully program the synthesizer, 3 words must be
2.1 Serial bus timing characteristics (see Figure 11)
V
Application information
2001 Aug 21
Serial programming clock; CLK
t
t
T
Enable programming; STROBE
t
t
t
Register serial input data; DATA
t
t
DD
r
f
START
W
SU;E
SU;DAT
HD;DAT
cy
2.5 GHz low voltage, low power
RF fractional-N/IF integer frequency synthesizer
= V
SYMBOL
DDCP
=+3.0 V; T
CLK
DATA
STROBE
Input rise time
Input fall time
Clock period
Delay to rising clock edge
Minimum inactive pulse width
Enable set-up time to next clock edge
Input data to clock set-up time
Input data to clock hold time
amb
= +25 C unless otherwise specified.
t
t
START
SU;DAT
PARAMETER
LSB
T
Figure 11. Serial Bus Timing Diagram
cy
t
HD;DAT
12
initially set to 0 for normal operation. When sending the B-word, data
illustrated in Figure 12. Table 2 shows the format and the contents of
sent: C, B, and A, in that order. A typical programming sequence is
each word. The D word is used for testing purposes and should be
bits FC7–0 for the fractional compensation DAC are not loaded
immediately. Instead they are stored in temporary registers. Only
when the A-word is loaded, these temporary registers are loaded
together with the main divider ratio.
1/f
MSB
MIN.
100
COMP
40
20
20
20
–
–
t
f
ADDRESS
t
r
TYP.
10
10
–
–
–
–
–
–
0
t
SU;E
t
MAX.
w
40
40
–
–
–
–
–
–
SR01417
SA8027
Product data
UNIT
ns
ns
ns
ns
ns
ns
ns
ns