8Data Sheet - Rev 2.1
02/2005
ACD2206
TCELES
STIB ROFRETSIGERNOITANITSED
ATADLAIRES
S
2
S
1
00 2LLProfretsigeRrediviDecnerefeR
01 2LLProfretsigeRrediviDniaM
10 1LLProfretsigeRrediviDecnerefeR
11 1LLProfretsigeRrediviDniaM
EDIVID
ROITAR
R
51
R
41
R
31
R
21
R
11
R
01
R
9
R
8
R
7
R
6
R
5
R
4
R
3
R
2
R
1
3 0000000000000 11
4 000000000000 100
- ---------------
76723 111111111111111
22 12 02 91 81 71 61 51 41 31 21 11 01 9 8 7 6 5 4 3 2 1
edoMmargorPR,oitaRediviDrediviDecnerefeRtceleS
D
5
D
4
D
3
D
2
D
1
R
51
R
41
R
31
R
21
R
11
R
01
R
9
R
8
R
7
R
6
R
5
R
4
R
3
R
2
R
1
S
2
S
1
LOGIC PROGRAMMING
Notes:
Divide ratios less than 3 are prohibited.
LSBMSB
Synthesizer Register Programming
The ACD2206 includes two PLL synthesizers. Each
synthesizer contains programmable Reference and
Main dividers, which allow a wide range of local
oscillator frequencies. The 22-bit registers that control
the dividers are programmed via a shared three-wire
bus, consisting of Data, Clock and Enable lines.
The data word for each register is entered serially
in order with the most significant bit (MSB) first and
the least significant bit (LSB) last. The rising edge
of the Clock pulse shifts each data value into the
register. The Enable line must be low for the duration
of the data entry, then set high to latch the data into
the register. (See Figure 4.)
Register Select Bits
The two least significant bits of each register are
register select bits that determine which register is
programmed during a particular data entry cycle.
Table 7 indicates the register select bit settings used
to program each of the available registers.
Table 7: Register Select Bits
Table 9: Reference Divider R Counter Bits
Table 8: Reference Divider Registers
Reference Divider Programming
The reference divider register for each synthesizer
consists of fifteen divider bits, five program mode
bits and the two register select bits, as shown in
Table 8. The fifteen divider bits allow a divide ratio
from 3 to 32767, inclusive, as shown in Table 9.