LM2326 National Semiconductor, LM2326 Datasheet - Page 8

• Manufacturer Part Number: LM2326
• Description: PLLatinum Low Power Frequency Synthesizer for RF Personal Communications
• Manufacturer: National Semiconductor

www.national.com
1.0 Functional Description
1.2 PROGRAMMABLE DIVIDER (N COUNTER)
The N counter consists of the 5-bit swallow counter (A counter) and the 13-bit programmable counter (B counter). If the Control
Bits are [C
a 13-bit latch (which sets the 13-bit programmable (B) Counter), and the GO bit (See Section 1.3.4 FastLock MODES section)
MSB first. For the LMX2306 the maximum N value is 65535 and the minimum N value is 56. For the LMX2316/26, the maximum
N value is 262143 and the minimum N value is 992. Serial data format is shown below.
Note: Data is shifted in MSB first.
1.2.1 5-BIT SWALLOW COUNTER DIVIDE RATIO (A COUNTER)
LMX2316/26
Note: Divide ratio: 0 to 31
B
1.2.2 13-BIT PROGRAMMABLE COUNTER DIVIDE RATIO (B COUNTER)
Divide ratio: 3 to 8191 (Divide ratios less than 3 are prohibited) B A
1.2.3 PULSE SWALLOW FUNCTION
fvco = [(P x B) + A] x fosc/R
f
B:
A:
f
R:
P:
vco
osc
Divide
A
Ratio
:
:
Divide
8191
Ratio
31
3
4
•
0
1
•
Output frequency of external voltage controlled oscillator (VCO)
Preset divide ratio of binary 13-bit programmable counter (3 to 8191)
Preset divide ratio of binary 5-bit swallow counter (0
or (0
Output frequency of the external reference frequency oscillator
Preset divide ratio of binary 14-bit programmable reference counter (3 to 16383)
Preset modulus of dual modulus prescaler
for the LMX2306; P = 8 for the LMX2316/26; P = 32
1
, C
A
2
] = [1,0], data is transferred from the 21-bit shift register into a 5-bit latch (which sets the Swallow (A) Counter),
18
N
0
0
1
•
7, A
N
5
0
0
1
•
B for LMX2306)
17
N
0
0
1
•
N
4
0
0
1
•
16
N
0
0
1
•
N
3
0
0
1
•
15
N
0
0
1
•
(Continued)
N
2
0
0
1
•
14
N
0
0
1
•
N
1
0
1
1
•
13
A
N
0
0
1
•
8
31; A
LMX2306
Note: Divide ratio: 0 to 7
B
X denotes a Don’t Care condition
A
12
Divide
N
0
0
1
•
Ratio
B for LMX2316/26)
0
1
7
•
11
N
0
0
1
•
N
5
X
X
X
•
10
N
0
0
1
•
N
X
X
X
4
•
N
9
0
0
1
•
N
3
0
0
1
•
DS100127-6
N
8
0
1
1
•
N
2
0
0
1
N
•
7
1
0
1
•
N
6
1
0
1
•
N
1
0
1
1
•