LMX2305 National Semiconductor, LMX2305 Datasheet - Page 7
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LMX2305
Manufacturer Part Number
LMX2305
Description
PLLatinumTM 550 MHz Frequency Synthesizer for RF Personal Communications
Manufacturer
National Semiconductor
Datasheet
1.LMX2305.pdf
(14 pages)
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LMX2305TMD
Manufacturer:
NS/国半
Quantity:
20 000
Functional Description
PROGRAMMABLE DIVIDER (N COUNTER)
The N counter consists of the 7-bit swallow counter (A counter) and the 11-bit programmable counter (B counter) If the Control
Bit (last bit shifted into the Data Register) is LOW data is transferred from the 19-bit shift register into a 7-bit latch which sets
the 7-bit Swallow (A) Counter and an 11-bit latch which sets the 11-bit programmable (B) Counter Serial data format is shown
below
Note S8 to S18 Programmable counter divide ratio control bits (3 to 2047)
7-BIT SWALLOW COUNTER DIVIDE RATIO
(A COUNTER)
Note Divide ratio 0 to 127
Divide
Ratio
127
A
0
1
B
t
A
N
7
0
0
1
N
6
0
0
1
N
5
0
0
1
N
4
0
0
1
N
3
0
0
1
N
2
0
0
1
N
1
0
1
1
(Continued)
7
11-BIT PROGRAMMABLE COUNTER DIVIDE RATIO
(B COUNTER)
Note Divide ratio 3 to 2047 (Divide ratios less than 3 are prohibited)
PULSE SWALLOW FUNCTION
f
f
B
A
f
R
P
VCO
VCO
OSC
Divide
Ratio
2047
B
3
4
e
B
Output frequency of external voltage controlled oscil-
lator (VCO)
Preset divide ratio of binary 11-bit programmable
counter (3 to 2047)
Preset divide ratio of binary 7-bit swallow counter
(0
Output frequency of the external reference frequency
oscillator
Preset divide ratio of binary 14-bit programmable ref-
erence counter (3 to 16383)
Preset modulus of dual modulus prescaler (64 or 128)
t
(P
s
A
18
N
0
0
1
c
A
B)
s
17
N
0
0
1
127 A
a
16
N
0
0
A
1
c
15
s
N
0
0
1
f
OSC
B)
14
N
0
0
1
R
13
N
0
0
1
12
N
0
0
1
http
11
N
TL W 12459 – 15
0
0
1
www national com
10
N
0
1
1
N
9
1
0
1
N
8
1
0
1