LMX2315TM National Semiconductor, LMX2315TM Datasheet - Page 10

• Manufacturer Part Number: LMX2315TM
• Description: IC FREQ SYNTHESIZER 20-TSSOP
• Manufacturer: National Semiconductor
• Series: PLLatinum™r
• Type: PLL Frequency Synthesizerr

Specifications of LMX2315TM

• Pll: Yes
• Input: CMOS, TTL
• Output: CMOS
• Number Of Circuits: 1
• Ratio - Input:output: 2:1
• Differential - Input:output: Yes/No
• Frequency - Max: 1.2GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Frequency-max: 1.2GHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *LMX2315TM

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Functional Description
The simplified block diagram below shows the 19-bit data register, the 14-bit R Counter and the S Latch, and the 18-bit N Counter
(intermediate latches are not shown). The data stream is clocked (on the rising edge) into the DATA input, MSB first. If the Control
Bit (last bit input) is HIGH, the DATA is transferred into the R Counter (programmable reference divider) and the S Latch
(prescaler select: LMX2315 and LMX2320: 64/65 or 128/129; LMX2325 32/33 or 64/65). If the Control Bit (LSB) is LOW, the DATA
is transferred into the N Counter (programmable divider).
PROGRAMMABLE REFERENCE DIVIDER (R COUNTER) AND PRESCALER SELECT (S LATCH)
If the Control Bit (last bit shifted into the Data Register) is HIGH, data is transferred from the 19-bit shift register into a 14-bit latch
(which sets the 14-bit R Counter) and the 1-bit S Latch (S15, which sets the prescaler: 64/65 or 128/129 for the LMX2315/20 or
32/33 or 64/65 for the LMX2325). Serial data format is shown below.
14-BIT PROGRAMMABLE REFERENCE DIVIDER RATIO
Notes:
Divide ratios less than 3 are prohibited.
Divide ratio: 3 to 16383
S1 to S14: These bits select the divide ratio of the programmable reference divider.
C: Control bit (set to HIGH level to load R counter and S Latch)
Data is shifted in MSB first.
Divide
16383
Ratio
LMX2315/20
R
3
4
•
128/129
64/65
Prescaler Select
14
S
0
0
1
•
13
S
0
0
1
•
12
S
0
0
1
•
LMX2325
11
64/65
32/33
S
0
0
1
•
10
S
0
0
1
•
S
9
0 0 0 0 0 0 0 1 1
0 0 0 0 0 0 1 0 0
1 1 1 1 1 1 1 1 1
•
S
8
•
15
S
0
1
S
7
•
S
6
•
S
5
•
S
4
•
S
3
• • •
S
2
S
1
10
DS012339-6
DS012339-18