LMX2315TM National Semiconductor, LMX2315TM Datasheet - Page 17

• 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

Application Information
Consider the following application examples:
Example # 1
K
K = 5 mA (*)
RF
F
N = RF
ATTEN = 20 dB
Converting to standard component values gives the follow-
ing filter values, which are shown in Figure 4 .
Note: *See related equation for K in Charge Pump Current Specification
p
ref
VCO
p
C1 = 1000 pF
R2 = 3.3 k
C2 = 10 nF
R3 = 22 k
C3 = 100 pF
opt
= 45˚
= 2
= 200 kHz
Definitions. For this example V
approximated using the curves in the Typical Peformance Character-
istics for Charge Pump Current vs. D
mA. You may also use K = (5 mA/2 rad), but in this case you must
convert K
= 20 MHz/V
= 900 MHz
opt
*
/f
20 kHz = 1.256e5
ref
VCO
= 4500
to (rad/V) multiplying by 2 .
P
= 5.0V. The value of K can then be
o
Voltage. The units for K are in
(Continued)
17
FIGURE 4. 20 kHz Loop Filter
DS012339-46
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