LMX2531LQE1226E/NOPB National Semiconductor, LMX2531LQE1226E/NOPB Datasheet - Page 26

• Manufacturer Part Number: LMX2531LQE1226E/NOPB
• Description: IC PLL FREQ SYNTH W/VCO 36-LLP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Clock/Frequency Synthesizer (RF)r

Specifications of LMX2531LQE1226E/NOPB

• Pll: Yes
• Input: Clock
• Output: CMOS
• Number Of Circuits: 1
• Ratio - Input:output: 2:2
• Differential - Input:output: No/No
• Frequency - Max: 1.268GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 2.8 V ~ 3.2 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-LLP
• Frequency-max: 1.268GHz
• For Use With: LMX25311226EVAL - BOARD EVAL FOR LMX25311226
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LMX2531LQE1226ETR

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2.4.4 DITHER -- Dithering
Dithering is useful in reducing fractional spurs, especially those that occur at a fraction of the channel spacing. The only exception
is when the fractional numerator is zero. In this case, dithering usually is not a benefit. Dithering also can sometimes increase the
PLL phase noise by a fraction of a dB. In general, if dithering is disabled, phase noise may be slightly better inside the loop bandwidth
of the system, but spurs are likely to be worse too.
2.4.5 FDM -- Fractional Denominator Mode
When this bit is set to 1, the 10 MSB bits for the fractional numerator and denominator are considered. This allows the fractional
denominator to range from 1 to 4,194,303. If this bit is set to zero, only the 12 LSB bits of the fractional numerator and denominator
are considered, and this allows a fractional denominator from 1 to 4095. When this bit is disabled, the current consumption is about
0.5 mA lower.
2.4.6 -- DIV2
When this bit is enabled, the output of the VCO is divided by 2. Enabling this bit does have some impact on harmonic content and
output power.
DITHER
DIV2
0
1
2
3
0
1
26
VCO Output Frequency
Dithering Disabled
Dithering Mode
Strong Dithering
Not Divided by 2
Weak Dithering
Divided by 2
Reserved