LMX2485E EVAL National Semiconductor, LMX2485E EVAL Datasheet - Page 10

• Manufacturer Part Number: LMX2485E EVAL
• Description: BOARD EVALUATION LMX2485E
• Manufacturer: National Semiconductor
• Series: PLLatinum™r

Specifications of LMX2485E EVAL

• Main Purpose: Timing, Frequency Synthesizer
• Utilized Ic / Part: LMX2485E
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

RF PLL Fractional Spurs with different Dithering Settings
L M X 2 4 8 5 E
E V A L U A T I O N
10
DITH=0 (Disabled)
(DITH=0 is the recommended setting)
Fractional Spurs measured at 49.2 MHz
CP gain set to 0.76 mA (8X)
Fraction Compensation set to 1/5
FM=2 (2
In these three plots, you will note that Fractional
Spurs decreases very little at 200 kHz as compared
with the higher harmonics with weak dithering
enabled. The spurs and waveform is different with
strong dithering enabled.
DITH=1 (Weak Dithering)
Fractional Spurs measured at 49.2 MHz
CP gain set to 0.76 mA (8X)
Fraction Compensation set to 1/5
FM=2 (2
DITH=2 (Strong Dithering)
Fractional Spurs measured at 49.2 MHz
CP gain set to 0.76 mA (8X)
Fraction Compensation set to 1/5
FM=2 (2
B O A R D
nd
nd
nd
order delta sigma modulator).
order delta sigma modulator).
order delta sigma modulator).
O P E R A T I N G
I N S T R U C T I O N S