LMX2531LQ2570E Evaluation Board Operating Instructions National Semiconductor Corporation Wireless Communications, RF Products Group 2900 Semiconductor Dr. M/S A2-600 Santa Clara, CA, 95052-8090 LMX2531LQ2570EFPEB Rev 1.18.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S TABLE OF CONTENTS GENERAL DESCRIPTION .................................................................................................................. 3 LOOP FILTER .................................................................................................................................. 3 PHASE NOISE ...............................................................................................
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S General Description The LMX2531LQ2570E Evaluation Board simplifies evaluation of the LMX2531LQ2570E PLL/VCO synthesizer system. The board enables all performance measurements with no additional support circuitry. The evaluation board consists of a LMX2531LQ2570E device, and a cable assembly. The cable assembly is bundled with the evaluation board for connecting to a PC through the parallel printer port.
Output Frequency = 2563 MHz Internal Divide by 2 Disabled (DIV2=0) Output Frequency = 1281.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Phase Noise with Narrow Loop Filter Output Frequency = 2563 MHz Internal Divide by 2 Disabled (DIV2=0) Output Frequency = 1281.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Spurs (Internal Divide by 2 Disabled) Spur at 200 kHz offset at a worst case frequency of 2340.2 MHz is -84.7 dBc. Worst case channels occur at exactly one channel spacing above or below a multiple of the crystal frequency (10 MHz). Spur at 200 kHz offset at a worst case frequency of 2570.2 MHz is -82.5 dBc. Spur at 200 kHz offset at a worst case frequency of 2790.2 MHz is -79.3 dBc.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Spurs (Internal Divide by 2 Enabled) Spur at 200 kHz offset at a frequency of 1170.1 MHz is –90.1 dBc. Since this mode uses the divide by 2 mode, the channel spacing here is actually 100 kHz. The spur at 100 kHz could be eliminated by doubling the channel spacing before the divider. The reason that the spur at 200 kHz is shown is to illustrate theoretical 6 dB impact of the divider.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S CodeLoader Settings For the CodeLoader program, the default reference oscillator used for these instructions was 10 MHz, but there is a mode for a 61.44 MHz oscillator as well. If the bits become scrambled, their original state may be recalled by choosing the appropriate mode. Note that if the internal divide by 2 is enabled, the VCO frequency still reflects the VCO frequency before the divide by 2.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S CodeLoader is set up to load the registers and initialize the part in the correct way. R5 (INIT1) and R5 (INIT 2) are just the R5 register being used to properly initialize the part. So a single CNT+L should load the part. The port setup tells CodeLoader what information goes where. If this is wrong, the part will not program.
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Schematic 1 2 3 Vcc R1 Vcc 1 3 5 7 4 6 5 C6 POWER R2 2 4 6 8 OSCin VccVCO C2 R3 C1 R6 VccBUF D D C3 Ftest/LD VccPLL C7 R7 C4 VccDIG C10 C100 C11 VccPLL VregPLL1 FLout CPout Vtune VccBUF Fout GND GND 27 26 25 24 23 22 21 20 19 R17 C1_LF VccDIG NC GND NC NC VregBUF NC DATA CLK C2pLF 1 2 3 4 5 6 7 8 9 C9 C R2_LF C18 VccDIG C2_LF R2pLF C R22 VccPLL VregDIG NC GND
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G Bill of Materials Item QTY Manufacturer I N S T R U C T I O N S LMX2531EB Part # Size Tol Voltage Material Value Designators Open Capacitors C2pLF, C2, C3, C4, C5, C9, C11, C14, C17, C18, C19, C21, C24, C100, C101, C102, C103, C104, C105 6 Open Resistors R7, R8, R17, R19, R21, R24 1 Open Miscellaneous Ftest/LD C0G 47pF C1_LF 19 0 1 Revision 1/3/2006 n/a 1 Kemet C0603C470J5GAC 603 5% 50V 2 1 Keme
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G Top Layer 12 I N S T R U C T I O N S
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Mid Layer 1 "Ground Plane" (15 Mils Down FR4) 13
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Mid Layer 2 "Power" 14
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Bottom Layer "Signal" Note: Total Board Thickness = 61 mils 15
L M X 2 5 3 1 L Q 2 5 7 0 E E V A L U A T I O N B O A R D O P E R A T I N G I N S T R U C T I O N S Top Build Diagram 16
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