LMX2471SLEX National Semiconductor, LMX2471SLEX Datasheet
LMX2471SLEX
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LMX2471SLEX Summary of contents
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... Integer-N PLL General Description The LMX2471 is a low power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. The device is fabricated using National Semiconductor’s advanced BiC- MOS process. With delta-sigma architecture, fractional spur compensation is achieved with noise shaping capability of the delta-sigma modulator and the inherent low pass filtering of the PLL loop filter ...
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Connection Diagram Pin Descriptions Pin # Pin I/O Name 1 CPoutRF O RF charge pump output. 2 GND - Ground 3 GND - RF Ground 4 GND - Ground for RF PLL digital circuitry. 5 FinRF I RF prescaler input. ...
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Absolute Maximum Ratings Parameter Power Supply Voltage Voltage on any pin with GND = Storage Temperature Range Lead Temperature (Solder 4 sec.) Recommended Operating Conditions Parameter Power Supply Voltage (Note 1) Operating Temperature Note 1: “Absolute Maximum ...
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Electrical Characteristics Symbol Parameter RF SYNTHESIZER PARAMETERS I SINK RF Charge Pump Sink CPoutRF Current I TRI RF Charge Pump CPoutRF TRI-STATE Current Magnitude I %MIS RF CP Sink vs. CP Source CPoutRF Mismatch Current vs. ...
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Electrical Characteristics Symbol Parameter DIGITAL INTERFACE (DATA, CLK, LE, EN, ENRF, Ftest/LD, FLoutRF, FLoutIF) V Low-Level Output Voltage OL MICROWIRE INTERFACE TIMING T Data to Clock Set Up Time CS T Data to Clock Hold Time CH T Clock Pulse ...
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Typical Performance Characteristics : Sensitivity www.national.com (Note Counter Sensitivity T = 25˚ Counter Sensitivity 20072145 20072146 ...
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Typical Performance Characteristics : Sensitivity (Note Counter Sensitivity T = 25˚ Counter Sensitivity (Continued) 20072147 20072148 www.national.com ...
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Typical Performance Characteristics : Sensitivity www.national.com (Note 6) OSCin Counter Sensitivity OSC 25˚ OSCin Counter Sensitivity OSC 2 (Continued) 20072149 20072150 ...
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Typical Performance Characteristic : FinRF Input Impedance Frequency (MHz) 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 FinRF Input Impedance (V =2 (Note 5) Real (Ohms) 389.9 270.8 160.4 95.7 ...
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Typical Performance Characteristic : FinIF Input Impedance Freqeuncy (MHz) 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 www.national.com FinIF Input Impedance (V =2 (Note 5) Real (Ohms) 377.4 ...
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Typical Performance Characteristic : OSCin Input Impedance Frequency (MHz 100 110 OSCin Input Impedance (V =2 (Note 5) Real (Ohms) Imaginary (Ohms) 2200 -4700 710 -2700 229 ...
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Typical Performance Characteristics : Currents www.national.com (Note 6) Total Current Consumption OSC=0 Powerdown Current EN = LOW 12 20072159 20072161 ...
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Typical Performance Characteristics : Currents (Note 6) RF Charge Pump Current V = 2.5 Volts CC IF Charge Pump Current V = 2.5 Volts CC 13 (Continued) 20072167 20072165 www.national.com ...
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Typical Performance Characteristics : Currents Note 5: The input impedance of the FinRF, FinIF, and OSCin pins does not change significantly with voltage or temperature. The impedance of the FinRF and FinIF pins also does not change much when the ...
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Bench Test Setups CHARGE PUMP CURRENT MEASUREMENT PROCEDURE The above block diagram shows the test procedure for test- ing the RF and IF charge pumps. These tests include abso- lute current level, mismatch, and leakage. In order to mea- sure ...
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Bench Test Setups (Continued) SENSITIVITY MEASUREMENT PROCEDURE Frequency Input Pin DC Blocking Capacitor OSCin 1000 pF FinRF 47 pF FinIF 100 pF Sensitivity is defined as the power level limits beyond which the output of the counter being tested is ...
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Bench Test Setups (Continued) INPUT IMPEDANCE MEASUREMENT PROCEDURE The above block diagram shows the test procedure measur- ing the input impedance for the LMX2471. This applies to the FinRF, FinIF, and OSCin pins and is measured ohm ...
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... GENERAL The basic phase-lock-loop (PLL) configuration consists of a high-stability crystal reference oscillator, a frequency synthe- sizer such as the National Semiconductor LMX2471, a volt- age controlled oscillator (VCO), and a passive loop filter. The frequency synthesizer includes a phase detector, current mode charge pump, as well as programmable reference [R] and feedback [N] frequency dividers ...
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Functional Description 1.4 DIGITAL LOCK DETECT OPERATION The RF PLL digital lock detect circuitry compares the differ- ence between the phase of the inputs of the phase detector generated delay of 10 nS. To enter the locked ...
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Functional Description 1.5 PCB LAYOUT CONSIDERATIONS Power Supply Pins For these pins recommended that these be filtered by taking a series 18 ohm resistor and then placing two capacitors shunt to ground, thus creating a low pass filter. ...
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Functional Description 1.6.1 Determining the Loop Gain Multiplier, K The loop bandwidth multiplier needed in order to de- termine the theoretical impact of fastlock/CSR on the loop bandwidth and also which resistor should be switched in parallel with ...
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Functional Description 1.6.4 RF PLL Fastlock Reference Table and Example The table below shows most of the trade-offs involved in choosing a steady-state charge pump current (RF_CPG), Parameter Advantages to Choosing Smaller RF_CPG 1. Allows capacitors in loop filter to ...
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Functional Description 1.6.5 Capacitor Dielectric Considerations for Lock Time The LMX2471 has a high fractional modulus and high charge pump gain for the lowest possible phase noise. One consideration is that the reduced N value and higher charge pump may ...
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Programming Description 2.0 GENERAL PROGRAMMING INFORMATION The descriptions below describe the 24-bit data registers loaded through the MICROWIRE Interface. These data registers are used to program the R counter, the N counter, and the internal mode control latches. The data ...
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25 www.national.com ...
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Programming Description 2.1 R0 REGISTER Note that this register has only one control bit. The reason for this is that it enables the N counter value to be changed with a single write statement to the PLL. REGISTER 23 22 ...
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Programming Description 2.2 R1 REGISTER REGISTER DATA[19:0] ( Except for the RF_N Register, which is [22: RF_PD 1 RF_R[5:0] 2.2.1 RF_FD[11: PLL Fractional Denominator The function of these bits are described in ...
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Programming Description 2.3 R2 REGISTER REGISTER DATA[19:0] ( Except for the RF_N Register, which is [22: IF_PD IF_P IF_CPG 2.3.1 IF_N[16: Divider Value The IF N divider is a classical dual modulus ...
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Programming Description 2.4 R3 REGISTER REGISTER DATA[19:0] ( Except for the RF_N Register, which is [22: RF_CPG[3:0] 2.4.1 IF_R[14: Divider Value For the IF R divider, the R value ...
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Programming Description 2.5 R4 REGISTER This register controls the conditions for the RF PLL in Fastlock. REGISTER DATA[19:0] ( Except for the RF_N Register, which is [22: CSR[1:0] RF_CPF[3:0] 2.5.1 RF_TOC -- RF ...
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Programming Description 2.5.3 RF_CSR[1: Cycle Slip Reduction CSR controls the operation of the Cycle Slip Reduction Circuit. This circuit can be used to reduce the occurrence of phase detector cycle slips. Note that the Fastlock charge pump current, ...
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Programming Description 2.7 R6 REGISTER REGISTER DATA[19:0] ( Except for the RF_N Register, which is [22: RF_ CPT 2.7.1 MUX[3:0] Frequency Out & Lock Detect MUX These ...
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Programming Description 2.7.5 FM[1:0] -- Fractional Mode Determines the order of the delta-sigma modulator. Higher order delta-sigma modulators reduce the spur levels closer to the carrier by pushing this noise to higher frequency offsets from the carrier. In general, the ...
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Programming Description 2.8 R7 REGISTER REGISTER RF_FD2[9:0] 2.8.1 Fractional Numerator Determination { RF_FN2[9:0], RF_FN[11:0], FDM } In the case that the FDM bit is 0, then the part operates in 12-bit fractional mode, and ...
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Programming Description 2.9 R8 REGISTER DITH [1:0] The R8 Register controls some additional bits that may be useful in optimizing phase noise, lock time, and spurs. 2.9.1 CPUD[2:0] -- ...
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... National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. inches (millimeters) unless otherwise noted Ultra Thin Chip Scale Package (SLE) For Tape and Reel (2500 Units per Reel) Order Number LMX2471SLEX NS Package Number SLE24A 2. A critical component is any component of a life support device or system whose failure to perform ...