LMX2571

Part: LMX2571 — Texas Instruments

Type: Low-Power RF Synthesizer / PLL with Integrated VCO and FSK Modulation

Description: Wideband fractional-N PLL synthesizer with integrated VCO covering 10 MHz to 1344 MHz, 24-bit delta-sigma modulator, direct digital FSK modulation, and 39 mA typical current in synthesizer mode.

Operating Conditions:

• Supply voltage (VCC): 3.15–3.45 V
• Operating temperature: -40 to 85 °C (ambient)
• Charge pump supply VCP: up to 5 V (PLL mode); VCC to 5 V (synthesizer mode)
• Junction temperature: up to 125 °C (recommended)

Absolute Maximum Ratings:

• Max supply voltage (VCC): 3.6 V
• Max IO supply voltage (VIO): 3.6 V
• Max charge pump supply voltage (VCP): 5.25 V
• Max input voltage (VIN): VCC + 0.3 V
• Max junction temperature: 150 °C
• Storage temperature: -65 to 150 °C

Key Specs:

• Supply current, synthesizer mode (internal VCO): 39 mA typ (Config A), up to 51 mA typ (Config D, SE OSCin, fOUT = 480 MHz)
• Supply current, PLL mode (external VCO): 9 mA typ (Config E) to 21 mA typ (Config G)
• Power-down current: 0.9 mA typ
• OSCin frequency range: 10–150 MHz (single-ended or differential); crystal 10–40 MHz
• Maximum phase detector frequency: 130 MHz
• Normalized PLL noise floor: -231 dBc/Hz typ (internal charge pump); -226 dBc/Hz typ with 5-V charge pump
• Normalized PLL 1/f noise: -124 dBc/Hz typ (internal charge pump)
• VCO frequency: 4300–5376 MHz
• Open-loop VCO phase noise at 480 MHz: -92.1 dBc/Hz at 100 kHz offset, -121.1 dBc/Hz at 1 MHz offset, -144.5 dBc/Hz at 10 MHz offset (typical values)
• Charge pump current: 312.5 μA step, up to 7187.5 μA (internal)
• FSK: 2-, 4- and 8-level in PIN mode, up to 8 kSPs baud rate
• Thermal resistance RθJA: 32.9 °C/W

Features:

• Any frequency from 10 MHz to 1344 MHz
• Low phase noise and spurs (spurs better than -75 dBc/Hz)
• New FastLock to reduce lock time (under 1.5 ms steps)
• Technique to remove integer boundary spurs
• Integrated 5-V charge pump and output divider for external VCO operation
• 2-, 4-, 8-level or arbitrary level direct digital FSK modulation
• One TX/RX output or two fanout outputs
• Crystal, XO or differential reference clock input
• 24-bit fractional-N delta-sigma modulator
• MICROWIRE serial interface

Applications:

• Duplex mode digital professional 2-way radio (dPMR, DMR, PDT, P25 Phase I)
• Low-power radio communication systems
• Satcom modem
• Wireless microphone
• Proprietary wireless connectivity
• Handheld test and measurement equipment

Package:

• WQFN (NJK), 36 pins, 6.00 mm × 6.00 mm

• 1 · Any Frequency from 10 MHz to 1344 MHz
• Low Phase Noise and Spurs
• --123 dBc/Hz at 12.5 kHz Offset at 480 MHz
• --145 dBc/Hz at 1 MHz Offset at 480 MHz
• -Normalized PLL Noise Floor of -231 dBc/Hz
• -Spurious Better Than -75 dBc/Hz
• New FastLock to Reduce Lock Time
• A Novel Technique to Remove Integer Boundary Spurs
• Integrated 5-V Charge Pump and Output Divider for External VCO Operation
• 2-, 4- and 8-Level or Arbitrary Level Direct Digital FSK Modulation
• One TX/RX Output or Two Fanout Outputs
• Crystal, XO or Differential Reference Clock Input
• Low Current Consumption
• -39-mA Typical Synthesizer Mode (Internal VCO)
• -9-mA Typical PLL Mode (External VCO)
• 24-Bit Fractional-N Delta Sigma Modulator

• Duplex Mode Digital Professional 2-Way Radio
• -dPMR, DMR, PDT, P25 Phase I
• Low Power Radio Communication Systems
• -Satcom Modem
• -Wireless Microphone
• -Propriety Wireless Connectivity
• Handheld Test and Measurement Equipment

Pin Functions

3.15 V ≤ VCC ≤ 3.45 V, VIO = VCC, -40 °C ≤ TA ≤ 85 °C, except as specified. Typical values are at VCC = VIO = 3.3 V, VCP = 3.3 V or 5 V in synthesizer mode, VCP = 5 V in PLL mode, TA = 25 °C.

over operating free-air temperature range (unless otherwise noted) (1)

over operating free-air temperature range (unless otherwise noted)

Use Equation 4 and Equation 6 to calculate the required FSK steps. For +10 kHz frequency deviation, the FSK step value is equal to [10000 * 16777216 / (104 * 10 6 )] * (5 * 1 / 2) = 4033. For -10 kHz frequency deviation, the FSK step value is equal to 2's complement of 4033 = 61502. Similarly, the FSK step values for ±30 kHz frequency deviation are 12099 and 53436.

All the required configuration values for F2, 928 MHz can be calculated in the similar fashion and are summarized as follows:

Table 41. Frequency Plan Summary

Assume here that the base charge pump current = 1250 μA, CP Gain = 1x and 3 rd order Delta Sigma Modulator without dithering is adopted in both frequency sets. The register settings are summarized as follows:

Table 42. Register Settings Summary

Table 42. Register Settings Summary (continued)

Table 42. Register Settings Summary (continued)