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Texas Instruments LMX2485ESQ/NOPB
- Part No.:
- LMX2485ESQ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LMX2485ESQ/NOPB.pdf
- Description:
- IC FREQ SYNTH 24WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:9,114
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Product details
Overview
LMX2485ESQ/NOPB from Texas Instruments is a dual-loop delta-sigma fractional-N/integer-N frequency synthesizer with separate RF and IF PLLs. It delivers 500–3000 MHz RF output and 75–800 MHz IF output, supports up to 4th-order programmable delta-sigma modulation, and operates from 2.5–3.6 V with 5.0 mA total supply current. It is used in cellular base stations for agile local oscillator generation with fast lock and low in-band spurs.
For engineers reviewing the LMX2485ESQ/NOPB datasheet, LMX2485ESQ/NOPB pinout, LMX2485ESQ/NOPB application, or LMX2485ESQ/NOPB equivalent, key selection criteria include RF/IF dual-PLL architecture, 50 MHz max RF phase detector frequency, MICROWIRE interface timing compliance, and WQFN-24 package thermal performance (RθJA = 47.2°C/W).
Technical Context
The LMX2485ESQ/NOPB integrates two independent PLLs: an RF PLL with 8/9/12/13 or 16/17/20/21 prescaler and 500–3000 MHz output range, and an IF PLL with 8/9 or 16/17 prescaler and 75–800 MHz output range. Both use digital delta-sigma fractional-N synthesis with selectable 12-bit or 22-bit fractional modulus.
Its MICROWIRE interface operates at up to 20 MHz with defined setup/hold/timing margins (tCS ≥25 ns, tCH ≥8 ns), and charge pump outputs (CPoutRF, CPoutIF) support programmable gain (RF_CPG = 0–15) and TRI-STATE control for loop filter flexibility.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| RF Output Range | 500–3000 MHz - covers UMTS, LTE, and WiMAX bands without external frequency multiplication |
| IF Output Range | 75–800 MHz - supports IF sampling and downconversion in cable TV and satellite tuners |
| Phase Detector Max Freq | 50 MHz (RF), 10 MHz (IF) - sets upper limit on comparison frequency and impacts loop bandwidth design |
| Total Supply Current | 5.0 mA @ 3.0 V - enables low-power portable and battery-backed RF subsystems |
| Delta-Sigma Order | Programmable up to 4th order - allows trade-off between close-in phase noise and out-of-band spur suppression |
| MICROWIRE Clock Rate | 20 MHz max - enables sub-10 µs frequency reprogramming for direct digital modulation |
| Charge Pump Gain Range | RF: 95–1520 µA; IF: ±3.5 mA - provides fine-grained loop filter optimization across PFD frequencies |
Pinout & Package
LMX2485ESQ/NOPB uses a 24-pin WQFN package (4.0 × 4.0 × 0.8 mm) with exposed thermal pad (Pin 0 = GND substrate). Power supplies are segregated: VddRF1–VddRF5 for RF analog/digital domains, VddIF1/VddIF2 for IF domain, and dedicated grounds (GND pins 2, 15, and substrate).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 CPoutRF | RF PLL charge pump output | Drives loop filter; sink/source current programmable (95–1520 µA); TRI-STATE capable |
| 4 FinRF / 5 FinRF* | Differential RF input | Accepts 500–3000 MHz signal; FinRF* requires 100-pF shunt to ground for common-mode termination |
| 6 LE / 7 DATA / 8 CLK / 10 CE | MICROWIRE interface control | 3-wire serial interface; LE latches 24-bit register data; CE must be high for operation |
| 12 Ftest/LD | Test frequency output / digital lock detect | Outputs divided reference for verification; asserts logic high when both PLLs achieve lock |
| 13 FinIF | IF PLL input | Single-ended 75–800 MHz input; −10 to +5 dBm sensitivity supports crystal or SAW filter sources |
| 16 CPoutIF | IF PLL charge pump output | ±3.5 mA fixed gain; supports narrowband IF loops with low ripple requirements |
| 19 ENOSC / 20 OSCin / 18 OSCout | On-chip oscillator interface | ENOSC enables buffered OSCout; OSCin accepts 5–110 MHz TCXO (with 2× doubler option) |
| 23 FLoutRF | RF fastlock output | Tri-state CMOS output indicating fast-lock event; usable as system timing flag or interrupt source |
Key Features
| Feature | Design Value |
|---|---|
| Quadruple-modulus prescaler | RF: 8/9/12/13 or 16/17/20/21; IF: 8/9 or 16/17 - enables integer division without fractional-N spurs in wideband tuning |
| Digital lock detect | Single-pin Ftest/LD output with logic-high assertion on successful RF+IF PLL lock - eliminates need for external monitoring circuitry |
| Hardware/software power-down | CE pin and register-controlled shutdown reduce ICC to ≤10 µA - preserves system-level power budget during idle periods |
| On-chip input frequency doubler | OSC2X bit enables 2× multiplication of OSCin (5–20 MHz → 10–40 MHz) - relaxes external oscillator cost and size constraints |
| Fastlock with cycle-slip reduction | Integrated time-out counter and single-word write enable <100 µs frequency change - critical for TDD and burst-mode systems |
Applications
| Cellular Base Station LO | Satellite TV Tuner |
|---|---|
Use Scenario: Generating agile local oscillator signals for multi-carrier LTE FDD/TDD transceivers with rapid channel switching. IC Role / Device Role / Timing Role: Dual-loop synthesizer providing synchronized RF (2.1–2.7 GHz) and IF (350–450 MHz) outputs with <100 µs lock time. Use Value: Eliminates need for multiple discrete synthesizers; 4th-order delta-sigma reduces adjacent-channel interference by pushing spurs >100 kHz offset. |
Use Scenario: Downconverting Ku-band satellite signals (10.7–12.75 GHz) to standard IF (950–2150 MHz) in set-top box tuners. IC Role / Device Role / Timing Role: IF PLL generates precise 44 MHz or 45 MHz first IF; RF PLL drives mixer LO via external doubler. Use Value: 75–800 MHz IF range matches DVB-S2 demodulator input specs; digital lock detect ensures reliable channel acquisition. |
| WLAN 802.11ac Radio | Cable Modem DOCSIS 3.1 |
Use Scenario: Providing clean, switchable LO for 5 GHz band (5.15–5.85 GHz) WLAN radios supporting 80/160 MHz channels. IC Role / Device Role / Timing Role: RF PLL synthesizes 5.15–5.85 GHz directly; IF PLL provides reference for ADC clock recovery. Use Value: −55 dBc in-band spurs meet IEEE 802.11ac spectral mask; 2.5–3.6 V operation simplifies PMIC integration. |
Use Scenario: Generating multi-tone upstream LO (5–85 MHz) and downstream LO (108–1002 MHz) in full-duplex DOCSIS 3.1 modems. IC Role / Device Role / Timing Role: IF PLL covers upstream band; RF PLL covers downstream; dual-loop isolation prevents cross-talk. Use Value: Separate RF/IF power domains (VddRFx/VddIFx) minimize supply coupling; 50 MHz RF PFD enables wide loop bandwidth for fast upstream agility. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-loop frequency synthesizer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMX2594RHBR | Wider RF range (10–13.6 GHz), JESD204B interface, no IF PLL - single high-frequency synthesizer with integrated VCO | Replaces LMX2485ESQ/NOPB only in systems requiring >3 GHz output without external multiplier | Select LMX2594RHBR when ultra-wideband coverage and JESD204B synchronization are required; not drop-in due to different architecture and pinout |
| ADF4351BCPZ | Integrated VCO (137.5–4400 MHz), SPI interface, no dedicated IF PLL - single-loop synthesizer with fractional-N + integer-N modes | Suitable for simpler single-LO architectures; lacks independent IF path for dual-conversion receivers | Choose ADF4351BCPZ for cost-sensitive, single-PLL designs where IF synthesis is handled externally; requires redesign of loop filter and interface |
Compared with LMX2485ESQ/NOPB, LMX2594RHBR offers higher frequency capability but removes IF synthesis flexibility, while ADF4351BCPZ simplifies BOM count at the expense of dual-loop isolation and independent IF control - making LMX2485ESQ/NOPB optimal for dual-conversion architectures requiring simultaneous RF/IF agility.
Availability
LMX2485ESQ/NOPB is available at Aetrix Electronics and suitable for cellular infrastructure, satellite TV tuners, WLAN radio front-ends, and DOCSIS 3.1 cable modems requiring stable component supply and long-term production continuity.
Supply support for LMX2485ESQ/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity solutions, with decades of RF IC design expertise and broad manufacturing scale.
The LMX2485x family targets high-performance wireless infrastructure and broadband equipment, delivering dual-loop synthesis with delta-sigma precision, low power, and fast lock - optimized for base station, tuner, and modem applications demanding spectral purity and agility.
FAQ
What is the RF output frequency range supported by the LMX2485ESQ/NOPB?
The LMX2485ESQ/NOPB supports an RF output frequency range of 500 MHz to 3000 MHz. This range is enabled by its quadruple-modulus prescaler (8/9/12/13 or 16/17/20/21) and delta-sigma fractional-N synthesis. The device achieves this coverage without requiring external frequency multipliers in most cellular and broadband applications, and the LMX2485ESQ/NOPB datasheet confirms operation across this band under recommended conditions (VCC = 2.5–3.6 V, TA = –40°C to +85°C).
Does the LMX2485ESQ/NOPB include an integrated oscillator or require an external crystal?
The LMX2485ESQ/NOPB does not include an integrated oscillator but provides a dedicated OSCin pin (Pin 20) for connecting an external TCXO or crystal oscillator. It supports input frequencies from 5 to 110 MHz, with an optional on-chip 2× frequency doubler (enabled via OSC2X bit) extending effective range to 5–20 MHz input → 10–40 MHz output. The LMX2485ESQ/NOPB also features OSCout (Pin 18) for buffered output and ENOSC (Pin 19) for hardware enable control.
How does the MICROWIRE interface of the LMX2485ESQ/NOPB differ from SPI, and what are its timing limits?
The LMX2485ESQ/NOPB uses a 3-wire MICROWIRE interface (CLK, DATA, LE) operating up to 20 MHz, distinct from SPI in its lack of MISO line and use of LE (load enable) instead of CS to latch data. Timing requirements specify minimum tCS (data setup) ≥25 ns, tCH (data hold) ≥8 ns, and tCWL/tCWH (clock low/high) ≥25 ns. These values ensure reliable 24-bit register writes for fast frequency changes, and the LMX2485ESQ/NOPB's single-word write capability enables sub-10 µs reprogramming - critical for direct digital modulation.
What is the function of the Ftest/LD pin on the LMX2485ESQ/NOPB, and how is lock detection implemented?
The Ftest/LD pin (Pin 12) on the LMX2485ESQ/NOPB serves dual functions: it outputs a divided test frequency for verification and acts as a digital lock detect indicator. Lock detection is asserted as a logic-high signal when both the RF and IF PLLs achieve phase lock simultaneously. This is implemented internally using digital comparators monitoring PFD outputs - no external components or software polling are needed. The LMX2485ESQ/NOPB datasheet specifies that Ftest/LD remains low until both loops meet lock criteria, ensuring robust system-level synchronization.
Can the LMX2485ESQ/NOPB operate with separate power domains for RF and IF sections, and why is this beneficial?
Yes, the LMX2485ESQ/NOPB supports fully segregated power domains: VddRF1–VddRF5 for RF analog/digital circuits and VddIF1/VddIF2 for IF circuits, each with dedicated ground pins (GND at Pins 2, 15, and substrate). This separation minimizes supply coupling between RF and IF paths, reducing crosstalk-induced spurs and phase noise degradation. In practice, this architecture enables cleaner dual-conversion receiver performance - a key advantage confirmed in the LMX2485ESQ/NOPB's application notes for satellite TV and DOCSIS 3.1 systems.
LMX2485ESQ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- PLLatinum™
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Frequency Synthesizer (RF)
- PLL:
- Yes
- Input:
- Clock
- Output:
- Clock
- Number of Circuits:
- 1
- Ratio - Input:Output:
- 3:2
- Differential - Input:Output:
- Yes/No
- Frequency - Max:
- 3GHz
- Divider/Multiplier:
- Yes/Yes
- Voltage - Supply:
- 2.5V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 24-WQFN (4x4)
LMX2485ESQ/NOPB FAQ
1.How can I place an order for LMX2485ESQ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LMX2485ESQ/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LMX2485ESQ/NOPB reliable?
The price and inventory of LMX2485ESQ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMX2485ESQ/NOPB is usually 5 days.
3.What payment methods are accepted for LMX2485ESQ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMX2485ESQ/NOPB transactions.
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4.How is shipping managed for LMX2485ESQ/NOPB?
LMX2485ESQ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMX2485ESQ/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LMX2485ESQ/NOPB?
For technical support, including LMX2485ESQ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMX2485ESQ/NOPB requirements.
6.How does Aetrix verify that LMX2485ESQ/NOPB is sourced from the original manufacturer or authorized distributors?
All LMX2485ESQ/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LMX2485ESQ/NOPB meets industry standards.
7.What is the process for return or replacement of LMX2485ESQ/NOPB?
All LMX2485ESQ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LMX2485ESQ/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LMX2485ESQ/NOPB part is unused and in its original packaging.
Return procedure for LMX2485ESQ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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