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Home > Products > Integrated Circuits (ICs) > Clock/Timing > Clock Generators, PLLs, Frequency Synthesizers

Asahi Kasei Microdevices/AKM AK1541

Name: AK1541
Brand: Asahi Kasei Microdevices/AKM
SKU: AK1541
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AK1541

Manufacturer:: Asahi Kasei Microdevices/AKM

Category:: Clock Generators, PLLs, Frequency Synthesizers

Package:: 24-WFQFN Exposed Pad

Datasheet:: AK1541.pdf

Description:: IC PLL RF FREQ SYNTHESIZER 24QFN

Quantity:: RFQ Add To RFQ list

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Product details

Overview

The AK1541 from AsahiKASEI is a Delta-Sigma Fractional-N PLL frequency synthesizer operating from 20 to 600 MHz, integrating an 18-bit Delta-Sigma modulator, low-noise phase frequency detector, dual-mode charge pump (10.6 µA–168.9 µA normal / 0.84–2.32 mA fast lock), and dual-module prescaler (4/5, 8/9, 16/17) for RF signal generation in wireless transceivers and test equipment.

For engineers reviewing the AK1541 datasheet, AK1541 pinout, AK1541 application, or AK1541 equivalent, this page delivers verified technical context, register-controlled fast-lock timing, analog/digital lock detect selection, and precise charge pump current scaling via external BIAS resistor - all critical for stable VCO-based frequency planning and loop filter design.

Technical Context

The AK1541 implements a 2²⁰ denominator fractional-N architecture with integer + numerator synthesis (INT + NUM/2²⁰), enabling sub-Hz frequency resolution. Its dual-charge-pump system (CP1 for steady-state, CP2 for fast lockup) is controlled via FASTEN bit and timer-driven switching synchronized to the phase detector clock.

Lock detection supports both analog mode (direct PFD output on LD pin) and digital mode (63-consecutive-cycle validation with user-configurable error window LDCKSEL[1:0]), with strict VCO frequency constraints tied to REFIN and dithering state (DITH). Prescaler selection (P=4/8/16) and R-divider (4–255) are register-programmable for wide-band coverage.

Key Specifications

Parameter	Value and Actual Design Meaning
Frequency Range	20–600 MHz output; covers UHF ISM, cellular front-end, and instrumentation bands with prescaler support for 4/5, 8/9, and 16/17 division ratios.
Fractional Resolution	2²⁰ denominator (1,048,576 steps); enables precise channel spacing down to sub-Hz increments in synthesizer programming.
Charge Pump Current	Normal mode: 16-step programmable (10.6–168.9 µA); Fast lock mode: 8-step (0.84–2.32 mA); scaled by external 22–33 kΩ BIAS resistor.
Supply Voltage	PVDD: 2.7–5.5 V (peripherals); CPVDD: up to 5.5 V (independent charge pump rail); enables noise-isolated analog biasing.
Interface	3-wire serial (CLK/DATA/LE); 24-bit register map across 4 addresses; LE-triggered write synchronization with 20 ns setup/hold timing.
Operating Temp	–40°C to +85°C; qualified for industrial-grade RF subsystems including base stations and portable radios.
Package	24-pin QFN (4 mm × 4 mm × 0.7 mm, 0.5 mm pitch); exposed thermal pad grounded per MS1043-E-05 spec.

Pinout & Package

24-pin QFN package (MS1043-E-05) with exposed thermal pad connected to ground. Pin 1 marked at top-left corner (top view); pins arranged in clockwise order with CPVDD (1), TEST4 (2), TEST1 (3), LE (4), DATA (5), CLK (6), LD (7), PDN2 (8), PDN1 (9), REFIN (10), TEST2 (11), TEST3 (12), VREF1 (13), DVSS (14), VREF2 (15), RFINN (16), RFINP (17), PVDD (18), BIAS (19), PVSS (20), CP (21), CPZ (22), SWIN (23), CPVSS (24).

Pin/Terminal	Circuit Role	Design Meaning
CP (21)	Analog output	Charge pump current source/sink output; connects to loop filter R1/C1 node; Hi-Z when CPHI=1 or during power-down.
CPZ (22)	Analog I/O	Internal loop filter intermediate node; must be connected to R2/C2 even in normal mode; enables fast-lock loop reconfiguration.
SWIN (23)	Analog input	Fast-lock resistance select; open-circuit allowed when fast lock disabled; sets parallel R2/R2′ value for bandwidth tuning.
BIAS (19)	Analog I/O	External resistor (22–33 kΩ) sets baseline charge pump current scaling for both CP1 and CP2 modes.
LD (7)	Digital output	Configurable lock detect: analog (PFD output) or digital (63-cycle validated phase error); active-low assertion.
RFINP/RFINN (16/17)	Analog input	Differential RF input to prescaler; –5 to +5 dBm sensitivity (20–250 MHz), –15 to +5 dBm (250–600 MHz).

Key Features

Feature	Design Value
Fractional-N Synthesis	2²⁰ denominator enables fine frequency resolution without sacrificing phase detector speed or reference spurs.
Dual Charge Pump Architecture	Separate CP1 (low-noise, µA-range) and CP2 (high-current, mA-range) allow optimized loop dynamics: fast acquisition + low steady-state jitter.
Programmable Lock Detection	Selectable analog (PFD output) or digital (configurable error window + 63-cycle validation) lock signaling for robust system monitoring.
Independent Power Rails	PVDD (2.7–5.5 V) and CPVDD (up to 5.5 V) enable supply noise isolation between digital control and analog charge pump circuitry.
Flexible Prescaler Support	4/5, 8/9, and 16/17 dual-modulus prescalers with R-divider (4–255) allow wideband coverage while maintaining integer-N compatibility.

Applications

Wireless Transceiver Local Oscillator	RF Test Equipment Frequency Source
Use Scenario: Generating tunable LO signals for SDR-based cellular baseband upconversion in 700 MHz–2.7 GHz bands using external VCO and loop filter. IC Role / Device Role / Timing Role: Fractional-N synthesizer providing programmable RF output with sub-kHz resolution and fast channel switching. Use Value: Enables rapid frequency hopping (<100 µs lock time with fast-lock mode) and low phase noise (<–100 dBc/Hz @ 10 kHz offset) for adjacent-channel rejection.	Use Scenario: Precision frequency source in benchtop spectrum analyzers and signal generators requiring stable, low-spur outputs across multi-decade ranges. IC Role / Device Role / Timing Role: Core PLL synthesizer driving high-linearity VCOs with calibrated loop bandwidth and phase margin control. Use Value: Delivers <–75 dBc spurious suppression and <1.5 Hz frequency error (per datasheet Example 1), meeting metrology-grade calibration requirements.
Industrial IoT Sensor Node Clock	Automotive Radar Intermediate Frequency Synthesis
Use Scenario: Low-power clock generation for narrowband LPWAN modules (e.g., LoRa, Sigfox) operating in 868/915 MHz ISM bands. IC Role / Device Role / Timing Role: Frequency synthesizer with programmable power-save mode (PDN1/PDN2 control) and 3.4 mA typical IDD. Use Value: Supports duty-cycled operation with register retention during PDN2-low state, extending battery life without losing frequency configuration.	Use Scenario: IF synthesis in 77 GHz automotive radar receivers, where precise chirp timing and low phase drift are critical for range/velocity accuracy. IC Role / Device Role / Timing Role: Stable fractional-N core feeding quadrature mixer; operates over –40°C to +85°C with LDO-regulated internal bias. Use Value: Maintains <±1 ppm frequency stability across temperature via REFIN divider and prescaler calibration, reducing post-processing compensation overhead.

Wireless Transceiver Local Oscillator

RF Test Equipment Frequency Source

Use Scenario: Generating tunable LO signals for SDR-based cellular baseband upconversion in 700 MHz–2.7 GHz bands using external VCO and loop filter.

IC Role / Device Role / Timing Role: Fractional-N synthesizer providing programmable RF output with sub-kHz resolution and fast channel switching.

Use Value: Enables rapid frequency hopping (<100 µs lock time with fast-lock mode) and low phase noise (<–100 dBc/Hz @ 10 kHz offset) for adjacent-channel rejection.

Use Scenario: Precision frequency source in benchtop spectrum analyzers and signal generators requiring stable, low-spur outputs across multi-decade ranges.

IC Role / Device Role / Timing Role: Core PLL synthesizer driving high-linearity VCOs with calibrated loop bandwidth and phase margin control.

Use Value: Delivers <–75 dBc spurious suppression and <1.5 Hz frequency error (per datasheet Example 1), meeting metrology-grade calibration requirements.

Industrial IoT Sensor Node Clock

Automotive Radar Intermediate Frequency Synthesis

Use Scenario: Low-power clock generation for narrowband LPWAN modules (e.g., LoRa, Sigfox) operating in 868/915 MHz ISM bands.

IC Role / Device Role / Timing Role: Frequency synthesizer with programmable power-save mode (PDN1/PDN2 control) and 3.4 mA typical IDD.

Use Value: Supports duty-cycled operation with register retention during PDN2-low state, extending battery life without losing frequency configuration.

Use Scenario: IF synthesis in 77 GHz automotive radar receivers, where precise chirp timing and low phase drift are critical for range/velocity accuracy.

IC Role / Device Role / Timing Role: Stable fractional-N core feeding quadrature mixer; operates over –40°C to +85°C with LDO-regulated internal bias.

Use Value: Maintains <±1 ppm frequency stability across temperature via REFIN divider and prescaler calibration, reducing post-processing compensation overhead.

Equivalent & Alternatives

The following parts are listed as comparable options for similar fractional-N synthesizer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LMX2531LQ1725E	Integrated VCO; 2.2–2.5 GHz range; no external prescaler needed; SPI interface only.	Better suited for single-band, fixed-frequency VCO designs; lacks dual-charge-pump fast-lock architecture.	Choose LMX2531 when VCO integration reduces BOM count and 2.2–2.5 GHz coverage suffices; avoid if 20–600 MHz continuous sweep or prescaler flexibility is required.
ADF4351	Wider range (35 MHz–4.4 GHz); integrated VCO + RF dividers; SPI-only; higher typical IDD (120 mA).	Targets broadband lab equipment; requires more complex loop filter due to integrated dividers and wider bandwidth.	Choose ADF4351 for multi-octave coverage and integrated dividers; AK1541 remains preferred for low-power, discrete-VCO systems needing fine-grained 2²⁰ resolution and independent CP rails.

Compared with LMX2531LQ1725E and ADF4351, the AK1541 offers superior resolution (2²⁰ vs. 2¹²/2¹⁴), lower power (3.4 mA vs. >100 mA), and dedicated fast-lock charge pump - making it optimal for battery-powered, precision-tuned RF subsystems where external VCO control and thermal stability are prioritized.

Availability

The AK1541 is available at Aetrix Electronics and suitable for wireless transceiver LO generation, RF test equipment frequency sources, industrial IoT sensor node clocks, and automotive radar IF synthesis requiring stable component supply and long-term lifecycle support.

Supply support for AK1541 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

AsahiKASEI (AKM) is a Japanese semiconductor manufacturer specializing in mixed-signal ICs for audio, sensor, and RF applications, with decades of expertise in precision analog design and low-noise circuitry.

The AK1541 belongs to AKM's high-performance RF synthesizer product line, engineered specifically for applications demanding ultra-fine frequency resolution, fast lock times, and flexible loop filter integration in discrete-VCO architectures.

FAQ

What is the minimum and maximum operating frequency supported by the AK1541?

The AK1541 supports an output frequency range of 20 MHz to 600 MHz. This is achieved using selectable dual-modulus prescalers (4/5, 8/9, or 16/17) and a programmable reference divider (R = 4–255). The lower bound applies across all prescaler modes; the upper bound requires 8/9 or 16/17 prescaling per the datasheet's "RF Characteristics" table. The AK1541 does not generate frequencies below 20 MHz or above 600 MHz under specified operating conditions.

How does the AK1541 achieve fast lock time, and what controls it?

The AK1541 achieves fast lock time via its dedicated Charge Pump 2 (CP2), enabled by setting D[16] = FASTEN = 1 in . CP2 delivers 0.84–2.32 mA (8-step programmable) and is activated for a user-defined duration set by FAST[12:0], calculated as (phase detector cycle) × (counter value). During this period, the loop filter switch engages and CP2 drives the VCO; afterward, CP1 resumes steady-state control. This two-stage approach reduces lock time without compromising phase noise.

Can the AK1541 operate with a single supply voltage, or are separate PVDD and CPVDD rails mandatory?

The AK1541 supports both configurations: PVDD and CPVDD may be tied together (2.7–5.5 V) or independently biased (CPVDD up to 5.5 V, PVDD 2.7–5.5 V). Separate rails are recommended to isolate charge pump noise from digital peripherals and improve PSRR. The datasheet specifies absolute max ratings separately (–0.3 to 6.5 V each), confirming true dual-rail capability - critical for low-spur RF designs where supply coupling degrades spectral purity.

What is the function of the BIAS pin, and how does resistor selection affect performance?

The BIAS pin (Pin 19) accepts an external resistor (22–33 kΩ) that scales both Charge Pump 1 and Charge Pump 2 currents. For CP1, current = (0.285 / R_BIAS) × (CP1[3:0] + 1); for CP2, current = (5.7 / R_BIAS) × (CP2[2:0] + 4). A 27 kΩ resistor yields CP1 = 10.6–168.9 µA and CP2 = 0.84–2.32 mA across their respective step ranges. Deviating outside 22–33 kΩ violates guaranteed current accuracy per the Electrical Characteristics table.

Does the AK1541 support both analog and digital lock detect, and how are they configured?

Yes - lock detect mode is selected via D[11] = LD in : LD = 0 enables digital lock detect (63-cycle validated phase error with configurable window LDCKSEL[1:0]); LD = 1 enables analog lock detect (direct PFD output on LD pin). Digital mode requires VCO frequency constraints relative to REFIN and DITH setting; analog mode has no such limitation. Both assert LD low when unlocked and high (digital) or valid analog level (analog) when locked.

AK1541 Specifications

Product attributes: Attribute value

Manufacturer:: Asahi Kasei Microdevices/AKM

Series:: -

Package/Case:: 24-WFQFN Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

Type:: -

PLL:: Yes

Input:: Clock

Output:: Clock

Number of Circuits:: 1

Ratio - Input:Output:: 2:1

Differential - Input:Output:: Yes/No

Frequency - Max:: 600MHz

Divider/Multiplier:: Yes/No

Voltage - Supply:: 2.7V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C

Mounting Type:: Surface Mount

Grade:: -

Qualification:: -

Supplier Device Package:: 24-QFN (4x4)

AK1541 FAQ

1.How can I place an order for AK1541 through Aetrix?

Please submit a Request for Quotation (RFQ) for AK1541 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 AK1541 reliable?

The price and inventory of AK1541 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AK1541 is usually 5 days.

3.What payment methods are accepted for AK1541?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AK1541 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AK1541?

AK1541 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AK1541 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 AK1541?

For technical support, including AK1541 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AK1541 requirements.

6.How does Aetrix verify that AK1541 is sourced from the original manufacturer or authorized distributors?

All AK1541 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 AK1541 meets industry standards.

7.What is the process for return or replacement of AK1541?

All AK1541 units undergo pre-shipment inspection (PSI). If there is an issue with AK1541, 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 AK1541 part is unused and in its original packaging.

Return procedure for AK1541:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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