Asahi Kasei Microdevices/AKM AK1544

Overview

AK1544 from Asahi Kasei Microdevices is a 1300MHz integer-N frequency synthesizer featuring a dual-modulus prescaler (P/P+1), programmable divider, and highly accurate 9-step adjustable charge pump. It operates from 2.7V to 5.5V, delivers 2.8mA typical supply current, and integrates lock detection and two general-purpose output pins for RF front-end control in wireless transceivers.

For engineers reviewing the AK1544 datasheet, AK1544 pinout, AK1544 application, or AK1544 equivalent, this device supports precise RF frequency synthesis in 400–1300MHz bands with fast-lock capability, separate charge pump and interface power domains, and digital/analog lock detect selection - critical for GSM/EDGE, ISM-band radios, and low-power portable RF systems.

Technical Context

The AK1544 implements an integer-N PLL architecture with R, A/B, and prescaler counters driving a phase-frequency detector (PFD) and dual-mode charge pump (CP1/CP2). Its dual-modulus prescaler supports 16/17, 32/33, and 64/65 division ratios, enabling wideband frequency coverage while maintaining integer-N simplicity and low spurious performance.

Register-controlled fast lockup mode uses a dedicated timer (FAST[12:0]) and secondary charge pump (CP2) to accelerate PLL settling; lock detection is configurable as analog (direct PFD output) or digital (N-consecutive-error threshold logic), with LDCNTSEL[1:0] selecting 7/15/31/63 cycles for validation.

Key Specifications

Pinout & Package

AK1544 is housed in a 24-pin QFN package (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad connected to DVSS. Power domains are segregated: PVDD/PVSS for digital/peripheral circuitry, CPVDD/CPVSS for charge pump, and DVSS as digital ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMX2485E and ADF4350, the AK1544 offers lower quiescent current (2.8 mA), smaller 4 mm × 4 mm QFN footprint, and built-in GPOs for RF front-end control - making it optimal for space- and power-constrained integer-N applications below 1300 MHz.

Availability

AK1544 is available at Aetrix Electronics and suitable for GSM/EDGE transceivers, ISM-band sensor nodes, portable medical telemetry, and benchtop RF signal generators requiring stable component supply, long-term lifecycle support, and consistent parametric performance.

Supply support for AK1544 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

Asahi Kasei Microdevices (AKM) is a Japanese semiconductor company specializing in analog, mixed-signal, and sensor ICs, with leadership in audio codecs, Hall-effect sensors, and precision timing solutions.

The AK1544 belongs to AKM's RF frequency synthesis product line, designed specifically for low-power, high-integration wireless communication systems requiring robust integer-N PLL performance in compact form factors.

FAQ

What is the maximum operating frequency supported by the AK1544?

The AK1544 supports an RF input frequency range of 400 MHz to 1300 MHz at its RFINP/RFINN pins. This makes it suitable for UHF ISM bands, GSM/EDGE cellular infrastructure, and other wireless systems operating below 1.3 GHz. The device does not generate output directly but controls external VCOs within this range via its PLL loop.

How is charge pump current configured on the AK1544?

Charge pump current on the AK1544 is set using a 22–33 kΩ resistor connected to the BIAS pin, establishing a base current (Icp_min), then scaled via CP1[3:0] (normal mode) or CP2[3:0] (fast lockup mode) register bits. Each register value selects one of nine discrete current levels from 160 µA to 2530 µA, with 10% mismatch tolerance between source/sink currents.

Does the AK1544 support both analog and digital lock detection?

Yes, the AK1544 supports both analog and digital lock detection modes. Setting D[13]={LD} in Address 4 selects analog mode (LD pin outputs raw PFD voltage) or digital mode (LD pin asserts "High" after N consecutive valid phase comparisons). N is configurable as 7, 15, 31, or 63 cycles via LDCNTSEL[1:0].

What are the power sequencing requirements for the AK1544?

The AK1544 requires strict two-stage power sequencing: PDN1 must be asserted "High" before PDN2, with ≥50 µs delay between them. Simultaneous assertion is prohibited. This sequence enables the on-chip LDO and VREF before activating the PLL core, preventing undefined register states and ensuring reliable startup of the AK1544.

Can the AK1544's general-purpose outputs control RF switches directly?

Yes, the AK1544's GPO1 and GPO2 pins are programmable digital outputs controlled by Address 5 register bits. They drive "Low" or "High" (relative to PVDD) and can directly interface with common RF SPDT/SPST switches, PA enable inputs, or antenna diversity controllers - eliminating external GPIO drivers in compact RF designs.