Asahi Kasei Microdevices/AKM AK4637EN

Overview

AK4637EN from Asahi Kasei Microdevices (AKM) is a low-power 24-bit mono audio CODEC with integrated microphone amplifier (+30dB to 0dB gain, 3dB step), digital ALC (−52.5dB to +36dB range), and 1W BTL speaker amplifier (at AVDD=5V, 8Ω load). It supports 8–48kHz sampling, DSP/I²S audio interface, and operates from −40°C to +85°C - designed for compact IP cameras and digital cameras requiring full-duplex voice capture and playback.

For engineers reviewing the AK4637EN datasheet, AK4637EN pinout, AK4637EN application, or AK4637EN equivalent, this page delivers verified specifications, validated QFN-20 (3×3mm, 0.4mm pitch) package mapping, confirmed analog/digital power domain separation (AVDD: 2.8–5.5V, DVDD: 1.6–1.98V), and real-world use cases in embedded imaging systems with acoustic noise suppression.

Technical Context

The AK4637EN integrates a single-ended or differential analog input path feeding a 24-bit sigma-delta ADC with programmable high-pass filter (HPF1/HPF2), 5-band notch filter, and wind-noise reduction logic. Its digital signal path includes configurable ALC, sidetone mixer (0dB to −18dB), and 24-bit DAC driving either a 400mW/1W BTL speaker output or mono line-out via LOSEL bit selection.

Audio clocking supports PLL master mode (11.2896MHz–27MHz MCKI input) or external slave modes (256fs–1024fs), with I²C control (400kHz fast-mode) managing register-based configuration of microphone power (2.0V/2.4V), digital volume (−89.5dB to +12dB, 0.5dB step), and speaker gain (SPKG1–SPKG0 bits).

Key Specifications

Pinout & Package

AK4637EN uses a 20-pin QFN package (3mm × 3mm, 0.4mm pitch) with exposed thermal pad. Pin functions are defined per AK4637 datasheet Rev. E-00 (2015), with VSS1/VSS2 ground separation, dedicated MIC power (MPWR), and dual-output capability (SPP/SPN for speaker, AOUT for line-out via LOSEL bit).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar mono audio CODEC applications.

Compared with AK4951EN and TLV320AIC3104IRHBT, the AK4637EN uniquely combines mono-optimized signal chain (differential mic input, wind filter, 5-band notch), integrated 1W speaker amplifier, and smallest QFN package - making it the most area- and feature-efficient solution for IP camera and digital camera audio subsystems.

Availability

AK4637EN is available at Aetrix Electronics and suitable for IP camera, digital camera, and MFP (multi-function printer) applications requiring stable component supply, long-term industrial temperature support, and compact audio subsystem integration.

Supply support for AK4637EN 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 high-precision analog and mixed-signal ICs, particularly audio codecs, Hall-effect sensors, and power management solutions.

The AK4637EN belongs to AKM's low-power mono audio CODEC product line, engineered specifically for embedded imaging and portable devices needing integrated microphone preamplification, noise suppression, and direct speaker drive in minimal footprint.

FAQ

What is the maximum output power of the AK4637EN speaker amplifier?

The AK4637EN speaker amplifier delivers 400mW into an 8Ω load at AVDD = 3.3V and 1W into 8Ω at AVDD = 5V, operating in BTL mode. This is confirmed in the Electrical Characteristics table (page 12) under "Speaker-Amp Characteristics" with SPKG1–SPKG0 bits set to "11". The 1W rating enables direct drive of small speakers in IP cameras without external amplification, reducing system cost and board area. AK4637EN thermal shutdown protection ensures safe operation under sustained load.

Does the AK4637EN support differential microphone input?

Yes, the AK4637EN supports full-differential analog input via IN+ and IN− pins when the MDIF bit is set to "1" in register 03H. This configuration provides improved common-mode noise rejection over single-ended AIN input - critical in electrically noisy environments like IP camera housings with motorized lenses or IR illuminators. Input impedance varies with gain setting (e.g., 16kΩ/244kΩ at +18dB), as documented in Note 8 of the datasheet.

How does the AK4637EN handle wind noise in outdoor applications?

The AK4637EN includes a dedicated hardware wind noise reduction filter targeting sub-200Hz frequency components caused by air turbulence - explicitly listed under "Features" (page 1) and implemented in the digital signal path prior to ALC. This is distinct from generic high-pass filtering and preserves speech intelligibility while suppressing low-frequency rumble. Real-world validation is supported by its targeted application in outdoor IP cameras, where wind-induced distortion is a primary failure mode.

What are the power supply requirements for the AK4637EN?

The AK4637EN requires three independent supplies: AVDD (2.8–5.5V) for analog circuitry including the speaker amp; DVDD (1.6–1.98V) for the digital core; and TVDD (1.6V or DVDD−0.2V to 3.6V) for I/O buffers. These rails must be decoupled per datasheet recommendations (e.g., 2.2μF on VCOM/REGFIL). Power-up sequencing requires PDN held low until all supplies stabilize - detailed in Section 7 (Recommended Operating Conditions) and Figure 11 (Control Sequence).

Can the AK4637EN operate in both master and slave audio clock modes?

Yes, the AK4637EN supports both master and slave modes via the M/S bit (bit 4 of register 01H). In PLL Master Mode (PMPLL=1, M/S=1), it generates internal audio clocks from MCKI (11.2896–27MHz). In PLL Slave Mode (PMPLL=1, M/S=0), it synchronizes to external BICK and FCK. EXT Master/Slave modes (PMPLL=0) accept 256fs–1024fs MCKI inputs. All modes support 8–48kHz sampling, enabling flexible integration with SoCs, FPGAs, or legacy audio controllers.