Asahi Kasei Fits Tiny ADC to Smart Security Sensors

Asahi Kasei Microdevices Corporation (AKM), a subsidiary of the Asahi Kasei Group, has developed the AK5707, an ultra-low-power monaural 16-bit A/D converter (ADC) equipped with the integrated Acoustic Activity Analyzer (AAA), an analog acoustic event detector (AED). Specifically, AK5707 excellently fits IoT security applications, like wireless cameras and smart doorbells. Its low power consumption, small package size, and advanced sound differentiation capabilities make it suitable for these applications.

AK5707 ultra-low-power monaural 16-bit A/D converter

Operating at only 34µA, the AK5707’s AAA block listens for acoustic events fitting user-customizable profiles. Further, upon detection, it activates the device’s built-in ADC, initiating recording to the integrated audio buffer. Simultaneously, it generates an interrupt to wake the external System-on-Chip (SoC). Since any qualifying acoustic event has been recorded into the AK5707’s internal buffer, the SoC can retroactively analyze the audio activity that occurred while it was asleep and/or booting up. This approach allows most of the system to sleep until the moment of detection, significantly reducing standby power and extending the end product’s battery life.

Moreover, flexible acoustic parameter settings allow for the detection of various sounds and patterns.

The AK5707’s Acoustic Activity Analyzer block consumes only 34µA while listening for qualifying audio events. In fact, it is far more capable than typical loudness-based detection. Also, the AAA constantly tracks the current noise floor and adjusts its detection parameters in response. This reduces false positives and increasing battery life in noisier environments.

AKM has created a suite of specific detection profiles for the AAA, including glass-break, alarm patterns such as T3/T4, crying baby, and human voice; these profiles are configurable, with multiple acoustic parameters that can be set by the user. Additionally, the AAA can perform general audio content classification as a function of frequency content and duration criteria, which are set by the user.

ADC Provides 95dB SNR for Only 200µA

The AK5707’s newly developed monaural ADC block (16-bit resolution, up to 48kHz) features significantly reduced power consumption without compromising on performance: it achieves 95 dB SNR while consuming only 200µA. This reduction in active power makes the AK5707 ideal for always-on battery-powered systems.

Integrated AC Coupling Caps Result in PCB Area Savings

Moreover, the AK5707 comes in a space-saving 1.53×1.58 mm CSP package. To minimize PCB space, AKM has integrated the ADC block’s AC coupling capacitors into the device. Thus, it reduces the number of external components needed. If a single 1.8V power supply powers the device, then only one external component (a single bypass capacitor) is necessary. This single-rail configuration makes it possible to implement the AK5707’s complete layout in under 3.2mm2 of PCB area.

The AK5707 is currently sampling, with mass production to begin in Sept. 2024.