WM7331 Compact, Low Profile, Bottom Port Analog Microphone Featuring 63 dB SNR, ±1 dB Sensitivity Tolerance, 55 µA Power Consumption Product Overview The Cirrus Logic WM7331 is an ultra small, high performance MEMS microphone targeted at mobile audio applications. The WM7331 utilizes the company’s proprietary CMOS/ MEMS membrane technology to facilitate the integration of a transducer and ASIC into a single die. This integration of the silicon eliminates wire bonds between the MEMS and ASIC and allows the die to be housed in a miniature package with a footprint of just 4 mm2. In addition to its very small size, Cirrus Logic’s rugged MEMS technology protects against membrane breakage during manufacture and customer use. The WM7331 operates at a very low current of 55 µA while delivering distortion free (<1% THD) audio capture through the dynamic range to 120 dB SPL, as well as a low noise floor of 31 dB SPL. The microphone’s frequency response is flat between 85 Hz and 14 kHz and supports ultrasonic frequency capture to above 80 kHz. The WM7331 also features tight tolerance on the microphone sensitivity and phase, giving reduced variation between parts. This makes it ideal for applications using algorithms to process the captured audio and those requiring multiple microphones, and it removes the need for in-line, part-to-part production calibration to resolve microphone variations. Block Diagram Schematic 2.2µF WM7331 Smart CODEC VDD MICBIAS OUTPUT 1µF Analog Input pin (eg. IN1xP) GND WM7331 Analog Microphone, Single-Ended Connection with Smart Codec 2.2µF WM7331 Smart CODEC VDD MICBIAS OUTPUT 1µF GND 1µF WM7331 Analog Microphone, Pseudo-Differential Connection with Smart Codec Analog Input pin (eg. IN1xP) Inverting Input pin (eg. IN1xN) WM7331 Compact, Low Profile, Bottom Port Analog Microphone Target Applications The WM7331 is targeted at mobile audio applications, including wearables and headsets where its extremely small size, low power consumption and high performance make it an ideal microphone solution. The WM7331 can be paired with Cirrus Logic smart codec products that feature SoundClear ® software. This combination takes advantage of Cirrus Logic’s advanced A/D converter IP to deliver a world-class audio input path. System Features • High 63 dB SNR • <1% THD to 120 dB SPL (distortion higher than 1% THD is generally audible) High quality audio capture • <10% THD to 124 dB SPL • Low frequency roll-off -3 dB point 85 Hz • High frequency +3 dB point 14 kHz • Power consumption 55 μA maximizes battery life Audio system optimized • Consistent part-to-part performance • ±1 dB sensitivity tolerance is standard • ±2° phase matching Smallest, bottom port • Tiny form factor measures 1.6 mm X 2.5 mm X 0.9 mm LGA package • Rugged MEMS technology Ultrasonic ready • Captures audio to >80 kHz Cirrus Logic, Inc. 800 West Sixth Street Austin, Texas 78701 United States T +1-512-851-4000 T +1-800-888-5016 F +1-512-851-4977 Toll-Free +1-800-888-5016 Sales Support North America +1 866-630-1158 Asia Pacific +852 2376-0801 Japan +81 (3) 6732-8477 Europe/UK +44 (0) 1628-89 1-300 www.cirrus.com MARCH2016 © 2016 Cirrus Logic, Inc. All rights reserved. Cirrus Logic, Cirrus, the Cirrus Logic logo designs, SoundClear and the SoundClear logo design are trademarks of Cirrus Logic, Inc.