MEMS Microphone

Overview

The LinkMems LMA3729T381-OY3S is a high-performance MEMS digital microphone featuring omnidirectional polar pattern, high SNR (63dB(A)), and ultra-compact package (3.76 × 2.95 × 1.00mm). Its low power design and excellent acoustic performance make it an ideal choice for voice interaction, smart speakers, and IoT voice devices.

1. Product Overview

1.1 Key Features

• Omnidirectional polar pattern: 360° uniform sound pickup, suitable for all-scenario voice acquisition
• High signal-to-noise ratio: 63dB(A) SNR, ensuring clear voice capture quality
• Low power consumption: Operating current of only 75µA, suitable for battery-powered devices
• Digital output: PDM digital interface with strong anti-interference capability and long transmission distance
• Ultra-compact package: 3.76 × 2.95 × 1.00mm, weight <0.03g, saving space
• Environmental compliance: RoHS compliant, halogen-free, meeting green manufacturing requirements

1.2 NE301 Application Scenarios

In the NE301 sensor expansion board, the MEMS microphone serves as a sound event trigger sensor, capable of detecting specific sound events such as glass breakage and abnormal noises to trigger NE301 snapshot capture. In security scenarios, sound triggering complements PIR/radar triggering to form a multi-detection mechanism, reducing missed reports.

Application Scenario	Description
Security Alert	Detects abnormal sounds such as glass breakage, immediately triggering NE301 snapshot capture
Environmental Monitoring	Detects abnormal equipment operating noise, triggering event snapshots
Voice Interaction	Detects voice commands or keywords, linking NE301 snapshot capture
IoT Gateway	Sound events trigger snapshots, working with other sensors for multi-modal perception

2. Specifications

2.1 Basic Parameters

Parameter	Specification
Model	LMA3729T381-OY3S
Manufacturer	LinkMems Acoustic Technology
Type	MEMS digital microphone
Package	3.76 × 2.95 × 1.00mm (4-pin)
Weight	<0.03g
Supply Voltage	1.6V ~ 3.6V (typical 2.0V)
Output Interface	PDM digital output
Acoustic Port Diameter	Ø0.325mm

2.2 Performance Parameters

Parameter	Condition	Min	Typical	Max	Unit
Polar Pattern	—	—	Omnidirectional	—	—
Sensitivity	94dB SPL @1kHz	-39	-38	-37	dB
Output Impedance	94dB SPL @1kHz	—	400	—	Ω
Operating Current	94dB SPL @1kHz	—	75	—	µA
Signal-to-Noise Ratio	A-Weighted	—	63	—	dB(A)
Total Harmonic Distortion	94dB SPL @1kHz	—	0.15	—	%
Acoustic Overload Point	10% THD @1kHz	—	125	—	dBSPL
Power Supply Rejection Ratio PSRR	200mVpp @1kHz	—	60	—	dB

2.3 Operating Conditions

Absolute Maximum Ratings

Parameter	Range
VDD to GND	-0.3V ~ +3.9V
OUT to GND	-0.3V ~ +3.9V
Input Current (any pin)	±5mA
Temperature Range	-40°C ~ +100°C

Reliability Test Standards

Sensitivity variation after each reliability test should be controlled within ±3dB.

3. Pin Definition

The LMA3729T381-OY3S uses a 4-pin package with the following pin definitions:

Pin #	Name	Type	Description
1	VDD	Power	Power supply input (1.6V ~ 3.6V)
2	GND	Ground	Ground
3	GND	Ground	Ground
4	OUT	Signal	PDM digital output signal

Note: Pin 2 and Pin 3 are both GND pins. During PCB layout, it is recommended that both GND pins be reliably grounded to reduce ground impedance and improve signal integrity.

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Item	Information
Document Version	v1.0
Last Updated	2026-04-08