The T3904 is a multi-mode, low noise digital MEMS microphone in a small package. The T3904 consists of a MEMS microphone element and an impedance converter amplifier followed by a fourth-order Σ-Δ modulator. The digital interface allows the pulse density modulated (PDM) output of two microphones to be time multiplexed on a single data line using a single clock.
The T3904 has multiple modes of operation: High Quality, Low-Power (AlwaysOn), and Sleep. The T3904 has high SNR in all operational modes. It has 135 dB SPL AOP in High Quality Mode and 120 dB SPL AOP in Low-Power mode.
The T3904 is available in a standard 3.5 × 2.65 × 0.98 mm surface-mount package. It is reflow solder compatible with no sensitivity degradation.
| Part # | Market Status | Output | Port Location | SNR | AOP | Sensitivity | Package Size | LF Cutoff |
|---|---|---|---|---|---|---|---|---|
| UNITS: | dBA | dB SPL | dbfs | (mm) | Hz | |||
 T3904 |
Production | PDM | Bottom | 66 | 135 | -46 | 3.5 × 2.65 × 0.98 | 40 |
AN-0078 – High-Performance Digital MEMS Microphone Simple Interface to SigmaDSP Audio Codec
AN-100 – MEMS Microphone Handling and Assembly Guide
AN-1003 – Recommendations for Mounting and Connecting InvenSense MEMS Microphones
AN-1112 – Microphone Specifications Explained
AN-1124 – Recommendations for Sealing InvenSense Bottom-Port MEMS Microphones from Dust and Liquid Ingress
AN-1140 – Microphone Array Beamforming
AN-000111 – Selecting PDM Microphone Clock Frequencies and Decimation Ratios
Low Self Noise: The First Step to High-Performance MEMS Microphone Applications
Inter-IC Digital Audio Interfaces
Analog and Digital MEMS Microphone Design Considerations
Understanding Microphone Sensitivity
