TO38-31638-B21

Overview

The Knowles TO38-31638-B21 is an omnidirectional microphone belonging to the TO/BTO series. It features a compact form factor designed for space-constrained applications. The device operates with a supply voltage of 900 mV and draws a working current of 38 uA. Key electrical specifications include a sensitivity of -56 dB and a signal-to-noise ratio (SNR) of 69 dBA. The unit has an impedance of 5.1 kohms and utilizes a bottom port configuration. Physical dimensions are 3.35 mm in length, 2.5 mm in width, and 0.96 mm in depth. It functions within a temperature range of -17°C to +63°C.

Feature Summary

• Omnidirectional acoustic response pattern
• Ultra-thin profile suitable for tight spaces
• Low power consumption operation
• High signal-to-noise ratio performance

Applications

• Mobile communication devices
• Portable audio recording equipment
• Voice recognition systems
• Consumer electronics with limited board space

Procurement Notes

Verify the specific suffix B21 against the manufacturer's latest datasheet to confirm packaging and tape-and-reel specifications. Ensure compatibility with RoHS directives if required by your manufacturing standards. Cross-reference the part number with official Knowles documentation to validate availability and any recent design changes before finalizing procurement orders.

Selection Notes

Select this component when a low-profile, omnidirectional microphone is required for portable devices. Consider the 900 mV operating voltage and 38 uA current draw for battery-powered designs. The 69 dBA SNR supports clear voice capture in moderate noise environments. Verify that the bottom port orientation fits the mechanical assembly constraints of the target application.

Part Context

This microphone is part of the Knowles TO/BTO series, which specializes in small, thin omnidirectional microphones. These components are engineered for integration into modern electronic devices where size and power efficiency are critical. The series offers consistent acoustic performance across various consumer and industrial applications requiring reliable voice input capabilities.

Replacement Considerations

Consult official Knowles substitution guides for verified alternatives. Generic replacements may not match the specific 0.96 mm height or 69 dBA SNR requirements. Validate pinout and acoustic characteristics before swapping.