CM-28421-000

Overview

The Knowles CM-28421-000 is a balanced armature receiver speaker designed for top-port applications. It features an impedance of 360 Ohms and achieves a high efficiency of 106 dBA. The component operates within a frequency range of 100 Hz to 5 kHz, with a self-resonant frequency at 300 Hz. It utilizes flex tabs for termination and is constructed with non-magnetic materials suitable for sensitive electronic environments.

Feature Summary

• Balanced armature technology for high-fidelity audio reproduction
• Non-magnetic design compatible with magnetically sensitive devices
• Top port configuration for directed sound output
• Flex tab termination for reliable surface mount integration

Applications

• Hearing aids
• Bone conduction devices
• Medical diagnostic equipment

Procurement Notes

Verify the specific datasheet revision when sourcing, as manufacturer documentation may update mechanical tolerances or material specifications over time. Confirm that the flex tab termination style matches the target PCB footprint exactly. Ensure the 360 Ohm impedance aligns with the driving circuit's output requirements to prevent signal distortion or power mismatch during final assembly validation.

Selection Notes

Select this component when high sensitivity is required in space-constrained medical or hearing applications. The 360 Ohm impedance necessitates careful consideration of the amplifier interface compared to standard low-impedance speakers. The non-magnetic construction is critical for devices containing magnetic sensors or components that could be interfered with by traditional speaker magnets.

Part Context

This part belongs to Knowles' portfolio of precision acoustic components, specifically their balanced armature receivers. These components are engineered for miniaturization and performance in wearable and implantable electronics. The CM series represents specialized solutions for niche audio markets requiring precise acoustic tuning and small form factors.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided source data. Due to the unique combination of 360 Ohm impedance, 106 dBA efficiency, and non-magnetic balanced armature design, direct replacements require rigorous electrical and acoustic re-validation.