SSZTDE7 October   2026 TAS2573 , TAS2781

 

  1.   1
  2. 1 Introduction
  3. 2 The physics of microspeaker vulnerability
  4. 3 Traditional versus smart approaches to audio design
  5. 4 Integrated IV-sense circuitry
  6. 5 The temperature protection algorithm
  7. 6 Thermal modeling and control
  8. 7 The excursion protection algorithm
  9. 8 Look-ahead limiter
  10. 9 Integrating the audio tuning chain
  11. 10Conclusion
  12. 11About the authors
  13. 12Additional resources
  14. 13Trademarks

2 The physics of microspeaker vulnerability

A standard microspeaker consists of a voice coil suspended in a magnetic field, attached to a diaphragm (or cone) and held in place by a suspension system. When an electrical signal passes through the coil, it creates an electromagnetic force that moves the cone, vibrating the air to create sound. See Figure 1.


Microspeaker construction

Figure 1 Microspeaker construction

When engineers increase audio output in these tiny components to produce louder sound, they encounter two catastrophic failure mechanisms: thermal overload and mechanical over-excursion.

From a thermal perspective, loudspeakers are highly inefficient, where 95% to 99% of input electrical energy becomes heat rather than sound. Thus, continuous high-voltage signals can push the voice coil past its rated temperature (Tmax), melting the wire insulation and causing electrical shorts. Mechanically, producing bass at high volumes requires large cone excursion; if the drive voltage pushes the cone past its physical travel limit (Xmax), the suspension can stretch beyond its elastic limit, letting the voice coil strike the magnet’s backplate (bottoming out) or tearing the diaphragm from its surround and causing distortion, buzzing or total acoustic failure.