SLVAFE1 December 2024 DRV8210 , DRV8220 , TLV9061
This application note provides a low-power and cost-efficient design for smoke alarm sounders that is capable of meeting NFPA 72 requirements and provides two output frequencies of 500Hz and 3kHz, which are proved to be the most effective designs within placement in sleeping areas. Additionally, audio playback is possible with this same hardware design through firmware. Use of an H-bridge driver over discrete implementations introduces several advantages, such as low power dissipation, and high SPL output due to differential drive of the piezo without expensive auto-transformer magnetics.
While not described in detail in this application note, an alternate design is possible for smoke alarms which use the TPS8802 analog AFE. The TPS8802 includes an H-bridge horn driver (selectable for either 2-terminal or self-resonant 3-terminal piezo drive) and a boost converter. In this case, the TLV61046A and DRV8220 shown in this demo are replaced by the functionality included in the TPS8802.