M41T00AUD is a highly integrated chip that combines real-time clock and audio functions. This chip is based on ST's M41T00 and has been enhanced with features such as trickle charging circuit, voltage reference, etc. It also has an input amplifier, low-pass filter, gain stage, and output stage in the audio section, which allows it to output 300 mW to 8 Ω load.
This application note explains how ST integrates audio functions into the M41TOOAUD real‑time clock, covering the internal audio front‑end, gain control, low‑pass filtering, and bridge‑output amplifier. It also discusses typical AIO (all‑in‑one) applications where the RTC drives beeps, telephone line tones, and other audio sources.
Key performance figures are provided, including a bridge‑output capable of delivering over 300 mW into an 8 Ω speaker at 3.3 V, a programmable gain range of –33 dB to +12 dB in 3 dB steps, an 8 kHz low‑pass filter, and a total harmonic distortion (THD) of less than 29 % at 1 kHz and 300 mW output. This manual is written in Chinese.
| Low‑pass filter bandwidth | 8 kHz |
|---|---|
| THD at 1 kHz, 300 mW | < 29 % |
The THD is specified to be less than 29 % at 1 kHz with a 300 mW output.
The low‑pass filter has an 8 kHz cutoff frequency.