Description The M41T00AUD is a low-power serial real-time clock (RTC) with an integral audio section with tone generator and 300 mW output amplifier. Features Combination real-time clock with audio ■ Serial real-time clock (RTC) based on M41T00 ■ Audio section provides: – 300 mW differential audio amplifier – 256 and 512 Hz tone generation – –33 to +12 dB gain, 3 dB steps (16 steps plus MUTE) ■ 0 °C to 70 °C operation ■ Small DFN16 package (5 mm x 4 mm) Real-time clock details ■ Superset of M41T00 ■ 3.0 to 3.6 V operation – Timekeeping down to 1.7 V ■ Automatic backup switchover circuit – Ultra-low 400 nA backup current at 3.0 V (typ) – Suitable for battery or capacitor backup – On-chip trickle charge circuit for backup capacitor ■ 400 kHz I2C bus ■ M41T00 compatible register set with counters for seconds, minutes, hours, day, date, month, years, and century – Automatic leap year compensation – HT bit set when clock goes into backup mode ■ RTC operates using 32,768 Hz quartz crystal – Calibration register provides for adjustments of –63 to +126 ppm – Oscillator supports crystals with up to 40 kΩ series resistance, 12.5 pF load capacitance ■ Oscillator fail detect circuit OF bit indicates when oscillator has stopped for four or more cycles Audio section ■ Power amplifier – Differential output amplifier – Provides 300 mW into 8 Ω (THD+N = 2% (max), fin = 1 kHz) ■ Summing node at audio input – Inverting configuration with summing resistors into the minus (-) terminal – 0 dB gain with 10 kΩ feedback resistor and 20 kΩ input summing resistors – Signal input centered at VDD/2 – 1.6 VP-P analog input range (max) ■ 256 or 512 Hz signal multiplexing with analog input to provide audio with beep tones ■ Volume control, 4-bit register – Allows gain adjustment from –33 dB to +12 dB – 3 dB steps – MUTE bit ■ Audio automatically shuts off in backup mode
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