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