December 2007
Rev 2
1/44
1
M41T00AUD
Serial real-time clock with audio
Features
■
Combination real-time clock with audio
– Serial RTC based on M41T00
– Audio section provides:
–
300mW differential audio amplifier
–
256 and 512Hz tone generation
–
-33 to +12dB gain, 3dB steps (16 steps
plus MUTE)
■
Real-time clock details:
– Superset of M41T00
– 3.0 to 3.6V operation
–
Timekeeping down to 1.7V
– Automatic backup switchover circuit
–
Ultra low 400nA backup current at 3.0V
(typ)
–
Suitable for battery or capacitor backup
–
On-chip trickle charge circuit for backup
capacitor
– 400kHz I
2
C 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 32,768Hz quartz
crystal
–
Calibration register provides for
adjustments of -63 to +126ppm
–
Oscillator supports crystals with up to
40k
Ω
series resistance, 12.5pF 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 300mW into 8
Ω
(THD+N = 2%
(max), f
in
= 1kHz)
– Summing node at audio input
–
Inverting configuration with summing
resistors into the minus (-) terminal
–
0dB gain with 10k
Ω
feedback resistor
and 20k
Ω
input summing resistors
–
Signal input centered at V
DD
/2
–
1.6V
P-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 -33dB to
+12dB
–
3dB steps
–
MUTE bit
– Audio automatically shuts off in backup
mode
■
0°C to 70°C operation
■
Small DFN16 package (5mm x 4mm)
DFN16 (5mm x 4mm)
“D” Suffix
www.st.com
