Rainbow Electronics AT73C246 - Manual (Page 2)

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11050A–PMAAC–07-Apr-10
AT73C246
1. Description
The AT73C246 is an integrated high performance Power Management and Audio IC. It is specif-
ically designed for advanced technology application processors with complex and low voltage
supplies targeting audio applications from low to high end. This System-on-Chip allows signifi-
cant savings in both cost and board area over previous discrete solutions.
Directly operated from a 2.9V to 5.5V input voltage, the PMU generates a set of 4 regulated
power supplies and an associated delayed reset signal. These 4 voltages are built up with 2 high
efficiency DCDC buck converters and 2 low noise LDOs. Featuring ultra fast transient responses
and integrating automatic voltage scaling function, these supplies perfectly fit with modern low
voltage MCU cores and memory supplies (DDR, Flash, ...). An additional 200mA LDO under
software control is provided for auxiliary application functions. The high performances of this
LDO (high PSRR, low noise, fast transient response) makes it ideal for analog front-ends (Audio,
RF...) as well digital peripherals.
Aside from the PMU, the AT73C246 integrates a complete state-of-the art low power audio
codec with headphone amplifier. On the input side, a stereo microphone preamplifier with differ-
ential or single ended connection (MICDIFF / MIC) and 2 selectable stereo inputs (LINE / AUX)
are directed to a 96dB Dynamic Range stereo audio ADC through an input mixer. On the output
side a 100dB dynamic range stereo audio DAC drives, through an output mixer, a 60 mW stereo
headphone amplifier which comes along with a VCM buffer. This VCM buffer allows to save two
large on-board coupling capacitors for area constrained applications. Additionally two fully ana-
log paths called bypass and sidetone from line / aux and microphone inputs to headphone
outputs allow to reduce the audio power consumption to minimum when needed.
The PMU is complemented with a low power RTC system including a recharging LDO, a crystal
oscillator and a programmable alarm that is fully integrated in the PMU digital core. Thus, the
RTC function is able to wake up the PMU, i.e the regulated power supplies, at a programmed
instant.
Also, a 10-bit ADC equipped with a 10:1 analog multiplexer is provided to the application to per-
form voltage measurements.
Finally, to reduce power consumption to minimum, the PMU features a flexible STANDBY mode
where the MCU is placed in reset state with selectable supplies ON, OFF or in low-power mode.
Power consumption in OFF mode is typically 20uA.