原标题：Atmel AT73C246带音频Codec的6路PMU方案

　　Atmel 公司的AT73C246是具有音频Codec的6路高性能电源管理单元(PMU),集成完整的新型低功耗音频编译码器(CODEC)和耳机放大器.工作电压2.9V-5.5V,PMU可产生4组稳压功率电源(2个高效DC/DC降压转换器和2个低噪音LDO)以及相关的延迟重置信号,一个200mA软件控制的LDO,2.5V/10mA备份电池充电器和RTC电源的LDO. 音频Codec的DAC具有100dB动态范围,ADC具有96dB动态范围,A加权的SNR为97dB,THD为-60dB,3.3V/16欧姆的最大输出功率为55mW.主要用在多媒体音频+电源解决方案.本文介绍了AT73C246主要特性,功能方框图,以及测量桥和10位ADC方框图, RTC方框图, 音频CODEC控制框图和应用框图.

　　AT73C246 6 Supply Channel PMU With Audio Codec

　　The AT73C246 is an integrated high performance Power Management and Audio IC. It is specifically 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 significant 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 differential 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 analog 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 perform 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.

　　AT73C246主要特性:

　　• AUDIO CODEC

　　– 100dB Dynamic Range Stereo Audio DAC - 8 to 96 kHz sampling frequency

　　– 96dB Dynamic Range Stereo Audio ADC - 8 to 96 kHz sampling frequency

　　– 16/32 Ohms headset amplifier with capless operation

　　• SNR: 97 dB A-Weighted

　　• THD: -60 dB (16Ohms/20mW/3.3V supply)

　　• Maximum output power: 55mW (16Ohms/3.3V supply)

　　– Stereo line inputs, stereo auxiliary inputs

　　– Stereo microphone inputs with bias generator for electret device

　　– Low power Analog Bypass mode (Line / Aux in to Headset Out)

　　– Low power Analog sidetone mode (Microphone in to Headset Out)

　　– Automatic Audio path control with smooth fade in/fade out operation

　　– I2S port

　　• Master / Slave Operation

　　• I2S / Left / Right justified modes

　　• 16 / 18 / 20 / 24 bit operation

　　• 6x SUPPLY CHANNEL VOLTAGE REGULATORS

　　– DCDC0:

　　• 1.85V - 600mA. 0.8 to 3.6V / 50mV step.

　　• 2 MHz switching buck regulator

　　• Fast load transient response - PWM / PFM modes.

　　• Efficiency up to 92%

　　– DCDC1:

　　• 1.2V - 600mA. 0.8 to 3.6V / 50mV step.

　　• 2 MHz switching buck regulator

　　• Fast load transient response - PWM / PFM modes.

　　• Efficiency up to 90%

　　– LDO2: 1V - 300mA. 0.8 to 1.35V / 50mV step - Fast transient response

　　– LDO3: 3.3V - 200mA. 2.7 to 3.6V / 50mV step - Fast transient response

　　– LDO4: 3.3V - 200mA. 2.7 to 3.6V / 50mV step - Audio codec supply

　　– LDO5: 2.5V - 10mA - Backup battery charger and RTC supply

　　• LOW CONSUMPTION POWER MANAGER

　　– 2.5V - 5.5V VIN Operation

　　– 20uA typical consumption OFF mode

　　– VIN monitor, CPU supplies monitor

　　– Die temperatue and over-current protections

　　– Reset and Interrupt generation

　　– Automatic Voltage Ramping on supply channels for DVS applications

　　– Standby mode with selectable supplies OFF

　　• RTC

　　– Ultra Low power crystal oscillator (<1uA typ.)

　　– Wake up function with programmable alarm or selectable inputs

　　• 10-b / 300kS/s ADC with 4 external / 6 internal selectable inputs

　　• Two-Wire Interface for PMU and Audio controls

　　• Available in 7.5 x 7.5 x 0.9 mm 64-pin QFN Package

　　AT73C246应用:

　　• Multimedia, Audio + Supply solution for MPU+DDR2 designs.

　　图1.AT73C246功能方框图

　　图2.AT73C246测量桥和10位ADC方框图

　　图3.AT73C246 RTC方框图

　　图4.AT73C246 音频CODEC控制框图

　　图5.AT73C246应用方框图