AS3517 Audio Front-End IC

Description

The AS3517 is a low power stereo audio codec and is designed for Portable Digital Audio Applications. It allows playback and recording in CD quality. It has a variety of audio inputs and outputs to directly connect electret microphones, 16 and 32 Ohm headphones and auxiliary signal sources via a 10-channel mixer. It only consumes 20mW in playback mode.

Further the device offers advanced power management functions. All necessary ICs and peripherals in a Digital Audio Player with flash or harddisk memory are supplied by the AS3517. The different regulated supply voltages are programmable via the serial control interface. The power management block generates 11 different supply voltages out of a single battery supply. CPU, NAND flash, SRAM, memory cards, harddisk, LCD, LCD backlight, USB-HOST and USB-OTG can be powered. AS3517 also contains a charger. The single supply voltage may vary from 3.0V to 5.5V.

The AS3517 has an on-chip, phase locked loop (PLL) controlled, clock generator. It generates 44.1kHz, 48kHz and other sample rates defined in MP3, AAC, WMA, OGG VORBIS etc. No additional external crystal or PLL is needed in slave mode.

Further the AS3517 has an independent 32kHz real time clock (RTC) on chip which allows a complete power down of the system CPU.

Key Features

• Multi-bit Sigma Delta Converters
  • DAC: 18bit with 94dB SNR (‘A’ weighted)
  • ADC: 20bit with 90dB SNR (‘A’ weighted)
  • Sampling Frequency: 8-48kHz
• 2 Microphone Inputs
  • 3 gain pre-setting (28dB/34dB/40dB) and OFF
  • 32 gain steps @1.5dB and MUTE
  • supply for electret microphone
  • microphone detection
  • voice activation
  • remote control by switch
• 2 Line Inputs
  • volume control via serial interface
  • 32 steps @1.5dB and MUTE
  • stereo or 2x mono or mono differential
• 2 Line Outputs
  • volume control via serial interface
  • 32 steps @1.5dB and MUTE
  • 1Vp @10k Ohm
• High Efficiency Headphone Amplifier
  • volume control via serial interface
  • 32 steps @1.5dB and MUTE
  • 2x60mW @16 Ohm driver capability
  • headphone and over-current detection
  • phantom ground eliminates large capacitors
• Audio Mixer
  • 10 channel input/output mixer
  • mixes line inputs and microphones with DAC
  • left and right channels independent
• Power Management
  • step down for harddisk (0.65V-3.4V, 500mA)
  • step down for CPUcore (0.65V-3.4V, 250mA)
  • step down for peripheral (0.65V-3.4V, 250mA)
  • charge pump for USB OTG (5V, 10mA)
  • step up for USB HOST/OTG (5V, 500mA)
  • step up for backlight (15V, 40mA), dimming
  • LDO for digital supply (2.9V, 200mA)
  • LDO for analog supply (2.9V, 200mA)
  • LDO for peripherals (1.2V-3.5V, 200mA)
  • LDO for peripherals (1.2V-3.5V, 200mA)
  • LDO for RTC (1.0V-2.5V, 2mA)
  • power supply supervision
  • hibernation modes
  • 5sec and 10sec emergency shut-down
• Battery Charger
  • automatic trickle charge (50mA)
  • prog. constant current charging (50-400mA)
  • prog. constant voltage charging (3.9V-4.25V)
• Real Time Clock
  • ultra low power 32kHz oscillator
  • 32bit RTC sec counter, 96 days auto wake-up
  • selectable alarm (seconds or minutes)
  • 128bit free SRAM for random settings
  • 32kHz clock output to peripheral
• Auxiliary Oscillator (only for master clock mode)
  • low power 12-24MHz oscillator
  • master clock input/output (e.g. from/to CPU)
• General Purpose ADC
  • 10bit resolution
  • 21 inputs analog multiplexer
• Interfaces
  • I²S digital audio interface and SPDIF
  • 2 wire serial control interface
  • reset pin, watchdog, power good pin
  • PWM output
  • 128bit unique ID (OTP)
  • 30 different interrupts
• Package BGA81 [9.0x9.0x1.15mm] 0.8mm pitch

Applications

• Portable Digital Audio Player and Recorder
• PDA, Smartphone

Block diagram for AS3517 Audio Front-End IC