AS3518 Audio Front-End IC

Description

The AS3518 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, 16Ω/32Ω headsets and auxiliary signal sources via a 10-channel mixer. It consumes less than 20mW in playback mode.

Further the device offers advanced power management functions. All necessary ICs and peripherals in a Digital Audio Player are supplied by the AS3518. The different regulated supply voltages are programmable via the serial control interface. AS3518 also contains a Li-Io battery charger. The single supply voltage may vary from 1.0V to 5.5V.

The AS3518 has an on-chip, phase locked loop (PLL) which generates the needed internal CODEC master clock. I2S Frame and shift-clock has to be applied from the processor for playback and recording. Further the AS3518 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
• 1 Microphone Input
  • 3 gain pre-setting (28dB/34dB/40dB) and AGC
    
  • 32 gain steps @1.5dB and MUTE
    
  • supply for electret microphone
    
  • microphone detection
    
  • remote control by switch
• 3 Line Inputs
  
  • volume control via serial interface
    
  • 32 steps @1.5dB and MUTE
    
  • stereo or 2x mono or mono differential
    
• Audio Mixer
  
  • 8 channel input/output mixer with AGC
    
  • mixes line inputs and microphones with DAC
    
  • left and right channels independent
    
• Line Output
  
  • volume control via serial interface
    
  • 32 steps @1.5dB and MUTE
    
  • 1Vp @10kW
    
  • Stereo 2*5mW @16W
    
  • Mono differential 10mW @32W (earpiece)
• High Efficiency Headphone Amplifier
  
  • volume control via serial interface
    
  • 32 steps @1.5dB and MUTE
    
  • 2x60mW @16W driver capability
    
  • headphone and over-current detection
    
  • phantom ground eliminates large capacitors
• Power Management
  
  • step down for CPU core (0.65V-3.4V, 250mA)
    
  • step down for peripheral (0.65V-3.4V, 250mA)
    
  • step up for backlight (15V (25V), 38mA),
    dimming, voltage control mode
    
  • LDO for AFE analog supply (2.9V, 200mA)
    
  • LDO for AFE digital supply (2.9V, 200mA)
    
  • LDO for peripherals (1.2V-3.5V, 200mA)
    
  • LDO for peripherals e.g. USB (1.2V-3.5V, 200mA)
    
  • power supply supervision
    
  • hibernation modes
    
  • 5sec and 10sec emergency shut-down
• Battery Charger
  
  • automatic trickle charge (50mA)
    
  • prog. constant current charging (50-460mA)
    
  • prog. constant voltage charging (3.9V-4.25V)
    
  • current limitation for USB mode
• 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
    
  • voltage generation
    
  • <1uA total power consumption
• 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
    
  • 64bit unique ID (OTP)
    
  • 23 different interrupts
• Package CTBGA64 [7.0x7.0x1.1mm] 0.8mm pitch

Applications

• Portable Digital Audio Player and Recorder
• PDA, Smartphone

Block diagram for AS3518 Audio Front-End IC