The ML2308 is a high-quality audio recording and playback LSI incorporating a digital audio signal processor. It uses a Δ-Σ type 1-bit A/D and D/A converter in conversion between audio analog and digital signals to provide audio sound quality comparing with CDs and includes OKI's original audio compression system, ADPCM. Since a microphone amplifier and a digital amplifier for driving a headphone and speakers are integrated in a single chip, this LSI can be used in a wide range of applications including sound recording and playback for compact digital video cameras and long digital recording using sound compression in voice recorders.

• Two channels each of Δ-Σ type 1-bit A/D and D/A converters (PWM output) are provided to allow stereo sound quality
• Direct driving of a microphone, speakers, and a headphone to reduce the number of components mounted
• Support for a variety of applications such as playback of audio data and voice memo recording
• Low power consumption and reduced development risks caused by analog noise

Data Sheet[PDF]

Main Applications

DSC, DVC, PDA, Voice memo recorder, Audio recording and playback system

Main Features and Specifications

User Interfaces

• Supports Serial Peripheral Interface (SPI) or 8-bit bus interface
• Memory for audio data buffer: 128 bytes (64 bytes each for left and right channels)

Codec Section/Audio Input and Output Sections

• μ-law G.711 compliant 8-bit PCM,
  8-bit/16-bit linear PCM, 8-bit OKI non-linear PCM,
  2-bit/3-bit/4-bit/5-bit/6-bit/7-bit/8-bit ADPCM2
• Sampling frequency: 4.0 kHz to 32 kHz variable (variable with commands)
• Auto Level Control (ALC) (automatic recording level adjustment)
• Built-in stereo Δ-Σ type 1-bit D/A converter
  S/(N+D): 75 dB DR, Dynamic range S/N: 85 dB (low-distortion complementary pulse output system)
• I2S format compatible/16-bit left-justified
• Built-in PWM driver for driving a speaker (150 mW max., RL = 16W, at BTL)
• Microphone amplifier X 2, Line amplifier X 2 (Stereo)

Control Commands

• Volume control: 256 steps, 0 dB to -48.16 dB, OFF
• PAN control: 16 steps, 0 dB to -24.08 dB, OFF
• Built-in microphone amplifier, line amplifier (Microphone can be used for monaural recording only)
• Power supply voltage : +2.7 V to +3.6 V
• Operating temperature : -20°C to +70°C
• Source oscillation frequency: 24.576 MHz
• Package: 48-pin QFN (7.2 mm′ 7.2 mm, 0.5 mm pitch)

Block Diagram

Magnified Figure

Example of Application Circuit

Magnified Figure

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