24-Bit 2ch ADC & 2ch DAC with Auto HPF, ALC/Eq and MIC/HP/SPK-Amp

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The AK4951 is a low power 24-bit stereo CODEC with a microphone, headphone and speaker amplifiers. The AK4951 supports sampling frequency from 8kHz to 48kHz. It is suitable for a wide range of application from speech signal processing for narrowband, wideband and super wideband to sound signal processing for audio band. The input circuits include a microphone amplifier, an automatic wind noise reduction filter of the proprietary algorithms and a high performance digital ALC (automatic level control) circuit, therefore the AK4951 can record with high-quality sound regardless of whether indoors or outdoors. In addition, the output circuits include a cap-less headphone amplifier with a negative voltage generated by charge pump circuit and a speaker amplifier with 1W output power. It is suitable for various products as well as portable applications with recording/playback function.


The AK4951 are available in a small 32-pin QFN (4mm x 4mm, 0.4mm pitch: AK4951AEN) and a 32-pin BGA (3.5mm x 3.5mm, 0.5mm pitch: AK4951EG) packages saving mounting area on the board.


 · Applications: IP Cameras, Digital Cameras, IC Recorders, Tablets, Wireless Headphones, Headsets

Key Features

        1. Recording Functions

                • Analog Input

                         (AK4951AEN) 3 Stereo Single-ended inputs with Selectors

                         (AK4951EG) 2 Stereo and 1 Monaural Single-ended inputs with Selectors

                • Microphone Amplifier: +30dB ~ 0dB, 3dB Step

                • Microphone Power Supply: 2.0V or 2.4V, Noise Level= −108dBV

                • Digital ALC (Automatic Level Control)

                        - Setting Range: +36dB ~ −52.5dB, 0.375dB Step & Mute

                • ADC Performance: S/(N+D): 83dB, DR, S/N: 88dB (MIC-Amp=+18dB)

                                                  S/(N+D): 85dB, DR, S/N: 96dB (MIC-Amp=0dB)

                • Microphone Sensitivity Correction

                • Automatic Wind Noise Reduction Filter

                • 5-Band Notch Filter: Include Dynamic Gain Control

                • Stereo Separation Emphasis Circuit

                • Digital Microphone Interface


        2. Playback Functions

                • Digital ALC (Automatic Level Control)

                        - Setting Range: +36dB ~ −52.5dB, 0.375dB Step & Mute

                • Sidetone Mixer & Volume Control (0dB ~ −18dB, 6dB Step)

                • Digital Volume Control

                        - +12dB ~ −89.5dB, 0.5dB Step & Mute

                • Capacitor-less Stereo Headphone Amplifier

                        - HP-Amplifier Performance: S/(N+D): 75dB@20mW, S/N: 97dB

                        - Output Power: 20mW@16Ω

                        - Pop Noise Free at Power-ON/OFF

                • Mono Speaker Amplifier (with Stereo Line Output Switch)

                        - Speaker Amplifier Performance: S/(N+D): 75dB@250mW, S/N: 99dB

                        - BTL Output

                        - Output Power:

                                 (AK4951AEN) 400mW@8Ω (SVDD=3.3V), 1W@8Ω (SVDD=5V)

                                 (AK4951EG) 400mW@8Ω (AVDD=3.3V)

                • Analog Mixing: BEEP Input

        3. Power Management

        4. Master Clock:

                 (1) PLL Mode

                        Frequencies: 11.2896MHz, 12MHz, 12.288MHz, 13.5MHz, 24MHz, 27MHz (MCKI pin)

                                               32fs or 64fs (BICK pin)

                 (2) External Clock Mode

                        Frequencies: 256fs, 384fs, 512fs or 1024fs (MCKI pin)

        5. Sampling Frequencies

                • PLL Master Mode:

                        8kHz, 11.025kHz, 12kHz, 16kHz, 22.05kHz, 24kHz, 32kHz, 44.1kHz, 48kHz

                • PLL Slave Mode (BICK pin): 8kHz ~ 48kHz

                • EXT Master/Slave Mode:

                        8kHz ~ 48kHz (256fs, 384fs, 512fs), 8kHz  24kHz (1024fs)

        6. Master/Slave Mode

        7. Audio Interface Format: MSB First, 2’s complement

                • ADC: 16/24bit MSB justified, 16/24bit I2S

                • DAC: 16/24bit MSB justified, 16bit LSB justified, 24bit LSB justified, 16/24bit I2S

        8. µP I/F:

                 (AK4951AEN) I2C Bus (Ver 1.0, 400kHz Fast-Mode)

                 (AK4951EG) 3-wire Serial, I2C Bus (Ver 1.0, 400kHz Fast-Mode)

        9. Operating Temperature: Ta = −40 ~ 85°C

        10. Power Supply


                        • Analog Power Supply (AVDD): 2.8 ~ 3.5V

                        • Speaker Power Supply (SVDD): 1.8 ~ 5.5V

                        • Digital & Headphone Power Supply (DVDD): 1.6 ~ 1.98V

                        • Digital I/O Power Supply (TVDD): 1.6 or (DVDD – 0.2) ~ 3.5V


                        • Analog & Speaker Power Supply (AVDD): 2.8 ~ 3.5V

                        • Digital & Headphone Power Supply (DVDD): 1.6 ~ 1.98V

                        • Digital I/O Power Supply (TVDD): 1.6 or (DVDD – 0.2) ~ 3.5V

        11. Package:


                        • 32-pin QFN (4 x 4 mm, 0.4mm pitch)


                        • 32-pin BGA (3.5 x 3.5 mm, 0.5mm pitch)

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