LCD Display Inverter

Display Inverter / VGA Board / LCD Controller

AK4687: Home Theater Stereo CODEC Solution

AKM’s AK4687 is an asynchronous stereo CODEC with two input selectors and line drivers. The ADC/DAC interface of the AK4687 can receive up to 24-bit input data and supports asynchronous operation. The input orientation of the preamp supports three-channel stereo inputs, selectable via external resistors. Both the input stereo selector and output driver support ground-referenced 2Vrms input/output, making it possible to get rid of AC coupling capacitors and reduce external components. The AK4687 has a dynamic range of 99dB for ADC and 105dB for DAC. The device is suitable for digital recording systems, digital TVs, Blu-ray disc players and home theaters.

AK4687 main features

• Asynchronous ADC/DAC operation

• 3:1 capless stereo line input selector

• 24-bit stereo ADC

64x oversampling

Figure 1 AK4687 block diagram

Figure 2 Typical connection diagram of AK4687 (I2C control mode, CAD0 pin = “L”, master mode)

– Sampling rate up to 48kHz

– Linear phase digital antialiasing filter

– S/(N+D): 83dB

– Dynamic range S/N: 99dB

– Digital HPF for offset cancellation

• 24-bit dual stereo DAC

– 128x oversampling

– Sampling rate up to 192kHz

– 24-bit 8x digital filter

– S/(N+D): 95dB

– Dynamic range S/N: 105dB

– De-emphasis filter

• High jitter tolerance

• External master clock input:

256fs, 384fs, 512fs 768fs


128fs, 192fs, 256fs 384fs

(fs=64kHz~96kHz)128fs, 192fs (fs=128kHz~192kHz)

• Dual audio serial I/F (PORT1, PORT2)

– Master/Slave Mode (PORT1)

– I/F format

• PORT2: MSB, LSB adjusted (16-bit/24-bit), I2S

• PORT1: MSB, LSB adjusted (16-bit/24-bit), I2S

• Hardware/I2C bus control

Figure 3 Typical connection diagram of AK4687 (H/W control mode, MCLK=768fs, master mode)

Figure 4 Block diagram of the evaluation board AKD4687

•Operating Voltage

– Digital I/O and charge pump: 3.0V~3.6V

– DAC analog: 3.0V~3.6V

• Package: 48-pin QFP

Evaluation Board AKD4687-A

The evaluation board for the AK4687, the AKD4687-A, is a single-chip 24-bit CODEC with dual-channel ADC and dual-channel DAC. It can evaluate not only the A/D and D/A conversion of the AK4687, but also the asynchronous operation characteristics. In addition, the evaluation board can easily interface with digital audio equipment through the S/PDIF connector.

AKD4687-A Features

• Compatible with two types of digital audio interfaces

– BNC (S/PDIF) input/output with DIT/DIR (AK4118A)

– 10-pin header for register control

For details, see:


The Links:   LC215WUE-TBB1 BSM100GD120DLC