What Is AK4499EQ Switched Resistor DAC？

What Is AK4499EQ?
The AK4499EQ is a high-performance 32-bit, 4-channel Switched Resistor DAC that incorporates advanced technology to deliver industry-leading low distortion and low noise performance. It supports PCM inputs up to 768kHz and DSD inputs up to DSD512, making it ideal for high-resolution audio playback in modern network audio systems and USB-DACs.
The DAC also features exceptional out-of-band noise suppression, ensuring clean and precise audio output. Additionally, the AK4499EQ offers six selectable 32-bit digital filters, providing flexible sound customization and adaptability for a wide range of audio applications.
Functions of AK4499EQ
PCM Data Interface: Execute serial/parallel conversion of SDATA1/2 input data by synchronizing with LRCK and BICK, and generate TDM output data.
External DF Interface: Receive external digital filter outputs. Execute serial/parallel conversion of DINL1/2 and DINR1/2 input data by synchronizing with BICK.
DSD Data Interface: 1-bit data that is input from DSDL1/2 and DSDR1/2 pins is received by synchronizing with DCLK.
DSD Filter: FIR filter that reduces high frequency noise of DSD input data
DATT, Soft Mute: Apply DATT and Soft Mute processes to input data.
De-emphasis & Interpolator: A digital filter that applies the De-emphasis process to input data and executes over sampling.
ΔΣ Modulator: Output multi-bit data to SR DAC. This block consists of a third-order digital delta-sigma modulator.
SR DAC: Convert multi bit output of ΔΣ Modulator into analog signal. This block consists of a switched resistor DAC.
Control Register: Keep register settings for each mode. Control registers are accessed in 3-wire (CSN, CCLK, CDTI) or I2C-Bus (SCL, SDA) control mode.
Clock Divider: Divide Master Clock In PCM mode, master clock is divided automatically by fs rate auto detection function. In DSD mode, the master clock frequency is set by DCKS bit.
MCLK Stop Detection: Detects when the master clock input is absent.
IREF: Generate reference current from the reference voltage generated internally, using an external resistor.
LDO: Generate power for internal digital circuits (1.8V typ.).
Circuit Principle of AK4499EQ
The circuit principle of the AK4499EQ is based on a switched resistor network conversion mechanism. Digital audio signals (such as PCM or DSD format) are first input through the interface into the chip's Digital Signal Processing (DSP) module. Inside the DSP, the audio data is pre-processed by filters, allowing users to select different sound effects according to their needs.
The filtered signal is then sent to the switched resistor network DAC circuit, which is the core of the AK4499EQ. The switched resistor DAC controls the opening and closing of high-speed electronic switches, dynamically adjusting the connection of a series of high-precision resistors to generate an analog voltage signal corresponding to the input signal level. The converted analog signal is passed through an output buffer circuit, which stabilizes the output and prepares it for subsequent processing.
The overall signal flow follows this sequence: Digital signal input → DSP digital filtering → Switched resistor network conversion → Output buffer circuit → Analog signal output.
Specification & Features of AK4499EQ
4-ch Switched Resistor DAC
THD+N: -124 dB
Dynamic Range, S/N: 140 dB (Mono), 137 dB (Stereo), 134 dB (4ch)
128x Over Sampling
Sampling Rate: 8 kHz  768 kHz
32-bit 8x Digital Filter
-Short Delay Sharp Roll-off, GD = 6.0/fs
-Short Delay Slow Roll-off, GD = 5.0/fs
-Sharp Roll-off
-Slow Roll-off
-Super Slow Roll-off
-Low Dispersion Short Delay Filter
DSD64, DSD128, DSD256, DSD512 Input Support
-Filter1 (fc = 37 kHz, DSD64 mode)
-Filter2 (fc = 65 kHz, DSD64 mode)
Digital De-emphasis for 32, 44.1 and 48kHz sampling
Soft Mute
-Digital Attenuator (0 dB ~ -127 dB, 0.5 dB step + mute)
Mono Mode
External Digital Filter Interface (EXDF Mode)
PCM/DSD, EXDF/DSD Mode Automatic Mode Switching Function
Audio I/F Format
- MSB Justified
- LSB Justified
- I²S
- DSD
- TDM
Daisy Chain
Master Clock
- fs = 8 kHz ~ 32 kHz: 256fs, 384fs, 512fs, 768fs, 1152fs
- fs = 32 kHz ~ 54 kHz: 256fs, 384fs, 512fs, 768fs
- fs = 54 kHz ~ 108 kHz : 256fs, 384fs
- fs = 108 kHz ~ 216 kHz: 128fs, 192fs
- fs = 384 kHz : 32fs, 48fs, 64fs, 96fs
- fs = 768 kHz : 16fs, 32fs, 48fs, 64fs
Register Control Mode with 3-wire Serial or I²C interface
Pin Control Mode
Power Supply: Internal LDO (LDOE pin = "H")
-TVDD = 3.0 ~ 3.6 V, AVDD = 4.75 ~ 5.25 V
-VDDL1/R1/L2/R2 = 4.75  5.25 V
External Supply (LDOE pin = "L")
-TVDD = 1.7 ~ 3.6 V, DVDD = 1.7 ~ 1.98 V
-AVDD = 4.75 ~ 5.25 V, VDDL1/R1/L2/R2 = 4.75 ~ 5.25 V
Operational Temperature: -40 ~ 85℃
Digital Input Level: CMOS
Package: 128-pin HTQFP
Where to Use AK4499EQ?
The AK4499EQ is primarily used in high-end audio devices, especially in Hi-Fi audio systems, network audio players, USB-DACs, portable music players, and professional audio equipment. With support for 32-bit high-resolution audio processing and the ability to decode up to 768kHz PCM and DSD512 audio formats, the AK4499EQ meets the demands for extremely high sound quality. Additionally, its built-in selection of digital filters enables more flexible audio playback, making it suitable for use in home theater systems, audiophile headphone amplifiers, and studio-grade audio equipment.
How to Use AK4499EQ?
First, when designing the circuit board, the power supply pins of the AK4499EQ must be connected to an appropriate power supply voltage. Next, the digital signal input ports are connected to the main control device, such as a DSP or microcontroller, to transmit audio signals in PCM or DSD formats. At the same time, the clock input pins should be connected to a high-precision clock source to ensure accurate synchronization.
The controller sends audio data to the AK4499EQ, where it passes through a configurable digital filter via I2C or SPI. It then enters the switched-resistor DAC, converting the digital signal to analog. The output buffer stabilizes the analog signal, which is sent to audio devices like headphones, amplifiers, or speakers for high-fidelity playback.
During the debugging process, it is essential to check the layout of decoupling capacitors on the power supply to minimize power noise. Additionally, maintaining the integrity of the ground (GND) connection is crucial to prevent signal interference and ensure stable and high-quality audio performance.
Package of AK4499EQ
The AK4499EQ uses an LQFP-128 package (Low-Profile Quad Flat Package), which features 128 pins in a low-profile, square flat design. This packaging style offers small pin pitch, compact size, and excellent thermal performance, making it suitable for high-density circuit board designs.
The package parameters are as follows:
Number of pins: 128
Pin pitch: 0.5mm
Package size: Approximately 14mm × 14mm (excluding pins)
Package thickness: 1.4mm (typical)
FAQs
What types of audio formats does the AK4499EQ support?
The AK4499EQ supports high-resolution audio formats, including PCM up to 768kHz and DSD512.
How is the AK4499EQ configured for different audio applications?
The AK4499EQ includes six types of 32-bit digital filters that users can configure via I2C or SPI interfaces.
Where can I use the AK4499EQ?
The AK4499EQ is used in high-end audio equipment, such as Hi-Fi systems, USB DACs, portable music players, and professional audio devices.