Texas Instruments DF1704EG4

Overview

DF1704EG4 from Texas Instruments is a stereo, 24-bit, 96kHz 8× oversampling digital interpolation filter IC designed for high-end audio systems. It provides programmable filter response (sharp/slow roll-off), digital de-emphasis, independent left/right attenuation, and supports I²S/standard/left-justified input formats with 16–24-bit word lengths. It serves as the companion digital filter to the PCM1704 DAC in premium CD players, DAC modules, and studio-grade audio converters.

For engineers reviewing the DF1704EG4 datasheet, DF1704EG4 pinout, DF1704EG4 application, or DF1704EG4 equivalent, key selection considerations include its 24-bit resolution, –115dB stopband attenuation, software/hardware configuration modes, SSOP-28 package compatibility, and precise 44.1/48/32kHz de-emphasis support - all critical for low-jitter, high-SNR audio signal chain design.

Technical Context

The DF1704EG4 implements an 8× oversampling FIR-based digital interpolation filter with two selectable frequency responses: sharp roll-off (–115dB stopband at 0.546f_S, ±0.00005dB passband ripple) and slow roll-off (–100dB stopband at 0.748f_S). Its internal architecture includes a 3-wire serial control interface (ML/MC/MD) for register programming in software mode and dedicated Schmitt-trigger input pins (I2S, IW0–IW1, OW0–OW1, SRO, DEM, SF0–SF1) for hardware mode configuration.

It operates on a single +5V supply and integrates an on-chip crystal oscillator (up to 24.576MHz), supporting system clock rates of 256f_S, 384f_S, 512f_S, or 768f_S. Audio output is right-justified, MSB-first, with fixed 8f_S word clock (WCKO) and BCKO at 256f_S (256/512f_S system clocks) or 192f_S (384/768f_S system clocks).

Key Specifications

Pinout & Package

DF1704EG4 is housed in a 28-pin SSOP (Shrink Small Outline Package) with 0.65mm pitch, optimized for compact high-fidelity audio PCB layouts. Pin 1 is marked by a dot or notch; pin numbering follows standard counter-clockwise orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital interpolation filter applications.

Compared with AK4128VN and CS8416-CQZ, DF1704EG4 offers superior stopband rejection (–115dB vs. –105dB typical) and integrated oscillator-based clocking - making it optimal for fixed-sample-rate, low-jitter audio systems where external clock dependency must be minimized.

Availability

DF1704EG4 is available at Aetrix Electronics and suitable for high-fidelity CD transports, studio reference DAC modules, and USB audio interface front-ends requiring stable component supply, long-term obsolescence planning, and traceable sourcing for Class-A audio production.

Supply support for DF1704EG4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and high-performance signal chain solutions.

The DF1704EG4 belongs to TI's premium audio digital filter product line, engineered specifically for ultra-low-distortion, high-SNR audio systems where precise digital filtering, flexible interface support, and deterministic timing are essential.

FAQ

What is the primary function of the DF1704EG4 in an audio signal chain?

The DF1704EG4 functions as a high-precision 8× oversampling digital interpolation filter that processes digital audio prior to conversion to analog. It performs sample rate conversion, image rejection, de-emphasis, and format alignment - specifically optimized to pair with the PCM1704 DAC. In every DF1704EG4 implementation, its role is to condition the digital signal for minimal jitter, ultra-low distortion, and accurate spectral reconstruction before the DAC stage.

Does the DF1704EG4 require an external crystal, or does it include an on-chip oscillator?

The DF1704EG4 includes an on-chip crystal oscillator supporting frequencies up to 24.576MHz, eliminating the need for external oscillators in most configurations. Pins XTI and XTO allow connection of a crystal (e.g., 24.576MHz for 48kHz systems) or an external clock source. The DF1704EG4 automatically detects and locks to the system clock multiplier (256f_S, 384f_S, etc.), making the DF1704EG4 self-synchronizing in oscillator-based designs.

Can the DF1704EG4 operate with sampling rates other than 44.1kHz and 48kHz?

Yes, the DF1704EG4 supports sampling rates from 32kHz to 96kHz, including 32kHz, 44.1kHz, 48kHz, and 96kHz. De-emphasis is explicitly supported only at 32kHz, 44.1kHz, and 48kHz (per SF0/SF1 pin settings or MODE3 register), but full interpolation filtering remains functional across the entire 32–96kHz range. For 96kHz operation, the DF1704EG4 requires an external 24.576MHz clock at XTI since the on-chip oscillator cannot exceed that frequency.

How does the DF1704EG4 handle digital attenuation, and what is its resolution?

The DF1704EG4 provides independent 8-bit digital attenuation for left and right channels, adjustable from –127.5dB to 0dB in 0.5dB increments. Attenuation is implemented via registers MODE0 (left) and MODE1 (right) in software mode, or via hardware pins in hardware mode. When ATC = 1 in MODE3, both channels share the same attenuation value. This precision allows fine-grained level matching in DF1704EG4-based multi-DAC or balanced-output systems without analog trimming.

Is the DF1704EG4 pin-compatible with other members of the DF17xx family, such as the DF1702 or DF1708?

No, the DF1704EG4 is not pin-compatible with DF1702 or DF1708. While all belong to TI's DF17xx digital filter family and share functional similarities, they differ in pin count, pin assignment, and feature set. The DF1704EG4 uses a 28-pin SSOP package with specific control pin allocations (e.g., SRO, DEM, SF0/SF1), whereas DF1702 is 24-pin and DF1708 is 32-pin with expanded functionality. Board layout and firmware for DF1704EG4 cannot be reused without redesign.