Texas Instruments DAC5681EVM

Overview

DAC5681EVM from Texas Instruments is an evaluation module designed to characterize the DAC5681 16-bit, 1-GSPS digital-to-analog converter under real-world signal, clock, and supply conditions. It supports transformer-coupled analog output via SMA J3, LVDS data input up to 1 GSPS through SEMTEK connector J5, and USB-based register programming of both DAC and CDCM7005 clock device. The board operates with 1.8-V and 3.3-V supplies and enables full-scale current tuning from 2 mA to 20 mA via external RBIAS resistor R18.

For engineers reviewing the DAC5681EVM datasheet, DAC5681EVM pinout, DAC5681EVM application, or DAC5681EVM equivalent, this module provides hands-on validation of high-speed DAC performance in RF signal chain prototyping, baseband waveform generation, and clock-synchronized data path verification - with direct access to register-level control, configurable output paths, and integrated clock distribution.

Technical Context

The DAC5681EVM implements a complete signal chain for evaluating the DAC5681, including on-board CDCM7005 clock synchronizer (with selectable buffer or PLL mode), configurable LVDS interface with DCLK/SYNC/data lanes, and transformer-coupled 50-Ω analog output path. It supports internal bandgap reference (1.2 V) or external reference via EXTIO/EXTLO pins, and full-scale output current is set by R18 (20 mA default).

Hardware configuration is managed via jumpers (JP8–JP19) for reference selection, VCXO routing, CDCM7005 power-down, and clock source choice. The EVM accepts external clock input at SMA J6 (1-Vrms sine wave) and delivers synchronized LVDS clock back to pattern generators via J5, enabling precise timing alignment in high-speed test setups.

Key Specifications

Availability

DAC5681EVM is available at Aetrix Electronics and suitable for RF transceiver development, high-speed waveform generation, and precision DAC characterization requiring stable component supply, traceable sourcing, and long-term evaluation platform availability.

Supply support for DAC5681EVM 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 company specializing in analog, embedded processing, and high-performance data conversion technologies, with decades of leadership in precision DACs and evaluation platforms.

The DAC5681EVM belongs to TI's high-speed data converter evaluation module family, engineered specifically to accelerate design-in of 16-bit, gigasample-per-second DACs in communications infrastructure, test equipment, and radar systems.

FAQ

What is the primary function of the DAC5681EVM?

The DAC5681EVM is an evaluation module built to validate the performance of the DAC5681 16-bit, 1-GSPS digital-to-analog converter under realistic operating conditions. It provides full hardware and software support - including LVDS data input, transformer-coupled analog output at SMA J3, USB-based register control, and configurable reference and clocking - enabling engineers to verify dynamic performance, timing margins, and system integration before final PCB design. DAC5681EVM does not include RF modulation capability (unlike DAC5682z variants) and is optimized for baseband DAC evaluation.

Does the DAC5681EVM support RF output or quadrature modulation?

No, the DAC5681EVM does not support RF output or quadrature modulation. Unlike the DAC5682z EVM variant, it lacks the TRF3703 analog quadrature modulator and associated 5-V power rail and RF LO input (J23). Its analog output path is limited to transformer-coupled baseband signals at SMA J3. DAC5681EVM is strictly intended for DAC-only evaluation - confirming SFDR, SNR, and glitch energy at 1 GSPS - and cannot perform RF upconversion. This distinction is confirmed in the SLAU236A User's Guide, which explicitly restricts TRF3703 use to DAC5682z configurations.

What clocking options are available on the DAC5681EVM?

The DAC5681EVM uses the CDCM7005 clock synchronizer, configurable in either buffer mode (external 1-Vrms sine wave clock applied to SMA J6) or PLL mode (with optional VCXO installed at U6). In buffer mode, the CDCM7005 distributes and levels-shifts the input clock to drive the DAC's LVDS DCLK input and provide feedback clock to the pattern generator via J5. DAC5681EVM does not include a factory-installed VCXO; jumper settings JP13/JP14 must be changed to enable PLL operation, and JP19 must be installed to power the VCXO.

How is the full-scale output current configured on the DAC5681EVM?

The full-scale output current of the DAC5681 on the DAC5681EVM is set by external resistor R18 (6.2 kΩ default) connected between the DAC's BIASJ pin and ground. Using the formula IOUTFS = (VEXTIO / R18) × 16, and assuming VEXTIO = 1.2 V (internal bandgap), the default current is 20 mA. DAC5681EVM supports adjustment down to 2 mA by increasing R18 value - verified in Section 4.8 of SLAU236A - and requires no firmware change; only physical resistor replacement is needed to scale output range for different load or filter requirements.

Can the DAC5681EVM be used with the TSW3100 pattern generator?

Yes, the DAC5681EVM is fully compatible with the TSW3100 pattern generator system. Its SEMTEK connector J5 provides bidirectional LVDS signaling: it accepts D15–D0 data and DCLK/SYNC from the TSW3100 while simultaneously returning a synchronized clock signal to the pattern generator for timing alignment. The included EVM Control Software (Section 5.5 of SLAU236A) includes dedicated TSW3100 Configuration and Pattern Generation functionality, allowing users to download custom waveforms directly to the TSW3100 and correlate them with DAC output measurements - a key capability for DAC5681EVM-based closed-loop testing.