AD7840ARS

Overview

The AD7840ARS is a complete 14-bit voltage output digital-to-analog converter (DAC) fabricated in LC2MOS technology. It integrates a 14-bit DAC, a 3 V buried Zener reference, and an output amplifier. The device supports both parallel and serial interfaces, featuring double-buffered logic with 14-bit input and DAC latches. It operates from ±5 V supplies, delivering a bipolar output range of ±3 V. Key electrical specifications include a minimum signal-to-noise ratio of 78 dB, integral nonlinearity of ±2 LSB max, and a typical power dissipation of 70 mW. The industrial temperature grade covers -25°C to +85°C.

Feature Summary

• Complete 14-bit CMOS DAC with integrated 3 V reference and output buffer
• Dual interface capability: Parallel mode with 21 ns setup time or Serial mode up to 6 MHz clock
• High dynamic performance: 78 dB min SNR and -80 dB max THD at 1 kHz
• Bipolar voltage output range of ±3 V with settling time typically under 2.5 µs

Applications

• Waveform generation for audio and test equipment
• Servo control systems requiring precise voltage adjustment
• High-speed modem signal synthesis
• Speech synthesis applications

Procurement Notes

Verify the specific suffix 'ARS' corresponds to the RS-24 package and industrial temperature range (-25°C to +85°C). Confirm RoHS compliance status as older datasheets may list non-compliant variants. Ensure supply voltages are strictly maintained within ±5% of nominal ±5 V to meet specified performance parameters. Check for ESD sensitivity precautions during handling.

Selection Notes

Select the AD7840ARS when a complete 14-bit solution with on-chip reference is required without external components. Choose this model over the J/K versions if operation below 0°C is necessary. Verify that the ±3 V output swing meets system requirements; otherwise, consider external reference adjustments. Ensure the microprocessor interface matches either the parallel timing constraints (45 ns WR pulse) or serial protocol (SYNC/SCLK/SDATA).

Part Context

The AD7840 belongs to Analog Devices' family of complete voltage output DACs. The 'A' suffix denotes the industrial temperature range, while 'RS' indicates the 24-pin SSOP package variant. This component bridges the gap between pure DAC cores and fully buffered amplifiers, simplifying PCB layout by integrating the reference and buffer stages.

Replacement Considerations

Direct pin-compatible replacements within the same package and specification class should be verified against the current manufacturer's cross-reference guide. Note that newer generations may offer improved SNR or lower power consumption but might require software adaptation for serial interface timing.