AD7840JNZ

Overview

The AD7840JNZ is a complete 14-bit CMOS digital-to-analog converter (DAC) fabricated in LC2MOS technology. It integrates a 14-bit DAC, a 3 V buried Zener reference, and a high-speed output amplifier. The device supports both parallel and serial interfaces, enabling direct connection to DSPs like the ADSP-2100. It operates from ±5 V supplies with typical power dissipation of 70 mW. The analog output provides a bipolar range of ±3 V. Key dynamic specifications include a signal-to-noise ratio of 76 dB minimum and total harmonic distortion of -78 dB maximum at 1 kHz.

Feature Summary

• Complete 14-bit voltage output DAC with on-chip 3 V reference and output buffer
• Dual interface capability: 14-bit parallel or 16-bit serial data loading
• High-speed performance: 45 ns minimum write pulse width and 6 MHz serial clock rate
• Low power consumption: typically 70 mW at ±5 V supplies

Applications

• Direct interfacing with high-speed DSP processors such as ADSP-2100 and TMS320 series
• Speech synthesis systems requiring precise waveform generation
• Servo control loops needing fast settling times
• High-speed modem applications for signal modulation

Procurement Notes

Verify the ordering suffix 'JNZ' against the official Analog Devices Ordering Guide. The datasheet lists 'JN' for Plastic DIP-24 and 'JP' for PLCC-28 within the commercial temperature range. Confirm if 'Z' denotes RoHS compliance or if the specific suffix combination matches current manufacturing codes, as the provided text primarily references 'JN' and 'JP'. Ensure the component meets the 0°C to +70°C operating temperature range specified for the J grade.

Selection Notes

Select the AD7840JNZ when a complete 14-bit solution with integrated reference and buffer is required. Choose this part over discrete solutions to reduce board space and calibration complexity. Verify that the ±3 V output range aligns with system requirements. For applications demanding higher resolution, consider 16-bit alternatives; for lower cost, 12-bit options may suffice. Ensure the interface logic matches either parallel microprocessor buses or serial DSP links.

Part Context

The AD7840 belongs to the Analog Devices LC2MOS family of complete DACs. It is functionally similar to the AD7535 but offers integrated buffering and referencing. The device is designed for applications where speed and accuracy are critical, bridging the gap between general-purpose DACs and specialized high-performance converters. It is often used in conjunction with ADCs like the AD7870 in mixed-signal data acquisition systems.

Replacement Considerations

The AD7840KN is a pin-compatible alternative with improved SNR (80 dB min) and linearity (±1 LSB max). The AD7840JP offers the same electrical performance as the JN variant but in a PLCC-28 package. Check if the 'Z' suffix indicates a lead-free version of the standard JN package.