AD7849ARZ

Overview

The AD7849ARZ is a 16-bit serial input multiplying digital-to-analog converter (DAC) from Analog Devices. It operates with analog supplies of ±15 V and a digital supply of 5 V. The device features a versatile three-wire serial interface supporting standalone and daisy-chain configurations. Monotonicity is guaranteed to 16 bits across the specified temperature range. Key electrical parameters include a typical output settling time of 7 μs to 0.006% FSR, a slew rate of 4 V/μs, and a power dissipation of 100 mW. The DAC clears to 0 V during reset sequences.

Feature Summary

• 16-bit resolution with guaranteed monotonicity over temperature
• Versatile serial interface with daisy-chain capability via SDOUT
• Internal voltage monitor for automatic output clamping to 0 V during power-up/down
• Configurable binary or two's complement coding via BIN/COMP pin

Applications

• Industrial process controls
• PC analog I/O boards
• Instrumentation systems

Procurement Notes

Verify the specific grade suffix (e.g., ARZ vs ANZ) against the required resolution and accuracy specifications in the official datasheet. Confirm that the 20-lead SOIC package matches the PCB footprint requirements. Ensure compatibility with the ±15 V analog supply rails and 5 V digital logic levels before procurement.

Selection Notes

Select the AD7849ARZ when a 16-bit resolution is required with guaranteed monotonicity. The A-grade variant offers higher accuracy but lower resolution compared to B and C grades. Consider the internal deglitching feature if minimizing digital-to-analog glitch impulse is critical for the application. Verify that the serial interface timing meets the microprocessor clock constraints.

Part Context

The AD7849 belongs to the AD7849 series of multiplying DACs. It is available in multiple packages including 20-lead PDIP and 20-lead SOIC. The 'AR' suffix denotes the SOIC package, while 'Z' indicates RoHS compliance. The device is functionally compatible with other members of the series, differing primarily in resolution grades and packaging options.

Replacement Considerations

Direct replacements within the same family include AD7849ANZ and AD7849BNZ. When substituting, verify that the replacement part number matches the required resolution (14-bit vs 16-bit) and package type (PDIP vs SOIC). Ensure that the pinout remains identical for direct socket replacement.

FAQ

How does the AD7849 handle output stability during power transitions?

During power-up and power-down, the VOUT pin is clamped to 0 V via a low impedance path. Transmission gate G1 opens to prevent shorting the amplifier output, maintaining this state until supplies stabilize and a valid word is written.

What is the function of the DCEN pin?

The Daisy-Chain Enable (DCEN) pin selects between standalone mode (logic low) and daisy-chain mode (logic high). In daisy-chain mode, it enables the SDOUT pin to cascade data to subsequent devices.

How is the DAC coding configured?

The BIN/COMP pin sets the coding format. Logic 0 selects straight binary for unipolar ranges or offset binary for bipolar ranges. Logic 1 selects two's complement for bipolar output ranges.