AD7226KR

Overview

The AD7226KR is a monolithic quad 8-bit digital-to-analog converter (DAC) fabricated in LC2MOS process. It integrates four voltage-output DACs with buffer amplifiers and interface logic on a single chip, eliminating the need for external trims. The device features separate on-chip latches for each DAC, accessed via a common 8-bit TTL/CMOS-compatible input port controlled by address lines A0 and A1. It supports dual supply operation (VDD: 11.4 V to 16.5 V; VSS: -5 V) or single supply (+15 V). Key electrical parameters include a settling time of 4 µs max, relative accuracy of ±0.5 LSB, and differential nonlinearity of ±1 LSB. The K version operates from -40°C to +85°C.

Feature Summary

• Four independent 8-bit DACs with integrated output buffer amplifiers capable of driving up to 5 mA.
• Microprocessor-compatible parallel interface with individual data latches and TTL/CMOS logic levels.
• Laser-trimmed amplifier offsets ensure full specified performance without user adjustment.
• Skinny 20-lead DIP package design optimizes board layout with analog and digital sections separated.

Applications

• Process control systems requiring multiple analog outputs.
• Automatic test equipment for signal generation.
• Automatic calibration of large system parameters such as gain and offset.

Procurement Notes

Verify the 'K' suffix indicates the commercial temperature range (-40°C to +85°C). Confirm the package type matches the required footprint, as the datasheet lists DIP, SOIC, SSOP, and PLCC options. Ensure power supply rails meet the specified ranges for dual or single supply configurations to maintain linearity specifications.

Selection Notes

Select the AD7226KR when multiple synchronized 8-bit voltage outputs are needed with tight channel-to-channel matching. The internal R-2R ladder architecture ensures monotonicity. Consider the 4 µs settling time and 2.5 V/ms slew rate for dynamic applications. Verify that the reference voltage source can handle the varying input impedance (2 kΩ to infinity) across all codes.

Part Context

The AD7226 belongs to Analog Devices' LC2MOS family of high-speed precision converters. This technology allows integration of high-speed digital logic and precision analog circuits on the same die. The KR variant specifically denotes the commercial temperature grade within the broader AD7226 product line, which also includes industrial grades.

Replacement Considerations

Direct pin-for-pin replacements may include other quad 8-bit DACs from the same manufacturer family, provided they support similar supply voltages and interface logic. Verify that any substitute maintains the 20-lead skinny DIP form factor and comparable settling times if speed is critical.

FAQ

Can the AD7226 operate with a single positive supply?

Yes, the AD7226 can operate from a single +15 V supply (VSS = AGND). However, dual supply operation (with VSS at -5 V) provides improved zero code error performance and better current sink capability near ground.

What determines which DAC receives data?

Data transfer is determined by the logic states of the address inputs A0 and A1 combined with the Write (WR) signal. When WR goes low, the DAC selected by A0 and A1 becomes transparent to the data bus.

Is external trimming required for accuracy?

No, the AD7226 requires no user trims. The amplifier offsets are laser-trimmed during manufacture to eliminate the need for offset nulling, ensuring full specified performance out of the box.