AD7225LRZ

Overview

The AD7225LRZ is a monolithic LC2MOS quad 8-bit digital-to-analog converter featuring integrated output buffer amplifiers. It provides four independent voltage outputs with separate reference inputs for each channel, allowing flexible signal conditioning. The device utilizes a double-buffered interface logic compatible with TTL and CMOS levels, enabling simultaneous update of all four outputs via the LDAC pin. It operates from single or dual supplies, typically requiring VDD between 11.4 V and 16.5 V. Key static performance metrics include ±1 LSB total unadjusted error and ±1/2 LSB relative accuracy for the L version. Dynamic characteristics feature a settling time of 4 μs to ±½ LSB and a voltage slew rate of 2.5 V/μs.

Feature Summary

• Four independent 8-bit DACs with integrated unity-gain output buffer amplifiers
• Separate reference input (VREFx) for each DAC channel
• Double-buffered interface allowing simultaneous update of all outputs
• TTL and CMOS compatible digital inputs

Applications

• Programmable transversal filters
• Digital word multiplication circuits
• Microprocessor-controlled analog signal generation

Procurement Notes

Verify the specific suffix 'LRZ' against the manufacturer's current ordering guide to confirm package type and temperature range availability. Ensure supply voltages remain within the specified 11.4 V to 16.5 V range for VDD and -5 V for VSS to maintain guaranteed performance specifications.

Selection Notes

Select this component when multiple low-resolution voltage outputs are required on a single chip. The L version offers improved accuracy (±1/2 LSB relative accuracy) compared to K/B versions. Ensure the application can provide separate reference voltages if independent scaling is needed, as internal references are not included.

Part Context

The AD7225 belongs to Analog Devices' LC2MOS family of data converters, combining high-speed digital logic with precision analog circuitry on a single CMOS process. This integration reduces board space and improves reliability in multi-channel systems. The LRZ designation indicates a specific package variant within the broader AD7225 product line.

Replacement Considerations

Direct replacements within the same family include AD7225KNZ, AD7225CRSZ, and AD7225LPZ. Verify pin compatibility and electrical specifications, particularly the accuracy grade (L vs K/C), before substitution.

FAQ

Can the AD7225 operate with a single positive supply?

Yes, the AD7225 supports single-supply operation using a +15 V VDD supply with VSS connected to AGND. However, dual-supply operation (-5 V VSS) provides better zero-code error and sink capability.

What is the maximum reference voltage allowed?

The reference voltage range is from 2 V to (VDD - 4 V). For a typical VDD of 15 V, the maximum reference voltage is 11 V.

How does the double-buffering mechanism work?

Each DAC has an input register and a DAC register. Data is loaded into the selected input register via WR. Simultaneous transfer to all DAC registers occurs on the rising edge of the LDAC signal, ensuring synchronized output updates.