AD7111ACRZ

Overview

The AD7111ACRZ is a monolithic logarithmic digital-to-analog converter (DAC) from Analog Devices, fabricated in LC2MOS technology. It attenuates an analog input signal over a dynamic range of 0 dB to 88.5 dB with a nominal resolution of 0.375 dB. The device accepts an 8-bit parallel data word which is decoded internally into a 17-bit word driving an R-2R ladder. Operating on a single +5 V supply, it features on-chip data latches and transparent latch operation for the AD7111A variant. The component is housed in a 16-pin SOIC package and operates within a temperature range of -40°C to +85°C.

Feature Summary

• Logarithmic attenuation range of 0 dB to 88.5 dB with 0.375 dB step resolution
• Internal decode logic translates 8-bit inputs to a 17-bit R-2R DAC structure
• Transparent latch operation available via level-triggered Write input
• Pin-compatible with industry standard AD7524 multiplying DAC

Applications

• Audio Attenuators
• Sonar Systems
• Function Generators
• Digitally Controlled AGC Systems

Procurement Notes

Verify that the ordering suffix 'CR' corresponds to the Industrial temperature grade (-40°C to +85°C) and the SOIC-16 package option as defined in the manufacturer's ordering guide. Confirm that the specific AC grade matches the required accuracy specifications for the target application environment.

Selection Notes

Select this model when interfacing with standard 8-bit microprocessor buses requiring wide dynamic range control. Ensure the output amplifier selection accommodates the varying source impedance of the DAC to minimize offset errors. Verify that the system timing requirements align with the specified write pulse width and data setup times for reliable data transfer.

Part Context

This component belongs to the LOGDAC family of logarithmic converters. The AD7111A variant is functionally identical to the AD7111 but offers transparent latch operation and pin compatibility with the AD7524. The 'AC' designation indicates the specific accuracy grade and industrial temperature rating within the product line.

Replacement Considerations

The AD7111A is explicitly designed as a drop-in replacement for the AD7524, offering wider dynamic range and finer resolution while maintaining pin compatibility. Other AD7111 grades may be considered if different temperature ranges or accuracy levels are acceptable.

FAQ

How does the AD7111A differ from the AD7111 regarding latch operation?

The AD7111A features a level-triggered Write (WR) input, allowing the internal data latches to operate transparently when CS and WR are low. In contrast, the AD7111 uses an edge-triggered WR input.

What is the mechanism for achieving attenuation in this device?

An 8-bit binary input word is applied to the onboard decode logic, which converts it into a 17-bit word. This word drives a 17-bit R-2R ladder to determine the degree of attenuation across the DAC.

Is the device monotonic over its entire dynamic range?

Monotonicity depends on the selected attenuation step size and the specific grade. For example, the AD7111L is guaranteed monotonic in 0.375 dB steps from 0 dB to -54 dB.