AD7111ACN

Overview

The AD7111ACN is a monolithic logarithmic digital-to-analog converter (DAC) from Analog Devices, packaged in a 16-pin plastic DIP. It attenuates analog input signals over a dynamic range of 0 dB to 88.5 dB with a nominal resolution of 0.375 dB. The device utilizes an onboard 8-bit decode logic to drive a 17-bit R-2R ladder. It operates on a single +5 V supply and features on-chip data latches for parallel microprocessor interfacing. The AD7111ACN is specified for industrial temperature ranges (-40°C to +85°C) and guarantees monotonicity up to 72 dB attenuation.

Feature Summary

• Logarithmic Attenuation: Provides 0 dB to 88.5 dB attenuation in 0.375 dB steps using a 17-bit internal R-2R ladder decoded from an 8-bit input.
• Industrial Temperature Range: Guaranteed operation from -40°C to +85°C with specified accuracy and monotonicity.
• Microprocessor Interface: Features edge-triggered Write (WR) input and on-chip latches for direct connection to standard 8-bit MPU buses.
• Low Power Consumption: Draws a maximum of 1 mA at +5 V when digital inputs are low or high.

Applications

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

Procurement Notes

Verify the ordering suffix 'N' corresponds to the 16-pin Plastic DIP package. Confirm the grade 'AC' matches the required industrial temperature range (-40°C to +85°C) and the specific accuracy guarantee of 0 dB to 72 dB. Ensure design compatibility with +5 V logic levels and single-supply operation requirements.

Selection Notes

Select the AD7111ACN when precise logarithmic signal control is needed within an industrial environment. The AC grade offers a wider guaranteed monotonic range (up to 72 dB) compared to the AB grade (60 dB). Consider the 16-pin DIP form factor for through-hole assembly needs. Verify that the output amplifier selection meets the bias current and offset voltage requirements to maintain specified static accuracy.

Part Context

The AD7111ACN belongs to the LOGDAC family of multiplying D/A converters. It is functionally similar to the AD7111A but distinguished by its specific temperature and accuracy grading. Unlike linear DACs, it provides exponential attenuation characteristics suitable for audio and sonar applications where large dynamic ranges are required in small packages.

Replacement Considerations

The AD7111A is pin-compatible with the industry-standard AD7524, allowing for upgrades from linear multiplying DAC designs. For direct replacements within the same family, consider the AD7111ABN for commercial/industrial use with a 60 dB monotonic range, or the AD7111ACR if a surface-mount SOIC package is preferred over the DIP.

FAQ

What is the difference between the AD7111 and AD7111A write triggers?

The AD7111 uses an edge-triggered Write (WR) input, requiring a rising edge to load new data. The AD7111A uses a level-triggered WR input, which allows for transparent latch operation if CS and WR are held low.

How does the AD7111ACN handle monotonicity at high attenuation levels?

The AD7111ACN is guaranteed monotonic in 0.375 dB steps up to 72 dB. Beyond this point, monotonicity is not guaranteed for every step, though the device remains functional up to 88.5 dB.

What is the typical propagation delay for the AD7111ACN?

The propagation delay is typically 1 µs at +25°C and increases to a maximum of 1.5 µs across the full industrial temperature range (-40°C to +85°C).