AD7837ANZ

Overview

The AD7837ANZ is a dual 12-bit multiplying digital-to-analog converter (MDAC) from Analog Devices, housed in a 24-lead Plastic DIP package. It integrates two complete DAC channels with buffered voltage outputs and internal R-2R ladder structures. The device operates on ±15 V power supplies (range ±14.25 V to ±15.75 V) and features parallel data interfaces with address selection for independent latch control. Key performance metrics include a typical settling time of 3 µs to within ±1/2 LSB, relative accuracy of ±1 LSB, and unity gain small-signal bandwidth of 750 kHz. It supports unipolar and bipolar offset binary coding schemes.

Feature Summary

• Dual 12-bit MDAC architecture with integrated output amplifiers
• Parallel interface with separate input latches for MSB (4-bit) and LSB (8-bit) data
• Simultaneous update capability via asynchronous LDAC pin
• ±1 LSB relative accuracy and differential nonlinearity

Applications

• Automatic Test Equipment
• Function Generation and Waveform Reconstruction
• Programmable Power Supplies
• Synchro Applications
• Programmable Gain Amplifiers

Procurement Notes

Verify the specific suffix 'ANZ' corresponds to the Plastic DIP (N-24) package variant with industrial temperature range (-40°C to +85°C). Confirm RoHS compliance status as indicated by the 'Z' suffix in current manufacturer documentation. Ensure supply chain sources provide original Analog Devices manufacturing data sheets to validate part authenticity and revision level.

Selection Notes

Select the AD7837ANZ when an 8-bit microprocessor interface is required, utilizing its split latch structure for efficient data loading. Choose this model over the AD7847 if simultaneous updating of multiple channels via a common LDAC signal is necessary. Verify that the application requires external feedback resistor connections, as the AD7837 does not internally connect RFBA/RFBB to VOUTA/VOUTB unlike the AD7847.

Part Context

The AD7837 belongs to the LC2MOS family of complete dual 12-bit MDACs. It is distinct from the AD7847 primarily in its digital interface logic; the AD7837 uses a parallel word input loading structure compatible with 8-bit buses, whereas the AD7847 accepts full 12-bit words directly. Both share similar analog performance characteristics but differ in pinout functionality regarding chip select and feedback resistor integration.

Replacement Considerations

Public confirmed substitute part numbers: AD7837BNZ (higher accuracy ±1/2 LSB), AD7837ARZ (SOIC package), AD7837BRZ (SOIC package, higher accuracy).

FAQ

How is data loaded into the AD7837ANZ?

Data is loaded into separate least-significant (8-bit) and most-significant (4-bit) input latches using CS, WR, A0, and A1 signals. Data is transferred to the DAC latches and updates the analog outputs when the LDAC pin is taken low.

What is the maximum operating temperature for the AD7837ANZ?

The AD7837ANZ is rated for an industrial temperature range of -40°C to +85°C.

Does the AD7837ANZ have internal feedback resistors connected to the outputs?

No, the AD7837 requires external connection of the VOUT pins to the RFBA and RFBB pins to close the feedback loop for the output amplifiers.