**AD7845JRZ: A Comprehensive Technical Overview of the 14-Bit CMOS DAC**
The **AD7845JRZ** from Analog Devices represents a high-performance, monolithic **14-bit digital-to-analog converter (DAC)** engineered for precision applications demanding high accuracy and stability. Fabricated on a **low-power CMOS process**, this DAC integrates a complete conversion solution into a compact package, making it a versatile component for a wide array of digital systems interfacing with the analog world.
At the core of the AD7845JRZ is a **14-bit R-2R ladder network**, the architecture responsible for the digital-to-analog conversion. This design, combined with **laser-trimmed thin-film resistors**, ensures high integral linearity (INL) and low gain error, which are critical for maintaining accuracy across the entire digital code range. The device offers a typical **±4 LSB maximum INL** error at 14 bits, guaranteeing that the transfer function from digital input to analog output remains highly linear.
The converter features a **double-buffered digital input interface**, which simplifies connection to microprocessors and digital systems. This input structure consists of an input register and a DAC register. The double buffering allows the user to **simultaneously update multiple DACs** in a system, a crucial feature for multi-channel applications such as automated test equipment and motion control systems. Data is loaded into the device in two 8-bit bytes, with the internal logic controlling the loading sequence for easy interface to 8-bit or 16-bit data buses.
A significant advantage of the AD7845JRZ is its **on-chip output amplifier**. This amplifier is designed to provide a **voltage output with a defined range**, typically 0 V to +2.5 V, 0 V to +5 V, ±2.5 V, or ±5 V, set by the configuration of the internal feedback resistors and the reference inputs. The inclusion of this amplifier saves board space and reduces the need for external components, streamlining design and manufacturing.
The device operates with an **external voltage reference**, which determines the full-scale output range and overall accuracy. This design choice provides flexibility, allowing designers to choose a reference that meets their specific requirements for precision and temperature drift. The AD7845JRZ itself exhibits excellent **reference feedthrough suppression**, minimizing noise and unwanted signals from the reference input in the analog output.
Power consumption is a key consideration, and the AD7845JRZ excels with its **low-power CMOS design**, typically drawing just 1.5 mW of power during operation. This makes it suitable for portable, battery-powered instruments and other power-sensitive applications. The device is offered in a **28-lead SOIC package (JRZ suffix)**, providing a robust and space-efficient solution for commercial temperature range (0°C to +70°C) environments.
In summary, the AD7845JRZ combines high resolution, excellent linearity, and flexible interface options in a single integrated circuit. Its robust architecture and integrated features make it a reliable building block for designers creating precise control and measurement systems.
**ICGOODFIND:** The AD7845JRZ is a stellar example of a highly integrated, precision 14-bit DAC. Its combination of a **laser-trimmed R-2R ladder**, **double-buffered input**, and an **on-chip output amplifier** delivers exceptional accuracy and ease of use, solidifying its position as a go-to solution for high-performance digital-to-analog conversion.
**Keywords:** 14-Bit DAC, CMOS, R-2R Ladder, Double-Buffered Interface, Low-Power.
