**The AD7547KN: A Comprehensive Technical Overview of the 12-Bit CMOS Multiplying DAC**
In the realm of precision digital-to-analog conversion, the **AD7547KN from Analog Devices** stands as a significant and versatile component. This integrated circuit is a **12-bit, four-quadrant multiplying digital-to-analog converter (DAC)** fabricated on a **low-power CMOS process**, making it a cornerstone for designers requiring accurate signal multiplication and control in both digital and analog domains.
At its core, the AD7547KN is designed to produce an output current that is the product of a digital 12-bit input word and an analog reference voltage. This **four-quadrant multiplying capability** allows the reference input to accept both positive and negative voltages, enabling a wide range of applications from automatic gain control to complex waveform generation. The device features a **fast settling time**, typically 600ns to ±1/2 LSB, which is critical for high-speed systems. Its architecture includes an R-2R ladder network, a hallmark of precision DACs, ensuring high linearity and minimal glitch energy.
A key feature of the AD7547KN is its **compatibility with microprocessors**. It incorporates a **double-buffered input latch** structure consisting of three 4-bit registers. This design allows the 12-bit data word to be loaded in three 4-bit nibbles, making it exceptionally easy to interface with 4-bit or 8-bit data buses without the need for additional external latching. This simplifies the design process and reduces component count in microprocessor-controlled systems.
The device operates from a single +5V to +15V power supply, with its **low power consumption** (typically just 20mW with a +5V supply) being a direct benefit of its CMOS construction. The analog section includes a reference input, feedback resistor, and the current output nodes. The **on-chip feedback resistor (RFB)** is trimmed to a precise value, matching the internal ladder network resistance and ensuring accurate scaling of the output. This allows for a simplified external op-amp configuration to convert the output current into a voltage.
The AD7547KN is offered in a 20-pin plastic DIP (Dual In-line Package), denoted by the 'N' suffix in its part number. This package was industry-standard for through-hole PCB assembly, ensuring robust mechanical and electrical connectivity.
**Applications** for this DAC are extensive. It is ideally suited for:
* **Digital Gain and Attenuation Control**
* **Programmable Filters and Power Supplies**
* **Motion Control Systems**
* **Synchro/Resolver Digital Conversion**
* **Audio and waveform synthesis equipment**
**ICGOOODFIND**
The AD7547KN is a quintessential component that masterfully blends precision, versatility, and microprocessor compatibility. Its robust four-quadrant multiplying architecture and integrated design features make it an enduring solution for complex analog computation and control tasks, solidifying its place as a valuable part in an engineer's toolkit.
**Keywords:**
1. **Four-Quadrant Multiplying DAC**
2. **12-Bit Resolution**
3. **CMOS Technology**
4. **Microprocessor Compatible**
5. **R-2R Ladder Network**
