AN-1243: Software Configurable 16-Bit Quad-Channel Unipolar/Bipolar Voltage Output Using the AD5754R DAC
Circuit Function and Benefits
This circuit provides unipolar and bipolar digital-to-analog conversion using the AD5754R, a quad, 16-bit, serial input, unipolar/bipolar voltage output DAC. The only external components needed for this 16-bit DAC are decoupling capacitors on the supply pins and reference input, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.
Figure 1. Unipolar/Bipolar Configuration for the AD5754R DAC (Simplified Schematic).
Circuit Description
The AD5754R is a digital-to-analog converter that offers guaranteed 16-bit monotonicity, integral nonlinearity (INL) of ±16 LSB, 0.1% total unadjusted error (TUE), and 10 μs settling time. The AD5754R also integrates a 2.5 V, 5 ppm/°C voltage reference, reference buffers, and output amplifiers. This provides further savings in both cost and board space. Performance is guaranteed over the following supply voltage ranges: AVDD supply range from +4.5 V to +16.5 V and AVSS supply range from −4.5 V to −16.5 V. The AVSS supply can be connected to 0 V if only unipolar outputs are required. The output range can be individually programmed for each of the four channels with these options: 0 V to +5 V, 0 V to +10 V, 0 V to +10.8 V, −5 V to +5 V, −10 V to +10 V, and −10.8 V to +10.8 V. The input coding is user selectable 2’s complement or offset binary for a bipolar output (depending on the state of the BIN/2sCOMP pin). Coding is straight binary for a unipolar output. Figure 2 shows that the typical output error of this circuit at 25°C ambient temperature is less than 0.07 %FSR.
Figure 2. Voltage Output Error.
The circuit must be constructed on a multilayer PC board with a large area ground plane. Proper layout, grounding, and decoupling techniques must be used to achieve optimum performance (see MT-031 Tutorial, Grounding Data Convertersand Solving the Mystery of AGND and DGND and MT-101 Tutorial, Decoupling Techniques).
Learn More
Kester, Walt. 2005. The Data Conversion Handbook. Analog Devices. Chapters 3 and 7.
MT-015 Tutorial, Basic DAC Architectures II: Binary DACs. Analog Devices.
MT-031 Tutorial, Grounding Data Converters and Solving the Mystery of AGND and DGND. Analog Devices.
MT-101 Tutorial, Decoupling Techniques. Analog Devices.
Voltage Reference Wizard Design Tool.