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Maxim > Design Support > Technical Documents > Application Notes > A/D and D/A Conversion/Sampling Circuits > APP 807
Maxim > Design Support > Technical Documents > Application Notes > Digital Potentiometers > APP 807
Maxim > Design Support > Technical Documents > Application Notes > Interface Circuits > APP 807
Keywords: DAC application circuits, Force/sense DAC, DAC, digital to analog convertor, selectable DAC
gain, programmable DAC gain, digital potentiometers, photodiode control, amperometric sensor bias
control, digitally programmable current source, temp sense
APPLICATION NOTE 807
Force/Sense DAC Applications
Oct 02, 2001
Abstract: This article discusses application circuits for Maxim force/sense digital-to-analog converters
(DACs). Applications include: selectable fixed-gain DAC, programmable gain DAC, photodiode bias
control, amperometric sensor control, digitally programmable current source, Kelvin load sensing,
temperature sensing, and high current DAC output. A brief description of the various DAC output
configurations is also given.
Force/Sense DACs are unique because they provide user access to the inverting node of the output
buffer amp in addition to the conventional output. These DACs are interesting because they provide
flexibility to create custom DAC gains, or other useful circuits by simply adding a few simple components.
Types of Buffered, Voltage DAC Outputs
Figure 1 shows three common types of buffered, voltage output DACs. The first has a fixed-gain defined
by an internal resistor ratio (typically +1.0, +1.638, or +2.0V/V), and no provision for adjusting the offset.
The second type also uses internal resistors to set a fixed gain, but the normally grounded resistor tap in
the non-inverting gain op amp topology is brought to an external pin allowing offset adjustment. The final
output type is force/sense, which provides a pin connecting directly to the inverting terminal of the output
op amp, yielding the most flexibility.
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