Designing Ideas

One way to obviate the nonlinear characteristic of an RTD sensor is to design analog hardware to perform the curve-fitting mathematics before any additional signal processing occurs. The approach in "Design an RTD interface with a spreadsheet" is especially attractive if you can keep both cost and component count low and if a microprocessor-driven design is not feasible.

Digital voltmeter (DVM) modules are very handy but also involve a significant number of design challenges. For example, their inputs are not isolated from the power supply, so you must add an isolated power supply. The opto-isolated flyback power supply in "Isolated supply powers DVM module" operates over a 0.7 to 15V input and supplies 9V at 10 mA.

Applications involving embedded microprocessors can require the reset output to hold high—that is, inactive—for a certain period of time upon power-up The circuit in "IC performs delayed system reset upon power-up" proves useful during power-up when there is no need to press the reset button once the device powers up, because reset occurs automatically with the predetermined hold time before you apply the reset-low signal.