In some temperature-sensing applications there are some problems caused by the placement of sensors on location where the potential is very different from that of the data-acquisition-system common. So the operating temperature sensor must be isolated from its data-acquisition system galvanically. And the power’s source for the sensor was isolated. This circuit is designed to solve that problem. It provides power and isolation for a temperature sensor. This is the figure of the circuit.
This circuit is use the MAX845 (IC1) as a power transformer driver. The power of the temperature sensor is generated by the secondary winding from transformer that feeds a Graetz bridge rectifier. This circuit uses the MAX6576 (IC2) as temperature sensor that is provides a digital output whose period encodes the temperature (10µs/°K to 640µs/°K) and isolated by transformer. The MAX6576 was chosen because it combines the temperature sensor, signal-processing electronics, and easy-to-use digital I/O interface in a single low-cost package. It draws very little current from a single supply voltage. The MAX6576 is operated in the range +3V to +5V but it can maintain its accuracy specs.
[Circuit schematic source: maxim-ic.com]
This circuit is use the MAX845 (IC1) as a power transformer driver. The power of the temperature sensor is generated by the secondary winding from transformer that feeds a Graetz bridge rectifier. This circuit uses the MAX6576 (IC2) as temperature sensor that is provides a digital output whose period encodes the temperature (10µs/°K to 640µs/°K) and isolated by transformer. The MAX6576 was chosen because it combines the temperature sensor, signal-processing electronics, and easy-to-use digital I/O interface in a single low-cost package. It draws very little current from a single supply voltage. The MAX6576 is operated in the range +3V to +5V but it can maintain its accuracy specs.
[Circuit schematic source: maxim-ic.com]
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