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LM57 V(TEMP) Design Considerations
I would like to design a simple board which controls a resistor as a heater. At T(1), heater (resistor) will be ON and at T(2), heater will be OFF and T(1)<T(2).I can set the R(SENSE) and hysteresis values and if i do so, I understand that my output voltage V(TEMP) is about 1V so it is not suitable to heat a 150k resistor for example.Can I increase the output voltage V(TEMP) via an op-amp and what possible errors will occur on hysteresis or on temperature sensing if I do so? Is there another way of doing this board via another product?It says LM57 uses NTC for V(TEMP) in datasheet. Does this mean I can not control the heater as temperature is inversely proportional to V(TEMP) output so that as temperature decreases, voltage on V(TEMP) is increased?Regards.
I want to inform you that I am currently working on this, and get back to you sometimes tomorrow.
Please refer to the LM57 datasheet pages 10, 11, and 12, which show the Vtemp value at each temperature. I hope that what you are looking for.
I don't see a problem if you use the op-amp to increase the V(temp) as long as you keep the output load regulation within the specs. Please see the LM57 datasheet on my page 6.
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