LM3524

Fig. 13-33 This circuit uses an LM3524 pulse-width modulator to convert the output of an LM135 temperature transducer into a pulse width that can be measured by a digital system (such as a microprocessor-based data-acquisition system). Although the example uses the temperature transducer as the input, the circuit will convert any 0.1- to 5-V input applied to the 100-kΩ resistor into a 0- to 500-ms output pulse width with 0. 1 % linearity. The overall temperature-to-pulse-width scale factor is adjusted with the 5-kΩ gain-trim potentiometer. The oscillator output pulse at pin 3 of the LM3524 (not shown) occurs just before the pins 11/14 output pulse and it can be used to reset counters or other digital circuits. National Semiconductor Linear Applications Handbook, 1991, p 857.