Two-simple-temperature-to-time-converters

Both converters utilize CMOS inverters. Figure 105-1A illustrates a free-running circuit where both pulse duration and pulse pause are influenced by the temperature of diode D8. This configuration is suitable for applications where synchronization between the converter and other systems is not necessary. Figure 105-1B depicts a one-shot circuit that generates a pulse with its duration also dependent on the temperature of diode D8. An additional diode, D1, should have an inverse current low enough not to affect the discharging process in the RC network when the INVA output is low. A silicon component or a GaAsP LED may be employed. The converter is designed for a digital system that produces a RADY pulse, which ceases after the conversion process is completed. Here, V0 represents the forward voltage of the sensor diode, and VDD denotes the supply voltage of the CMOS chip. The resistance R must be significantly greater than R8. A 0.1 µF capacitor can be connected in parallel with D5, if required, to mitigate stray pickup and noise in long cables. The circuits described can also utilize a temperature-sensitive resistor in place of diode D5.

The described circuit configurations leverage CMOS technology to create versatile pulse generation systems that are responsive to temperature variations. In the free-running circuit (Figure 105-1A), the output pulse characteristics—duration and pause—are directly influenced by the thermal properties of diode D8, making it ideal for applications that do not demand precise timing synchronization with external devices. This characteristic allows for flexibility in various applications, including temperature monitoring and control systems.

In the one-shot configuration (Figure 105-1B), the circuit is designed to produce a single pulse whose duration is also a function of the temperature of diode D8. The inclusion of diode D1 serves a critical role by ensuring that its reverse current does not interfere with the RC network's discharging behavior when the INVA output is low. This design consideration is essential for maintaining the integrity of the pulse output.

The choice of components is crucial for the performance of these converters. The use of a silicon diode or a GaAsP LED provides options for different applications, depending on the required wavelength and efficiency. The design is tailored for a digital system that generates a RADY pulse, emphasizing the need for rapid response and minimal delay after the conversion process.

The specifications for resistances highlight the importance of component selection; R must be much larger than R8 to ensure proper operation of the circuit. Additionally, the optional 0.1 µF capacitor across D5 can be implemented to filter out noise and prevent interference from stray signals, particularly in scenarios involving long cable runs. This feature enhances the reliability of the circuit in noisy environments.

Furthermore, the adaptability of the circuit allows for the substitution of diode D5 with a temperature-sensitive resistor, expanding its utility in applications requiring temperature-dependent behavior. Overall, these circuits exemplify a robust design approach, integrating temperature sensitivity with pulse generation capabilities suitable for various electronic applications.Both of these converters use CMOS inverters. Figure 105-1A shows a free-running circuit having both the pulse duration and pulse pause dependent on temperature of the diode D8. It can be used where a synchronization between the converter and something else is not required. Figure 105-lB shows a one shot circuit that produces a pulse with its duration dependent of temperature of diode D8.

The additional diode D1 should have inverse current low enough to not influence the discharging process in the network rc when the INVA output is low. A silicon component or a GaAsP LED can be used. The converter is intended for a digital system producing a RADY pulse which disappears after the conversion process is ended. Where V0 is the sensor diode forward voltage and VDD is the supply voltage of the CMOS chip. Resistance R must be much higher than R8. A 0.1-I"F capacitor can be applied in parallel with D5, if necessary, to repulse stray pickup and noise in a long cable.

The circuits described can be used with a temperature sensitive resistor instead of the diode D5. 🔗 External reference