Over Temperature Protection Circuit

When an overcurrent flows the temperature of the ntc thermistor rises and its resistance decreases thus suppressing the drive voltage of the microcontroller.

Over temperature protection circuit.

This characteristic is self regulating. Frequently the monitoring circuit is built on a small printed circuit board that is attached to the main printed circuit board from the power supply. Idea super brigth led light will include 100 leds which consume 1 watt per led. The resistance of ptc thermistors rises rapidly when a certain temperature is exceeded thus stopping the flow of current.

A circuit is used to monitor and generate a trigger signal that starts the shutdown process at the high temperatures. A wide variety of over temperature protection circuit options are available to you such as power tools. Over temperature protection otp 6. The same method is used in the design of this battery over charging protection circuit.

For example a zener diode of 7 v can be used in series with a 1n4007 diode. The transistor must be attached physically closest to the heat source ideally it should be attached to the heatsink of the power transistors. Simplified block diagram of the smart over temperature protection circuit it is important to note that the v drive signal is compared with an internal sawtooth signal to generate an internal pwm signal for the dimming. Once the ptc cools down it permits the current to flow again.

That is why there will be a lot of dissipating heat. The 1n4007 diode has forward voltage drop of 0 7 v so it will provide the extra 0 7 v drop. The temperature monitor circuit works by comparing the voltage drop of a cold diode t1 with the base emitter voltage of a warm transistor t2. The diagram below shows a microcontroller temperature protection circuit that employs a voltage dividing circuit consisting of a combination of ntc thermistor and fixed resistors r s.

The current i temp is composed on the. Temperature protection devices are used to protect internal circuits or devices from overheating. When the over temperature protection otp is present we usually find a thermistor attached to the secondary heat sink the fan control unit usually uses a thermistor in the same heat sink. I made simple over temperature protection circuit which will shut down leds when a certain temperature is reached.