温度传感器毕业论文中英文资料外文翻译文献(4)

Figure 4. A user-programmable temperature sensor monitors its own local temperature and the temperatures of four remote p-n junctions.

Controlling a fan while monitoring remote temperature is the chief function of the IC shown in Figure 5. Users of this part can choose between two different modes of fan control. In the

PWM mode, the microcontroller controls the fan speed as a function of the measured temperature by changing the duty cycle of the signal sent to the fan. This permits the power consumption to be far less than that of the linear mode of control that this part also provides. Because some fans emit an audible sound at the frequency of the PWM signal controlling it, the linear mode can be

advantageous, but at the price of higher power consumption and additional circuitry. The added

power consumption is a small fraction of the power consumed by the entire system, though.

Figure 5. A fan controller/temperature sensor IC uses either a PWM- or linear-mode control scheme.

This IC provides the alert signal that interrupts the microcontroller when the temperature violates specified limits. A safety feature in the form of the signal called "overt" (an abbreviated version of "over temperature") is also provided. If the microcontroller or the software were to lock up while temperature is rising to a dangerous level, the alert signal would no longer be useful. However, overt, which goes active once the temperature rises above a level set via the SMBus, is typically used to control circuitry without the aid of the microcontroller. Thus, in this

high-temperature scenario with the microcontroller not functioning, overt could be used to shut