Controlling Method, Power Supply, Power Controller, and Power Controlling Method

Abstract

A power supply has an inductor and determines loading state of the power supply according to a compensation signal. When the loading state is determined to be a light loading state or a no-loading state, a switch is operated at a low operating frequency. When the loading state is determined to be a heavy loading state, the switch is operated at a high operating frequency. If the compensation signal exceeds a critical value, it is determined that the loading state is an overloaded state. When the overloaded state continues past a tolerable duration, the switch is turned off. The tolerable duration is determined by an external capacitor and is independent of the operating frequency.

What is claimed is: 
     
         1 . A controlling method utilized in a power supply comprising a switch and an inductive element, the controlling method comprising:
 detecting an inductive current flowing through the inductive element;   determining the power supply under a normal loading state or an overloaded state according to a feedback signal;   controlling a peak of the inductive current to be smaller than or equal to a constant magnitude and controlling the switch to be operated in a first frequency when the power supply is operated under the normal loading state;   controlling the peak of the inductive current to be approximately the constant magnitude and controlling the switch to be operated in a second frequency when the power supply is operated under the overloaded state, wherein the second frequency is higher than the first frequency;   calculating a duration during which the power supply is operated under the overloaded state; and   stopping the inductive current when the duration exceeds a tolerable duration;   wherein the tolerable duration is independent of variation of the operating frequency.   
     
     
         2 . The controlling method of  claim 1  further comprising:
 adapting the operating frequency according to the feedback signal. 
 
     
     
         3 . The controlling method of  claim 1  further comprising:
 resetting a counter for calculating the duration when the power supply leaves the overloaded state. 
 
     
     
         4 . The controlling method of  claim 1  further comprising:
 providing a clock generator to generate the operating frequency; 
 wherein the tolerable duration is independent of the operating frequency. 
 
     
     
         5 . A power supply comprising:
 a controller, for controlling an inductive current flowing through an inductive element, the controller comprising:
 a clock generator for generating an operating frequency; 
 a current limiter for controlling a peak of the inductive current to be approximately a constant magnitude, wherein when the current limiter controls the peak to be approximately the constant magnitude, the operating frequency is lower than or equal to a first frequency; and 
 an overloading limiter comprising:
 an overloading identifier for identifying whether the power supply should enter an overloaded state according to a feedback signal, wherein when the power supply is operated in the overloaded state, the operating frequency is a second frequency higher than the first frequency; and 
 a current supply, for providing a charging/discharging current to an external capacitor and for calculating a duration during which the power supply is operated in the overloaded state; 
 
   wherein when the duration exceeds a tolerable duration, the controller stops the inductive current, and the tolerable duration is independent from variation of the operating frequency.   
     
     
         6 . A power controller utilized for a power supply comprising an inductive element and a switch, the power controller comprising:
 a first comparator, for receiving a compensation signal and a current detection signal to control the switch, wherein the current detection signal corresponds to an inductive current flowing through the inductive element, the compensation signal corresponds to a loading state of the power supply, and the first comparator is utilized for approximately determining a peak of the inductive current according to the compensation signal;   a clock generator, for roughly providing an operating frequency of the switch according to the compensation signal, wherein the operating frequency is a high operating frequency when the loading state is a heavy loading state and the operating frequency is a low operating frequency when the loading state is a light loading state or a no-loading state; and   an overloading limiter, comprising a charge/discharge device coupled to an external capacitor, for detecting the compensation signal to determine whether an overload event occurs, and for outputting an overload limiting signal to turn off the switch when a tolerable duration is exceeded after the overload event occurs;   wherein the external capacitor and the charge/discharge device forming a clock oscillator, and the tolerable duration is determined by the external capacitor and independent of the clock oscillator.   
     
     
         7 . The power controller of  claim 6  wherein the overloading limiter further comprises:
 a second comparator, for comparing the feedback signal with a critical signal and outputting an overload signal indicating the overload event occurred if the compensation signal is higher than the critical signal; and 
 a counter coupled to the second comparator, for receiving a clock signal and starting to count when the comparator outputs the overload signal; 
 wherein the overload limiting signal is outputted after an the overload signal outputted from the counter fulfills a condition. 
 
     
     
         8 . The power controller of  claim 7 , wherein a frequency of the clock signal is determined by both the external capacitor and the charge/discharge device, and the tolerable duration is related to both the condition and the frequency of the clock signal. 
     
     
         9 . The power controller of  claim 6 , wherein the clock oscillator determines the operating frequency to be an overloaded frequency higher than the high operating frequency within the tolerable duration after the occurrence of the overloading event. 
     
     
         10 . The power controller of  claim 6  further comprising:
 a peak limiter, for detecting the current detection signal and outputting a peak limiting signal to control the switch, and thereby approximately limiting the peak of the inductive current to be a limit peak. 
 
     
     
         11 . The power controller of  claim 10 , wherein the peak of the inductive current is the limit peak within the tolerable duration after the occurrence of the overload event. 
     
     
         12 . A power controlling method utilized for a power supply, the power supply comprising an inductive element and a switch, the power controlling method comprising:
 determining a loading state of the power supply according to a compensation signal, controlling the switch to be operated under a high operating frequency when the loading state is a heavy loading state, and controlling the switch to be operated under a low operating frequency when the loading state is a light loading state or a no-loading state; and   determining the loading state to be an overloaded state when the compensation signal exceeds a critical value, and turning off the switch when the overloaded state lasts beyond a tolerable duration;   wherein the tolerable duration is determined according to an external capacitor and is independent of both the high and low operating frequencies for operating the switch.   
     
     
         13 . The power controlling method of  claim 12  wherein the switch is controlled to be operated under an overloaded frequency higher than the high operating frequency within the tolerable duration when the loading state is the overloaded state. 
     
     
         14 . The power controlling method of  claim 12  further comprising:
 detecting an inductive current flowing through the inductive element for generating a current detection signal; and 
 roughly determining a peak of the inductive current according to both the compensation signal and the current detection signal. 
 
     
     
         15 . The power controlling method of  claim 14  further comprising:
 providing a limit signal for limiting a peak of the inductive current to approximately be a limit peak; 
 wherein the peak of the inductive current is limited to be the limit peak within the tolerable duration after the compensation signal exceeds the critical value. 
 
     
     
         16 . A power controlling method utilized for a power supply, the power supply comprising an inductive element and being controlled by a switch to charge or discharge for generating an output power, the power controlling method comprising:
 providing a clock generator for roughly providing an operating frequency of the switch;   detecting a loading state of the power supply;   adjusting the operating frequency according to the loading state, wherein the operating frequency is a first frequency when the loading state is a heavy loading state;   controlling the operating frequency to approximately be a second frequency higher than the first frequency within a tolerable duration when the loading state is an overloaded state; and   ceasing operations of the switch after the tolerable duration is exceeded;   wherein the tolerable duration is independent of a clock oscillator.   
     
     
         17 . The power controlling method of  claim 16  further comprising:
 providing a compensation signal according to a voltage level of the output power; 
 wherein detecting the loading state of the power supply comprises:
 comparing the compensation signal with a critical signal, and determining the loading state to be the overloaded state when the compensation signal is higher than the critical signal.