| 摘要 |
A voltage regulator for pulse width modulation in dual frequencies is provided to be able to operate under a PWM voltage regulation mode, which can take a different frequency according to the degree of loading effect under light load or heavy load. In order to determine the degree of loading effect, a heavy-load reference voltage and a light-load reference voltage are predetermined to be served as reference voltages. When the error signal is greater than the heavy-load reference voltage, the load is a heavy load and then a modulation signal at a higher frequency, such as 200 KHz, is used to drive a transistor of the voltage regulator. Conversely, when the error signal is less than the light-load reference voltage, the load is a light load and then a modulation signal at a smaller frequency, such as 20 KHz, is used to drive the transistor. In this way, improved power conversion efficiency can be achieved.
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