Adjustable driving voltage source and method thereof for adjusting driving voltage

Abstract

The invention discloses an adjustable driving voltage source and a method thereof for adjusting a driving voltage. The adjustable driving voltage source is applied to a switch-mode power supply and adjusts a driving voltage supplied to a driver according to the load change of the switch-mode power supply, thus the driving voltage can be regulated in light load and the power consumption efficiency of the switch-mode power supply can be improved. The adjustable driving voltage source comprises a linear adjuster used for providing a driving voltage to the driver, so as to determine the voltage level of the control signal. The linear adjuster comprises a transistor connected with the voltage output terminal of the linear adjuster, an operational amplifier which is connected with the transistor and controls the current of the transistor according to a feedback signal to determine the driving voltage, a feedback circuit which is connected with the operational amplifier and the voltage output terminal of the linear adjuster and generates the feedback signal according to the driving voltage and an adjuster which is connected with the linear adjuster and controls the linear adjuster according to the load change of the switch-mode power supply so as to adjust the driving voltage.

Description

technical field [0001] The invention relates to a switching power supply, in particular to an adjustable driving voltage source applied to the switching power supply and a method for adjusting the driving voltage. Background technique [0002] figure 1 It is a traditional asynchronous switching power supply, in which the power switch M1 and the diode D1 are connected in series between the voltage input terminal Vin and the ground terminal GND, the inductor L is connected between the switching node 14 and the voltage output terminal Vo, and the capacitor Co is connected at the voltage Between the output terminal Vo and the ground terminal GND, the driver 12 generates a control signal S1 according to a PWM signal provided by a pulse width modulation (PWM) controller 10 to switch the power switch M1 to convert the input voltage Vin to the output voltage Vo. The voltage level of the control signal S1 is determined by the driving voltage Vcc supplied to the driver 12 . Under li...

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Problems solved by technology

However, this driver chip 20 needs two sets of power supplies LVCC and UVCC to provide driving voltages to the high-order side driver 24 and the low-order side driver 26 respectively, so the circuit is more complicated.

U.S. Patent No. 7,345,463 also proposes a driving voltage adjustment method applied to a single chip. This method changes the driving voltage supplied to the driver by detecting the load current of the power supply, and even uses the load current, input voltage, output voltage and power The characteristic parameters of the switch to find the best driving voltage, however, this method requires a more complex circuit

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