Power circuit and liquid crystal display

Abstract

A power circuit comprises a current source, a switch, first and second comparators, a latch, a drive, second and third resistors, a first capacitor, first and second electric switches, and a proportional converter. The current source is grounded through the first capacitor. The cathode and the anode of the current source are connected to a voltage input end through the proportional converter to make a second current change according to the change of a voltage input by the voltage input end. The first comparator compares a fixed voltage with the voltage on the first capacitor. A second capacitor is grounded through the switch which is controlled by a reverse PWM signal. The first comparator is connected with the drive through the latch, and makes the drive output a PWM low level signal. The second and third resistors are connected in series between a voltage output end and the ground. The second comparator compares the voltage at a node between the second and third resistors with a reference voltage. The second comparator is connected with the drive through the latch, and makes the drive output a PWM high level signal. The system stability is improved.

Description

technical field [0001] The invention relates to the field of display technology, in particular to a power supply circuit and a liquid crystal display. Background technique [0002] With the development of science and technology, the requirements for electronic equipment are getting higher and higher. For example, the performance of electronic equipment is more reliable, the function is continuously increased, the use is more convenient, and the volume is decreasing day by day, which makes the DC-DC (direct current to direct current) conversion. Technology becomes more important. At present, in the current DC-DC scheme, due to the fixed high-level on-time of the PWM signal and the relatively poor linear adjustment rate, when the input voltage fluctuates greatly, the output voltage fluctuates greatly, thus affecting the system stability. SUMMARY OF THE INVENTION [0003] The purpose of the present invention is to provide a power supply circuit to improve the stability of th...

AI Technical Summary

Problems solved by technology

At present, due to the fixed high-level conduction time of the PWM signal and the relatively poor linear adjustment rate of the current DC-DC scheme, when the input voltage fluctuates greatly, the output voltage fluctuates greatly, which affects system stability.

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