Proportional voltage follower and constant-current power supply adopting same

Abstract

The invention discloses a proportional voltage follower and a constant-current power supply adopting the same, wherein the voltage follower comprises a current sampling module, an isolating circuit module, a voltage proportional amplifying module and an output control module, wherein the current sampling module is used for sampling input current and outputting the sampling result to the isolating circuit module; the sampling result is isolated by the isolating circuit module and then output to the voltage proportional amplifying module; and the sampling result is amplified by the voltage proportional amplifying module and then output by the output control module. The proportional voltage follower samples the anode voltage output by a Buck circuit constant-current control module, converts the anode voltage into control signals, and outputs the control signals to a constant-voltage feedback loop module; the constant-voltage feedback loop module feeds the control signals back to a PWM (pulse width modulation) driving module; and the PWM driving module controls a pulse switch voltage reduction module to adjust the voltage. The proportional voltage follower has a simple circuit structure, is extremely smart to apply, and can maintain the efficiency of the Buck circuit to be higher than 95 percent under a normal condition.

Description

[0001] technical field [0002] The invention discloses a voltage follower and a constant current power supply, in particular to a proportional voltage follower and a constant current power supply using the follower. Background technique [0003] With the increasing application of LEDs in people's daily life, the driving of LEDs has become the focus of people's research. The current LED light strings are all powered by Buck circuits to convert the mains electricity into low-voltage direct current. In the Buck circuit in the prior art, when the output end is not connected to the load, the constant voltage power supply of the previous stage maintains the highest voltage supply to the Buck circuit, and the Buck circuit also outputs the highest voltage; when the output end is connected to the load LED light, because the Buck According to the constant current principle of the circuit, the voltage at the output terminal will become lower, which is low enough to meet the requireme...

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Problems solved by technology

In the Buck circuit in the prior art, when the output end is not connected to the load, the constant voltage power supply of the previous stage maintains the highest voltage supply to the Buck circuit, and the Buck circuit also outputs the highest voltage; when the output end is connected to the load LED light, because the Buck According to the constant current principle of the circuit, the voltage at the output terminal will become lower, which is low enough to meet the requirement of constant current. If the connected load LED lights continue to decrease, the Buck circuit can also maintain a constant current output, but at this time the Buck circuit is due to the input If the voltage difference with the output is too large, the duty cycle of the pulse switch will become very large, so that the efficiency of the Buck circuit will become very low

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