Low-cost self-adaptive input voltage ultra-low standby dimming circuit

Abstract

A low-cost self-adaptive input voltage ultra-low standby dimming circuit belongs to the field of circuits, is used for solving the problems of crosstalk and high energy consumption of control signals,and comprises a lithium battery pack power supply unit, an LDO unit, an MCU control unit, a PWM control switch and an LED lighting unit. The lithium battery pack power supply unit is electrically connected with the LDO unit, the MCU control unit and the LED lighting unit, and the LDO unit, the MCU control unit, the PWM control switch and the LED lighting unit are electrically connected in sequence. The circuit has the beneficial effects that the PWM can be adjusted by collecting the input voltage and according to the calculation relation input in advance, the current effective value of an LEDlamp can be kept stable, a voltage reduction circuit is saved, the standby current is reduced, the cost performance and reliability are improved, and the cruising ability of a lithium battery pack isalso greatly prolonged.

Description

technical field [0001] The invention relates to a circuit, in particular to a low-cost adaptive input voltage ultra-low standby dimming circuit. Background technique [0002] At present, more and more smart homes, beds, sofas, and massage chairs will be equipped with reading lights, which are convenient for users to read and illuminate. Reading lights are optional accessories that need to be selected according to customer needs. [0003] Smart homes, beds, sofas, massage chairs and other systems generally have their own lithium battery packs for power supply, and reading lights are used as optional accessories, which can be directly powered by the DC terminal of the lithium battery pack. It is different. The commonly used ones are 7-cell ternary lithium battery pack or 8-cell lithium iron phosphate battery pack. The input range is about 20-29V. etc.) and then supply power to the LED, through the adjustment of resistor current limiting and PWM duty cycle, dimming can be real...

AI Technical Summary

Problems solved by technology

[0004] However, the existing control scheme connects the bridge stack / diode / silicon controlled rectifier in series on the N line, which has defects. When the motor is controlled to reverse, there is a voltage drop of 1V+ on the bridge stack DB2, which causes a drop in efficiency on the one hand, and another On the one hand, when the power is relatively large, the bridge stack (or thyristor, diode) will generate serious heat

If other circuits are adopted, both the forward and reverse control buttons need to be powered by AC-DC power supply, which will cause crosstalk of the control signals, and it is impossible to accurately distinguish whether the forward rotation button is pressed or the reverse rotation button is pressed

[0005] Moreover, the existing control circuit has a step-down circuit. The step-down circuit brings additional loss and heat. At the same time, the circuit becomes more complicated and the cost rises. If the step-down circuit is not used, the output range of the lithium battery pack will be reduced. If it is too wide, the brightness of the LEDs will change too much, making the user experience bad

[0006] In addition, due to the existence of the step-down circuit and the existence of the touch dimming circuit, the overall power consumption of the touch reading light is too large, reaching 1-6mA, which means that when the reading light is not in use, the reading light is also continuous Consuming the power of the lithium battery pack, resulting in a serious shortening of the battery life of the lithium battery pack

[0007] Based on the above background, it is necessary to propose a new type of circuit, which meets the requirements of AC button control DC, and at the same time solves the situation of reduced efficiency and severe heat caused by extra loss.

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