LED Dimming Circuit Using PWM-Controlled DCDC Current
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Solution Overview
Problem
Existing dimming circuits for LED lamps are limited by the overcurrent capability of dialing codes, restricting the adjustment of DCDC output current and preventing high current flow due to fixed resistance values and impedance limitations.
Innovation Solution
A dimming circuit that includes a control module generating PWM control signals based on dimming demand information to control a DCDC module, eliminating the need for dialing codes and allowing maximum current output limited only by the DCDC chip design, with an optional anti-jamming module to prevent overcurrent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dialing codes are used to adjust DCDC output current, then current adjustment is achieved, but the current is limited by the overcurrent capability of the dialing code
Solution Approach 1:
The patent extracts the dialing code component from the current control system and replaces it with a PWM-based control method. The sampling resistor remains in the circuit but is now controlled through PWM duty cycle adjustment rather than through dialing code resistance changes, thereby eliminating the overcurrent limitation imposed by the dialing code while maintaining the sampling function for current feedback.
Solution Approach 2:
The patent replaces the mechanical/digital dialing code system with an electronic PWM control system. Instead of physically or digitally changing resistance values through dialing codes, the system uses pulse width modulation to control the effective resistance and current output, enabling continuous and precise current adjustment without the discrete steps or current limits of the dialing code approach.
2Device complexity
If fixed sampling resistance is used in DCDC circuit, then circuit simplicity is maintained, but current adjustment range is limited
Solution Approach 1:
The patent introduces dynamic control through PWM modulation to the previously static sampling resistor configuration. The effective resistance value is no longer fixed but dynamically adjusted through PWM duty cycle variation, allowing the circuit to adapt its current output to match different LED lamp requirements while maintaining the physical simplicity of having a single sampling resistor in the circuit.
Solution Approach 2:
The patent changes the operational parameter of the sampling resistor from a fixed resistance value to a dynamically variable effective resistance through PWM control. By modulating the duty cycle of the PWM signal, the effective resistance seen by the DCDC controller varies, enabling a wide range of current adjustments without requiring multiple physical resistors or complex switching networks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient adjustment of DCDC current to meet varying brightness demands without dialing code limitations, ensuring high current output and protecting LED lamps from overcurrent damage.
Implementation Method 1
a corresponding PWM control signal is generated according to the dimming demand information. The control module controls the DCDC module according to the PWM control signal
Implementation Method 2
the DCDC module outputs corresponding current according to the dimming demand information to drive the LED lamp accordingly
Data Source
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AI summary
The invention provides a dimming circuit for LED lamps, comprising a control module and a DCDC module, wherein the input end of the control module is connected to receive an external dimming demand information, the output end of the control module is connected with the DCDC module, and a corresponding PWM control signal is generated according to the dimming demand information. The control module controls the DCDC module according to the PWM control signal, so that the DCDC module outputs corresponding current according to the dimming demand information to drive the LED lamp accordingly. According to the dimming circuit for LED lamps provided by the invention, the DCDC module is controlled by the control module, so that the DCDC module drives the LED lamp according to the current lamp demand information and a proper adjustment of the DCDC current is implemented. According to the invention, a dialing code is not required for adjustment, and the maximum current output by the DCDC module is only limited by the design of the DCDC chip, and the limitation of the impedance and the dial overcurrent capacity of the dialing according to the prior art is avoided.