LED Driver Dimming Circuit Using Transformer Isolation
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Solution Overview
Problem
Existing LED dimming technologies using voltage-type dimmers suffer from high power losses and inconsistent drive currents due to the need for large current-limiting resistors and manual adjustments, leading to poor load capacity and output voltage deviations.
Innovation Solution
A dimming signal generation circuit with a transformer and power switch, where the secondary side receives the dimming voltage and the primary side generates a dimming reference signal, reducing power losses and improving efficiency by eliminating the need for large current-limiting resistors and integrating the dimming control circuit within an IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage-type dimmers are used with large current-limiting resistors, then manual adjustment capability is achieved, but power losses increase and drive current consistency deteriorates
Solution Approach 1:
The patent extracts the dimming control function from the power supply circuit by using a separate voltage-type dimmer that outputs dimming voltage. This allows manual adjustment capability to be maintained while eliminating the need for large current-limiting resistors in the power supply path, thereby reducing power losses.
Solution Approach 2:
The patent introduces a dimming voltage as an intermediary signal between the voltage-type dimmer and the LED driver. This dimming voltage controls the LED dimming without requiring direct current control through large resistors, thus maintaining ease of operation while reducing energy loss.
2Ease of operation
If voltage-type dimmers are used with large current-limiting resistors, then manual adjustment capability is achieved, but drive current consistency deteriorates
Solution Approach 1:
The patent extracts the dimming control function to a separate voltage-type dimmer that provides manual adjustment. The LED driver then receives dimming voltage and generates dimming reference signals without needing large current-limiting resistors, ensuring consistent drive current while maintaining ease of operation.
Solution Approach 2:
The patent changes the control parameter from direct current control (which requires large resistors and causes inconsistency) to voltage control. The voltage-type dimmer outputs dimming voltage that is converted to dimming reference signals, improving drive current consistency while preserving manual adjustment capability.
3Reliability
If isolated voltage converters are used to transmit dimming voltage, then voltage-type dimmer isolation is achieved, but device complexity increases
Solution Approach 1:
The patent merges the isolated voltage converter functionality into the LED driver circuit. The LED driver integrates the isolation mechanism and dimming voltage reception, eliminating the need for a separate isolated voltage converter and reducing overall device complexity while maintaining isolation.
Solution Approach 2:
The LED driver is designed with multi-functionality, serving both as the power supply for LEDs and as the receiver for dimming voltage from the voltage-type dimmer. This universal design achieves isolation without requiring additional dedicated isolation components.
4Loss of energy
If transformer and power switch are used in dimming control circuit, then power losses are reduced and efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the transformer and power switch into an integrated dimming control circuit within the LED driver. This integration achieves reduced power losses through efficient voltage conversion while minimizing the increase in device complexity through consolidated design.
Solution Approach 2:
The dimming control circuit with transformer and power switch is designed to be self-regulating, automatically converting dimming voltage to appropriate dimming reference signals without requiring external complex control mechanisms. This self-service approach reduces power losses while keeping the added complexity manageable.
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
This solution enhances the operational efficiency of LED drivers by reducing power losses and stabilizing the output voltage, improving the load capacity and consistency of the dimming process, while minimizing peripheral components and standby power consumption.
Implementation Method 1
a secondary side of the transformer is coupled to the voltage-type dimmer and is configured to receive the dimming voltage; a primary side of the transformer is configured to receive the first voltage and is configured to generate a dimming reference signal in accordance with the dimming voltage
Data Source
AI summary
A dimming signal generation circuit configured for an LED driver can include: a voltage-type dimmer configured to generate a dimming voltage; a dimming control circuit comprising a transformer and a power switch coupled in series between a first voltage and ground; where a secondary side of the transformer is coupled to the voltage-type dimmer is configured to receive the dimming voltage; where a primary side of the transformer is configured to receive the first voltage; and where a dimming reference signal is generated at the primary side of the transformer in accordance with the dimming voltage.