LED Driver Circuit Using Segmented Switching and Linear Control
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Solution Overview
Problem
Existing driver circuits for LED, OLED, and LASER diodes face challenges in providing accurate current pulses with minimal distortion and low losses, especially in pulsed applications where high dynamic behavior and efficiency are required.
Innovation Solution
A driver circuit combining a switching converter and a linear current driver, controlled by a programmable microcontroller that adjusts the switching output voltage and drive current to achieve precise current control, minimizing losses and exploiting the dynamic properties of both components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear current driver is used, then accurate current control and high dynamic behavior are achieved, but energy losses increase
Solution Approach 1:
The driver circuit is segmented into two functional parts: a switching converter that handles power conversion and a linear current driver that handles precise current control. This segmentation allows each part to optimize for its specific function, with the switching converter reducing overall power losses and the linear driver maintaining precision during pulsed operation.
Solution Approach 2:
The system uses periodic pulsed operation where the linear current driver is activated only during the pulse duration rather than continuously. This periodic activation reduces energy losses during non-pulse intervals while maintaining accurate current control during the active pulse periods.
2Loss of energy
If a switching converter is used, then energy efficiency is improved, but dynamic behavior is limited
Solution Approach 1:
The driver circuit is segmented into two functional parts: a switching converter that handles power conversion and a linear current driver that handles precise current control. This segmentation allows each part to optimize for its specific function, with the switching converter reducing overall power losses and the linear driver maintaining precision during pulsed operation.
Solution Approach 2:
The system uses periodic pulsed operation where the linear current driver is activated only during the pulse duration rather than continuously. This periodic activation reduces energy losses during non-pulse intervals while maintaining accurate current control during the active pulse periods.
3Productivity
If current pulses are used for pulsed applications, then accurate on-current is required, but pulse distortion and overswing increase
Solution Approach 1:
The linear current driver incorporates feedback control that monitors the actual current and adjusts the drive signal to compensate for distortions and overswing during pulse transitions. This feedback mechanism ensures accurate on-current delivery while minimizing pulse distortion and reducing rise/fall time overshoot.
Data Source
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AI summary
A driver circuit 10 is described for driving loads such as LED, OLED or LASER diode devices L. A switching converter 12 has a switching element M1 and reactive elements L1, C1 to provide an output switching voltage V1 by sequential switching operations of the switching element M1. The load L is connected to the output switching voltage. A linear current driver circuit 14 is connected in series to the load L and comprises an amplification element Q1 and a feedback circuit R1, 22 with a current control input V L,set, I B. In order to enable the circuit to be easily used, a control unit 16, 116, 216 is provided with a sensing input V L,1, V L,2 for a current or voltage at the linear current driver 14. A microcontroller 30, 130, 230 executes a control program for processing the sensing input and providing both a current control output V L,set, I B and a switching control output V 1, set in accordance with a set current value I set.