LED Driver Circuit with External Resistor Current Limiting
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Solution Overview
Problem
Existing LED driver systems lack versatility in adjusting the upper limit of drive current, requiring separate designs and components to accommodate varying current demands, which increases system complexity and component count.
Innovation Solution
A light emitting element drive device with a driving circuit and a drive reference voltage generation circuit that operates in multiple modes, allowing the upper limit of the drive current to be adjusted by connecting an external resistor, enabling flexible current adjustment without the need for additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an external resistor is used to set the drive reference voltage, then the setting accuracy of the upper limit value of the drive current is improved, but the number of components of the whole system increases
Solution Approach 1:
The specific external terminal is designed to serve multiple functions: it can be used for setting the drive reference voltage when an external resistor is connected, and it can also be used for current output in normal operation. This multi-functionality eliminates the need for separate terminals or components, resolving the contradiction between measurement precision and component quantity.
2Device complexity
If the drive reference voltage is set in advance in the design stage, then the device structure is simplified, but the adaptability to different current requirements is reduced
Solution Approach 1:
The drive reference voltage generation circuit is designed to dynamically respond to the connection state of the external resistor at the specific external terminal. When the external resistor is connected, the circuit automatically adjusts to generate a higher drive reference voltage, enabling the device to adapt to different current requirements without increasing structural complexity.
3Adaptability or versatility
If separate LED drivers are prepared for different current requirements, then the current requirements of different systems are satisfied, but the design and manufacturing complexity increases
Solution Approach 1:
A single LED driver design incorporates the specific external terminal that enables the drive reference voltage generation circuit to adapt to different current requirements. This universal design eliminates the need for separate LED driver models for different current applications, reducing design and manufacturing complexity while maintaining versatility.
Data Source
AI summary
A light emitting element drive device includes a driving circuit that supplies a variable drive current to a light emitting unit having one or more light emitting elements so that the light emitting unit can emit light, a drive reference voltage generation circuit that generates a drive reference voltage defining the upper limit value of the drive current and supplies the same to the driving circuit, and a specific external terminal capable of connecting to an external resistor. The drive reference voltage generation circuit operates selectively in a first mode to generate the drive reference voltage regardless of the state of the specific external terminal, or a second mode to generate the drive reference voltage in accordance with a second mode current through the specific external terminal.