Segmented LED Driver Circuit for High Current Low Dropout
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Solution Overview
Problem
Existing LED driver circuits are not suitable for high power, colored LEDs, lacking low dropout, high current capability, high dimming ratio, monotonicity, and low quiescent current requirements.
Innovation Solution
A driver circuit with a current DAC, equalizer circuit, and regulator circuit that activates or deactivates transistors based on input codes, using a replica device to maintain equal drain voltages and provide a constant current with low dropout and high dimming ratio, suitable for high power LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If existing LED driver circuits are used, then the circuit can drive LEDs, but the circuit lacks high current capability and low dropout performance
Solution Approach 1:
The current source is divided into multiple parallel devices (first current source device, second current source device, etc.) that can be independently controlled. This segmentation allows the circuit to provide high current capability by activating multiple devices while maintaining low dropout performance through selective activation based on dimming requirements.
Solution Approach 2:
The circuit dynamically adjusts the number of active current source devices based on the dimming ratio control signal. The decoder converts digital codes to selectively enable or disable specific current source devices, allowing the circuit to adapt its current output level while maintaining optimal dropout performance for each operating condition.
2Adaptability or versatility
If existing LED driver circuits are used, then the circuit can provide current to LEDs, but the circuit lacks high dimming ratio and monotonicity
Solution Approach 1:
The current source is segmented into multiple independently controllable devices with different current weights. This allows the circuit to achieve high dimming ratios by selectively combining different current levels while ensuring monotonicity through the structured arrangement of current source devices and their corresponding control logic.
Solution Approach 2:
Different current source devices are assigned different current contributing weights (e.g., first current source device provides different current than second current source device). This local differentiation enables precise control over the total current output, achieving both high dimming ratio and monotonic response to control signals.
3Use of energy by stationary object
If existing LED driver circuits are used, then the circuit can drive LEDs, but the circuit lacks low quiescent current performance
Solution Approach 1:
The circuit dynamically adjusts its power consumption by activating only the necessary number of current source devices based on the required current output. When low current is needed, fewer devices are active, reducing quiescent current. When high current is needed, more devices are activated to provide the required power while maintaining efficiency.
Data Source
AI summary
A high current, low dropout driver circuit is disclosed. The circuit includes a decoder configured to decode a plurality of control bits to generate a plurality of control signals, and a current source having a plurality of devices. The current source is configured to activate at least a subset of the plurality of devices using the control signals to provide a load current to a load circuit, such as a light-emitting diode (LED), using activated ones of the plurality of devices and a control voltage. A control circuit is configured to generate the control voltage based on the load current and a reference current.