Multi-Channel LED Controller With Synchronized Power-Save Dimming
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Solution Overview
Problem
Existing LED dimming technologies face inefficiencies in power consumption and energy savings, particularly in high-frequency PWM dimming, leading to significant power loss when LEDs are turned off.
Innovation Solution
A system utilizing a controller circuit with parallel switches and a switching LED driver circuit that synchronously turns off both the driver and switches to manage LED current flow, minimizing power loss by allowing residual inductor current to dissipate before turning off all LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-frequency PWM dimming is used to control LED brightness, then dimming precision is improved, but power loss increases significantly
Solution Approach 1:
The patent applies preliminary action by turning off the switches before the driver circuit to allow residual inductor current to dissipate. This preliminary switch-off action prevents the residual current from flowing through the LEDs during the driver's off-time, eliminating unnecessary power loss while maintaining high-frequency PWM dimming operation above 20 kHz
Solution Approach 2:
The patent implements periodic action through synchronized switching control where switches and driver circuit are turned on and off in coordinated cycles. The switch logic circuit generates periodic control signals that synchronize the switches' off-time with the driver's off-time, creating a rhythmic switching pattern that minimizes power loss during each PWM cycle
2Loss of energy
If switches are turned off immediately with the driver circuit, then power loss is reduced, but residual inductor current causes harmful effects
Solution Approach 1:
The switch logic circuit performs preliminary action by generating control signals that turn off the switches before the driver circuit shuts down. This timing offset allows the inductor's residual current to dissipate through the driver's internal resistance without flowing through the LEDs, preventing harmful effects like reverse current or unintended LED conduction
Solution Approach 2:
The switch logic circuit acts as an intermediary between the controller and the switches, mediating the timing relationship between switch off-time and driver off-time. It processes the controller's dimming signal and generates appropriately timed switch control signals that coordinate the switch shutdown with the driver's shutdown sequence
Data Source
AI summary
A circuit includes a plurality of switches, each switch of the plurality of switches having a respective first switch terminal, a respective second switch terminal and a respective switching terminal. The circuit further includes a switch logic circuit including a plurality of switch logic input terminals, a plurality of switch logic output terminals and a switch control terminal, each switch logic output terminal of the plurality of switch logic output terminals being coupled to the switching terminal of a respective one of the plurality of switches. Furthermore, the circuit includes a switching driver control circuit including a plurality of driver input terminals, a driver output terminal and a driver logic terminal, the driver logic terminal being coupled to the switch control terminal of the switch logic circuit, and each of the plurality of driver input terminals being coupled to a respective one of the plurality of switch logic input terminals.