Single chip design for detection and recovery of series LED open/short fault tolerance circuit
Light emitting diode (LED) lighting is widely used in current. However, lighting robustness is low in a series loop since the lighting shuts down as one LED fails. This study proposes a power chip for fault detection and isolation for enhancement of LED's fault-withstanding capability. The chip can automatically detect the failed LEDs and bypass them, and let others continue to work. The authors implemented four bypass loops using a power metal oxide semiconductor (MOS) on the single chip. This chip can drive 1 A with 4-bit current dimming, which includes four bypass power P-type MOSs, one power N-type MOS, schedule controller, level shifter and over voltage protection. The schedule controller with a state machine can quickly find which one LED fail and recover it soon. The prototyping chip was designed using TSMC 0.25 μm, which is the second generator high-voltage technology, and the resulting chip area with pads is only 1.3 × 1.7 mm2. The chip had been successfully implemented and measured to drive and bypass four LED components or modules.
