Drivers and driving methods for a LED string, capable of providing LED short protection or avoiding LED flickering

摘要

The disclosure regards to drivers and driving methods for a LED string consisting of LEDs. The LED string and a current switch are coupled in series between a power line and a ground line. The power line is powered to regulate a signal representing a current passing through the LED string. An enable signal capable of switching the current switch is provided. Whether a predetermined event occurs is detected. When the predetermined event occurs, the enable signal is clamped to have a predetermined logic value, the current switch thereby being kept either open or short.

主权项

1. A driver for driving a LED string consisting of LEDs, the driver comprising:
a current switch connected in series with the LED string between a power line and a ground line; and a switched mode power supply, for powering the power line to regulate a signal representing a current passing through the LED string, wherein the switched mode power supply comprises an enable node and a clamping circuit; wherein an enable signal at the enable node is capable of switching the current switch; and when a predetermined event occurs the clamping circuit clamps the enable signal to have a predetermined logic value, the current switch thereby being kept either open or short; wherein the predetermined event is the signal exceeding a predetermined value, and when the predetermined event occurs the clamping circuit clamps the enable signal to be deasserted and to make the current switch open, thereby providing LED short protection.