Light emitting diode driver

摘要

A driver circuit for driving light emitting diodes (LEDs). The driver circuit includes a string of LEDs divided into n groups and the n groups of LEDs is electrically connected to each other in series, where a downstream end of group m−1 is electrically connected to the upstream end of group m. The driver circuit also includes a power source coupled to an upstream end of group 1 and provides an input voltage. The driver circuit further includes current regulating circuits, where each of the current regulating circuits is coupled to the downstream end of the corresponding group at one end and coupled to a ground at the other end. Each of the current regulating circuits includes a sensor amplifier and a cascode having first and second transistors. The driver circuit also includes detectors, where each of the detectors detects a source voltage of the first transistor.

主权项

1. A driver circuit for driving light emitting diodes (LEDs), comprising:
a string of LEDs divided into n groups, wherein n being a positive integer, the n groups of LEDs being electrically connected to each other in series, a downstream end of group m−1 being electrically connected to the upstream end of group m, where m being a positive number equal to or less than n; a power source coupled to an upstream end of group 1 and operative to provide an input voltage; and a plurality of current regulating circuits, each of the current regulating circuits being coupled to the downstream end of a corresponding group at one end and coupled to a ground at an other end and including a sensor amplifier and a cascode having first and second transistors, wherein an output pin of the sensor amplifier of the current regulating circuit corresponding to group m−1 is directly connected to a component of the current regulating circuit corresponding to group m.