Abstract: A TRIAC dimmable light-emitting diode (LED) driver circuit is disclosed, compromising: An alternating-current (AC) voltage connected to a rectifier bridge; An LED load, which is connected to an inductor or a transformer, a power MOS transistor, a low voltage MOS transistor and a current sensing resistor. The LED driver also compromises: a peak current comparator which is used to compare the voltage between a current sensing resistor and a reference voltage; a maximum on-time timer, which is used to detect the on time of the low voltage MOS transistor. When the voltage on the current sensing resistor is higher than the reference voltage or the on time of the low voltage MOS transistor reaches the preset time of the maximum on-time timer, the low voltage MOS transistor is turned off.

Abstract: A current ripple canceling light-emitting diode (LED) driver is disclosed. The input current source contains a current ripple. The LED load is connected to the drain of a power switch. The source of the power switch is connected to a current sensing resistor. The gate of the power switch is connected to the output of an operational amplifier. The operational amplifier compares the voltage signal across the current sensing resistor with a dynamic reference voltage. The dynamic reference voltage is adjusted according to the gate or drain voltage of the power switch. The LED load current is controlled to be a nearly no ripple DC current.

Abstract: An average linear light-emitting diode (LED) driver circuit is disclosed. An inputting alternating-current (AC) voltage is connected to a rectifier bridge. An LED load is paralleled with a filtering capacitor and connected to a power switch. A compensation network and a voltage feedback network are included. When the output voltage of the rectifier bridge is higher than the voltage of the filtering capacitor, the drain voltage of the power switch is increased. The voltage feedback network decreases or turns off the current in the power switch. The compensation network controls the average current in the power switch to be equal to the desired LED load current. The average linear LED driver circuit intelligently controls the driver current, reduces the system power loss and increases the system efficiency. The LED driver maintains high conversion efficiency, especially under wide input voltage conditions.