LED driver and controller thereof, and LED lighting device

A LED driving controller, comprising:

• a power transistor having a control terminal for receiving a switching control signal, a first terminal being coupled to an LED load through an inductor and a second terminal being grounded through a sampling resistor;
• a zero-crossing detection circuit having an input terminal being coupled to said first terminal of said power transistor and configured to generate a zero-crossing detection signal;
• a first comparison circuit, configured to compare a reference voltage with a sampling voltage to generate a first control signal;
• a control circuit being coupled to said zero-crossing detection circuit and said first comparison circuit and configured to generate a switching control signal in accordance with said zero-crossing detection signal and said first control signal, wherein said switching control signal is used to turn on and off said power transistor;
• an overvoltage protection circuit having an input terminal being grounded through an overvoltage protection resistor and configured to generate an overvoltage protection signal in accordance with an off-time provided by said control circuit and a reference voltage;
• a shielding circuit being disposed between said overvoltage protection circuit and said control circuit and configured to shield said overvoltage protection signal from being effective in accordance with a shielding signal when said power transistor is turned off and to be reset to make said voltage protection signal to be effective when said power transistor is turned on.