Patent ID: 9288852
Filing Date: 2016-03-15
CPC Classification: H05B,Y02B

Claim Text:
1. A circuit for driving a string of light emitting diodes, the circuit comprising: a first MOS transistor; a second MOS transistor including a drain for electrical coupling to a first string of light emitting diodes and including a source coupled to ground; a first resistive element electrically coupling a source of the first MOS transistor to ground; circuitry, comprising an operational amplifier, operable to regulate a voltage across the first resistive element, the operational amplifier including an inverting input electrically coupled to the source of the first MOS transistor, and an output electrically coupled to the gate of the first MOS transistor; a second resistive element having a first end electrically coupled to a gate of the first MOS transistor and having a second end electrically coupled to a gate of the second MOS transistor; a first current source electrically coupled between the gate of the second MOS transistor and ground; a second current source electrically coupled between a drain of the first MOS transistor and a power supply voltage; and a third resistive element electrically coupled between the drain of the first MOS transistor and a drain of the second MOS transistor.