Patent ID: 7629752

Claim:
A light source driving device is for driving a plurality of light sources of a light source module, comprising: an inverter circuit, for converting a received DC signal to an electrical signal adapted for driving the light sources; a current sampling circuit, for sampling current flowing through the inverter circuit, the current sampling circuit comprising: an impedance detecting component, for detecting current from the inverter circuit; and an amplifying circuit, connected to the impedance detecting component for amplifying the current signal, comprising: an amplifier, including a positive electrode input, a negative electrode input and an output; a first impedance component, one end of thereof being connected to the negative electrode input of the amplifier, and the other end thereof being connected to one end of the impedance detecting component; and a second impedance component, connected between the negative electrode input and the output of the amplifier; a first filter circuit connected between the positive electrode input of the amplifier and the other end of the impedance detecting component, comprising: a first resistor, one end thereof being connected to the other end of the impedance detecting component; a first capacitor, connected between the positive electrode input of the amplifier and ground; and a second resistor, connected to the first capacitor in parallel; and a PWM controller, connected to the current sampling circuit, for receiving the amplified current signal output from the current sampling circuit, and generating a control signal to the inverter circuit to control output thereof.