| 摘要 |
PURPOSE: An electronic ballast for a high intensity discharge lamp is provided to reduce the number of parts, and to prevent power loss occurred in a circuit thereof. CONSTITUTION: A converter part(2) has first to fourth rectifying diodes(D1-D4) for converting an input current from the input power supply part(1) to a DC power source, a choke coil(TR2) and the first condenser(C4). An inverter part(3) has first and second switching transistors(K1, K2), the second condenser(C13), a DIAC(D11), and first and second gate wave shaping integrated circuits(IC1, IC2). An output matching part(4) has a resonant coil(TR4), first to third resonant condensers(C7-C9), and a transformer(TR3) setting a winding rate according to a tube voltage. An absorbed DC power source part(5) has first and second diodes(D7, D8) and third and fourth condensers(C5,C6). A power control part(6) for controlling the saturation voltage of the gate transformer(TR5) has the first operational amplifier(U2), first and second DC voltage detection resistors(R8, R9), the first resistor(R15), the second operational amplifier(U1), the second resistor(R7), the third resistor(R6), the first comparator(U3), the fourth resistor(R11), the second comparator(U4), the fifth resistor(R14), the first switch(SW1), the third comparator(U5), a timer, the sixth resistor(R16), the fifth condenser(C15) and an undervoltage lockout.
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