| 摘要 |
PROBLEM TO BE SOLVED: To have an inexpensive constitution, prevent a control IC from being broken due to an excess current, and improve the reliability in a DC-DC converter with a phase compensating circuit. SOLUTION: A PWM pulse having a duty ratio corresponding to an error signal is generated by comparing a triangular wave with the error signal as an output signal from an error amplifier Q1 in a comparator. A DC voltage is generated and supplied to a load by turning on/off a MOS transistor by the PWM pulse. When the DC-DC converter is normally operated, one end of a resistor R3 connected to an input of the error amplifier Q1 and one end of the phase compensating circuit of a capacitor C3 are connected to a non-inverting input terminal of the error amplifier Q1 by switches SW2, SW3. When a short circuit in the load (a short circuit at an output) is detected, they are connected to the ground. COPYRIGHT: (C)2007,JPO&INPIT
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