| 摘要 |
PURPOSE: A power control circuit for DC-DC converter is provided to increase the battery life by improving the low current efficiency in the standby mode by adding a transistor and a hysteresis circuit for controlling an input current to the pulse width modulation(PWM) circuit. CONSTITUTION: The DC-DC converter(10) comprises a PWM controller(11) for generating the pulse signal corresponding to the applied voltage wave, a NPN transistor(TR1), an output condenser(Co), and a hysteresis circuit(100) connected between the output condensor and the controller for turning on or off according to the measured condensor charging voltage. In the standby mode the hysteresis circuit switches the transistor according to the charged voltage magnitude of the output condensor, which controls the input current to the PWM controller and applies the output condensor charging current to the system.
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