| 摘要 |
<p>A method and a system for reducing an input current in a photoflash charger are provided to measure a primary winding without increasing an inductance of the primary winding by increasing an off-time of a power switch of the charger. A switching regulator supplies a current to a load and includes a converter and a delay circuit. The converter includes primary and secondary windings. During a first interval of a switching cycle, the current is accumulated in the primary winding. During a second interval of the switching cycle, the current is discharged to the secondary winding. The delay circuit applies a delay between an end point of the second interval of the switching cycle and a start point of the first interval of the switching cycle. The delay circuit is a voltage-controlled variable delay circuit. When an input voltage to the switching regulator is higher than a first threshold value, the delay circuit is disabled.</p> |
