Aimtron Technology Corp.

Ching-Kun Lin

Tien-Tzu Chen

Rong-Chin Lee

Yung-Chih Chen

Ching-Sung Wu

When a primary winding current increases to an upper limit determined by a reference voltage having a soft-start characteristic, a power switch is turned OFF. When a secondary winding current decreases to a lower limit determined by another predetermined reference voltage, the power switch is turned ON. A minimum ON-time limiting unit prevents the power switch from being turned OFF before a minimum ON-time expires. The minimum ON-time may be provided with a soft-start modulation. A minimum OFF-time limiting unit prevents the power switch from being turned ON before a minimum OFF-time expires. A maximum ON-time limiting unit prevents the power switch from still remaining ON after a maximum ON-time expires.

Capacitor charging circuit with a soft-start function

A camera strobe recharging IC includes a one-shot unit, an R-S latch block unit, a PWM control unit, and a ready control unit. The one-shot unit provides square wave signals. The R-S latch block unit is electrically connected with the one-shot unit. The PWM control unit includes a reference voltage source, an oscillator, a PWM comparator, a voltage boost comparator, and a current source. The ready control unit includes an FET, which has a gate contact electrically connected with an output contact of the R-S latch block unit. Accordingly, the present invention is compact and structurally tiny to facilitate integration and is good at modulating charging current, accelerating charging, and automatically recharging.

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Hsin-Chu, Taiwan

Ching-Kun Lin