Himax Analogic, Inc.

Jyi-Hung Tseng

A soft-start circuit is provided. The soft-start circuit comprises: an input stage, a pump stage, a second resistor and a capacitor. The input stage comprises a first resistor to receive an input voltage to provide a reference current at a first node. The pump stage comprises N current branches connected in parallel each comprising a current source connected to the first node and a switch to transfer the current from the current source to the second node while the switch operates in a connecting state. The switches has 2connecting modes performed one after another to generate an output current with a gradual increment output current at the second node with 2current levels; and the second resistor and the capacitor are connected in parallel between the second node and the ground potential to generate an output voltage with a gradual increment with 2voltage levels according to output current.

Soft-start circuit

A delay circuit includes current sources, switches, a transistor switch, a charging unit and a comparator. Each of the switches is provided for receiving an enable signal to activate and convey one of the current sources. The transistor switch is activated for pulling down voltage of an operating node coupled to the switches. The charging unit provides an operating voltage for the operating node based on one of the current sources when the transistor switch is deactivated and one of the switches is activated to convey one of the current sources to the charging unit. The comparator is provided for comparing the operating voltage with a reference voltage.

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Sinshih, Taiwan

Jyi-Hung Tseng