Patent ID: 9257898
Filing Date: 2016-02-09
CPC Classification: H02M,H03K

Claim Text:
1. A soft-start circuit comprising: a first charging transistor conducted in response to a plurality of activating pulses to provide a first charging current to a first output node every predetermined time interval; a first capacitor electrically connected to the first output node to receive the first charging current such that a first output voltage at the first output node gradually increases; a second charging transistor conducted in response to the first output voltage to provide a second charging current to a second output node; a second capacitor electrically connected to the second output node to receive the second charging current such that a second output voltage at the second output node gradually increases; and a clamping p-type transistor comprising a source terminal electrically connected to a clamping node, a drain terminal connected to a ground terminal and a gate electrically connected to the second output node, wherein the clamping p-type transistor is conducted when a voltage at the clamping node exceeds a clamping threshold value to pull low the voltage at the clamping node, wherein the clamping node is an amplifier output node of an operational amplifier disposed in a voltage converting circuit.