Bandgap device and start-up circuit thereof

Abstract

A bandgap device and a start-up circuit thereof are disclosed. The start-up circuit includes a first transistor, delay circuit, second transistor, switch circuit, and startup switch. Control terminals of first transistor and second transistor are controlled by an internal bias voltage of the bandgap circuit. The delay circuit is coupled to the first transistor. The switch circuit is coupled to the second transistor. The switch circuit is controlled by the delay circuit. A control terminal of startup switch is coupled to the second transistor and the switch circuit. At a power-up instant time of the bandgap circuit, the startup switch is turned on to provide a startup bias to an internal startup node of the bandgap circuit. After the bandgap circuit completes startup, the internal bias voltage of the bandgap circuit turns off the startup switch, the first transistor, and the second transistor, so the start-up circuit consumes no current.