Power-good signal generator and controller with power sequencing free

A controller with power sequencing free adapted to control a power-good signal generator to generate a power-good signal when an output voltage of a converting circuit controlled by the controller reaches a predetermined value, the controller comprising:

• a first logic circuit coupled to a first voltage source;
• and
• a second logic circuit coupled to a second voltage source, in which a second output end of the second logic circuit is coupled to an first output end of the first logic circuit;
• wherein the first logic circuit outputs a signal at the first output end when the first voltage source is provided and the output voltage reaches the predetermined value, and the second logic circuit outputs a signal at the second output end when the second voltage source is provided and the output voltage reaches the predetermined value, thereby enabling the first logic circuit and the second logic circuit to jointly generate a control signal to control the converting circuit.

A power-good signal generator with power sequencing free for generating a power-good signal according to a control signal of a controller, wherein an input power terminal of the controller is coupled to a first voltage source, the power-good signal generator comprising:

• a controlled transistor of which an operating state is changed in response to the control signal of a controller, the controlled transistor having a first input/output end coupled to a second voltage source, a second input/output end and a controlled end;
• an impedance element, wherein an end of the impedance element is coupled to the second input/output end of the controlled transistor to generate the power-good signal, and the other end of the impedance element is coupled to a common potential;
• and
• a power sequencing free circuit coupled to the controlled end of the controlled transistor and one of the second input/output end of the controlled transistor and the common potential;
• wherein when the second voltage source is provided before the first voltage source is provide, the power sequencing free circuit turns off the controlled transistor.