US 10,594,202 B1 · Current in-rush limiter

Abstract

Circuits and methods for limiting excessive current in circuits (such as step-up DC-to-DC converter circuits) in which very low ohmic FETs (VLOFETs) are used in circuit pathways that are subjected to startup in-rush current. Embodiments include a current mirror driver circuit that can be coupled to the gates of a VLOFET to form a current mirror that limits current flow through the VLOFET. The current mirror driver circuit provides for pulsed operation so that a coupled VLOFET still toggles between an OFF state and a current limited mode, particularly during a startup period. By using the current mirror driver circuit in conjunction with VLOFETs in circuit pathways that are subjected to startup in-rush current, in-rush current can be regulated to an acceptable level. Notably, no additional impedances are required in circuit pathways that are subjected to startup in-rush current to limit in-rush current, thus avoiding loss of efficiency.

Claims20

Dependent claims

A circuit for limiting current through a very low ohmic FET (VLOFET) having a control gate, the circuit including:

(a) a current mirror driver circuit coupled to or couplable to the control gate of the VLOFET and configured to be coupled to a general circuit supply voltage and to a source of a clock phase;
and
(b) a switch coupled to the current mirror driver circuit and configured to selectively apply to the control gate of a coupled VLOFET either the clock phase limited to a first voltage range by the current mirror driver circuit, or the clock phase limited to a second, wider voltage range;
wherein the current mirror driver circuit and VLOFET, when coupled, comprise a current mirror that limits current flow through the VLOFET when the clock phase is limited to the first voltage range.

1 more element

Dependencies are inferred from the claim text.

Current in-rush limiter

Life of this patent

Current in-rush limiter

Life of this patent

Abstract

Claims20