Variable time clamp for a power supply controller
AssigneePower Integrations, Inc.
InventorLeif Lund
Life of this patent
Estimating the term…
Abstract
An example integrated circuit for use in a power supply includes a feedback terminal and a controller having a variable time clamp (VTC). The feedback terminal is to be coupled to receive a feedback signal and the controller is to be coupled to enable or disable the conduction of a power switch during a switching cycle in response to the feedback signal. The controller includes a current limit comparator coupled to terminate the conduction of the power switch during an enabled switching cycle in response to a current through the power switch exceeding a variable current limit. The VTC is coupled to clamp the feedback terminal to a voltage for a clamp time that is responsive to the variable current limit.
Claims25
An integrated circuit for use in a power supply, the integrated circuit comprising:
- a feedback terminal to be coupled to receive a feedback signal;
- a controller to be coupled to enable or disable the conduction of a power switch during a switching cycle in response to the feedback signal, wherein the controller includes a current limit comparator coupled to terminate the conduction of the power switch during an enabled switching cycle in response to a current through the power switch exceeding a variable current limit;
- and
- a variable time clamp (VTC) included in the controller and coupled to clamp the feedback terminal to a voltage for a clamp time that is responsive to the variable current limit.
A power supply, comprising:
- an energy transfer element coupled to transfer energy from a primary side of the power supply to a secondary side of the power supply, wherein the primary side is galvanically isolated from the secondary side;
- a power switch coupled to control the transfer of energy through the energy transfer element;
- and
- an integrated circuit coupled to control the switch, wherein the integrated circuit includes:
- a feedback terminal to be coupled to receive a feedback signal;
- a controller coupled to enable or disable the conduction of the power switch during a switching cycle in response to the feedback signal, wherein the control circuit includes a current limit comparator coupled to terminate the conduction of the power switch during an enabled switching cycle in response to a current through the power switch exceeding a variable current limit;
- and
- a variable time clamp (VTC) included in the controller and coupled to clamp the feedback terminal to a voltage for a clamp time that is responsive to the variable current limit.
A method, comprising:
- receiving a current sense signal representative of a current flowing through a power switch of a power supply;
- disabling conduction of a power switch of the power supply during an enabled switching cycle in response to the current through the power switch exceeding a variable current limit;
- and
- enabling conduction of the power switch and in response thereto, clamping a feedback terminal to a voltage for a clamp time that is responsive to the variable current limit.
Dependencies are inferred from the claim text.