Patent ID: 6100677
Filing Date: 2000-08-08
Classification: H02M

Abstract:
A DC-to-DC converter for producing a regulated output potential in response to an input potential, wherein the DC-to-DC converter operates in a soft start mode during a soft start period and in a steady state mode after the soft start period, said DC-to-DC converter comprising:a switching controller implemented as an integrated circuit, wherein the controller includes circuitry configured to periodically switch on a power switch during both the soft start mode and the steady state mode and switch off the power switch during the steady state mode at times determined by a reset signal, wherein the controller includes circuitry configured to generate the reset signal during both the soft start mode and the steady state mode in response to a first feedback potential; andexternal circuitry coupled to the controller, wherein the external circuitry includes circuitry configured to generate a second feedback potential and assert the second feedback potential to the controller, wherein the second feedback potential is proportional to the output potential and is regulated by at least one of the controller and the external circuitry so as not to significantly exceed a target value, and wherein one of the controller and the external circuitry includes the power switch,wherein the controller includes soft start circuitry coupled to receive the second feedback potential and the reset signal, wherein the soft start circuitry includes a soft start capacitor and is configured to generate a soft start reset signal during the soft start period in response to the second feedback potential, the reset signal, and a voltage across the soft start capacitor, wherein the controller is configured to switch off the power switch during the soft start mode at times determined by the soft start reset signal, whereby the controller controls operation of the DC-to-DC converter in the soft start mode without employing any component of the external circuitry other than components of the external circuitry that the controller employs to implement the steady state mode.