DYNAMIC OPERATING FREQUENCY CONTROL OF A BUCK POWER CONVERTER HAVING A VARIABLE VOLTAGE OUTPUT

摘要

A switch controller for a variable output voltage power converter includes a pulse width modulator (PWM) output producing a pulsed signal for driving a power converter switch. A mode selector output is connected to a multiplier. A period selector output is connected to the multiplier and to a PWM input. The multiplier output is connected to another PWM input. A comparator output is connected to a period selector input. The period selector outputs a nominal cycle time to the PWM when an operating on-time state is greater than a minimum operating on-time. The period selector outputs an updated cycle time greater than the nominal cycle time when the operating on-time state is less than the minimum operating on-time causing the PWM to output a pulsed signal with the updated cycle time and a duty cycle equal to a duty cycle of an immediately preceding pulsed signal.

主权项

1. A switch controller for a power converter having a variable output voltage range comprising:
a pulse width modulator having an output producing a pulsed signal for driving a power converter switch; a mode selector having an output indicative of an operating on-time state of the power converter connected to a multiplier; a period selector having an output indicative of a cycle time for the pulsed signal connected to the multiplier and to an input of the pulse width modulator; the multiplier having an output indicative of a switch on-time of the cycle time connected to another input of the pulse width modulator; a comparator having an output indicative of the operating on-time state relative to a minimum operating on-time and connected to an input of the period selector; and wherein the period selector outputs a nominal cycle time to the pulse width modulator when the operating on-time state is greater than the minimum operating on-time and wherein the period selector outputs an updated cycle time greater than the nominal cycle time when the operating on-time state is less than the minimum operating on-time such that the pulse width modulator outputs a pulsed signal with the updated cycle time and a duty cycle equal to a duty cycle of an immediately preceding pulsed signal.