Dual mode regulation loop for switch mode power converter
View Patent ↗The invention relates to a DC-DC converter, which includes a power stage driven by a pulse width modulator, a first error amplifier with a first input coupled to a first reference voltage source and a second input coupled to a current sink through which a current is fed from an output of the power stage to receive a first feedback voltage (FB 1 ), a second error amplifier with a first input coupled to a second reference voltage source and a second input coupled to the output of the power stage to receive a second reference voltage (FB 2 ), and switching means (SW 1 ) for connecting a control input of the pulse width modulator with the output of the first error amplifier in a current regulation mode and with the output of the second error amplifier in a voltage regulation control mode.
1. A DC-DC converter comprising
a power stage driven by a pulse width modulator;
a first error amplifier with a first input coupled to a first reference voltage source and a second input coupled to a current sink through which a current is fed from an output of the power stage to receive a first feedback voltage;
a second error amplifier with a first input coupled to a second reference voltage source and a second input coupled to the output of the power stage to receive a second feedback voltage; and
a switch for connecting a control input of the pulse width modulator with the output of the first error amplifier in a current regulation mode and with the output of the second error amplifier in a voltage regulation control mode;
a reference voltage controller for dynamically changing the value of the second reference voltage source to reduce transients, upon switching between the voltage and current regulation modes, wherein the reference voltage controller is configured and adapted to change the value of the second reference voltage source from a predetermined value towards the first reference voltage after a transition from the voltage regulation mode to the current regulation mode; to supply a first comparison result to the input of the pulse width modulator by the switch only when the second reference voltage is substantially equal to the first reference voltage; to keep the second reference voltage close to the second feedback voltage in the current regulation mode; and to change the second reference voltage back to the predetermined reference voltage value only after connecting the output of the second error amplifier to the control input of the pulse width modulator by the switch in response to a transition from the first voltage regulation mode to the current regulation mode.