Switch-mode power supply with over-current protection

A switch mode power supply apparatus, comprising: a source of an input supply voltage; an inductance coupled to said source of said input supply voltage; a first transistor switch coupled to said inductance and responsive to a periodic, switch control signal for generating current pulses in said inductance that are coupled to a load circuit for generating an output of said power supply; a modulator responsive to a signal indicative of a given current pulse for generating said switch control signal to control said power supply output in a current mode control, on a current-pulse-by-current-pulse basis; an over-current protection circuit responsive to said current pulse indicative signal for disabling said power supply output when an over-current condition occurs; and a current sensor responsive to said given current pulse for generating said current pulse indicative signal that is coupled to each of said over-current protection circuit and said modulator via corresponding signal paths.

A switch mode power supply apparatus, comprising: a source of an input supply voltage; an inductance coupled to said source of said input supply voltage; a transistor switch coupled to said inductance and responsive to a periodic, switch control signal for generating current pulses in said inductance that are coupled to a load circuit for generating an output of said power supply; a modulator responsive to a given current pulse for generating said switch control signal to control said given current pulse in a current mode control, on a current-pulse-by-current-pulse basis, said current pulse varying in a ramping manner and being coupled to a first regenerative switch that is coupled to said control terminal of said transistor switch to disable said transistor switch in each period of said current pulses, when a threshold level of said first regenerative switch is exceeded; and an over-current protection circuit responsive to said current pulses, and including a second regenerative switch that is coupled to said control terminal of said first transistor switch for disabling said transistor switch when an over-current condition occurs, said over-current condition occurring when a magnitude of said current pulses exceeds a first value and persists longer than a first interval that is substantially longer than a period of said given current pulse, the operation of said transistor switch being undisturbed, when said magnitude of said current pulses exceeds said first value during a shorter interval than said first interval.