A circuit and method for controlling a switching voltage regulator having (1) a switch including one or more switching transistors and (2) an output adapted to supply current at a regulated voltage to a load including an output capacitor. The circuit and method generates a control signal to turn said one or more switching transistors OFF under operating conditions when the voltage at the output is capable of being maintained substantially at the regulated voltage by the charge on the output capacitor. Such a circuit and method increases the efficiency of the regulator circuit particularly at low average current levels.

Control circuit and method for maintaining high efficiency over broad current ranges in a switching regulator circuit

A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times of the controlled rectifiers. The control inputs to the controlled rectifiers are cross-coupled from opposite secondary transformer windings.

High efficiency power converter

A DC to DC converter which maintains high efficiency over broad current ranges in a current mode switching regulator circuit without changing operational mode. A low ripple voltage is maintained over the entire load range and good voltage regulation is maintained with high efficiency. This is possible because the switching frequency is adjusted in accordance with the load without changing operational states, thus making it unnecessary to define plural states of operation. The timing of turning on the switch(es) varies since the switch(es) is (are) turned on when two set (ready) signals both become ready. For fixed frequency switching applications, switching pulses from a fixed frequency oscillator as a first set signal are skipped when a second set signal is not ready. On the other hand, for a variable frequency switching scheme which is implemented by driving the switching with a one-shot having a constant OFF time, the switching pulse is created after both set signals become active. A low pass filter is also used to dynamically adjust the minimum peak inductor current and to minimize ripple voltage for low load conditions so that a smaller output capacitor may be used.

DC to DC converter with high efficiency for light loads

Multiple phase switching regulators with stage shedding are provided. Multiple phase switching regulators of the present invention have a plurality of single phase switching regulators coupled in parallel to an output capacitor. The plurality of single phase switching regulators supply current to a load at a regulated voltage. A comparator monitors the load current and causes one or more of the single phase switching regulators to be OFF at a low load current threshold. At least one of the single phase switching regulators that remains ON increases its output current so that the multiple phase switching regulator output current continues to match the load current. The present invention may include a second comparator that causes additional single phase switching regulators to be OFF at a second low load current threshold that is lower than the first low load current threshold.

Multiple phase switching regulators with stage shedding

The present invention comprises a user-programmable control circuit for use in a power converter to automatically transition the converter into BURST mode when load current demand is low. The control circuit senses load current demand by monitoring the output current of the converter, and generating a signal representative of the monitored output current. The control circuit may automatically transition the converter into BURST mode when the signal indicative of the average monitored output current decreases below a user-programmable threshold. BURST mode may increase overall converter efficiency by turning OFF a plurality of electronic components, and maintaining the converter's output voltage at a regulated level by energy stored in an output capacitor.

Methods and circuits for programmable automatic burst mode control using average output current

A circuit is employed utilizing the low collector-emitter voltage of a saturated transistor to obtain more efficient rectification of an alternating current supply than is achieved by a diode. A regenerative feedback circuit to the base of the transistor is provided so that once collector-to-emitter current is initiated, current is fed back to the base of the transistor to further drive the transistor into its conducting condition. However, since transistors may operate in a reverse direction when the load voltage is greater than that of the power supply, such regenerative feedback circuit is employed in series with the saturated transistor whereby any reverse collector current due to inverted operation causes the base of such transistor to be cut off, preventing any undesired reverse transistor operation.

Gunn John B

Papers

Rectifier using low saturation voltage transistors