An output voltage VC obtained by boosting an input voltage VIN by means of a charge pump control circuit 3 of a charge pump 102 is supplied as a power supply voltage to a control circuit 4 of a step-up converter. It is thus possible to eliminate the need for a conventional self-bias method, eliminate switching from startup oscillation to main oscillation of the conventional self-bias method upon startup, and overcome problems caused by the switching of oscillation states, thereby achieving switching power supply circuitry starting in a reliable and stable manner.

Switching power supply circuitry

A DC-to-DC (buck) converter comprises a PWM regulation loop and a hysteretic control loop, which are alternatively enabled by a mode selection circuit of the converter in function of the load level. When the level of load drops below a preset limit related to a design load level, the converter passes from a PWM control mode to a hysteretic control mode, thus eliminating switching losses during periods of operation at relatively low load level.

Buck converter with operating mode automatically determined by the load level

Dual interleaved DC to DC switching circuits realizable in an integrated circuit form, capable of monitoring individual inductor current using only one current sense resistor and providing automatic duty cycle adjustment to keep the inductor currents in the interleaved DC to DC switching circuits balanced. The preferred embodiment includes a gain error amplifier, an integral error amplifier, and a differentiator error amplifier and circuits for controlling the nominal duty cycle, with the gain error amplifier, integral error amplifier and differentiator error amplifier being adjustable independently by external components. The circuit further includes a high speed load regulation circuit that momentarily overrides the control circuitry to take over control of the interleaved converters during sudden load changes, such control also being programmable. The circuit further includes a load variation circuit to target the output voltage of the circuit to an optimal value with load to better keep the output voltage within a targeted range in the event of major step changes in the load. The disclosed embodiment is for two interleaved buck converters, though the principles of the invention are applicable to interleaved step up converters and the interleaving of more than two converters.

Dual interleaved DC to DC switching circuits realized in an integrated circuit

A DC power converter is disclosed for converting an input voltage to a final output voltage that is higher than the input voltage. The power converter includes an input terminal for receiving the input voltage and a final output terminal. A boost converter generates an intermediate voltage that is higher than the input voltage and lower than the final output voltage. The boost converter includes an inductor having a primary winding that has a first end connected to the input terminal, a switch for selectively connecting the second end of the first winding to ground, a first diode connected between the second end of the first winding and an intermediate node, and a first output capacitor connected between the intermediate node and ground. The boost converter produces at the first output capacitor an intermediate voltage higher than the input voltage. The step up converter described further includes a second winding on the inductor, a first end of which is connected to receive the intermediate voltage. A diode is connected between the second end of the second winding and the converter output terminal. A second output capacitor is connected between the converter output terminal and ground.

High efficiency DC step-up voltage converter

Ripple canceling, soft switching isolated DC/DC converters with reduced voltage stress synchronous rectification. The converters include interleaved switching converters providing power to a node supplying power to a zero volt switching bi-phase power conversion stage driving synchronous rectifiers feeding an output filter. In one embodiment, the interleaved converters are boost mode converters operating in continuous conduction mode boost converters. Various embodiments are disclosed.

Ripple canceling, soft switching isolated DC/DC converters with reduced voltage stress synchronous rectification

A DC/DC voltage converting device is obtained for boosting a DC power supply voltage to provide a higher output voltage, comprising soft start circuit 20 for gradually increasing the turning-on duration of transistor 34 in boosting circuit 30; pulse width control circuit 60 for providing a modulated pulse signal P2 to control the boosted voltage. The device further comprises boosting circuit 30 including an inductor 32, diode 36 and transistor 34. Boosting circuit 30 provides a predetermined boosted voltage higher than the power supply voltage by alternately turning on and off transistor 34. The turning-on duration of transistor 34 is gradually increased during the initial operation period by soft start circuit 20, and is controlled by modulated pulse signal P2 during a stable operation period. The device further comprises gate circuit 40 having diode 46 and transistor 44, and step up circuit 70. Step up circuit 70 turns off transistor 44 during the initial operation period, and turns it on while transistor 34 is off during the stable operation period to allow an efficient current flow from boosting circuit 30 to output terminal 58. Any counter current flow from output terminal 58 to boosting circuit 30 is inhibited during the initial operation period.

Dc/dc voltage converting device

A voltage converter for stably converting, even a low input voltage, to a predetermined output level is provided. The output of cell 20 is increased by first and second step-up circuits 21 and 22, and then smoothed by smoothing circuit 31. The output is converted by the first step-up circuit from the start of voltage conversion until a predetermined output voltage, and then converted by the second step-up converter thereafter. The output voltage of smoothing circuit 31 is compared against a first reference voltage by first comparator circuit 35, the output of which activates the integral circuit in second comparator circuit 37. The charge voltage of the integral circuit is compared to a sawtooth wave STW generated by oscillator circuit 43 to derive a signal for forcefully shutting down MOS transistor 29 in the second step-up circuit. On the other hand, a error voltage between the output of smoothing circuit 31 and a second reference voltage is amplified, followed by comparison with the sawtooth wave, and the resulting output is combined with the output of the second comparator circuit to control the pulse width of MOS transistor 29 for a desired output voltage.

Dual dc/dc voltage converter power system

A voice coil motor driving circuit 10 with retracting function used in a disk drive unit for driving a read/write head by means of a voice coil motor VCM, comprising a voltage up-converter 12; a voice coil motor control circuit 16 for driving the voice coil motor during normal operation; a retract power source Vrr for supplying a retract current to the voice coil motor during head retract action; a retract control circuit 24 for allowing the retract current from the retract power source to the voice coil motor in response to a retract signal. The driving circuit also includes a capacitor C for providing an uninterrupted supply of voltage to the retract control circuit 24 during head retract action.

Voice coil motor driving circuit with retracting function

A voltage converting circuit receiving an input voltage and an increased voltage and providing an output voltage higher than the input voltage at an output terminal, comprises a first pair of gate devices serially connected between the input voltage and a ground, a second pair of gate devices serially connected between the input voltage and the output terminal, a first capacitor connected between a node between the first pair of gate devices and a node between the second pair of gate devices for boosting the output voltage, a second capacitor connected between the output terminal and the ground for smoothing the output voltage, a control circuit for controlling said pairs of gate devices, and a pair of drivers for driving the second pair of gate devices respectively under the control of the control circuit. The pair of drivers are connected so as to operate between the increased voltage and the input voltage.

Voltage converting circuit with low consumption driver

PURPOSE:To provide a voice coil motor driving circuit having function for retracting a head without requiring an additional auxiliary power supply in a magnetic disc unit for moving a magnetic head by means of a voice coil motor. CONSTITUTION:A capacitor 14 is connected in parallel with the output terminal of a booster circuit 12 for feeding power to a retract control circuit 24, and voltage supply to the retract control circuit 24 is sustained with accumulated charges at the time of retract operation.

Kotaro Okada

Papers

Dc/dc voltage converting device

Dual dc/dc voltage converter power system

Voice coil motor driving circuit with retracting function

Voltage converting circuit with low consumption driver

Voice coil motor driving circuit provided with retract function