Astec International Limited

David A Smith

Neal George Stewart

Carl K Sawtell

Kenneth A Check

Carl E Arvidsson

A semiconductor packaging structure comprising a hybrid IC package having at least one IC chip mounted therein is disclosed. The semiconductor packaging structure includes a DC-DC switching power supply mounted within the hybrid IC package that is electrically coupled to at least one of the IC chips by conductive paths formed in said hybrid IC package for supplying at least one specified voltage to the at least one IC chip. Power is supplied to the DC-DC switching power supply from a remote power source.

Integrated circuit mounting structure including a switching power supply

A mounting structure for providing DC power to an IC package is disclosed. The mounting structure comprises a socket for receiving an IC package, having one or more IC chips, and a power supply for supplying at least one specified DC voltage to the IC package. The power supply is coupled to the IC package by conductive paths formed in the socket.

A detection circuit for use in an electrical power converter having at least one negative output rail, for detecting the voltage of the negative output rail and for converting the voltage to a positive output voltage. The detection circuit includes an input port for receiving the negative output rail voltage from an electrical power converter, an output port, a ground reference potential, a node having a voltage that is positive with respect to the ground reference potential, and a circuit for generating a measurement current from the node to the ground reference potential. The value of this measurement current is a function of the negative output rail voltage received at the input port. A circuit is further provided for generating an output voltage at the output port that is positive with respect to said ground reference potential and whose value is a function of said measurement current. The detection circuit can be used with conventional pulse-width modulators of switch mode power supplies in order to regulate the value of the negative rail voltage.

Circuit for detecting negative output rails

An improved temperature control system for a power conversion circuit having two or more power converters operating in parallel and providing output power to a single load. The temperature control system maintains the temperature of each of these power converters at approximately the average temperature of the power converters. A detector coupled to each power converter detects the temperature of the power converter and generates a measurement signal that is a function thereof. A reference signal is generated that is a function of each measurement signal. A control circuit responsive to the measurement signal of each power converter adjusts the output power of that respective converter as a function of the difference between that converter's measurement signal and the reference signal such that the temperature of each power converter approximates the average of temperature of the power converters.

Temperature share scheme

The present invention provides a heat sink and electromagnetic interference shield assembly for a plurality of semiconductor elements. The semiconductor elements are connected with other circuit elements to form an electrical circuit. Each semiconductor element has a metal portion for dissipating heat generated by the semiconductor element. The metal portion also emits electrical energy as a result of the operation of the semiconductor element thereby causing unwanted electromagnetic interference. The assembly comprises an insulator attached to the meted portion of the semiconductor element and a substrate for mounting the plurality of semiconductor elements. The insulator is of a thermally conductive material to facilitate the conduction of thermal energy away from the semiconductor element. The substrate has a metal base layer, a middle insulating layer, and a plurality of metal mounting areas for mounting the plurality of semiconductor elements. The electrical energy emitted by each semiconductor element is capacitively coupled to its corresponding metal mounting area. The assembly also contains a conductive path for returning the electrical energy coupled to the metal mounting area to one of the circuit elements such that the amount of electromagnetic interference is reduced.

Heat sink and electromagnetic interference shield assembly

An improved gate drive circuit for use with a switching power device in a power converter and other power-transfer type circuits and the like is described. The gate drive circuit according to the present invention requires fewer components and space that convention prior art gate drive circuits. The drive circuit provides isolation between the control circuitry and the device without storing a significant amount of long-term (i.e., D.C.) energy and is also more energy efficient than many prior art gate drive circuits. Additionally, the present invention comprises means for cleanly terminating the drive signal to the switching power device when the control circuitry terminates operation. This prevents an incorrect signal to the switching power device, which may conduct at an inappropriate time, causing damage to the power converter or power-transfer circuit. Many prior art drive circuits have D.C. blocking capacitors that discharge slowly upon termination and, consequently, cause the switching power device to inadvertently conduct, which may damage the converter.

Gate drive circuit

A flyback-type power converter having a secondary-side resonant circuit which shapes the current waveform in the secondary winding and secondary circuit to reduce the RMS current values therein is described. The shaping reduces conduction losses and improves conversion efficiency. With the resonant circuit, the energy stored in the transformer is transferred during the OFF-period in substantially a fixed time duration, enabling a fixed-OFF period operation mode. The converter may further have a primary-side resonant circuit for capturing and recycling the energy stored the leakage inductance of the primary winding, which is normally wasted in snubber circuitry.

Multi-resonant clamped flyback converter

A Circuit for reversing the direction of current flow in a rectifying device of a power converter during a time interval just prior to when the rectifying device is to be rendered non-conductive is described. The current reversal substantially reduces or eliminates reverse-recovery currents in the rectifying device, which may cause short circuits and needlessly dissipates power. The circuit comprises an energy source, a magnetic storage device, and a switch for coupling the magnetic storage device to the energy source. The magnetic storage device may comprise an inductor or a transformer. The energy source may include a voltage source, the converter's input voltage, the output voltage, or a winding magnetically coupled to another magnetic storage device of the converter. The reversal circuit includes a circuit for coupling the reversing current to the rectifying device such that it partially or completely reverses the flow of current in the rectifying device.

Power converters with improved switching efficiency

A circuit for utilizing the magnetizing current in the transformer of a power converter to reset the transformer's core and to provide a zero voltage switching condition on the converter's primary switch is disclosed. The transformer includes a primary winding and a secondary winding, the secondary winding being coupled to an output load and a primary switch connected in series between the primary winding and a voltage source. The closing of the primary switch causes energy to be stored in the transformer and the opening of the primary switch causes the energy to be released from the transformer. A transformer flux reversal circuit is used to reverse the direction of the magnetic flux built up in the transformer when the primary switch is opened. A secondary switch is coupled in series with the secondary winding of the transformer and is operated to prevent any loading effects of the load from disrupting the creation of the zero voltage switching condition.

Zero voltage switching power converters

A circuit for the fast turn off of a field effect transistor (FET) for use in circuits such as a power converter circuit. The FET turn off circuitry includes a gate current sink transistor and a capacitor linked between the base of the gate current sink transistor and the drain of the FET. This capacitor increases the current into the base of the gate current sink transistor, and enables an increased magnitude of current to flow from the FET, thereby increasing the speed with which the FET turns off. A diode is preferably also connected between the base and the emitter of the gate current sink transistor to provide a return path to discharge the capacitor.

Circuit for the fast turn off of a field effect transistor

A dual active clamp (DAC) converter comprising two active-clamp, zero-voltage switching (ZVS) converters for converting electrical power from an input source to an output load is described. The two active-clamp ZVS converters are coupled in parallel to one another at their respective inputs and outputs, and are operated in a manner which reduces the overall input and output ripple currents of the DAC converter, which reduces the EMI emissions of the DAC converter. Each of the active-clamp ZVS converters achieves zero-voltage switching on its primary switch means, which also improves EMI emissions. Each active-clamp ZVS converter includes a transformer having a primary winding and a secondary winding, the secondary winding being coupled to the output load and the primary switch means being coupled between the primary winding and a voltage source, and an active clamp circuit comprising a series combination of a storage capacitor and a first switch means. The active clamp is coupled to the transformer to capture energy released from the transformer at specific times, which is then used to reset the transformer's core and to create a zero voltage switching condition across the primary switch means. A second switch means is connected in series with the secondary winding of the transformer and is operated to prevent the loading effects of the secondary from interrupting the creation of the zero-voltage switching condition.

Dual active clamp, zero voltage switching power converter

A efficient circuit for driving two switching transistors of an electrical power transfer circuit in an anti-phase relationship is described. The drive circuit is applied to a power transfer circuit, such as a switching-type power converter, having a first switching transistor, a second switching transistor, and a magnetic storage element electrically coupled to the first switching transistor. The first switching transistor is coupled to the magnetic storage element and operates to vary the magnetic flux in the storage element. The present invention comprises a drive circuitry for operating the first switching transistor, the drive circuitry being responsive to a first control signal generated by the power transfer circuit. For driving the second switching transistor, the present invention comprises circuitry for generating a second control signal as a function of the magnetic flux in the magnetic storage element. The second control signal causes the second switching transistor to be conductive when the first switching transistor becomes non-conductive. The present invention further comprises a shunting circuitry responsive to the first control signal for causing the second switching transistor to be non-conductive when the first switching transistor becomes conductive. The circuitry for generating the second control signal and the shunting circuitry of the present invention may be constructed from components requiring less board area than standard drive circuitry for the second switching transistor.

Efficient transistor drive circuit for electrical power converter

Power converter module

A circuit for utilizing the magnetizing current in the transformer of a converter to reset the transformer's core and to provide a zero-voltage-switching condition on the converter's primary switch and to regulate the output voltage is disclosed. The power converter includes a transformer having a primary winding and a secondary winding, the secondary winding being coupled to an output load and a primary switch connected in series between the primary winding and a voltage source. The closing of the primary switch causes energy to be stored in the transformer and the opening of the primary switch causes the energy to be released from the transformer. The utilization circuit includes a series combination of a storage capacitor and a first switch coupled in parallel with one of the transformer's windings to capture the energy released from the transformer. The captured energy is used to reset the transformer's core and to create a zero voltage switching condition across the primary switch. A second switch means is connected in series with the secondary winding of the transformer and is operated to prevent the loading effects of the secondary from interrupting the creation of the zero-voltage switching condition. A secondary side regulation circuit is included to both regulate the output voltage and to prevent the loading effects of the secondary circuit from interfering with zero-voltage switching in the primary circuit.

Zero voltage switching power converter with secondary side regulation

An adjustable power converter which allows the output voltage of the power converter to be controlled linearly by a programming resistor or a programming voltage is provided. The adjustable power converter includes a linear programming circuit which generates a current as a linear function of the programming voltage or the resistance of the programming resistor. The current is connected to the feedback loop of a conventional power converter such that the output voltage of the power converter is a linear function of the current. As a result, the output voltage of the power converter can be linearly adjusted by adjusting the programming voltage or the programming resistor.

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Hong Kong, China

David A Smith