Method and apparatus for extending the operating range of a flyforward converter
Granted: June 13, 2006
Patent Number:
7061778
A technique for extending the operating range of a flyforward converter to low input voltages. In one aspect, power converter includes a positive input supply rail and a negative input supply rail. A power converter input voltage is to be applied between the positive and negative input supply rails. A flyback energy transfer element having a flyback input winding and a forward energy transfer element having a forward input winding are also included. The flyback and forward input windings…
Method for reducing the cost of voltage regulation circuitry in switch mode power supplies
Granted: May 23, 2006
Patent Number:
7049794
A reduced cost voltage regulation circuit for switched mode power supplies. In one embodiment, a voltage regulation circuit includes a current sense circuit having a current sense terminal to conduct a current to be sensed by the current sense circuit. A voltage difference between the current sense terminal and a voltage reference terminal is substantially fixed when the current to be sensed by the current sense circuit is substantially equal to a first current sense threshold. The…
Method and apparatus for reducing audio noise in a switching regulator
Granted: May 16, 2006
Patent Number:
7045994
A switching regulator utilizing on/off control that reduces audio noise at light loads by adjusting the current limit of the switching regulator. In one embodiment, a switching regulator includes a state machine that adjusts the current limit of the switching regulator based on a pattern of feedback signal values from the output of the power supply for a preceding N cycles of the drive signal. The state machine adjusts the current limit lower at light loads such that cycles are not…
Off-line converter with digital control
Granted: May 2, 2006
Patent Number:
7038439
A DC to DC converter comprising an energy storage element comprising an energy storage element input and an energy storage element output the energy storage element input coupled to receive a first power level and the energy storage element output providing a second power level. The converter also comprises a feedback circuit comprising a feedback input and a feedback output, the feedback input coupled to the energy storage element output. The converter further comprises a regulator…
Method and apparatus for extending the size of a transistor beyond one integrated circuit
Granted: May 2, 2006
Patent Number:
7038524
A technique for extending the size of a power transistor beyond one integrated circuit. In one embodiment, a method of extending the size of a power transistor beyond one integrated circuit includes a master integrated circuit comprising a master control circuit, master driver circuit and master semiconductor switch and one or more slave integrated circuits comprising a slave semiconductor switch and a slave driver circuit. In one embodiment the master semiconductor switch terminals are…
Method and apparatus to improve frequency stability of an integrated circuit oscillator
Granted: April 25, 2006
Patent Number:
7034625
A method and apparatus providing a simple low cost integrated circuit oscillator with improved frequency stability over a range of selected frequencies by reducing the impact of process and temperature variations on a base current of bipolar transistor of the integrated circuit oscillator. A voltage follower circuit included in an integrated circuit oscillator provided to is injected with a base current provided by a current mirror instead of a capacitor such that variations in the base…
Method and apparatus for output voltage regulation in primary controlled switched mode power supplies
Granted: April 11, 2006
Patent Number:
7027312
A voltage sense circuit and power supply regulation technique. In one aspect, a voltage sense circuit utilized in a power supply regulator includes a transformer including a sense winding and an output winding. A first diode is coupled to the sense winding, a first resistor is coupled to the first diode and a first capacitor coupled to the first resistor and the first diode. A second diode coupled to the first capacitor, the first resistor and the first diode. A second capacitor coupled…
Method and apparatus for sensing current and voltage in circuits with voltage across an LED
Granted: February 28, 2006
Patent Number:
7005914
Methods and apparatuses to sense current and voltage in circuits with voltage drop. A sense circuit includes a series combination of a diode and a resistor in the path of the current to be sensed, the voltage across this series combination coupled to drive a light emitting diode (LED).
Method and apparatus for controlling a circuit with a high voltage sense device
Granted: February 21, 2006
Patent Number:
7002398
A control circuit with a high voltage sense device. In one embodiment, a circuit includes a first transistor disposed in a first substrate having first, second and third terminals. A first terminal of the first transistor is coupled to an external voltage. A voltage provided at a third terminal of the first transistor is substantially proportional to a voltage between the first and second terminals of the first transistor when the voltage between the first and second terminals of the…
Method and apparatus for substantially reducing electrical earth displacement current flow generated by wound components
Granted: February 7, 2006
Patent Number:
6995990
An energy transfer element having an energy transfer element input winding, an energy transfer element output winding and energy transfer element windings that reduce displacement currents. In one aspect, an energy transfer elements includes an energy transfer element core with first and second windings wound around the energy transfer element core. The first winding is capacitively coupled to the second winding. A third winding is wound around the energy transfer element core to…
Switched mode power supply responsive to current derived from voltage across energy transfer element input
Granted: February 7, 2006
Patent Number:
6995986
A switched mode power supply having a regulated reflected voltage. In one embodiment, a switched mode power supply includes a power supply regulator coupled between a positive input supply rail of the power supply and a primary winding of an energy transfer element. The reflected voltage across the primary winding of the transfer element is related to the output voltage across a secondary winding of the energy transfer element according to the turns ratio of the energy transfer element.…
Method and apparatus for trimming current limit and frequency to maintain a constant maximum power
Granted: January 31, 2006
Patent Number:
6992471
Methods and apparatuses to trim current limit (Ip ) and frequency (f) to maintain a constant maximum power. In one aspect of the invention, a power supply regulator having a peak current limit detection threshold and an operating frequency is disclosed. The peak current limit threshold or the operating frequency are adjusted specifically to maintain the Ipm·fn product substantially constant from one power supply controller to another where m is substantially equal to 2 and n is…
Method and apparatus for substantially reducing electrical earth displacement current flow generated by wound components
Granted: January 31, 2006
Patent Number:
6992903
An energy transfer element having an energy transfer element input winding and an energy transfer element output winding. In one aspect, the energy transfer element input winding is capacitively coupled to the energy transfer element output winding. The energy transfer element is capacitively coupled to electrical earth. One or more additional windings are introduced as part of the energy transfer element. The one or more additional windings substantially reduce capacitive displacement…
High-voltage lateral transistor with a multi-layered extended drain structure
Granted: January 17, 2006
Patent Number:
6987299
A high-voltage transistor with a low specific on-state resistance and that supports high voltage in the off-state includes one or more source regions disposed adjacent to a multi-layered extended drain structure which comprises extended drift regions separated from field plate members by one or more dielectric layers. The layered structure may be fabricated in a variety of orientations. A MOSFET structure may be incorporated into the device adjacent to the source region, or,…
Method and apparatus for output voltage regulation in primary controlled switched mode power supplies
Granted: January 10, 2006
Patent Number:
6985368
A voltage sense circuit and power supply regulation technique. In one aspect, a voltage sense circuit utilized in a power supply regulator includes a transformer including a sense winding and an output winding. A first diode is coupled to the sense winding, a first resistor is coupled to the first diode and a first capacitor coupled to the first resistor and the first diode. A second diode coupled to the first capacitor, the first resistor and the first diode. A second capacitor coupled…
Method and apparatus for substantially reducing electrical displacement current flow between input and output windings of an energy transfer element
Granted: January 3, 2006
Patent Number:
6982621
An energy transfer element with substantially reduced electrical displacement current flow between an input circuit coupled to the energy transfer element input winding and an output circuit coupled to the energy transfer element output winding. In one aspect, an energy transfer element includes an input winding, an output winding, an electrically conductive shield coupled to the input winding and a first cancellation winding coupled to the input winding. The electrically conductive…
Method and apparatus for balancing active capacitor leakage current
Granted: December 27, 2005
Patent Number:
6980451
A circuit that provides a method and apparatus to actively balance capacitor leakage current from series stacked capacitors and disconnects itself when stacked capacitors are configured for doubler operation. In one embodiment, the active circuit includes high voltage low current transistors, such as for example a PNP bipolar transistor and an NPN bipolar transistor, that are configured in a sink-source voltage follower arrangement with the bases of the transistors connected to a voltage…
Method and apparatus for substantially reducing electrical displacement current flow between input and output windings of an energy transfer element
Granted: December 20, 2005
Patent Number:
6977803
An energy transfer element with substantially reduced electrical displacement current flow between an input circuit coupled to the energy transfer element input winding and an output circuit coupled to the energy transfer element output winding. In one aspect, an energy transfer element includes an input winding, an output winding, an electrically conductive shield coupled to the input winding and a first cancellation winding coupled to the input winding. The electrically conductive…
Method and apparatus for maintaining an approximate constant current output characteristic in a switched mode power supply
Granted: November 22, 2005
Patent Number:
6967472
A regulator circuit maintaining an approximate constant current output characteristic. In one aspect, a disclosed regulator controls a switch that has a current limit threshold. A supply terminal and feedback terminal of the regulator are connected together as a control terminal such that a shunt regulator current is the control terminal current in excess of the internal supply current consumed by the regulator. The current limit threshold of the switch is changed as a function of the…
Method and apparatus providing final test and trimming for a power supply controller
Granted: October 11, 2005
Patent Number:
6954057
A power supply controller having final test and trim circuitry. In one embodiment, a power supply controller for switched mode power supply includes a selector circuit, a trim circuit, a shutdown circuit and a disable circuit. The trim circuit includes a programmable circuit connection that can be selected by the selector circuit by toggling a voltage on an external terminal such as for example a power supply terminal, a control terminal or a function terminal of the power supply…
