HAI NGUYEN
Cosmetology at Dekadine Ct, Spring, TX

7105950, Sep 12, 2006

Sep 26, 2003

10/672522

Mohamed A. Bemat - Cypress TX, US
Hai N. Nguyen - Spring TX, US

Hewlett-Packard Development Company, L.P. - Houston TX

H02J 1/10

307 52

A system may include a plurality of loads, a plurality of power supplies adapted to provide power to the loads, and control logic coupled to the power supplies. The control logic may determine whether output current from at least one of the power supplies to a load is below a lower threshold and, if so, may cause at least one of the power supplies to be disabled.

5402055, Mar 28, 1995

Sep 30, 1992

7/954334

Hai N. Nguyen - Spring TX

Compaq Computer Corporation - Houston TX

H02J 704

320 23

A differential input comparator for controlling the output voltage of an AC adapter to track the voltage of a rechargeable battery during trickle charge. An output voltage sensing circuit typically used to regulate the AC adapter output voltage at a maximum level is modified to regulate the output voltage at a minimum DC voltage approximately equivalent to a fully discharged battery plus a nominal voltage level. The differential input comparator is coupled to a current limiter coupled in the charge path of the battery and to the sense signal to provide a separate current path used to modify the voltage level of the sense signal. The differential input comparator regulates the voltage across the current limiter to the nominal voltage level by controlling the AC adapter output voltage through the sense signal during trickle charge of the battery.

5455757, Oct 3, 1995

Jan 28, 1994

8/188484

Hai N. Nguyen - Spring TX
James S. Dinh - Spring TX

Compaq Computer Corp. - Houston TX

H02M 3335

363 21

A power converter including a complementary regeneration circuit for eliminating oscillations and conserving leakage energy to increase the efficiency of a flyback power converter. The complementary regeneration circuit includes a regeneration capacitor, a regeneration switch, a diode and appropriate timing circuitry to switch the regeneration capacitor in and out of the circuit at the appropriate times. Due to the operation of the regeneration switch, the capacitance of the regeneration capacitor is much larger than a typical snubber/clamp capacitor, so that it overdamps the circuit eliminating voltage overshoot typically appearing across the primary switch. The regeneration capacitor charges with regeneration energy and drives negative current into the primary inductor, holding the voltage across the primary switch constant when the secondary current goes to zero. When the regeneration switch is turned off, the negative current in the primary inductor drains the capacitance in the primary switch, which activates the inherent diode of the primary switch causing low voltage across the primary switch when it is turned on. A simple resistor or transistor circuit may be added between the input voltage and the PWM timing circuit to change the frequency of operation to compensate the regeneration energy for changes in the input voltage.

2006013, Jun 22, 2006

Dec 16, 2004

11/012242

Atluri Prasad - Houston TX, US
Hai Nguyen - Spring TX, US

G05F 1/656, G05F 1/10

323222000

A control circuit and method for controlling a power factor correction circuit comprising: an inductor having an input terminal to receive an input voltage and an output terminal series connected to an anode of a diode; a first capacitor connected between a cathode of said diode and ground; a first switch connected between an anode of said diode and ground; a series arrangement of a second capacitor and a parallel arrangement of a resistor and a second switch series connected with said second capacitor. The control circuit is operable to generate synchronous first and second switch control signals to respectively control said first and second switches, wherein during inrush current conditions when said input voltage drops-in after an interruption, said control circuit is operable to cause said first and second switches to be synchronously switched at increasing duty cycles. The method comprises charging a first capacitor from an input voltage source; isolating the first capacitor from the input voltage source; transferring a portion of charge stored in said first capacitor to a second capacitor while said input voltage source is isolated from said first capacitor and from said second capacitor; and repeatedly said charging, isolating, and transferring until a voltage is formed on said second capacitor that is approximately equal to said input voltage source.

7531918, May 12, 2009

Mar 30, 2005

11/093934

Prasad R. Atluri - Houston TX, US
Hai N. Nguyen - Spring TX, US
Reynaldo P. Domingo - Spring TX, US

Hewlett-Packard Development Company, L.P. - Houston TX

H02J 7/00, H02J 9/00

307 65, 307127

Disclosed is a power supply module for use in an electronic system having redundant power supply modules connected to a power bus. The power supply module includes an output filter. The output filter is configured, upon insertion of the power supply module into the electronic system during operation of the electronic system, to limit reverse current flow into the power supply module from the power bus for a period of time until steady state voltage conditions exist on the power bus. The output filter is configured to then remove the current-limiting, leaving an output inductor-capacitor filter.

7514816, Apr 7, 2009

May 19, 2005

11/133122

Mohamed Amin Bemat - Cypress TX, US
Hai N. Nguyen - Spring TX, US

Hewlett-Packard Development Company, L.P. - Houston TX

H02J 7/00

307 64

A power supply comprises an alternating current-to-direct current converter (ADC) and an input signal adapted to couple to an output signal of another power supply. The output signal is indicative of the operational status of the other power supply. The power supply further comprises logic coupled to the ADC that receives the input signal and causes an output current threshold to be increased when the output signal from the other power supply indicates that the other power supply has experienced a failure.

7015682, Mar 21, 2006

Jan 30, 2003

10/354745

Jose A. Santin - Cypress TX, US
Atluri Rama Prasad - Houston TX, US
Hai N. Nguyen - Spring TX, US

Hewlett-Packard Development Company, L.P. - Houston TX

G05F 1/44

323285, 323222, 323283

The specification may disclose a switching power supply operated in a discontinuous current power factor corrected mode, having multiple boost circuits or boost modules, and controlled by a digital signal processor. The digital signal processor may implement a control scheme whereby the duty cycle of the switching signals applied to the boost modules may be controlled, in part, by the amount of power delivered to the load in the previous half cycle of the source voltage. In another aspect, an output voltage correction to the switching signals may be applied at the end of each half cycle, which may result in voltage correction at twice the source frequency.

7053593, May 30, 2006

Jun 14, 2004

10/867457

Mohamed Amin Bemat - Cypress TX, US
Reynaldo P. Domingo - Spring TX, US
Hai N Nguyen - Spring TX, US

Hewlett-Packard Development Company, L.P. - Houston TX

G05F 1/40

323272, 323288, 363 65

A DC-to-DC converter comprises a first power module, at least a second power module coupled to the first power module, and a protection circuit coupled to the first and second power modules. The protection circuit causes a system power good signal to be at a state indicative of a power problem when the protection circuit detects that a switching node of one of the power modules has ceased switching.

5469320, Nov 21, 1995

Oct 29, 1993

8/145484

Richard E. Walker - Spring TX
Hai N. Nguyen - Spring TX

Compaq Computer Corp. - Houston TX

H02H 300

361 33

An efficient fan drive circuit to drive a variable fan used in a power supply of a personal computer system. The fan drive circuit uses a diode to establish the minimum fan speed during operation in the normal temperature range. The bleeder resistor normally coupled between the fan and a negative output voltage is removed and replaced with a current source. The current source also serves to shut down the power supply if the fan is not operating properly or is not installed. A shut down circuit remains to shut down the power supply when excessive temperature occurs, or when the current source detects that the fan is malfunctioning or not installed.

7400067, Jul 15, 2008

Oct 31, 2005

11/264244

Prasad R. Atluri - Houston TX, US
Hai N. Nguyen - Spring TX, US
Reynaldo P. Domingo - Spring TX, US

Hewlett-Packard Development Company, L.P. - Houston TX

H02J 1/00

307 85

Methods and apparatuses are disclosed that may allow elimination of isolation devices for redundant power supplies while mitigating the undesirable effects of their elimination.