John M Fogg115 Haven Dr, Chapel Hill, NC 27516

6836095, Dec 28, 2004

Apr 28, 2003

10/424266

John Kenneth Fogg - Cary NC

Semtech Corporation - Morrisville NC

H01M 1044

320128

A battery charging circuit senses charging current using a sense circuit that includes a time-averaging amplifier circuit that nulls amplifier offset errors from the sensed current signal. With such offset correction, the sense circuit provides accurate current sensing over a wide dynamic range of charging current and thus may be used for low and high charging currents, and accurate detection of trickle and end-of-charge currents. The substantial elimination of amplifier-offset errors from charging current sensing permits use of a single sense resistor over a wide range of charging currents. Such accurate current detection supports zero-current regulation of the battery, which allows the battery to remain connected to the charging circuit even after reaching its end-of-charge condition. The battery charging circuit further may include digital switchover circuitry, which reduces charging control discontinuities by allowing both current and voltage feedback loops to drive the same regulation control circuit.

7471072, Dec 30, 2008

Oct 16, 2006

11/549744

John Kenneth Fogg - Cary NC, US
Yin-Chih Yang - Taipei, TW

Semtech Corporation - Morrisville NC

G05F 1/575
G05F 1/618

323284, 323285

In a switched mode power supply (SMPS) then selectively operates in continuous current mode (CCM) and discontinuous current mode (DCM), the minimum switching frequency of the SMPS is adjusted by setting a minimum duration for DCM operation. A resistance value applied to an external pin of the SMPS controls the duration of a timer that is reset in CCM and activated upon entering DCM. Upon expiration of the variable duration, the SMPS reverts to CCM for at least one switching cycle. This allows the SMPS minimum effective switching frequency to be set, for each application in which the SMPS is deployed, at a level that avoids audible noise (but which may be lower than an ultrasonic frequency), thus taking maximum advantage of the efficiencies of DCM operation under light load conditions.

7714547, May 11, 2010

Aug 8, 2008

12/188613

John Kenneth Fogg - Cary NC, US
Pankaj Kashikar - Raleigh NC, US

SEMTECH Corporation - Morrisville NC

G05F 1/70

323224, 323283

The teachings presented herein provide a method and apparatus for operating constant on-time DC/DC converters, including pseudo constant on-time variants, with a virtual current-mode slope signal. Use of the slope signal provides, among other advantages and improvements, greater noise immunity and the ability to operate with a wider range of converter output filters. More particularly, incorporating a properly synchronized slope signal into the on-time triggering comparison provides for a maximum slope offset at on-time triggering. Doing so prevent double-pulsing (i. e. , erroneous on-time retriggering) and other undesirable behavior of conventional constant on-time DC/DC converters and, as a particular but non-limiting advantage, allows ready and advantageous use of the slope-compensated converter as taught herein with low ESR capacitors in the output filter.

2006014, Jul 6, 2006

Jan 3, 2005

11/028120

John Fogg - Cary NC, US
Robert Walker - Chapel Hill NC, US
Warren Schroeder - Fuquay Varina NC, US

G05F 1/40
G05F 1/618

323282000

A voltage regulating circuit, such as a voltage regulator or battery charger, limits inrush current by buffering an associated supply input decoupling capacitor through a current path that is selectively configured to have a high impedance for startup charging of the decoupling capacitor at a low current, and a low impedance for normal operations of the circuit. Where the circuit uses multiple supply input connections for operation from two or more supply voltages, it may include buffering for each one of two or more supply input connections. It may further include a crossover switching control circuit that ensures make-before-break switching between supply input connections to avoid supply interruptions to the circuit during switchover.

2009006, Mar 12, 2009

Nov 19, 2008

12/274165

John Kenneth Fogg - Cary NC, US
Yin-Chih Yang - Taipei, TW

Semtech Corporation - Morrisville NC

G05F 1/00

323284

In a switched mode power supply (SMPS) that regulates an output voltage in response to load conditions by switching an inductor circuit between a supply voltage and ground at a switching frequency, under light loading conditions, the switching frequency of the SMPS is reduced down to a variable minimum switching frequency sufficiently high to avoid audible noise generation.

5610503, Mar 11, 1997

May 10, 1995

8/438636

John K. Fogg - Durham NC
Wayne Utter - Endicott NY
George Dohanich - Endicott NY

Celestica, Inc. - Ontario

G05F 140

323283

A dc-to-dc converter circuit for generating an output voltage from a source voltage includes a plurality of first metal oxide semiconductor field effect transistors (MOSFETs) connected in parallel and collectively defining a gate, a source and a drain. A driver circuit preferably includes a bipolar transistor connected to the gate for turning on the first MOSFETs. A second MOSFET is preferably connected to the gate for turning off the plurality of first MOSFETs. The dc-to-dc converter also preferably includes a clamp circuit connected to the plurality of first MOSFETs across the drain and source thereof. Protection, soft-start and status features are also preferably incorporated into the dc-to-dc converter. A voltage divider is connected to a reference voltage for dividing a first reference voltage to thereby generate a second reference voltage less than a desired output voltage. An error amplifier is connected to the voltage divider for generating an error signal based upon a difference between the second reference voltage and an actual output voltage.

5805020, Sep 8, 1998

Jun 27, 1996

8/671453

George Edward Danz - Cary NC
Larry A. King - Durham NC
John K. Fogg - Durham NC

Harris Corporation - Melbourne FL

H03F 338

330 10

Start up noise in a class D amplifier--is corrected by adding an analog switch S1 to the integrator circuit A1. A resistor R3 in the feedback path of A1 prevents A1 from saturating. In an alternate embodiment silent start switch connects a variable resistance to the comparator input. The resistance gradually increases.

5870266, Feb 9, 1999

Jun 6, 1996

8/656987

John K. Fogg - Durham NC

Harris Corporation - Melbourne FL

H02H 324

361 92

A method and control circuit for an electronic switch, and more particularly the high side switch in a bridge circuit. Control is established by continuous and/or the combination of continuous and pulsed signals. Fail safe undervoltage protection is provided for the high side switch based on the adequacy of both high side and low side control voltages.