Clarita C Poon

US Patent:

8049481, Nov 1, 2011

Filed:

Oct 29, 2009

Appl. No.:

12/608854

Inventors:

Yong Li - Campbell CA, US
Carrie Seim - Campbell CA, US
Junjie Zheng - Santa Clara CA, US
John W. Kesterson - San Jose CA, US
Liang Yan - Milpitas CA, US
Clarita Poon - Pleasanton CA, US
Fuqiang Shi - Cupertino CA, US

Assignee:

iWatt Inc. - Los Gatos CA

International Classification:

G05F 1/575
H02M 3/335

US Classification:

323283, 323284, 363 2105, 363 2113

Abstract:

Adaptive multi-mode digital control schemes that improve the light-load efficiency (and thus the overall average efficiency) in switch-mode power converters without causing performance issues such as audible noises or excessive voltage ripples. Embodiments include a switch-mode power converter that reduces current in the power converter using a second pulse-width-modulation (PWM) mode before reaching switching frequencies that generate audible noises. As the load across the output of the power converter is reduced, the power converter transitions from a first PWM mode in high load conditions to a first pulse-frequency-modulation (PFM) mode, then to a second PWM mode, and finally to a second PFM mode. During the second PFM mode, the switching frequency is dropped to audible frequency levels. Current in the power converter, however, is reduced in the second PWM mode before transitioning to the second PFM mode.

US Patent:

8199537, Jun 12, 2012

Filed:

Feb 19, 2009

Appl. No.:

12/388709

Inventors:

Liang Yan - Milpitas CA, US
Xiaoyan Wang - Milpitas CA, US
Jun Zheng - Shenzhen, CN
Junjie Zheng - Santa Clara CA, US
Clarita Poon - Pleasanton CA, US

Assignee:

iWatt Inc. - Campbell CA

International Classification:

H02M 3/335

US Classification:

363 2112, 363 2115, 363 2117, 363 2118

Abstract:

A switching power converter detects low load conditions based on the ratio of a first peak current value for peak current switching in constant voltage regulation mode to a second peak current value for peak current switching in constant current regulation mode. The power supply load is considered to have a low load if the ratio is lower than a predetermined threshold. Once a low load condition is detected, the switching frequency of the switching power converter is reduced to a level that minimizes switching loss in the power converter. In addition, the switching power converter also adjusts the switching frequency according to the sensed input line voltage. An offset is added to the switching period to reduce the switching frequency of the switching power converter, as the input line voltage is increased.

US Patent:

8199539, Jun 12, 2012

Filed:

Aug 4, 2011

Appl. No.:

13/198358

Inventors:

Xiaoyan Wang - Milpitas CA, US
Liang Yan - Milpitas CA, US
Junjie Zheng - Santa Clara CA, US
John William Kesterson - San Jose CA, US
Clarita Poon - Pleasanton CA, US

Assignee:

iWatt Inc. - Campbell CA

International Classification:

H02M 3/335
H02M 3/157

US Classification:

363 2118, 323284, 363 2113

Abstract:

In a switching power converter, PWM mode and PFM mode are separated into two independent control sections with the control voltage range in each control section determined independently. Each of the PWM and PFM modulation modes cannot operate continuously beyond its boundaries, thereby forming a control gap between the two control sections within which no continuous operation is allowed. In order to supply a load condition within the control gap, the power supply operates at the two boundaries of the control gap. Transition between PWM and PFM modes occurs fast, with low output voltage ripple. No limitation needs to be imposed on the control voltage range in each of the PWM and PFM control sections, because the control parameters in the PWM and PFM control sections need not be matched to one another, due to separation of the PWM and PFM modes by the control gap.

US Patent:

20100225293, Sep 9, 2010

Filed:

Mar 5, 2009

Appl. No.:

12/398878

Inventors:

Xiaoyan Wang - Milpitas CA, US
Liang Yan - Milpitas CA, US
Junjie Zheng - Santa Clara CA, US
John William Kesterson - San Jose CA, US
Clarita Poon - Pleasanton CA, US

Assignee:

IWATT INC. - Los Gatos CA

International Classification:

G05F 1/10

US Classification:

323290

Abstract:

In a switching power converter, PWM mode and PFM mode are separated into two independent control sections with the control voltage range in each control section determined independently. Each of the PWM and PFM modulation modes cannot operate continuously beyond its boundaries, thereby forming a control gap between the two control sections within which no continuous operation is allowed. In order to supply a load condition within the control gap, the power supply operates at the two boundaries of the control gap. Transition between PWM and PFM modes occurs fast, with low output voltage ripple. No limitation needs to be imposed on the control voltage range in each of the PWM and PFM control sections, because the control parameters in the PWM and PFM control sections need not be matched to one another, due to separation of the PWM and PFM modes by the control gap.

US Patent:

20130241441, Sep 19, 2013

Filed:

Mar 5, 2013

Appl. No.:

13/786268

Inventors:

Clarita C. Poon - Pleasanton CA, US
Liang Yan - Milpitas CA, US

Assignee:

IWATT INC. - Campbell CA

International Classification:

H05B 33/08

US Classification:

315307

Abstract:

A dimmable light emitting lamp configured to interface with cat-ear dimmer switches. The lamp includes one or more light emitting devices. The lamp also includes circuitry configured to receive an input voltage and provide regulated current to the one or more light emitting devices. The input voltage has a first voltage pulse that does not represent a dimming level of a dimmer switch and a second voltage pulse that represents the dimming level of the dimmer switch. The circuitry determines a first duration corresponding to a length of the first voltage pulse and a second duration corresponding to a length of the second voltage pulse responsive to first duration. The circuitry adjusts the regulated current to the light emitting devices according to the second duration to adjust output light intensity of the light emitting devices.

US Patent:

20130242625, Sep 19, 2013

Filed:

Mar 13, 2012

Appl. No.:

13/419329

Inventors:

Liang Yan - Milpitas CA, US
Clarita C. Poon - Pleasanton CA, US
Hien Huu Bui - San Jose CA, US
Chuanyang Wang - Cupertino CA, US
Andrew Kwok-Cheung Lee - Union City CA, US
John William Kesterson - Seaside CA, US

Assignee:

IWATT INC. - Campbell CA

International Classification:

H02M 1/36

US Classification:

363 49

Abstract:

A power converter that controls a collector current of a bipolar junction transistor (BJT) by controlling the base current to the BJT after having determined the gain of the BJT. A gain detection block determines a gain of the BJT during a first mode. A current calculation block generates a current setting for the base current based on the gain of the BJT determined by the gain detection block during a second mode distinct from the first mode. In some embodiments, the power converter may be included in a LED lamp system.

US Patent:

20130249437, Sep 26, 2013

Filed:

Feb 8, 2013

Appl. No.:

13/763256

Inventors:

John William Kesterson - Seaside CA, US
Clarita Poon - Pleasanton CA, US
Liang Yan - Milpitas CA, US

Assignee:

iWatt Inc. - Campbell CA

International Classification:

H05B 33/08

US Classification:

315307

Abstract:

A dimming controller for an LED lamp controls dimming using an adaptive filter to reduce or eliminate perceivable flickering and to provide smooth transitions during active dimming. During stable conditions, the adaptive filter operates with a relatively narrow bandwidth to filter noise that may lead to perceivable flickering. During active or startup conditions, the adaptive mapping filter operates with a high bandwidth to provide a quick response to the dimmer switch.

US Patent:

20130257280, Oct 3, 2013

Filed:

Feb 22, 2013

Appl. No.:

13/774513

Inventors:

Clarita C. Poon - Pleasanton CA, US
Liang Yan - Milpitas CA, US

Assignee:

IWATT INC. - Campbell CA

International Classification:

H05B 37/03

US Classification:

315122

Abstract:

A LED lamp that includes a LED lamp controller with delayed startup after a fault condition is detected. The type of the fault condition is used in determining a length of the startup delay, such as a number of power cycles during which the LED lamp controller is prevented from completing its configuration. Examples of different types of fault conditions include faults in a supply voltage or faults in a feedback voltage to the LED lamp controller. Fault type information can also be stored in circuitry that retains data and is not reset across the power cycles.