Joseph C Buxton

US Patent:

6473280, Oct 29, 2002

Filed:

Oct 12, 2000

Appl. No.:

09/688412

Inventors:

Joseph C. Buxton - Palo Alto CA

Assignee:

Analog Devices, Inc. - Norwood MA

International Classification:

H02H 700

US Classification:

361 18, 361 78, 307140, 323282

Abstract:

A failure detection scheme for switching voltage regulators senses a parameter which normally transitions above and below a predetermined threshold during each clock cycle. A decision circuit tracks the sensed parameter, and toggles an output when the sensed parameter transitions normally. A counter counts clock cycles, and toggles its output when a predetermined number is reached. The counter also has a reset input which receives the output of the decision circuit, and is reset to an initial value when the decision circuit output toggles. If the sensed parameter fails to transition normally, the reset input is not toggled and the count value increments with each clock cycle. If the failure persists for the predetermined number of clock cycles, the counter output toggles to indicate a failure, enabling the failed regulator to be repaired or replaced before additional failures occur.

US Patent:

6680837, Jan 20, 2004

Filed:

Jun 14, 2001

Appl. No.:

09/882998

Inventors:

Joseph C. Buxton - Palo Alto CA

Assignee:

Analog Devices, Inc. - Norwood MA

International Classification:

H02H 908

US Classification:

361 939, 361 931, 327309

Abstract:

A hiccup-mode short circuit protection circuit and method for a linear voltage regulator using a FET pass transistor uses the capacitance of the pass transistors gate as a timing element. The regulators output voltage is monitored, and when it droops below a voltage indicative of a short-circuit condition, the regulators drive signal is disconnected from the pass transistor. While the short-circuit condition persists, a first current is provided to charge the pass transistors gate capacitance. When the gate voltage rises above a first predetermined threshold, a second current is provided to further charge the gate capacitance. When the gate voltage rises above a second predetermined threshold, the gate capacitance is discharged. The gate capacitance is cyclically charged and discharged in this way unless the output voltage rises to indicate that the short-circuit condition has cleared, in which case the regulators drive signal is restored to the pass transistors gate. To reduce average power consumption, the magnitudes of the first and second currents and the values of the threshold voltages are chosen such that the pass transistors ON duty cycle is about 10%.

US Patent:

6683441, Jan 27, 2004

Filed:

Oct 30, 2002

Appl. No.:

10/284222

Inventors:

Tod F. Schiff - Portland OR
Joseph C. Buxton - Palo Alto CA
Richard Redl - Farvagny-le-Petit, CH

Assignee:

Analog Devices, Inc. - Norwood MA

International Classification:

G05F 1652

US Classification:

323222, 323224, 323285

Abstract:

An N-phase switching voltage regulator includes N current sensing elements which carry respective phase currents. The voltages present at the switch node sides of the sensing elements are summed and presented to an amplifier which also receives the regulators output voltage, to produce an output which is proportional to the regulators total output current I. The invention also provides a means for direct insertion of total inductor output current information into a regulators voltage-mode control loop, to provide active voltage positioning (AVP) for the output voltage. A voltage based on total inductor output current is summed with the regulators reference voltage; this sum and V are applied to the voltage control error amplifier, the output of which is processed to operate the regulators switches. This enables the regulators output to have a desired droop impedance and to provide AVP of V as a function of total filtered inductor output current I.

US Patent:

6984969, Jan 10, 2006

Filed:

Mar 19, 2004

Appl. No.:

10/805459

Inventors:

Gang Liu - Sunnyvale CA, US
Joseph C. Buxton - Palo Alto CA, US

Assignee:

Analog Devices, Inc. - Norwood MA

International Classification:

G05F 1/40

US Classification:

323286, 323280, 323284, 323303

Abstract:

A voltage regulator includes a linear mode regulator having a high pass filter circuit connected between its output and an output node, and a switch mode regulator having an low pass filter circuit connected between its output and the same output node. The high pass filter passes high frequency AC current provided by the linear mode regulator to the output node and reduces the low frequency AC and DC currents to substantially zero, and the low pass filter prevents the high frequency AC current produced by the linear mode regulator from being drawn by the switch mode regulator and passes the low AC and DC currents provided by the switch mode regulator to the output node. Thus, the present regulator offers the high response speed and low noise of a linear mode regulator, and the high power efficiency and large continuous output current capability of a switch mode regulator.

US Patent:

RE39976, Jan 1, 2008

Filed:

Jan 26, 2006

Appl. No.:

11/342235

Inventors:

Tod F. Schiff - Portland OR, US
Joseph C. Buxton - Palo Alto CA, US
Richard Redl - Farvagny-le Petit, CH

Assignee:

Analog Devices, Inc. - Norwood MA

International Classification:

G05F 1/652

US Classification:

323285, 323222, 323224

Abstract:

An N-phase switching voltage regulator includes N current sensing elements which carry respective phase currents. The voltages present at the switch node sides of the sensing elements are summed and presented to an amplifier which also receives the regulator's output voltage, to produce an output which is proportional to the regulator's total output current I. The invention also provides a means for direct insertion of total inductor output current information into a regulator's voltage-mode control loop, to provide active voltage positioning (AVP) for the output voltage. A voltage based on total inductor output current is summed with the regulator's reference voltage; this sum and Vare applied to the voltage control error amplifier, the output of which is processed to operate the regulator's switches. This enables the regulator's output to have a desired droop impedance and to provide AVP of Vas a function of total filtered inductor output current I.

US Patent:

20120049772, Mar 1, 2012

Filed:

Aug 1, 2011

Appl. No.:

13/195423

Inventors:

Zaki Moussaoui - San Carlos CA, US
Jifeng Qin - San Jose CA, US
Joseph Buxton - Palo Alto CA, US

Assignee:

INTERSIL AMERICAS INC. - Milpitas CA

International Classification:

H02P 3/14
G05F 1/10

US Classification:

318376, 323271

Abstract:

A system and method for regulating power flow and limiting inductor current in a bidirectional direct current (DC)-to-DC converter is provided. In one aspect, a feedback circuit is provided to control power flow and/or limit inductor current based on the input/output voltage and/or current conditions in the bidirectional DC-DC converter. During a boost mode of operation, the duty cycle of a low-side switch within the bidirectional DC-DC converter is reduced, based on an analysis of the high-side voltage and positive inductor current. Further, during a buck mode of operation, the duty cycle of the low-side switch is increased, based on an analysis of the low-side voltage and negative inductor current. Moreover, the duty cycle of the low-side switch is adjusted, such that, the high-side voltage, low-side voltage and inductor current (in both directions) do not exceed preset threshold and the bidirectional DC-DC converter returns to a steady state.

US Patent:

20120049820, Mar 1, 2012

Filed:

Apr 26, 2011

Appl. No.:

13/094007

Inventors:

Zaki Moussaoui - San Carlos CA, US
Jifeng Qin - San Jose CA, US
Joseph Buxton - Palo Alto CA, US

Assignee:

INTERSIL AMERICAS INC. - Milpitas CA

International Classification:

G05F 1/618

US Classification:

323282

Abstract:

A system and method for reducing negative inductor current during soft start of a bidirectional direct current (DC)-to-DC converter is provided. Typically, the bidirectional DC-to-DC converter includes an active switch and a passive switch. The system employs a soft start circuit that controls the duty cycle of the passive switch during soft start of the active switch. In one aspect, the soft start circuit gradually increases the duty cycle of the passive switch from zero to a steady state value, and provides a soft start for the passive switch concurrently/simultaneously during the soft start of the active switch. Moreover, the soft start circuit disclosed herein can avoid the reverse transient inductor current during start-up, prevent system damage and make the design of the bidirectional DC-to-DC converter more robust.

US Patent:

57740216, Jun 30, 1998

Filed:

Oct 3, 1996

Appl. No.:

8/725557

Inventors:

Thomas S. Szepesi - Saratoga CA
Joseph C. Buxton - Palo Alto CA
Zoltan Zansky - San Carlos CA
Derek F. Bowers - Sunnyvale CA

Assignee:

Analog Devices, Inc. - Norwood MA

International Classification:

H03F 345
H02J 700
G05F 326

US Classification:

330257

Abstract:

Operational transconductance amplifiers (OTAs) are combined at their outputs, yielding a single frequency compensation connection point. In a preferred embodiment, the output of each OTA is asymmetric, i. e. , they can only source current and the OTA outputs are tied together to a constant current sink. Consequently, the OTA that sources more current controls the voltage of the merged output. This merged output point provides a voltage output that may be used as a frequency compensation point.