Engineer Power

ABCD

Your Hosts: Sandy Spinning Spider & Cordovir

Patrice Lethellier Home: 408-***-****

*******.**********@*******.*** Work: 510-***-****

E-mail is preferred and works much better to reach me.

Summary of topologies and power levels used:

Low power conversion starting from a few watts to 250 W for Lap-Tops, PCs and peripherals

using buck, boost, flyback and forward topologies.

Magnetics with ferrites, powder iron, MPP and Kool Mu .

Experienced with EMI problems.

Designed high power conversion products up to 15 KW for mainframe systems requiring

close to 100 % power factor.

PFC first stage with single or three phase inputs.

Topologies used on the second stage were half / full bridge

or single ended forward with active reset.

The Phase Shift Full Bridge scares a few people.

However it is very efficient with a fast step response.

For systems requiring 100% up time, N+1 was the solution.

But now we are facing :

The units have to be able to be paralleled.

With synchronous rectification, it is an issue.

Current Sharing is probably the easiest.

Low signal, offset and noise are the problem.

And now, there is " Hot Swap " .

No miracle recipe here. It is very application dependant.

I got recently interested in an adaptive non invasive drive

for universal synchronous rectification.

It has the adaptive simplicity and yet is extremely fast.

No leakage inductance current built up. No voltage overshoot.

A total over 15 patents with 2 currently in process.

Education:

Engineer Diploma, ISEN, Lilles France

Rated between and MSEE and PhD by the US Immigration Service.

Employment History:

Volterra, Fremont, CA

2010 to Now

Senior Staff Corporate Application Engineer.

New Multi Phase full Redundancy Systems for IBM Mainframes.

Exclara, Santa Clara, CA

2007 to 2010

Senior Application Engineer.

Development of integrated LED drivers.

Patent on a Split Secondary technique driving at regulated current

several channels from a single primary control.

EMI noise reduction & control.

Patent on wide range surge control.

Patent on a new more efficient topology

with reduced noise and cost.

Self driven synchronous rectification.

The first design in production has been the Split secondary series

with now 5 units in mass production in China.

Picture of the first installation by Everlight (Exclara customer)

powered by the Split Secondary design:

Qspeed semiconductor, Santa Clara, CA

2006 to 2007

Principal Staff Application Engineer

Responsibilities include:

Defining new products.

Providing guide lines to development.

Defining new characterization standards.

Designing new test equipment.

Helping marketing to promote products.

Technical help to sales.

National Semiconductor

2003 to 2005

Sr. Application Engineer

Responsible for defining new topologies and new chips.

Controller for Secondary Side Synchronous Post Regulated channel with current injection

to improve stability and step response.

Equal priority type, daisy chain link type, current sharing chip able to be configured

in four different modes.

Mirror interface for a feed back opto-coupler .

The cross over improved buy a factor of 10.

Re shaping a current sense to allow for jitter free operation.

Integrated level shifter for 0 to 100 % duty cycle operation.

Semtech, Newbury Park, CA

1999 to 2003

Sr. Applications Engineer

Application engineer with a team which has been accounted for $50 millions sales

in one year on a single part # : SC 1175.

Invented Combisense :

Combisense is a loss less way to perform the current sense.

It adds three info and deliver a signal which is high and noise free.

The Peak & Valley control is easy and user friendly.

It does not require any slope or frequency compensation.

EOS Corporation, Camarillo, CA

1998 to 1998

Sr. Development Engineer

Designed high volume switchmode power supply products.

C&D Power Technology, Tucson, AZ

1996 to 1998

Sr. Design Engineer

Design custom medium and high wattage power supplies.

Grimes Aerospace, Urbana, OH

1995 to 1996

Senior Project Engineer

Back up light system for Douglas and a strobe anti-collision power supply for Boeing

Aircraft.

Design of a 10 KW low cost converter for flash tubes providing higher peak power

during discharge, lower stress on the storage capacitors, extended life of cathode,

and dimmable light without spectrum shift.

Varo Power Systems, Garland, TX

1993 to 1995

Senior Engineer

Overall project responsibility of a high density, high frequency, multiple output

DCDC converters for a Navy program.

Developed a 1 KW power conditioner with back up and battery charger using silver-zinc

cells.

Designed a 1500 W (28V-55A) power factor corrected unit for

telecommunications systems.

Patented an active EMI filter including inrush function.

Tandy, Fort Worth, TX

1991 to 1992

Senior Engineer

Designed power supplies for Tandy's line of PCs.

Worked on DC to AC converters and small UPS systems.

Dealt with FCC, VDE, TUV, UL, CSA and Semco agency approvals.

Unisys, San Diego, CA

1990 to 1991

Principal Engineer

Updating power supplies designs that were transferred from Canada.

Elgar, San Diego, CA

1989 to 1990

Principal Engineer

Designed a 20 KW 300V back up system for a Navy station:

production units were approved.

Also performed various consulting tasks on DCDC converters

and AC power sources.

Pioneer Magnetics, Santa Monica, CA

1988 to 1989

Sr. Engineer

New product development: high density DCDC modules (1KW 500KHz) with active PFC (>99%).

One patent issued.

UNISYS, San Diego formerly Burroughs

1976 to 1987

Senior Engineer, San Diego (7/1986 to 12/1987)

Designed new mainframe power systems for Unisys: current sharing and true N+1 redundancy,

high frequency, 600A programmable output voltage.

Two patents issued.

Senior Engineer, Coral Springs, FL (8/1982 to 6/1986)

Switchmode power supplies for mainframes and terminals: used high frequency switchers

with high power density.

Improved the packaging for easier EMI and safety agency approvals. Three patents

issued.

Design Engineer, Villers Ecalles, FR

1976 to 1982

Design of analog circuits for printer and cassette drives and low power

switchmode power supplies for computer terminals.

Patents List

1 7,319,232 Apparatus and method for high-bandwidth opto-coupler interface

2 6,703,812 Power converter having improved step down response for low duty cycle

operation

3 6,664,774 Offset peak current mode control circuit for multiple-phase power converter

4 6,625,045 Multiphase modular power module employing star link topography

5 6,472,852 Resonant buck-type voltage converter using swinging inductance

6 6,441,597 Method and apparatus for sensing output inductor current in a DC-to-DC

power converter

7 6,424,129 Method and apparatus for accurately sensing output current in a DC-to-DC

voltage converter

8 6,144,565 Variation on a single-ended primary inductor converter

9 6,094,038 Buck converter with inductive turn ratio optimization

10 4,975,821 High frequency switched mode resonant commutation power supply

11 4,760,276 Power supply system, for segmented loads, having phantom redundancy

12 4,729,086 Power supply system which shares current from a single redundant supply

with multiple segmented loads

13 4,654,538 Dual input voltage power supply

14 4,602,323 Single-ended transformer drive circuit

15 4,595,974 Base drive circuit for a switching power transistor

Testimonials:

Hi All,

The presentations went very well in my opinion as I read the IBM team. I had an

opportunity to talk alone with the IBM team after the meeting. Mike Miller and

Pat Egan are genuinely impressed with the concepts behind the Master Redundancy controller.

Choosing to present the alternative was a very good decision. Excellent job Patrice!

The highlight of all the presentations was the Master Redundancy Controller concept

in watching the reaction from the IBM team. To hear from Kevin Covi, Pat Egan.

and Mike Miller. say the word Clever! was about as much of a compliment as you

can get from these guys! Mike Miller asked me the following after the meeting, Timmy .

Did you have anything to do with that? (master redundancy controller) I said,

No it is this French guy Patrice he is brilliant!

Nice work all around!

Regards,

Tim Daun-Lindberg

Senior Staff Corporate Applications Engineer 3265 19th ST NW Suite 380 Rochester,

MN 55901 507-***-**** (cell)

********@********.*** http://www.volterra.com

Hi Patrice,

I do appreciate that you are a very talented scientist, and I thank you for your

past contribution while working for Exclara.

I wish you the best in your new job, I am sure you are doing well.

Best Regards,

Harry

Interesting subjects:

An analog control which is always stable without the need for slope or frequency

compensation.

It is constant frequency and can be used in multi phase with ripple

cancellation.

An isolated DC - DC converter above 95% efficiency with loss-less

resonant commutations.

All the regulating elements are on the secondary providing

direct sense & drive.

N+1 redundancy with Hot Swap. Equal priority current sharing

and auto phasing.

After the loss of one channel, the others reconfigure themselves

automatically around the clock.

PFC input - Isolated step down - Multi independent

controlled channel with a single magnetic.

It is the conventional 3 stages ( PFC

- DC / DC - Regulators ) combined in one.

Power Point presentation available on request.

Ideal diode drive with no turn Off

delay. A Mosfet driven to act as a diode with no drive delay.

Perfect to add Synchronous

Rectification on a supply without the need of a drive signal.

The output ripple

steam roller which irons the ripple at (almost) no efficiency cost.

Nothing is better

and faster than an (almost) loss-less linear.

Multi phase output impedance current sharing with no or shallow load line droop using

an error rejecting multiphase analog/digital signal mixer for N+x redundancy.

Cancellation of current cumulative miss-sharing between channels due to a repetitive

step load at a frequency close to the operating frequency in a multi-phase unit.

New topology:

The Micro Processor voltages are going lower and lower. There is a recent request

at .5 V or less.

With an input voltage of 12V, the operating duty cycle is lower than 5%.

For Laptop applications, the input voltage can even be higher.

Like with the Buck, the step down is achieved with no transformer and use of turn

ratio.

This topology solves the low duty cycle problem and allows to step 12V down to .5V

with an x2 and 20V down to .5V with an x3. Both are single stage designs with built

in ripple cancellation.

Duty cycle and current multiplier (x2) for high performance multiphase core converter.

Allows to regulate cores voltages below 500mV (from 12V) without hitting minimum

duty cycle.

Expendable to x3 and over enabling one stage converters for laptops.

The application field for this new topology ranges from small Laptops to huge Mainframes.

Power Management Engineer Web-Site / Resume:

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