Engineers on the Run

July 17, 2009

If you drove by the South Portland, Maine corporate site, on July 15, 2009, you may have been surprised to see a fleet of engineers running! Yes…that was us and one of Maine’s most recognized celebrities- Joan Benoit-Samuelson, the first Olympic Gold Medalist for the Women’s Marathon in 1984.

Joan led us for a memorable fun run to cap off the day! Prior to the run, Joan, who is also the founder of the Beach to Beacon 10k Road Race, thanked us for being the first Green Energy Sponsor of the race this year. Our sponsorship enables the race to expand its Green Program, which will include recycling, composting, using eco-friendly portable toilets, recycling shoes and paperless communications for the race.

On August 1, 2009, at the TD Banknorth Beach To Beacon 10k, you will see engineers on the run again! Over 50 of our employees are participants in the race, as well as many additional volunteers who will be manning our booth and helping facilitate the race.

Tags: Beach to Beacon, engineers, Fairchild Semiconductor, green energy sponsor, recycling

Cell Phone Connection Failed – AGAIN!?

July 17, 2009

Standing in the park, I have been checking emails, making phone calls and taking a few precious pictures of my darling dog. Wishing to send the pictures to a friend’s cell phone, I press the button and stare at the cell phone display. Suddenly, it says “connection failed.” What! I try again and realize that the cell phone battery is too low with barely one bar showing.

Does this sound familiar to you?

We all want to be connected via cell phone whenever and wherever we are. Unfortunately, our cell phone battery does not always keep up with our busy lifestyle.

Inside of every cell phone is a radio frequency (RF) transmitter. Every time you talk, text or send data, the transmitter drains power from the battery. Often the transmitter consumes only 10% of the phone’s total power. However, if you’re in a poor coverage location, surf the net or up-load photo/video, the transmitter’s battery consumption can top six times, sapping 60% of the battery’s charge. This transmitter can be a huge power drain and dramatically reduce your talk time on the cell phone.

Today’s feature-rich 3G phones require more power than ever before. The design challenge facing engineers today is how to improve efficiency in existing areas such as RFPA, display and increased talk time so more power is available for new features.

One solution is to install a step down DC-DC converter with dynamic voltage scaling to control V_OUT between the battery and the RF Power Amplifier (RFPA). This reduces current consumption by 30-50%, and makes power available for other functions (such as MP3, GPS and video). In addition to reducing current consumption, a step down DC-DC converter also reduces heat and increases talk time.

If you would like to check out Fairchild’s solution, please watch a short video demonstrating a solution to extend battery power for a 3G phone by improving the efficiency of the RFPA. More information on RF Power is available at www.fairchildsemi.com/rfpower.

Tags: battery life, cell phone, DC-DC converter, Fairchild, Fairchild Semiconductor, power, RF Power Amplifier, RF transmitter

Lifetime of an LED

July 2, 2009

Richard Chung

LED options are advertised as longer lifetime and more efficient lighting options to the traditional CFL, LFL, and HIDs. Is this really true? What are the factors that determine LED product life?

LED lifetime is measured in lumens depreciation. It is percentage of light output degradation from initial light output. LED Industry standard from IESNA (Illumination Engineering Society of North America) such as LM-80 specifies procedure for determining lumens depreciation. Researching the different LED vendors and their datasheets, the common theme is proper heat sink and thermal management of silicon junction temperature extends the lifetime of the LEDs. Look for lifetime versus junction temperature graphs in LED vendor datasheets that accounts for lumens depreciation. For example, L70 notation means that light output is 30% less than initial output. It is the percentage decrease that a “typical” eye starts to detect a decrease in light output. Different end applications can determine suitable lumens depreciation levels.

Thermal management of LEDs is half the effort to ensure the advertised lifetime. The LED power supply or driver design is the other factor for lifetime. When the LED does not work, the end user does not care if it is caused by LED’s lumens depreciation or the LED power supply that failed.

Because LEDs are non-linear (varying forward voltage versus forward current) devices, a constant current LED driver or power supply is required. Because non-linear LEDs produce power factor less than 1, PFC (Power Factor Correction) LED drivers are needed when it exceed a certain power level and/or harmonic current limits. Requirement to light high brightness LEDs is a power supply. There are components in a power supply that can decrease the life. More details next time!

Work cited:

www.ssl.energy.gov

Tags: efficient lighting, Fairchiild Semiconductor, HID, LED, LFL, lighting