AnalogTalk

The Local Interconnect Network (LIN) is being implemented in vehicles around the world to help embedded system designers meet challenges including lower system cost, lower power consumption, weight reduction, and faster time to market for innovative electronic solutions. LIN is a low-cost, serial communication system for distributed electronic systems, such as window controls, seat movement, mirror positioning, LED lighting, and other body-oriented applications.

~20 LIN nodes already populate cars today and that # is growing

Some of the advantages of LIN are:

• Ease of use for the new and experienced designers
• Many components are drop in compatible
• Cheaper than other alternative network communication buses
• Harness reduction
• Provides for a more reliable vehicle
• No protocol license fee required
• Can be used in non-automotive environment similar to CAN

Some frequently asked LIN questions:

Does LIN replace CAN?
Answer:
No, LIN and CAN co exist in the automotive market.

LIN addresses an application space that requires less bandwidth and versatility when compared to the CAN application space.

What are the target applications for LIN Bus?
Answer:
Target automotive applications include mirrors, window lift, doors switches, door lock, HVAC motors, control panel, engine sensors, engine cooling fan, seat positioning motors, seat switches, wiper control, light switches, interface switches to radio/navigation/phone, rain sensor, light control, sun roof, RF receivers, body computer/smart junction box, interior lighting and more.

Can LIN be used for non-automotive applications?
Answer:
Although designed for automotive applications, LIN is not limited to automotive applications and has found it’s way already into applications such as appliance and consumer.

Microchip is a provider of some of the best in class Transceivers that have been accepted by the major OEMs.  Meeting automotive requirements allows our products to more easily proliferate across other non-automotive applications since the parts already meet stringent requirements.

Related Links

LIN Product Pages

LIN Design Center

Remember the good old days when one had to manually turn a hand-crank on the inside of the car door to make the window go up or down?  Or how about when a ‘portable’ drill was only as portable as the length of its power cord?  For those of you who don’t remember these two applications, I’m feeling a bit nostalgic.  I still use an old-fashioned ‘portable’ drill like this on occasion.  So what has been happening that makes these two old-school manual processes (and many others too) a thing of the past?

Advancements in DC motor technology, manufacturing capabilities and sophisticated, low-cost digital and analog electronics have enabled small DC motors to be used as a cost-effective way to automate operations that used to be done manually in a variety of applications including medical devices, toys, industrial automation, power tools and automobiles.  Nowhere is this trend more obvious then in the automobile.  Many of the operations that used to be done manually are now automated using motors.  Seat adjustment, window open/close, mirror adjustment, and cabin temperature control are just a few examples of where small DC motors automate processes that used to be done manually.  Market data suggests that there are more than 30 small DC motors per vehicle today with a forecast of close to 40 per vehicle in five years.  At a worldwide manufacturing rate of between 50M and 60M automobiles per year, it is easy to see why the automotive market helps to drive this automation trend.

So what the does future hold?  The trend to automate simple manual processes by the use of small DC motors will continue as the costs of the motors and drive electronics continue to go lower.  I look forward to the day when there is a cost-effective automated solution that allows me to not have to get up from what I am doing to the age-old question, “Honey, can you take out the trash?”

Ceramic capacitors offer low cost, small size, and can offer improved reliability over tantalum and aluminum capacitors. The ultra-low ESR attribute of ceramic capacitors, however, does effect choice of LDO when used at the output as most older LDOs require the ESR of a capacitor on its output for loop stability.  Although almost all newer designs include loop compensation so that they can be used with ceramic capacitors,  there’s still hope for ones favorite older workhorse LDO (or dirt cheap).  Simply add a small resistance in series with desired ceramic capacitor.

The region of stability is shown in the graph above (in this case for a TC1017).  Any decent datasheet will provide this graph.  Selecting the lowest value for the ESR, while keeping in mind resistor tolerance, is best to minimize load transients.

Figure 1 Region of Stability of ESR vs Load Current

Related Links

LDOs

In the past decade, “green” energy and energy efficiency have become one of the most talked about technology trends. To some, it is a concern about impact on the environment, to others it is a way to cut energy costs. One of the darlings of energy saving technologies have been LEDs and for good reasons. They run cooler than incandescent lights, rival or even beat fluorescent lights in efficiency and can be designed into many space-constrained applications with ease. As a result, LEDs can be found in anything from a blinking light on a remote control, to a flash on camera phone, a light source in a flashlight or headlights on a supercar.

With the prices on LEDs continuously going down, manufacturers push them into more and more application at prices competitive with technologies they are replacing. Sometimes this push for “everything LED” goes a bit far and results in products that are not very useful or even inferior to the “old” technologies they are replacing.

Exhibit A: 100(!) LED flashlight versus 1 LED flashlight. Now we all like to have more of stuff: more salary, more helpings at dinner, and more vacation days. So more LEDs should clearly be better than less LEDs, let alone just one, right? Well, it certainly depends on whether you like to shine the light beyond 10 feet or carry it in a pocket. With 100 small LEDs in a flashlight with no optics, what you get is a flood light that lets you see your feet very well and not much beyond that. If your aim at night is to see the rabid dog before its chewing on your leg, a single LED light with good optics will be a considerably better choice as it will easily have a throw of 100 feet or more. The only saving grace for 100 LED flashlight is that it serves as a good weapon to fight off that rabid dog.

Exhibit B: Cheap LED car light bulb versus halogen light bulb. Pictured are 9005 lights bulbs, an LED based one and a regular halogen bulb. Both fit the same socket and are intended for use as Day Light Running (DLR) lamps or fog lights. This is where their similarities end. A regular halogen light bulb can be approximated with a point light source and the reflectors of car headlights are optimized for it. With the LED bulb, there are numerous directional light sources that are not optimized for the existing reflector design and lead to scattered light and glare for oncoming traffic. Beyond that, even 19 surface mounted LEDs with little to no heat sinking cannot compete in light output with a halogen light bulb. The end result of replacing a halogen light with cheap LED light is less light where a good chunk of it is wasted on useless glare.

So, lesson for the day? If you want your LED fix with the most light output, get the Audi R8 with LED headlight option, it’s only $10,000! On top of the actual price of the car.

Related Links

MCP1650 Multiple White LED Demo Board