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This page is updated March 10th 2017. It is only available in English.

  Max-i Association
c/o Innovatic
Bøgebakken 3, Gjessø
DK-8600 Silkeborg
Phone:  (+45) 86 84 72 92



Welcome to the official home page for the Max-i fieldbus
and Max-i Association.

Specification v9.1 has been released!

  • Voltage regulated line interface to allow up to 3 times more voltage drop on cables.



Max-i is a new, very cheap, but extremely powerful fieldbus, which enables the lowest, total, automation and LED-lighting costs ever seen combined with maximum performance! It may be regarded as a combination between a highly improved CAN bus and a 20-V power supply and may be used for virtually all low to medium speed applications (up to 15,000 telegrams per second) like:

  • Industrial, building and home automation including motion control and safety applications.
  • Transportation applications such as automotive, special vehicles, railway, ships and aerospace.
  • Traffic lights and supervision on bridges and tunnels.
  • Intelligent LED lighting including demanding stage light and architectural lighting.
  • Supplementary 20-V supply with control possibilities in the houses of the future.
  • Internet of Things - IoT.
  • Military applications.

Max-i has four basic properties:

  • It is possible to make a complete bus interface in one integrated circuit (IC), which is small (16 pin) and cheap enough to be built into even the smallest and most price sensitive actuator, sensor or lamp, gets its supply voltage of 20 V (14-22 V) directly from the bus and only needs an absolute minimum amount of external components - often only 3 capacitors. This enables a whole new world of single-chip sensors and IoT devices and it not only saves the traditional distributed coupling boxes, components for transient protection and a lot of cabling, but also the expensive and time consuming conformance tests, which are required by most other fieldbus standards. It also makes it possible to do with only one bus in automotive applications because Max-i is as cheap as LIN, more powerful than CAN, as deterministic as TTCAN (Time Triggered CAN) and for a given amount of money, it offers the same speed and safety as FlexRay.

  • It is possible to use cheap, standard, unshielded and un-terminated installation cables instead of special communication cables. This not only saves a lot of money and troubles, but also makes it possible to transfer much more power over the bus than any other fieldbus - in practice up to approximately 800 W per segment on 4 x 4 mm2 cables in a ring structure and even 1500 W if 5 x 4mm2 flat cables are used! If more than one power supply/segment is used, a vertually unlimited amount of power is possible. With a 5-conductor flat cable it is even possible to mix Max-i with 230 Vac or 115 Vac mains voltage for example to control lighting, window openers and sun shielding in big buildings. Because the cable is not shielded, the traditional dilemma with the shield connection is avoided. For the sake of noise immunity, a shield must be connected to ground/chassis in both ends, but it is simultaneously a very bad idea to establish ground loops and potential equalization between different parts of the plant through a thin fieldbus cable - especially in plants, which use a TN-C net with a common neutral and protective earth! Nevertheless, it is common practice with most other fieldbus systems!

  • The total reliability of the bus with single chip interfaces is at least as high as the internal parallel or serial bus in a microprocessor plus the necessary I/O cards. This enables the replacement of hundreds of cables and conductors with a few fieldbus cables without any sacrifice in reliability.

  • It is the first fieldbus designed directly for highly demanding safety applications according to IEC 61508 SIL 3. Many fieldbus systems are approved to this level, but they all obtain that by means of an additional safety protocol on top of the fieldbus, separate safety monitors etc. In Max-i, all data processing for simple functions supported by the chip like Boolean I/O, A/D and D/A conversion, SPI interface and lamp driving is done entirely in hardware, which cannot "go down" in the same way as software and is much more predictable and failure tolerant. If a transistor fails, you will only lose the function(s) that transistor is a part of. In a microprocessor, all data processing is done in the same core (CPU) and it may be possible for one program to overwrite the memory of other programs so it is much more likely that you lose everything.

The name Max-i means Multiple Access Cross (X) coupled interface. It refers to Max-i being an event driven multi-master bus (no dedicated master and slave units), which for industrial applications, railway applications, stage light control and long distance communication uses a cable with 4 conductors connected as a balanced 4-wire line (X-coupled). For applications in homes, a (partly) unbalanced, 3-wire or 5-wire cable may be used, and for automotive applications it is enough with a 2-wire line plus chassis. The name also refers to the Max-i-mum performance, which by far exceeds comparable fieldbus systems on most fields.


Simple, but Powerful

Max-i combines the outstanding performance with a remarkable simplicity. There are just a few registers to setup and a new numbering system - PNS, which allows the various process values to be addressed directly as properties of the equipment to which they belong like for example HX127AT4 for Heat Exchanger 127A Temperature 4. The new Max-i specification (9.0) fills only 209 pages where approximately half is used for background material and annexes. As a comparison, most other fieldbus systems have specifications way over 1000 pages, which requires several months to study and implement. Released specifications can be downloaded from this page and used free of charge for all non-commercial use. Commercial use requires membership of Max-i Association.

"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away."
Antoine de Saint-Exupéry


Event Driven
Multi-master Bus

Event driven multiple master busses have many very important advantages compared to master-slave (single master) systems, token passing and time division multiple access (TDMA) systems:

  • The responce time is much faster for the same speed. A device on a master-slave, token passing or TDMA bus needs to wait for a poll, the token or the time slot before it can send a message.

  • The bandwidth utilization is much better since no time is lost on devices, which do not need communication.

  • The failure tolerance is much higher since there is no dedicated master unit, no need for a centralized database and no device needs to insert a new token if the token is lost.

  • New devices may just be connected or removed at any time without any reconfiguration. This is especially important during commissioning and for applications like "Internet Of Things" (IoT) where the new devices may be debuggers, mobile phones, tablets etc. In a master-slave, token passing or TDMA system, the new device needs to be inserted in the ring before any communication is possible, and if a device is removed without reconfiguration or fails, time is lost forever. In a token passing system, it may even stop all communication until the system has been reconfigurated.

  • It is possible to use many different protocols simultaneously. On Max-i, it is for example possible to run any CAN protocol like DeviceNet or CANOpen together with the Max-i protocol. In a master-slave system, the master needs to understand all communication if it should know what to do with the data.

The disadvantage is the time needed to do bus arbitration, but since Max-i does not use termination resistors (!), the minimum bit length is anyway set by the propagation delay of the line, so there is almost no overhead due to bus arbitration.


Highly Improved CAN

Max-i is very similar to CAN, which is the only other event driven multi-master bus, but as can be seen from the table below, it is not just much cheaper, but also much more powerful, reliable and safe.

Comparison between CAN and Max-i CAN Max-i
Economy Possibility for cheap, single chip interface No Yes
Product certification and registration needed Most protocols Not necessary
Use of cheap, unshielded, standard installation cables No Yes
Maximum practical power transfer per segment 384 W at 24 V 1) ≥1500 W at 20 V 1)
Maximum practical number of devices per bus 64-127 ≈1000
Environment Power saving mode / sleep mode (≤0.5 mA) Only partial network Not necessary
Group control No 255 groups
Data Multiple master bus with bit wise bus arbitration Yes Yes
Producer/consumer model Partly 2) Yes
Identifier length 11 or 29 bit 12 or 31 bit
Multiple use of same identifier No 3) Yes 3)
Number of addressing modes per identifier 1 4
Local and global data and global poll of local data No Yes
Possibility for temporary change of (erroneous) values No Yes 4)
Maximum number of bytes 8 1028 or infinite
Different data to more devices in same telegram No Yes 5)
Specified layers of OSI 7-layer model 1, 2 1, 2, 3, 4, 6, 7
Setup attributes per I/O (OSI layer 6) 0 16-1024
Reliability Uncritical timing on all bus length and nothing to setup No Yes
Timing not affected by galvanic separation/insulation No Yes
No bias distortion at capacitive loads (symmetrical drive) No Yes
No termination resistors = high failure tolerance No Yes 6)
Possibility for closed ring topology No Yes 6)
Unshielded cable = no ground loops and potential equalization No Yes
Tolerant to contact or conductor failure No Up to 2 contacts 7)
Contact fritting No 7) 0.15 - 0.2 µm 7)
Typical transmitter power / total power loss 0.2 W / 0.4 W 7.3 W / 2.7 W 8)
Receiver hysteresis 0.1-0.2 V 2 V
Sensitivity to vibrations and low temperatures Crystal oscillator RC oscillator
Safety Error detection 15-bit BCH (CRC) 11) 20-bit CRC
Protection against masquerading (wrong identifier) No 7-bit Hamming code
Detection of wrong number of telegrams No 7-bit serial number
Predictable response time (babbling idiot protection) No Yes
Designed for IEC 61508 SIL 3 without additional layers No Yes
Speed 4-bit / 20-bit polled values/s on a 1 km trunk line 612 / 530 635 / 465 9)
4-bit / 20-bit event driven values/s on a 1 km trunk line 1136 / 880 10) 635 / 465 9)
4-bit / 20-bit values/s on a 1 km closed ring Not possible 1270 / 930 9)
4-bit / 20-bit polled values/s at maximum speed 9800 / 8472 16300 / 11930 9)
4-bit / 20-bit event driven values/s at maximum speed 18176 / 14080 10) 16300 / 11930 9)

1) 1500 W requires 5 x 4 mm2 flat cables and two power supplies - one from each end. For the 384 W power level, CAN requires a very expensive thick DeviceNet cable (12.2 mm with 15 AWG / 1.65 mm2 conductors for DC).

2) CAN uses the producer/consumer model, but many protocols such as DeviceNet and CANopen need to establish a communication channel between devices before communication can take place and may even divide the network into masters and slaves.

3) Without this feature, it is not possible to make for example two-way/landing switches for LED lighting, and it is not possible to have more control buttons for the same process function or the same function in for example coupled trains, but most (all) CAN protocols such as DeviceNet and CANopen actually has a feature to prevent multiple use of the same identifier!

4) Most process values use 4, 20 or 36 bits, and it is possible to change a value temporary, which can save a lot of time during commissioning in case of sensor errors. It also makes it possible to run tests without material simply by simulating the presence of material.

5) Max-i can send individual 8-bit, 16-bit, 24-bit or 32-bit values to more devices in a common telegram with up to 1028 bytes and in this way ensure 100% data synchronization and a very high efficiency for example for motion control, positioning systems and for stage light control where Max-i with advantage can replace DMX512. CAN is only able to transmit 8 bytes in each telegram and is therefore not able to synchronize more than two servo axes with 32-bit precision.

6) In Max-i, the traditional termination resistors have been replaced by multi diode clamps in each device. This gives a very high failure tolerance even without multiple communication lines as the bus may be cut in as many parts as there are power supplies, and each part will still work! A closed ring with a length less than half the maximum length can be cut at any place without any loss of communication. The diode clamps also reduce the power loss in the line termination to approximately the half compared to termination resistors and they utilize the reflections to improve the signal waveform and prevent bias-distortion due to noise rectification.

7) In case of a balanced 4-wire line, where the two communication conductors are connected together in all devices, Max-i will usually survive a failure on one of these conductors or connectors. If more power supplies are used, Max-i may also survive a failure on one of the supply lines so that Max-i is able to survive a failure on two neighbor conductors or connectors.

Usually, a fritting voltage of approximately 100 V/µm is required to burn through contact corrosion. Since the supply and communication voltage of Max-i is approximately 20 V, approximately 0.2 µm can be accepted. Below 3-5 V, no fritting can be expected. This makes CAN inexpedient for connections between for example tractors and trailers (trucks) and between train wagons.

8) The power is the pulse power in a closed ring where it is twice as high as in a trunk line. Because Max-i does not use any termination resistors, the transmitter only draws current for the time it takes the pulse to travel to the end of the line and back to the transmitter, so the energy (power multiplied by time) may be quite small. This reduces the emitted noise and enables battery operation and operation in explosive atmosphere - especially if the speed is lower than the maximum speed for the given line length.

9) In Max-i, it does not take longer time to poll a value than to transmit it event driven as the first and last part of the telegram are just transmitted by two or more devices.

10) Because CAN does not have any "babbling idiot" protection, it is not possible to reach this number of telegrams in practice without a completely unpredictable delay of low priority telegrams. Max-i may run even at 100% and is faster than CAN for safety telegrams where CAN needs an extra layer and it is much faster if the possibility for different data to more devices in the same telegram is utilized as it is the case for stage light and motion control systems.

11) In CAN, two bit errors may on rare occasion remain undetected when the first generates a bit stuffing condition and the second then removes a stuff condition (or vice versa), shifting the position of the frame bits between the two bit errors. The shifted area may lead to a burst error that is too long for the CRC mechanism.


Supplement to Ethernet

Ethernet is growing fast in industrial process control. This puts traditional 5-V based fieldbus systems under pressure. Because they need a power supply to convert the supply voltage to 5 V, a timing crystal and some microprocessor assistance to handle the communication stack, they are too big and expensive to be included in the smallest and most price sensitive devices like push buttons, lamps, micro switches, motor contactors etc. It is therefore only possible to use these bus systems for distributed I/O and for connection to more complicated devices, but Ethernet can do that too at very much the same price. There may even be Ethernet in the building already, which may save some money for cabling. Ethernet will however never get out to individual actuators and sensors - even if the price and size is not taken into consideration. Because Ethernet is today a point-to-point communication, the signals in a big plant would have to pass so many routers and with that so many cable connectors and so much electronics that the reliability would fall to a totally unacceptable level with maybe up to one failure per week.

In the future, there will therefore probably only be room for two types of bus systems - Ethernet with an added layer to make it deterministic, and an ultra-low-cost, but still high performance and deterministic bus system for connection to individual actuators, sensors and lamps. This bus system must:

  • Be cheap and small enough for even the smallest and most price sensitive devices as these devices by far make up the majority of devices in most plants. A vendor of a complex device may find it easy to add for example a CANOpen or Profibus Interface if the device already contains a power supply and a sufficient powerful microprocessor with bus controller, and the necessary software stack is available, but selecting a bus system, which is too complex for simple devices on the same bus, will not lead to an optimized total solution.

  • Be powerful enough for even very complex and demanding devices like mass flow gauges and motion/motor control. On a 35 m trunk line or a 70 m closed ring, Max-i is able to synchronize 7 servo motor axes with 32-bit precision to an accuracy of 0.1 μs at an industrial state-of-the-art communication cycle of 400 μs. This is much faster than CAN and close to or even better than the performance of a much more expensive and complex Ethernet solution, which also has much lower reliability due to the necessary routers and other complicated electronics.

  • Be able to supply enough power for even big actuators and lamps where more amperes may be needed and do it in a cost efficient way. This demand excludes all fieldbus systems, which use special communication cables. A lot of fieldbus systems are really only sensor busses due to the low power or the use of communication methods, which do not allow switching of heavy loads, but in a typical process plant there are only approximately 1.5-2 times more inputs than outputs, so a bus, which does not take the actuator side seriously, will not lead to an optimized solution.

With its outstanding versatility, Max-i is so far the only fieldbus, which fulfills all these demands!


Internet of Things

Internet of Things (IoT) has become the new buzz-word, but there is really not much new in that. For years, thousands of industrial process signals have been available on the internet - simply because it is very practical and saves a lot of time and money to be able to perform remote service. There is also nothing new in controlling the various devices in an intelligent manner. In the industry, this has been done by means of for example programmable logic controllers for over 40 years.

In the home, you may for example connect the coffee maker and the refrigerator to the internet and control the light from an App on your smart phone, but although such technology has been available for years - I/O Consulting (now Prevas) connected a coffee maker back in 1998 - most people don't care about IoT except for a few geeks, who may use it to impress their friends. In daily life, it simply gives too less value for the extra money needed to put a device on the internet and it doesn't solve problems like the very fast growing chaos of charger and converter boxes with related cable spaghetti and the fairly high cost and size of today's LED lighting. It also doesn't give you any environmental improvements like the possibility to drive LED lighting, window openers, door locks, PC's and PC peripherals etc. from solar panels.

The only area where IoT makes sense to most people is alarm systems, but this is an area where present IoT technology based on wireless communication and batteries is least suitable:

  • If an alarm system should not give you false security, it must be fail-safe, that is, an alarm is also generated in the absence of a sensor signal - not just as an active signal. If a wire is cut or a wireless system is jammed, an alarm must be generated immediately or at least within approximately 1 second, but due to the battery life, it is usually not possible to supervise a device more frequently than approximately once every 10 minutes, which makes such a system quite useless in practice.

  • Wireless communication is very easy to jam and may generate many false alarms due to other wireless communication in the same frequency band. False alarms are not only very irritating, but they also makes you nervous.

  • It can be very difficult to ensure that wireless communication do not disclose information about for example when your home is empty or transmit unwanted information about your behavior to third parties. This is especially a problem with alarm systems with cameras where it is almost imposible to guarantee that your behaviour in your home is never transmitted to third parties or transmitted to second parties such as alarm centers when you don't want it. If you connect a camera and don't set the security code immediately or forget it, you may find a nice picture of your home half an hour later on a russian web-site. There is an example of that! Everybody may be able to see exactly, when you leave your home, and it can be very embarrassing with for example a public video transmission from your bed room. Some cameras have a red light showing when the camera is recording, but it may be switched off to hide the position of the camera, and a hacker may also be able to switch it off if he is able to penetrate into the system.

  • Battery driven systems have only enough power for low-power sensors such as infrared detectors, but these kind of detectors generate many false alarms and may be triggered by high temperatures as low as 28 °C. Cameras are a very good solution to avoid false alarms, but due to privacy, it is not a good idea to transmit the raw picture. A much better solution is to use modern person and face recognition technics and then just send the alarm and perhaps the necessary parameters to possibly identify the person. However, image processing in the camera requires a lot of power as many people know from their smart phones, which can discharge the battery very fast and even get quite hot when working with pictures or videos.

With Max-i, it is different. Since it is a combination between a low-voltage DC power supply and a communication network, it has all the power needed for even the most advanced alarm system, it can simultaneously control the lamps to make the home looks inhabited and/or destroy the night vision of a thief, and it can be used for many other purposes than just IoT and therefore offers much more value for money. It is very easy to build fail-safe networks up to very high safety standards, it is easy to log all communication so that you can be absolutely sure that no device transmits unwanted information behind your back and you can just disconnect the internet when you don't need it and in this way keep even the best hacker out. Unlike for example WiFi, there is also virtually no limitations on how many devices you can connect without any noticeable degrade of performance.

With Max-i, it is possible to bring decades of industrial experience into the home.

For developers or just people, who wants to play with home automation, the extreme simplicity of Max-i and the easy connection to most small computer systems will be a completely new feeling compared to any other IoT and home automation technologies. There is no need to download and maybe pay for very big design suites, study specifications, new operative systems and user manuals with way over 1000 pages for months and finaly go through an expensive and time consuming conformance test before your product is ready for sale. In the future, you just buy a Max-i chip, put it into your device and program a few registers over the bus (no special programming tools needed). For the majority of devices, where the function is supported by the chip such as most buttons, lamps, actuators and sensors, you can have a prototype ready in a few hours - even if you have not used Max-i before. This also makes it possible to use Max-i technology for companies without programmers. If you for example want to make a multi-color lamp, you just need a Max-i chip and three capacitors plus a current generator with 4 - 5 LED's for each color (up to RGBWaA or RGBAaC). Home automation and IoT has never been, and will never be simpler and cheaper than that.


No Charger or
Converter Chaos


Today, most homes have a very fast growing chaos of clumsy charger and converter boxes with related cable spaghetti and outlet distribution boxes for smartphones, tablets, laptop computers, computer peripherals, cameras, LED lamps and lighting, toys etc. This destroys the smartness of the new, compact technology, generates a lot of electrical noise and creates an increasing fire risk due to the often very doubtful quality and cooling. Besides, due to the laws of nature, the efficiency of many small converters is way below what can be achieved with fewer devices with higher power - especially if 50 Hz transformers are used, so a lot of power may be wasted, and many of these small converters have been shown to be very noise sensitive and in many cases cut off for a short period of time in case of voltage transients or voltage drops. Max-i offers the ideal solution for that. The high power and use of standard installation cables also makes Max-i extremely suited as a supplementary 20 Vdc power supply and control in the houses of the future where it may be used not only for intelligent LED lighting and all kinds of battery chargers including all levels of USB Power Delivery and Quick Charge, but also for window openers and energy management and alarm systems such as fire, smoke, burglary, water and power failure. Calculations done by the Danish engineering company Rambøll shows that such a network partly driven by solar cells can save the Danish households in the order of 1 billion Danish kroner per year corresponding to approximately $150,000,000.

Max-i has all the features needed for these kinds of applications. For example, it is very easy to make two-way/landing switches and light dimmers with the LED controller and all Boolean outputs may be divided in up to 255 groups, which may be switched off in three steps for example during lunch breaks, when you leave a building or in case of failing "green" energy supply or a heavily loaded power net.


Environmental Friendly


Incandescent lamps are not considered environmental friendly due to the very low efficiency and high power loss, but in many cases, the generated heat is not lost, but used as supplementary heating where it is mostly needed near people, and they do not require many resources for production or recycling. LED's on the other hand have a very high efficiency and with that a low power consumption, but in case of lamps driven by the mains voltage (230 or 115 Vac), the necessary converter requires many production and recycling resources. Therefore, these types of LED lighting are not as environmental friendly as it may look at a first glance - especially because of the often very low life time of the converter. The life time of the LED's themselves are usually estimated to 50,000 hours although it is highly temperature depending, but due to the high voltage levels and the use of cheap electrolytic capacitors, the life time of the converter is usually way below this limit. However, with a 20-V DC net, a LED lamp only needs a simple series connection of for example 5 LED's and a current generator, which can bypass one LED in case of a low voltage – plus a Max-i controller if remote control is wanted. Such a solution has an efficiency of at least 75 - 80 %, and although this may be slightly lower than possible with a state-of-the-art switch-mode supply, the total environmental account becomes better. Besides, such a solution is much cheaper and smaller and can be contained in even the smallest and most architectural designed lamps, and because the full life time of the LED's can easily be utilized, it may not be necessary to be able to replace the light source.


LED controller

Max-i includes a very advanced LED controller with a lot of features:

  • Suitable for even the most demanding stage light and architectural lighting applications (DMX512 replacement).
  • Pulse code modulation with 1.25 µs pulses (not PWM) for very small decoupling capacitors, no flicker or stroboscopic effects and very long LED life (less thermal stress).
  • No violation of the Philips PWM patent for color changing (RGB) lamps or the similar Infineon sigma-delta patent.
  • Full 8-bit RGBWaA or RGBAaC with build-in gamma correction (linear, 2.00, 2.23 or 2.44) and automatic amber (RGBW) or cyan (RGBA) generation.
  • Contrast ratio of over 11,000:1 with a gamma of 2.44.
  • 3rd order smoothing filter on each color with 7 time constants (bypass, 2.5 ms, 5 ms, 10 ms, 20 ms, 40 ms and 80 ms), which may be selected on a per-telegram basis.
  • 6-bit dot correction on each color removes the necessity for expensive bin selected LED's.
  • Integrated one-button light dimmer with 60 levels, night light and possibility for synchronized landing switches.
  • Daylight control (dimming) in up to 255 groups with all-off (and all-on) function and slow smoothing filter to convert the 60 levels to 240 steps and in this way make each step invisible.
  • Integrated traffic light controller with dimming, programmable minimum level and green safety output.

The very advanced controller has previously unseen control possibilities. Without changing the settings, a lamp can simultaneously be controlled and dimmed by means of wall switches and automatic daylight control, be set to a specified color for example by means of a mobile phone or tablet and be controlled together with other lamps in a common group telegram with individual reception delay to set a scene or even control the lamps in real time from for example a TV set or a computer with the same speed and performance as professional stage light.

With the 5-color RGBWaA system, which can generate excellent pastel colors, and the possibility to address many light sources in the same telegram, the lamp controller is perfect for illuminated ceiling panels with diffused light where it can create an illusion of being outside with drifting clouds and varying color temperature depending on the time of the day. This may for example be used to create a pleasant feeling in stores, treatment rooms in hospitals and in rooms without daylight such as rooms in the basement.

The ceiling may simultaneously hide alarm sensors etc., which can just be connected to the same bus.

If 5 colors is not enough, any number of Max-i controllers can very easily collaborate by means of common telegrams. Just two controllers where the reception in one is delayed 4 bytes can create an absolute state-of-the-art 8-color system (plus 2 artificial colors) at a previously unseen low cost. With for example a royal-blue, artificial blue, cyan, green, lime, amber, orange, red and deep red system, any color and color temperature can be created with excellent accuracy for example for lighting in art museums etc., and because of the multiple master scheme and the easy possibility for battery backup, the lamp units for such applications can simultaneously be used for emergency lighting, which can show the way to the nearest exit by means of running light for example controlled by means of a common group telegram. They may even be equipped with sensors and used for alarm systems for example for burglary and fire.

The lamp controller is also extremely suitable for smart high beam lamps in automobiles, which consist of a high mumber of LED's, which can be dimmed individually to prevent dazzling of the drivers in oncomming cars and dazzling from reflections in signs and falling snow. Each Max-i controller can drive 4 LED's and all LED's in both head lamps can be controlled in a single telegram.

The low beam is not enough for more than approximately 60 km/h, but most people drives much faster with low beam, so smart headlamps will in the future increase the safety considerably.

There are other chips, which are able to drive a chain of LED's, but they are usually based on a serial connection where each chip strips off the number of bytes it needs and then transmit the remaining telegram to the next chip in the chain. However, with such techniques, it is not possible with any error detection, which for example can switch to low beam, and a failure on one chip may disable the rest of the chain. Besides, these chips usually do not have advanced features such as gamma correction, digital smoothing filter and dot correction (enables uniform lighting with cheap LED's).


Military Applications

Strong electromagnetic fields may be very destructive for most kinds of electronics. This is utilized in various kinds of electromagnetic weapons. One of the most powerful discharges occurs when a nuclear weapon is detonated in the upper atmosphere. This creates an electromagnetic pulse (EMP) with field strength up to approximately 50 kV/m, a rise time of 5 ns and a duration of approximately 1 µs. One way to survive such a pulse is to keep the system fully balanced - even in case of very high voltage levels (good insulation) - and keep the physical dimensions very small and this is exactly what Max-i can offer. With a well insulated 4-wire cable and a very small (single chip) interface, there is a good chance that the system will survive. A field strength of 50 kV/m is only 50 V/mm, so a chip with a size of 1 × 1 mm will be exposed to a maximum of 70 V (diagonally), which is in the same order of magnitude as the maximum working voltage and therefore easy to limit.


Evaluation Board

Until the final IC solution is available, Innovatic can offer an evaluation board - EB1, which simulates an 8-pin IC solution by means of an FPGA and other standard components. This solution may be very interesting for vendors, who want to take the step into the future and have a possibility to influence the standard before the IC is made. It may also be interesting for semiconductor companies, who may be looking for a new product family and/or can see the enormous potential in one fieldbus for virtually all low to medium speed applications from the most price sensitive ones to the most demanding.

Vendors, who want to utilize the outstanding properties of Max-i and embed this preliminary Max-i interface directly into their products, can buy the pre-programmed FPGA from Innovatic (or through Microsemi - previously Actel), which simultaneously grants the vendor a royalty free, non-exclusive right to use the schematic of the evaluation board and the PCB layout. The entire logic fils only approximately 5600 gates in a Microsemi A3P250 FPGA plus a serial EEPROM underlining the simplicity of Max-i. In this way, it is not necessary to wait for the final IC! As the interface does not need any microprocessor assistance, it is not more expensive that most other fieldbus interfaces and may therefore be used for example for distributed I/O, but of course, Max-i will not release its potential of very low cost and very small size before the IC is ready.