Introducing Be-ON: Beganto Electronics Open Network

We are creating an online open network for the electronics industry and would like your opinion on it. Here is some background. The engineers designing electronics equipment need samples or 5-10 pieces of the components needed to go into the equipment. Samples can be purchased off the web of distributor websites or obtained from manufacturer's reps for free. Once samples for the entire board are obtained, the board can be tested and it can be determined if the design was a success. Sounds simple? Its not. A new equipment design could contain 100s of components. The first challenge is to find what the part numbers for these component are. Once you are past that hurdle, these may or mayn't be available through online distributors. Samples may or may not be available either. It becomes a challenge because your design requires 100 components from a total potential possibility of over 25 million components.

That is why we are creating an online network. It is open i.e. there is no cost to join and anyone can join. How are we doing it? By keeping it simple. The first thing that will be available through this online network will be samples. So we are engaging the manufacturers reps representing thousands of lines and inputing their information in the system. An engineer can now come to the Beganto system by accessing www.needasample.com and select the manufacturer for whom he/she wants a sample.

This request gets automatically routed to the manufacturer's rep in his territory who can get him/her that sample. Its that simple!

We think that as more engineers get their samples fulfilled through needasample.com and more reps will be able to generate design wins, component manufacturers would like to get involved too and use this as an online mechanism for sending samples and generating sales leads. As more component makers join, more engineers will join and the network will grow.

That's why this online network is call Be-ON, short for Beganto Electronics Open Network. Its the positive impact that this online program can have on accelerating new product design and innovation that gets us all at Beganto so very excited. So, what turns you ON?

Sunil Grover
co-Founder CEO
Beganto, Inc.

Boost LED Performance Via Current Source

For optimum performance, high brightness LEDs should be driven by a current source rather than by a voltage source. This article examines the design of a constant-current LED driver that can be used for driving a string of series-connected LEDs. The number of series-connected LEDs can vary from one to several. To drive the LEDs, the power-stage topology is a modified buck boost converter.
There are many integrated driver solutions in the industry; one possible integrated driver solution to implement the controller subsystem is using the MAX16818 from Maxim Integrated Products. This is an average current mode controller with a transconductance amplifier for the current error amplifier. The current-sense voltage across the current-sense resistor is amplified internally by a factor of 34.5. The transconductance of the current error amplifier is 550μS and the peak-to-peak saw tooth is 2V. In this circuit, the input current is sensed by a resistor, Rs in the return leg.
The value of the current-sense resistor is set by the average current limit required. The maximum voltage across the LEDs is where n is the number of LEDs and is the maximum voltage drop in the LEDs at the full-load current, if the maximum output power is P max = VLED max * If and the efficiency is η. Thus, the maximum input current is:

I in max = P max/ η x V in max

The minimum value of the average current limit threshold is 24mV. The current-sense resistor value can be calculated as:

Rs ≤ 0.024/ I in max * Ω

To prevent oscillations in the PWM comparator section of the controller, the slope of the signal on the negative input of the comparator should be less than the slope of the saw tooth on the positive input. The slope of the saw tooth is given by Vsfs. while the gain of the current error amplifier is given by

Gca = 34.5 * gm * Rc.

In this equation, gm is the transconductance of the CEA The output of this amplifier goes to the negative input of the pulse-width modulation (PWM) comparator. Positive input of the PWM comparator is the saw tooth that has a peak-to-peak amplitude of Vs with a switching frequency, fs. This is the AC gain of the current-error amplifier from the current-sense voltage across Rs to the output of the amplifier at the high frequencies below the pole from the compensation capacitor, Cp. This is the gain of interest at the PWM comparator section.

INFRARED SENSOR

Infrared (IR) sensors are used in night vision cameras and goggles to detect heat emitted by objects. Since ambient light is absent, radiations emitted by the object are picked up by the sensors and used to form an image of the object. These devices can detect the presence of an intruder and are very important in guarding sensitive infrastructure. They are also used for non-contact temperature measurement.

How it works:
Red color has the longest wavelength and infrared means the wavelengths below this visible red. The IR detecting unit uses a silicon photodiode as the light-detecting source to convert the infrared radiation into an electric current. Since an object like a human body has different temperature zones, the electric current that is produced will also vary and can be used to form a map of temperatures or varying infrared colors from dark red to blue.

Selection:
The following factors are useful in selection:

• Responsivity - the responsivity at different frequency range measured in mV


• Sensitivity is a very crucial factor in infrared sensors and it should be very high and efficient.


• Field of view - the circular range in which the unit can sense radiation


• Stability


• Type of electrode


• Response time is the time taken by the sensor to detect, sense the object and send response.

Applications:

• IR sensors are used to build cameras or radiation detecting units, night vision goggles, and security and monitoring equipment.

• IR sensors find usage in process industries where the temperature can be between –30 deg C to 3000 deg C. Some of the process industries are paper, glass, metals, plastics, cement, chemical, food, petrochemical, textiles, etc.


• They also help firefighters to see smoke and save lives. PDAs and other computers and digital cameras use infrared technology to send and receive data.


• They are also used in motion detection and other equipment.

Author: Ashutosh Saini (Component Engr.)

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Brief about ISDN Line Interface

Integrated services digital network (ISDN) is a type of telephone circuit that allows digital signals of data and voice to be sent using the standard telephone wire. It gives better reproduction of signals and speed of transmission. ISDN line interfaces allow routers and multi-channel port boards to be connected to the ISDN system or the central office. A set of protocols and codecs are defined that allow the encoding of digital voice and data so that they are understood by analog systems.

Types of ISDN line interfaces:

• Basic rate interface (BRI): These are used in TV and radio broadcasting centers and use the MPEG codec. They use up to two 64 kbps channels.
• Primary rate interface (PRI): These are used for PBX connections. They can have up to 23 channels.
• There are two types of channels: B (bearer) type used for data and information transmission and D (delta) channel used for signaling.

Selection parameters for ISDN line interfaces:

• Send/receive separation: To reduce leakage of signals from send and receive paths, extra circuits are attached so that signals from the send path do not mix with those from the receive path.
• Acoustic coupling reduction: In studios, when the speakers use a microphone, an acoustic path is formed between the sent and received paths. By using functions like reducing the dynamic gain and adaptive cancellation, this issue is reduced.
• DAC conversion: 16bit digital to analog converters are used for connecting the analog equipment to the digital.
• Sampling rate conversion: The studio and the ISDN equipment operate at different frequencies. A suitable step-up and down process is needed to get them both in sync.
• Auto gain control: This is used for both the send and receives signals to smooth out the variations and takes care of different types of phone instruments.
• Dynamic equalization: This feature balances the frequencies of different makes of equipment. The processor of three band dynamic equalization is used.
• Caller ducking: the host to ‘kill’ unwanted conversation from other callers.
• Caller ID verification: Allows caller ID information to be transmitted.

Other parameters to be considered are: memory per channel, voltage/current, tempratures, etc.

Applications:

ISDN line interfaces are used to transmit voice and data in studios, PBX, TELCO, radio broadcasting stations, conferencing between remote speakers, etc.

Author: Deepak Raina (Component Engr.)

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Advancement In Visible LEDs Technology

IRC Advance Film Division which is TT Electronics Company has developed company’s Anotherm Aluminum Substrate material which offers superior thermal management for use with LED technology.

IRC’s patented Anotherm substrate provides display system design engineers a lighter, cooler and less expensive method of mounting multiple visible LEDs.

IRC’s Advance Film Division recently developed this economical anodized aluminum substrate material with superior thermal conductivity to address the problem of heat dissipation in direct mounted LEDs and LED arrays.

The Thermally conductive aluminum alloy enables design engineers to mount Visible LEDs and other components directly to it, eliminating the need for attached heat sinks, mounting hardware and associated assembly costs.

Economical solderable thick film conductors can be screen-printed directly to the Anotherm substrate to connect surface mount packaged components. The rugged Anotherm technology can operate in extreme temperatures – up to 400 degrees centigrade.

Author: Sanjay Chawla

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Introduction to Beganto Inc.

Beganto is a rapidly growing Silicon Valley company that has developed patent-pending technology to provide search, sample management and tracking solutions for the electronics industry. Beganto is privately held and profitable with headquarters in Fremont, California and development center in India.

Engineers, planners and buyers from electronics manufacturers (customers) use BeON to search, sample, source and track parts for their projects.

Basic membership in BeON is free for qualified suppliers, reps and distributors, and only requires that participants agree to uphold Beganto's quality of service pledge to the end users.