How a Cell Phone Call Works

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Article by
ECE Department
Tadipatri Engineering College (TECH) , Anantapur

Tadipatri Engineering College

Golden Rules For Electronic Circuit Design

- All components must conform to the specified temperature range. For resistors, de-rating of power rating at peak temperature must be considered. For capacitors de-rating of capacitance, leakage and increase in ESR at peak temperature may be important. For other components such as diodes and transistors, parameters such as recovery times and current gain vary with temperature and must be considered at extreme temperatures. In summary, no design calculation must be left to chance (as is often the case with designs put together in haste), temperature effect calculations are indispensable to success.

- Devices connected to interfaces must be well protected from ESD (Electrostatic Discharge) damage. ESD damage may occur at the time of prototype construction, during manufacturing or during use. Contrary to common misconception ESD at the time of production may not render a device defunct, but may cause progressive deterioration which may result in field failure. Therefore built in ESD protectors are necessary and Mansi Engineering ensures that all its designs incorporate them where necessary. IEC 61000-4-2 is a widely accepted ESD test conformance standard. ESD protectors include MOVs, TVS diodes, ESD Protection Clamping diodes and the newly introduced Polymer based devices. Selection of the right type of protector depends on capacitance that can be tolerated without signal deterioration and other factors such as tolerable leakage current, cost, pin outs and board area required. In addition, ESD protectors must be placed as close as possible to the signal entry location and as far away as possible from the device being protected so that the resulting large trace impedance attenuates the high frequency ESD energy as it travels towards the protected device. Zener or TVS diodes must be placed between power supply lines and ground to absorb ESD energy traveling via other protector diodes towards power supply line, while the device is powered off.

- Terminals connecting to inductive sources must be protected from switching overshoots or undershoots using clamping diodes or other devices. Long traces that carry heavy currents may act as sufficiently large inductors to cause unwanted switching transients and therefore protection is necessary.

- Signal lines must be well protected from radiated and conducted EMI. Ferrite beads and capacitor filters are effective means to block EMI.

- Within limits of budget, every design must incorporate sufficient protections from wrong connections, such as battery polarity reversal and accidental grounding of an output line. Large resistors are recommended to be used in series with microprocessor outputs driving drivers that drive large inductive loads. This ensures that the processor is well protected from switching transients.

- Functioning of the system at power up must be analyzed. For example it is important to deploy pull-up resistors on microprocessor output signals that need to be high on power up. Similarly functioning of relevant parts when powering down deliberately or accidentally, must be analyzed. For example, when processor state saving is involved during power down, a power down detect functionality might prove indispensable.

- For EMC, it is recommended to use inductors (preferably shielded) to slow down sharp current rise and fall times. Sharp current transients cause a sharp varying and traveling electromagnetic field.

- It is important to assign test points to relevant nets. Especially all ground and power nets, bias or threshold points and other serviceable signals must have a test point, which add convenience during testing and troubleshooting. Test points may be free vias with suitable drill size to accept and retain stainless steel needles or header leads.

- Having an on board power on LED indicator has its own importance. It warns the engineer and people around that the circuit is live and prevents accidents."

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Article by

Dept. of ECE

Tadipatri Engineering College (TECH) , Anantapur

Tadipatri Engineering College

A Highly Efficient Solar Lantern by Texas Instruments

TI had designed solar lantern solution specifically for Indian rural market with circuit protections, more shelf life, user control interface with dimming feature and the most important thing, very high power efficiency providing great backup time.

Key Solution Features : 

• Boost Drive Stage for 3W (3 LEDs in Series)
• Stand-by current < 500uAReverse
• Polarity protection for Battery and Panel
• 4 Stage Charging profile for Battery
• User interface in form of Keys and Indication LEDs
• Under-voltage Cutoff

TI Hero Products in this Solution

• MSP430G2231
• TLV70433
• TPS61165

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Article by
Department of ECE
Tadipatri Engineering College (TECH) , Anantapur

Tadipatri Engineering College

Tadipatri Engineering College , Anantapur

ABOUT COLLEGE : 

Tadipatri Engineering College offers the ultimate urban campus: the institute has a sprawling campus spread across 40 acres of land, the green spaces and pathways of a traditional college campus combined with the energy and diversity of a college set in a vibrant town called Tadipatri located on the By-pass road from Anantapur to Kadapa. 

VISION :

          We at TADIPATRI ENGINEERING COLLEGE,TADIPATRI will strive continuously for excellence in education by providing best possible education facilities and creative atmosphere. Through our sincere and planned hard work will attain academic integrity.

MISSION :

            Our mission is to inculcate technical knowledge through effective teaching - learning process creating a community of learning with due considerations for ethical and social responsibilities.

WHY TEC ?

• Approved by All India Council for Technical Education (AICTE), New Delhi.
• ISO 9001 - 2008 Certified Institution.
• TEC has a separate Communication & Soft Skills (CSS) dept.
• TEC is a member in the prestigious “B.TECH GURU”. This network enables the students to take advantage of the facilities such as virtual class rooms, virtual laboratories, journal sharing through online, video conference lectures and many more. One Gbps backbone is used for this network.
• TEC has a strong Industry Relations & Placement Department (IRP) and has been consistent in achieving 100% Placements.
• 24 Mbps hi-speed internet connectivity round the clock in the campus and in the hostels.
• Discipline is the hallmark with 100% ragging free environment.
• E-Learning mode of teaching is practiced in the campus.
• Yoga and meditation classes for the students.
• A large playground is provided for sports.
• Research Oriented Problem Solving Techniques.

Tadipatri Engineering College , Anantapur