Technical Resources

Ohm’s Law is a fundamental principle in electronics that describes the relationship between voltage (V), current (I), and resistance (R) to better understand passive components behavior within an electrical circuit. It is named after the German physicist Georg Simon Ohm, who first formulated it. Ohm’s Law is typically expressed by the equation:  

V=I⋅R where:  

• V is the voltage across the component (measured in volts) 
• I is the current flowing through the component (measured in amperes or amps) 
• R is the resistance of the component (measured in ohms) 

The power dissipated in a resistor can be calculated using Ohm’s Law and the formula for electrical power. Ohm’s Law states that the voltage (V) across a resistor is equal to the current (I) through the resistor multiplied by the resistance (R): 

• Ohm’s Law:  
  • V = I * R 
• The electrical power (P) is given by the formula: 
  • P = I * R 
• Substituting the Ohm’s Law equation into the power equation you get:  
  • P = I * (I * R) = I2 * R 
• Alternatively, you can use the formula for power in terms of voltage and resistance: 
  • P = V2 / R

Let’s consider an example:  

Suppose you have a resistor with a resistance R = 100Ω and a current I = 0.5A. 

 You can use the formula P = I2 * R to calculate the dissipation:  

• P = (0.5A)2 * 100Ω = 0.25A *100Ω = 25W 

Calculating the power dissipation within a resistor is essential to ensure the proper functioning and reliability of electronic circuits, as it helps determine the amount of heat generated, aiding in component selection, thermal management, and preventing potential damage or degradation of the resistor due to excessive power. 

In the context of electronic components, the terms ‘active’ and ‘passive’ refer to their distinct roles in electrical circuits. Passive components, such as resistors, capacitors, and inductors, operate without an external power source and manipulate electrical signals by exhibiting characteristics like resistance, capacitance, or inductance. They primarily resist, store, or release energy within a circuit. On the other hand, active components, exemplified by transistors and integrated circuits, rely on an external power source to actively control the flow of electrical signals, providing functionalities such as amplification, signal processing, or switching. The key distinction lies in the autonomy of operation, with passive components functioning independently and active components requiring external power for enhanced signal control and processing.

Surface mount and through-hole passive components differ primarily in their mounting methods on a printed circuit board (PCB). Surface mount components (SMD) attach directly to the PCB’s surface, utilizing small, flat leads or pads for connection. This mounting style allows for compact and efficient use of PCB space, making it suitable for modern electronic devices with space constraints. While through-hole technology has been widely used historically, surface mount components have gained popularity in recent years due to their space-saving advantages and compatibility with automated assembly processes.

RoHS, or Restriction of Hazardous Substances, compliance refers to adherence to a European Union directive that restricts the use of certain hazardous materials in the manufacturing of electronic and electrical equipment. The importance of RoHS certification lies in its contribution to environmental protection and human health. By adhering to RoHS standards, the manufacturing and use of electronic devices become safer, minimizing the risk of exposure to toxic substances, protecting the environment, and contributing to the overall well-being of individuals who interact with these products throughout their lifecycle.   

RoHS 3 (Directive 2015/863) restricts the use of ten specific hazardous materials in the manufacturing of various types of electronic and electrical equipment. These substances are:  

1. 1. Cadmium (Cd): < 100 ppm  
   2. Lead (Pb): < 1000 ppm  
   3. Mercury (Hg): < 1000 ppm  
   4. Hexavalent Chromium: (Cr VI) < 1000 ppm  
   5. Polybrominated Biphenyls (PBB): < 1000 ppm  
   6. Polybrominated Diphenyl Ethers (PBDE): < 1000 ppm  
   7. Bis(2-Ethylhexyl) phthalate (DEHP): < 1000 ppm  
   8. Benzyl butyl phthalate (BBP): < 1000 ppm  
   9. Dibutyl phthalate (DBP): < 1000 ppm  
   10. Diisobutyl phthalate (DIBP): < 1000 ppm