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How To Use Resistors For Current Sensing


Today, as technology rises, current sensing resistors are used to focus on managing and tracking of power from the source to an end device. Current sensing resistors are used in a lot of electronic devices. That is why it is important to have knowledge of the advantages and disadvantages of various technology available today.

Let us take a closer look at how Current Shunt Resistors or current sense shunt resistor work. Current sense resistors are put in sequence with a power supply and an end device. All currents must pass through the resistor to get to the end unit. After that, the current that went through the resistor is determined by means of reading the voltage across the resistor and this kind of information is utilized by the power source to adjust its output. Because the power will be consumed by this function symmetrical to the resistance value, you would want the value to be as small as it can be since this will diminish the amount of power consumed by the current sensing function for a particular current level. On the other hand, as the resistance values decrease, the voltage change for a particular current level decreases as well. If this happens and the resistance value became insufficient, it will be difficult for the power supply to distinguish if the voltage difference is still tolerable or not. Due to this, current sense resistors are normally used for those applications that require only 100amps below. For high current applications, precise sense resistors should be used.

Thick Film Current Sense Resistors

This kind of resistors have a wide variety of sizes (including the smallest current sense resistor chip in the industry) and they are somewhat economical. Thick film resistors are made by applying a resistive film or paste, a combination of glass and conductive materials, to a base. Thick film engineering allows high resistance values to be printed on a cylindrical or flat base whether covered entirely or in diverse patterns. They also prefer to be printed in a serpentine design to remove inductance for applications with steady frequencies. After application, the resistance is modified using a laser or abrasive trimmer. Thick film current sense resistors are the first product to be recommended for portable scanners and barcode readers, cell phones, MP3 players, DC to DC converters, and voltage regulator applications.

Metal-Based Resistors

The metal foil resistor has the best accuracy and stability compared to all resistor types. The foil is made of an alloy (material made from two or more metallic elements) to protect it from damage. A mixture of nickel, chromium, and additives are used to form the foil because these materials have high resistance to electric current. The foil resistor has a low-temperature coefficient of resistance. Thus, the foil resistors have high precision and stability. Metal-based resistors can be applied to switching and linear power supplies, buck controllers for datacom and telecom equipment, LED drivers, motor control, electric power tools, and power amps.

Precision  Current Sensing Chip Resistors 

This resistor type is the best choice when it comes to precision and high current handling because these resistors are capable of processing high surge currents such as medical equipment, testing equipment, automatic equipment controllers, converters and communication device.

Current monitoring has become more significant as systems make an effort to be more effective, mainly when it is about battery-powered equipment. Current sense monitoring can help extend both battery life and the functional life of your electronic equipment.

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