Current Sensors

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  How to Select a Sense Resistor

  Nov 24, 2022

  
  Sense resistors can be used in many applications, including motor control, power management, and battery charging. However, these circuits are complicated and require careful implementation. Because of this, it's important to hire the services of an application engineer who has experience in the use of current sense resistors. This engineer can guide how to select the proper resistor for your application.

  When selecting a current sense resistor, it's important to consider how the resistor is going to be dissipated. The heat produced by the resistor represents wasted power. This will affect the performance and reliability of the circuit. If you want to avoid this, it's important to select a resistor with a low TCR. This will also increase the accuracy of the measurement.

  It's also important to consider the temperature coefficient of resistance (TCR) of the resistor. A low TCR means that there's less temperature drift over time. This is important for applications that require high accuracy.

  In addition, a current sense resistor must be able to withstand high surges in current. For example, in a motor drive, a high surge in current can arise from an inrush condition. The delay between a motor stalling and a protective current trip can also cause high surges. For these applications, it's important to choose a resistor that can withstand a high peak temperature.

  Resistors that are designed for this application are specially fabricated to have a low self-inductance. They can be made in many different shapes and sizes. Many are manufactured with bulk metal technology, which gives the lowest ohmic values. When choosing a current sense resistor, it's also important to consider its temperature coefficient of resistance. A low TCR will also ensure that the temperature dependency of the measurement is low.

  Sense resistors come in different sizes and are usually available in a range of milliohms. In some cases, values can be as low as a single milliohm, while other values can be as high as 10 milliohms. The resistor is designed to minimize the voltage drop across it, which reduces the impact of noise and increases the accuracy of the reading. The hall effect sensor also has a high power rating, which is important for handling the maximum current.

  Current sense resistors can be used in a variety of applications, including motor control, power management, battery charging, and more. However, they're best suited for DC applications. If you need a high-power resistor, you'll want to make sure that it has a power rating of at least 3W. This is so it can dissipate its maximum amount of power without damage.

  If you're designing a motor drive, you'll want to measure the current as accurately as possible. This is especially important when you're measuring high-frequency current. A standard, low-cost 2-pad sense resistor can achieve high accuracy, but higher accuracy requires 4-pad designs. These types of resistors are often used in high-accuracy applications.

  Many current sense resistors are also designed to be small. A PC-board copper trace can be used as a sense resistor. If you need a smaller sense resistor, you can use an SMD part that extends down to fractions of a milliohm. The PC-board copper trace can be calculated to give you the exact resistance value you need. If you want to know more about this topic, then click here: encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/electrical-resistance.

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