The most common type of current sense resistor is a bipolar one. The resistance of the current sense resistor is determined by the voltage drop between the input and output terminals. The sense resistor is almost always placed on the high side of the circuit, while the resistor on the low side is usually referred to as the circuit common, or ground. A bipolar current sensing circuit should use four tracks to form a Kelvin connection.
Current sense resistors are used for snubbers, current sensing in power supplies, and electric motor control. They are available from industry-leading manufacturers and distributors like IBS Electronics. Thick film on ceramic is used for lower current ranges. It also offers low-temperature rise, compact chip sizes, and low surge resistance. On the other hand, metal element resistors are generally larger and offer better performance. However, it is important to note that the TCR of a current sense resistor varies across its operating range, so you need to consider this when selecting a current sense resistor.
Although the principle of resistor current sensing is simple, the implementation can be complex. Specialty microcontroller chips can be used to amplify the output voltage of a current sense resistor. They may include internal circuitry to amplify the current, so they do not require external amplification. If you choose a non-resistor current sensing resistor, make sure to check with your manufacturer before purchasing.
When you're buying a current shunt resistor, be sure they have a low-temperature coefficient. Temperature coefficient affects resistance, and resistors can degrade due to self-heating. The temperature coefficient of resistance of a resistor depends on the material used to make it. A typical chip resistor has a temperature coefficient of resistance of +500 ppm/degC, while a precision-performance unit can have a coefficient of resistance as low as 0.0.
Current sense resistors are an excellent option for measuring the current flow of a circuit. The technology is affordable, and the device is RoHS-compliant. Moreover, current sense resistors can extend as low as one milliohm. With so many uses, current sense resistors are a cost-effective and practical solution to current flow measurement. It is easy to use and maintain and can be found in a variety of electronic and industrial products.
A current sense resistor is positioned along the conduction path, and its value is determined by the maximum current and input voltage. The higher the resistance value, the higher the power rating and heat dissipation of the current sense resistor. The smaller the value, the less power it generates, and it overrules the use of an extra heat sink. So, how do you choose the right current sense resistor?
One of the main reasons why braking resistors are preferred is its low ESL. Low ESL current sense resistors are more cost-effective because they use a standard low-cost 2-pad sense resistor. A four-pad layout can achieve high Kelvin sensing and can save space. In this way, current sense resistors can be used on batteries that are close to the input terminals. So, if you are designing a new circuit with a battery, a low-ESL current sense resistor is a must.
To get more enlightened on this topic, see this page: https://en.wikipedia.org/wiki/Current_sensing.
