What Is A Slim Metal Precision Alloy Current Sensing ResistorsUnderstanding Metal Alloy Current Sense Resistor
Definition and Role of Resistance
When electric charge moves through a conductor, it collides and rubs against molecules, atoms, and other particles. These collisions and friction create an obstruction to the flow of current within the conductor, which is the most evident characteristic of the conductor’s consumption of electrical energy and heat. This obstruction to the current is known as the object’s resistance. In everyday life, a resistor (Resistor) is generally referred to directly as a “resistor.” It is often abbreviated as “R” and is a fundamental property of a conductor, related to the conductor’s size, material, and temperature.
Ohm’s law states that I=U/R, and from this we can derive R=U/I. The basic unit of resistance is the ohm, represented by the Greek letter “Ω”. Ohm means the resistance to the flow of an ampere of current through a conductor when subjected to a voltage of 1 volt. The primary function of a resistor is to impede the flow of current. The term “resistance” refers to a property, while “resistor” is commonly used in electronics to refer to a component that exhibits that property. The term “ohm” is often shortened to “ohm”. Common units of resistance include kilo-ohm (kΩ), mega-ohm (MΩ), and milli-ohm (mΩ). The primary physical characteristic of a resistor is its ability to convert electrical energy into heat. It is an energy-consuming element that, when current passes through it, generates internal energy. In a circuit, a resistor typically functions as a voltage and current divider. It allows both AC (alternating current) and DC (direct current) signals to pass through.
What is a Slim metal precision alloy current detection resistor?
Slim metal alloy current sense resistors are specifically designed for accurate current measurement in electronic circuits. They offer low resistance values, high precision, and good thermal stability, making them ideal for applications where precise current monitoring is crucial. These resistors are often used in power supplies, motor control, and battery management systems to ensure efficient and reliable operation.
Characteristics and Parameters of Slim Metal Precision alloy current sensing resistors
| Item | Test condition/ Methods | Limited | Standard | ||
|---|---|---|---|---|---|
| Temperature coefficient of resistance | TCR =(R-R0)/R0(T2-T1)X 106 R0 : resistance of room temperature R: resistance of 125℃ T1: Room temperature T2: Temperature at 125℃ | Refer to Spec | MIL-STD-202 Method 304 | ||
| Short time Overload | Applied Overload for 5 seconds, then measure its resistance variance rate. (Test condition refer to below): | ≤±1.0% | IEC60115-1 4.13 | ||
| Type | Resistance(mΩ) | Rated power | |||
| 0612 | 1 ≤R≤10 | 4 times | |||
| 10 ＜R≤25 | 3 times | ||||
| 0508 | 1 ≤R≤8 | 4 times | |||
| 9≤R≤10 | 3 times | ||||
| Resistance to Soldering Heat | 260℃±5℃ time ：12sec± 0.5sec | ≤±0.5% | MIL-STD-202 Method 210 | ||
| Solderability | Temperature of Solder：245±5℃ Dipping time:3±0.5s | Solder coverage over 95% | IEC60115-1 4.17 | ||
| Temperature Cycling | -55℃ (15min)/+150℃(15min), 300 cycles | ≤±1.0% | MIL-STD-202 Method107G | ||
| Low temperature Storage | -55℃ for 1000hours, No power | ≤±1.0% | IEC60115-1 4.23.4 | ||
| High Temperature Storage | 150℃ for 1000hours, No power | ≤±1.0% | IEC60115-1 4.25 | ||
| Bias Humidity | +85℃ , 85% RH ，10%bias, 1000hours | 0612： 1.5~10mR,△R≤±1% 11~20mR,△R≤±2% 0508： 1~8mR,△R≤±1% 9~10mR,△R≤±2% | MIL-STD-202 Method103 | ||
| Vibration | 5g's for 20 minutes 12 cycles each of 3 orientations. Test from 10 Hz - 2000 Hz | ≤±0.5% | MIL-STD-202 Method 201 | ||
| Operational life | 70℃±2℃, 1000 hours, at rated power 1.5 hours “ON”, 0.5 hours “OFF” | 0612： 1.5~9mR, △R≤±1% 10~14mR, △R≤±3% 15~20mR, △R≤±5% 0508： 1~8mR,△R≤±1% 9~10mR,△R≤±3% | MIL-STD-202 Method 108 | ||
| Moisture resistance | MIL-STD-202,method106 ， No power, 7b not required | ≤±0.5% | MIL-STD-202 Method 106 | ||
Slim Metal Alloy Current Sense Resistors in Circuits
The principle of the current sense resistor is to convert a portion of the current or voltage in a circuit into a measurable signal by means of a resistor dividing the voltage in the circuit according to Ohm’s law. For current sense resistors, you can use Ohm’s law to calculate the amount of current in the circuit, i.e., I=V/R, where V is the voltage difference between the two ends of the resistor, and R is the resistance value of the resistor.
In a current‐sense circuit, the voltage across the sense resistor is given by the formula
U2=U1×R2 ÷ (R1+R2)
Here, U₁ is the total voltage of the circuit under test, R₁ is the series resistance of the rest of the circuit, R₂ is the resistance of the current‐sense resistor, and U₂ is the resulting voltage drop across R₂.
When implementing the performance of a current-sense resistor, the printed circuit board (PCB) must be designed with precision. Current sensing should be as comprehensive as possible, utilizing multiple layers and through-holes connected near the sensing component. This approach also enhances heat dissipation. The optimal method is to connect the four terminals to a two-port through-hole resistor and to use the reverse side of the PCB to route the current and voltage paths. If this is not feasible, the current and voltage detection connections should be made to the component pins on either side.
PROSEMI’s ultra-thin, ultra-low resistance resistor series combines outstanding performance and compactness, with package sizes ranging from 0402 to 1206, rated power from 0.25W to 1W, and resistance values from 5mΩ to 50mΩ. These resistors have a thickness of less than 0.4mm and are designed for applications that require extremely small space and high efficiency, such as battery packs, inverters, consumer electronics, and other fields.