How Do I Choose the Best Resistor Power Rating?

SMD Resistor and Chip Fixed Resistor are one of the metallic glass glaze resistors. It is a resistor made by mixing metal powder and glass glaze powder and printing on the substrate by screen printing method ^[1] . Resistant to humidity and high temperature with a small temperature coefficient. Can greatly save circuit space costs and make the design more refined.

Chip resistors are divided into the following categories:

Types of	Reference International Classification
Conventional series thick film chip resistor	General purpose General purpose, 0201-0805 General purpose, 1206-2512
High precision and high stability chip resistor	High precision-high stability High precision-high stability, 0201-0603 High precision-high stability, 0805-1210 High precision-high stability, 2010-2512

High Precision Chip Resistors-Features and Applications of AR Series

Super precision ± 0.01% ~ ± 1%

TaN and NiCr vacuum sputtering

Temperature coefficient is only ± 5PPM / ° C ~ ± 50PPM / ° C

Wide R-Value range

Products with Pb-free Terminations Meet RoHS Requirments

Medical equipment

Precision measuring instrument

-Electronic communications, converters, printers

Automatic Equipment Controller

Communication Device, Cell phone, GPS, PDA

General consumer products

Conventional series thin film chip resistors

General purpose thin film General purpose thin film, 0201-2512

Low resistance chip resistor

Low ohmic Low ohmic, 0402-1206

Low ohmic, 2010-2512

Chip resistor array

Arrays Arrays, convex and concave

SMD Current Sensor

SMD current sensors Current Sensors-Low TCR

SMD network resistor

Network Network, T-type and L-type

Other chip thick film exclusion, chip wire resistance, chip high voltage resistance, chip

Small size and light weight;

Adapt to reflow and wave soldering;

· Stable electrical performance and high reliability;

· Low assembly cost and match with automatic placement equipment;

· High mechanical strength and excellent high frequency characteristics.

Naming method of domestic chip resistors:

1. Naming with 5% accuracy: RS-05K102JT

2. Naming with 1% accuracy: RS-05K1002FT

R-for resistance

S-indicates that power 0402 is 1 / 16W, 0603 is 1 / 10W, 0805 is 1 / 8W, 1206 is 1 / 4W, 1210 is 1 / 3W, 1812 is 1 / 2W, 2010 is 3 / 4W, and 2512 is 1W.

05-indicates the size (inch): 02 means 0402, 03 means 0603, 05 means 0805, 06 means 1206, 1210 means 1210, 1812 means 1812, 10 means 2010, and 12 means 2512.

K-the temperature coefficient is 100PPM,

1025% precision resistance value representation: the first two digits represent significant digits, and the third digit represents how many zeros, the basic unit is , 102 = 1000 = 1K. 1002 is a 1% resistance value representation: the first three digits represent significant digits, and the fourth digit represents how many zeros there are. The basic unit is , 1002 = 10000 = 10K.

J-indicates the accuracy is 5%, F-indicates the accuracy is 1%.

T-indicates taping packaging

The accuracy of the chip resistor resistance has ± 1%, ± 2%, ± 5%, and ± 10% accuracy. The most commonly used are ± 1% and ± 5%.

The convention of ± 5% accuracy is to use three digits to represent Example 512, the first two digits are significant digits, and the third digit 2 indicates how many zeros there are. The basic unit is , which is 5100 ohms, 1000 = 1K, 1000000 = 1M

In order to distinguish between ± 5% and ± 1% resistance, the ± 1% resistance is usually represented by 4 digits.

In this way, the first three digits indicate significant digits, and the fourth digit indicates how many zeros 4531 is 4530, which is equal to 4.53K

SMD components have small size, light weight, high installation density and strong shock resistance. It has the advantages of strong anti-interference ability and good high-frequency characteristics. It is widely used in computers, mobile phones, electronic dictionaries, medical electronics, camcorders, electronic watt-hour meters and VCD machines. SMD components can be divided into rectangular, cylindrical and special shapes according to their shape ^[2]

At present, the most widely used chip resistor size codes are 0805 and 1206. And gradually there is a trend to 0603. Two packages of 0402 and 0201 are often used in products with higher integration, and they also have higher requirements for the SMT process level. The most commonly used tolerance is J.

When selecting various resistors, capacitors, and inductors, users need to make targeted selection and purchase according to the application of the component. If you encounter the use of several types of chip components, you can purchase more, but because the chip resistors are very small How to save and organize has brought a lot of trouble to the engineer. It is recommended that the engineer can purchase a small component box to store the component while purchasing the component, but because this small box is not tightly sealed, when the component is When stored in a humid area for a long time, oxidation will be caused at the welding place to cause false welding, or a sample book of Transistor chip resistors can be purchased to avoid the above problems and a full range of resistors can be purchased, but the cost is higher, and the number of each type not much.

SMD resistor is a product with small size, light weight, stable electrical performance, high reliability, low assembly cost, high mechanical strength, and excellent high frequency characteristics. Its minimum precision can reach ultra precision ± 0.01% ~ ± 1% ^[4]

What is a precision chip resistor? The precision chip resistor is that the error of the chip resistor is relatively small. It is generally called the 1% chip resistor. The minimum error (accuracy) can reach 0.01%. The temperature coefficient is as low as ± 5ppm / , which is rarely done in the industry: its Can be applied to precision instruments, communication electronic products and portable electronic products.

So many people will ask, if the chip resistance is so small, can it be distinguished without testing 5% and 1%?

Good question, then let's compare the difference between 5% and 1% chip resistors.

5% series chip resistors are represented by 3 characters: the first two digits of this method represent the significant digits of the resistance value, and the third digit represents the number of "0" should be added after the significant digits. When the resistance is less than 10 In the code, R is used to indicate the position of the decimal point of the resistance value.This representation is usually used in the series with a resistance error of 5%. For example: 330 means 33 instead of 330; 221 means 220; 683 means 68000 or 68k; 105 means 1M; 6R2 means 6.2.

1% series precision chip resistors are represented by 4 characters: the first 3 digits of this representation represent the significant digits of the resistance value, and the 4th digit represents the number of 0s that should be added after the significant digits. When the resistance is less than 10, the code still uses R to indicate the position of the decimal point of the resistance value. This representation method is generally used in precision resistor series with a resistance value error of 1%. For example: 0100 means 10 instead of 100; 1000 means 100 instead of 1000; 4992 means 49900, which is 49.9k; 1473 means 147000, which means 147k; 0R56 means 0.56.

Chip resistors are engraved on the surface. If there are only three digits, the error is 5%. If there are four digits, the error is 1%.