ERJ-2RKF1004X vs ERJ-3EKF49R9V
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| Category | Chip Resistor - Surface Mount | Chip Resistor - Surface Mount |
| Manufacturer | Panasonic Electronic Components | Panasonic Electronic Components |
| Description | RES SMD 1M OHM 1% 1/10W 0402 | RES SMD 49.9 OHM 1% 1/10W 0603 |
| Package | Tape & Reel (TR) | Tape & Reel (TR) |
| Series | ERJ-2RK | ERJ-3EK |
| Features | Automotive AEC-Q200 | Automotive AEC-Q200 |
| Operating Temperature | -55°C ~ 155°C | -55°C ~ 155°C |
| Package / Case | 0402 (1005 Metric) | 0603 (1608 Metric) |
| Supplier Device Package | 0402 | 0603 |
| Tolerance | ±1% | ±1% |
| Temperature Coefficient | ±100ppm/°C | ±100ppm/°C |
| Size / Dimension | 0.039" L x 0.020" W (1.00mm x 0.50mm) | 0.063" L x 0.031" W (1.60mm x 0.80mm) |
| Power (Watts) | 0.1W, 1/10W | 0.1W, 1/10W |
| Ratings | AEC-Q200 | AEC-Q200 |
| Height - Seated (Max) | 0.016\" (0.40mm) | 0.022\" (0.55mm) |
| Failure Rate | - | - |
| Resistance | 1 MOhms | 49.9 Ohms |
| Composition | Thick Film | Thick Film |
| Number of Terminations | 2 | 2 |
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1. How to choose Chip Resistor?
The application of surface mount technology (SMT) has been very common, and the proportion of electronic products assembled by SMT has exceeded 90%. my country began to introduce SMT technology in the 1980s. With the development of small SMT production equipment, the application scope of SMT is further expanding. Aviation, aerospace, instrumentation, machine tools and other fields are also using SMT to produce various small-volume electronic products or components.
In recent years, in addition to electronic product developers using SMT devices to develop new products, maintenance personnel have also begun to repair electronic products assembled by SMT technology in large quantities.
The models of SMT resistors are not uniform, and are set by each manufacturer, and the models are particularly long (consisting of more than a dozen English letters and numbers). If you can correctly propose various parameters and specifications of SMT resistors when purchasing, you can easily purchase (or order) the required resistors.
There are 5 parameters for SMT resistors, namely size, resistance, tolerance, temperature coefficient and packaging.
1. Size series SMT resistor series generally have 7 sizes, represented by two size codes. One size code is a 4-digit EIA (Electronics Industry Association) code, the first two digits and the last two digits represent the length and width of the resistor, in inches. The other is a metric code, also represented by 4 digits, in millimeters. Resistors of different sizes have different power ratings. Table 1 lists the codes and power ratings of these seven resistor sizes.
2. Resistance series The nominal resistance is determined by series. Each series is divided by the tolerance of the resistor (the smaller the tolerance, the more resistance divisions), among which the most commonly used is E-24 (the tolerance of the resistance value is ±5%), as shown in Table 2.
The resistance value is indicated by three digits on the surface of the chip resistor, of which the first and second digits are valid numbers, and the third digit indicates the number of zeros. When there is a decimal point, it is indicated by "R" and occupies one valid digit. The nominal resistance code representation method is shown in Table 3.
3. Tolerance The tolerance of chip resistors (carbon film resistors) has 4 levels, namely F level, ±1%; G level, ±2%; J level, ±5%; K level, ±10%.
4. Temperature coefficient The temperature coefficient of chip resistors has 2 levels, namely W level, ±200ppm/℃; X level, ±100ppm/℃. Only resistors with tolerance level F use level x, and resistors with tolerance levels of other levels are generally level w.
5. There are two main types of packaging: bulk and tape and roll.
The operating temperature range of chip resistors is -55--+125℃, and the maximum operating voltage is related to the size: 0201 is the lowest, 0402 and 0603 are 50V, 0805 is 150V, and other sizes are 200V.
6. The numbers on the surface of the chip resistors are arranged horizontally, and are specified to be represented by three digits, of which the first two are valid digits, and the third is the exponent of 10, in units of ohms. For example: 473 means 47×103=47 kΩ. If the second character on the surface of the resistor used to indicate the resistance value is the letter R, it represents a decimal point, for example: 5R1 means the resistance value is 5.1Ω. -
2. Resistance value representation method
In the digital identification of chip resistors, the first three digits are usually used to indicate the resistance value. These digits are interpreted in decimal, such as "100" means the resistance value is 100 ohms. In some cases, if the resistor value is large, "R" may be used to indicate the decimal point position, such as "1R0" for a resistor value of 1.0 ohm.
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3. Resistor tolerance accuracy representation method
The tolerance accuracy of chip resistors refers to the allowable deviation range between the actual value of the resistor and the nominal value. In the digital identification, the tolerance accuracy is usually indicated by the last one or two digits. These numbers correspond to different accuracy levels, for example, 1% accuracy is usually indicated by the number "1", while 0.1% accuracy is indicated by the number "01".
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4. Resistor digital identification interpretation example
To better understand the interpretation method of chip resistor digital identification, let's look at an example. Assuming that the digital identification on a chip resistor is "1001", what is the resistance value of this resistor? What is the accuracy?
First, we interpret the first three digits "100", indicating that the resistance value is 100 ohms. Next, we look at the last digit "1", which indicates that the tolerance accuracy of the resistor is 1%. Therefore, the resistance of this chip resistor is 100 ohms and the tolerance accuracy is ±1%.
