8 ingenious applications of zero-resistance resistors in circuit design
A component often used in electronic circuit design is resistor. We all know that resistors play a role in dividing voltage and limiting current in a circuit. However, in real life, a special type of resistor is used: a zero-resistance resistor. As name implies, resistance value of a zero-resistance resistor is zero. For beginners, question may arise: since resistance is zero, then how does it differ from a wire? Why not connect directly?
Actually, there is still a difference between zero-resistance resistors and direct-wiring, and zero-resistance resistors have many ingenious uses in circuitry.
Debugging and Compatibility
When designing PCBs, we need to consider compatibility issues as much as possible, since PCB is physically fixed after it has been physically printed and copper plated. If compatibility issues are not fully taken into account during design, this will cause a lot of inconvenience to engineers during board debugging stage.
For example: a certain chip pin has two functions, for example, it can control a buzzer, and it can also be used to control an LED. However, these two functions cannot work at same time. In order to realize excitation period on same PCB, you can choose which period to control. At this time, you can add a zero resistance resistor to line connecting buzzer and LED, and solder resistor with zero resistance on which path. The European circuit decides whether to drive buzzer or LED.
At stage of PCB layout and routing, sometimes there is a situation where wiring always fails, especially when PCB area is small, there are many connections, and number of layers is small. If you come across a certain connection that needs to be wound in a large circle for connection, at this time you might consider whether it is easy to run wire in front of you by connecting a resistor with zero resistance instead of winding large circle. .
Reserved space for resistance
If it is not clear at circuit design stage which resistor value to connect to a particular position, at this time you can reserve a welding position for resistor at that position and solder resistor with zero resistance. When debugging actual circuit, it is convenient to change resistors with different resistance values, and then connect corresponding resistors after debugging and confirming resistance parameters.
Convenient to test current one
After designing a circuit system, it is usually necessary to check power consumption of entire circuit during its operation. The usual method is to calculate power consumption by checking current and then using current, and current checking method is usually to include an ammeter in circuit to measure.
Currently, if you place a zero ohm resistor where you want to measure current, remove resistor and connect an ammeter when you need to measure current. In normal operation, just solder zero ohm resistor directly.
Due to characteristics of zero resistance resistor itself, it can effectively suppress loop current, thereby suppressing noise. Actually zero resistance is not really an impedance, only superconductors can really achieve zero impedance. Thus, resistors with zero resistance actually play the role of attenuation in all frequency ranges.
Many PCBs often have many pins that need to be bridged. Or use a DIP switch to control whether circuit is closed. Although these two methods are more convenient during debugging phase, it is best to use them as little as possible during production. Since free spikes are equivalent to antennas in high frequency circuits, it is easy to interfere with signal.
In addition, DIP switches can be easily confused by uninformed people, resulting in circuit system errors. Therefore, for safety reasons, it is better to use resistors with zero resistance instead of pins and DIP switches. This can not only avoid improper operation, but also reduce maintenance costs.
Act like a capacitive inductor
In a high-frequency circuit system, a zero-resistance resistor can act as a small capacitor or inductor if it matches characteristics of external circuit, which can solve EMC problem well. For example, between ground and ground, or between power and chip pins.
Ground wire insulation
In ICs, analog ground is called AVSS and digital ground is called VSS. AVSS and VSS are usually separated internally because separation of bottom row can prevent current signals from interfering with each other when analog circuit and digital circuit work.
However, at board level, foundations usually end up connected to each other. At this time, let AVSS and VSSPIN chip first pass through zero resistance resistor, and then connect together to play a role in isolation.
Above are eight great uses for zero ohm resistors that have been featured this time around. If you are an electronics engineer, knowing some design skills will help you solve problems at work comfortably and quickly. In addition to use of zero-resistance resistors presented this time, transistors, magic use of capacitors, use of inductors, and various design and simulation software used in circuit design are also used, which can improve work efficiency. .
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