What are passive electronic components?

Passive electronic components are those that do not require an external power source to work, they do not produce energy, but can absorb, store, or dissipate energy. Such components do not need to be connected to an external power source to function properly, and they rely solely on the energy of the input signal to perform their functions. This feature makes passive components more convenient in specific application scenarios, because there is no need to worry about power supply and related management issues. Because passive components do not have built-in energy or power amplification, they cannot amplify the input signal and can only transmit, adjust, or transform the signal characteristics. Therefore, in circuit design, passive components are mainly used for signal connection and matching, rather than signal amplification. Common passive components include resistors (which limit current and consume electrical energy), capacitors (which store charge and release it when needed), and inductors (which store energy through magnetic fields). These components are widely used in filters, oscillators, voltage dividers and other circuits, and are the cornerstone of building complex electronic systems.

What are passive electronic components and their functions

Resistors: Control parameters such as current, voltage, and power in a circuit by blocking the flow of current. Resistors can be used for voltage division, current limiting, energy dissipation, etc.

Capacitor: A passive element that can store charge, mainly for storing and releasing charge. Capacitors can be used for signal filtering, coupling, decoupling and separation.

Inductor: A component with induced electromotive force and self-inductance, mainly used for frequency selection and signal filtering in circuits. Inductors can also be used for energy storage and choke.

Diode: A diode is a component that allows current to flow in only one direction and is used to rectify AC signals to DC, voltage regulation, limiting, and other operations.

Transformer: Although sometimes considered a passive component, it is primarily used to transform alternating voltage or current. Transformers can raise or lower the voltage and can also be used to isolate the circuit.

Relay: A switching device that controls the on-off state of one or more circuits, usually by electromagnetic or mechanical force.

Button: A simple switch used to manually control the on-off of a circuit.

Buzzer, horn: used to convert electrical signals into sound signals, used as alarm or audio output devices.

Photoelectric switch: A sensor that uses blocked or reflected light to detect the presence or absence of an object, often used as a switch in automated control.

Connectors: Used to connect different circuits or devices to ensure the continuity of signal and power.

What are the important parameters of different passive components?

Different types of passive components have their own unique and important parameters, which determine the performance and application range of the component. Below INFINITECH lists the main parameters of some common passive components:

resistor

• Resistance value: Indicates the degree to which the resistor prevents the flow of current, usually in ohms (Ω).

• Rated power: The maximum power at which a resistor can operate continuously for a long time, usually in watts (W).

• Temperature coefficient: The ratio of resistance to temperature, usually in ppm/°C.

• Tolerance: The maximum percentage at which the resistance value may deviate from the nominal value during manufacturing.

• Noise: Fluctuations in voltage or current caused by a material over a certain frequency range.

condenser

• Capacitance: Indicates the ability of a capacitor to store charge, usually in farads (F) or microfarads (μF).

• Voltage resistance: The maximum voltage that a capacitor can withstand, beyond which damage may result.

• Loss Angle tangent: indicates the ratio of energy loss within the capacitor, also known as the loss factor.

• Temperature coefficient: The ratio of capacitance to temperature, usually measured in ppm/°C.

• Equivalent series resistance: Resistance inside a capacitor that affects high frequency performance.

inductor

• Inductance: Indicates the ability of the inductor to store magnetic field energy, usually in Henry (H) or millihen (mH) units.

• Dc resistance: The DC resistance of the inductor coil.

• Quality factor: A measure of the efficiency of the inductor, the higher the Q value, the smaller the loss.

• Saturation current: The maximum DC current of the inductor before it begins to enter the magnetic saturation state.

• Self-resonant frequency: The frequency at which the parasitic capacitance of an inductor resonates with its inductor.

diode

• Forward voltage drop: The voltage at both ends of the diode when it is on.

• Reverse breakdown voltage: The reverse voltage at which the diode starts to turn on.

• Maximum rectified current: The maximum DC current that the diode can continuously pass through.

• Reverse leakage current: The current through which the diode is reverse-biased.

transformer

• Transformer ratio: The ratio of turns between primary and secondary windings.

• Efficiency: The ratio of output power to input power.

• Operating frequency: The operating frequency range of the transformer design.

• Insulation class: indicates the highest temperature that the transformer can withstand.

relay

• Switching ability: The maximum voltage and current that the relay contact can switch.

• Coil resistance: The resistance value of the relay coil.

• Operating voltage: The minimum voltage required to make the relay pull in.

• Release voltage: The minimum voltage required by the relay to release the contact.

How to understand the data table of passive components?

Data table structure

Data tables usually organize information in a certain format and contain the following sections:

Product description: Basic information of the component, such as type, model, manufacturer, etc.

Technical specifications: key technical parameters of components.

Electrical characteristics: specific technical parameters and their numerical ranges.

Physical characteristics: size, weight and other physical attributes.

Environmental conditions: Operating temperature range, humidity requirements.

Installation Guide: Recommended installation methods and precautions.

Certification and standards: Compliant safety standards and certification information.

Other general information

Package type: The physical size and package form of the component.

Installation mode: Surface mount (SMD) or through-hole (Through Hole).

Certification information: Compliant safety standards and certification information.

Tips for reading data sheets

• Before you read the data sheet, determine which parameters your application needs.

• Verify that the units and magnitude used are correct.

• Pay attention to the limit parameters of the components and avoid exceeding these limits.

• If there are multiple options, compare the data from different components to make the best choice.

• If something is unclear in the data sheet, you can contact the manufacturer for more information.

What types of circuits or devices are passive components commonly used in?

Passive components are widely used in various types of circuits and devices because of their simplicity and reliability. Below, INFINITECH lists some examples of passive components used in typical circuits and devices:

1. Power supply circuit

Passive components play a key role in power supply circuits. Resistors are used to limit current, divide voltage, and protect circuits from overcurrent. Capacitors are used to filter, regulate and smooth the supply voltage to ensure stable output voltage. Inductors are used in filtering circuits to help remove ripples and noise from power supplies, but also to store energy and improve power efficiency.

2. Filter

In filter design, resistors and capacitors can be combined to form RC filters for low-pass, high-pass, band-pass, or band-stop filtering. The inductor and capacitor combine to form an LC filter, which is especially suitable for high-frequency filtering and effectively removes noise and clutter in the signal.

3. Amplifier circuit

In the amplifier circuit, resistors are used to set the gain, bias and feedback path to ensure the stability and linearity of the amplifier. Capacitors are used for coupling, decoupling and bypass to ensure signal purity and reduce signal distortion.

4. Oscillator circuit

The oscillator circuit uses passive components to produce a stable frequency output. Resistors are used to set the frequency and amplitude of the oscillation. The capacitor and the inductor together form the core of the LC oscillator and together determine the oscillation frequency.

5. Signal processing circuit

In signal processing circuits, resistors are used for signal attenuation, matching, and balancing. Capacitors are used for signal coupling, decoupling, and filtering, helping to maintain signal integrity. Inductors are used to build notch filters or notch circuits to remove unwanted frequency components.

6. Radio and communication equipment

In radio and communication equipment, resistors are used in signal modulation and demodulation circuits. Capacitors are used for frequency selection and signal filtering to ensure the clarity of the signal. Inductors are used for antenna tuning and impedance matching to optimize signal transmission efficiency.

7. Measuring instruments

In measuring instruments, resistors are used to construct voltage dividers in order to accurately measure voltage. Capacitors are used to build integrators and differentiators to help analyze trends in the signal. Inductors are used to construct filters to ensure signal accuracy and stability.

8. Control system

In a control system, resistors are used to set the time constant of the control loop to ensure that the response speed of the system is appropriate. Capacitors are used to delay or smooth control signals, improving the stability and reliability of the system. Inductors are used to build filters in the control loop to prevent electromagnetic interference.

9. Sensor interface circuit

In the sensor interface circuit, a resistor is used to convert the sensor signal into a readable voltage or current. Capacitors are used to filter out the noise in the sensor signal and improve the signal quality. The inductor is used to construct the filter circuit of the sensor signal to ensure the purity of the signal.

10. Protect the circuit

In protection circuits, resistors are used to limit current and prevent overload. Capacitors are used to absorb transient voltage spikes and protect the circuit from voltage shocks. Inductors are used to limit the rate of current change, prevent electromagnetic interference, and ensure the safe operation of the circuit.

These are just a few examples of the practical applications of passive components. Due to their simplicity and reliability, passive components can be found in almost any type of circuit or device. Whether in consumer electronics, industrial control systems, or scientific research instruments, passive components are indispensable basic components.

How to select suitable passive components in actual circuit design?

Define application requirements

Understand the specific uses of the circuit, such as amplification, filtering, oscillation, etc.

Determine the most critical parameters in the circuit design, such as frequency response, signal gain, noise level, etc.

Select element type

Resistor: Select the appropriate resistance value and power level according to the needs of the circuit.

Capacitors: Select the appropriate capacity and voltage level according to the frequency range and operating voltage of the circuit.

Inductors: Select the appropriate inductance and saturation current according to the desired operating frequency and current level.

Lookup table

Carefully review the data sheet of the component to ensure that the component specifications meet the requirements of the circuit design.

Verify that the operating temperature range, voltage range, etc. of the component are suitable for your application environment.

Consider electrical characteristics

Make sure the resistance and capacitance match the circuit design.

For capacitors, low loss factors are selected to improve the efficiency of the circuit.

For inductors, select a high Q value to reduce loss.

Consider mechanical and physical properties

Make sure the package size of the component is appropriate for the board layout.

Choose between surface mount (SMD) or through-hole (Through Hole) depending on the board design.

Consider the heat dissipation capacity of the components and the thermal management scheme of the board.

Consider cost and availability

Consider cost effectiveness while meeting performance requirements.

Make sure components are easy to procure, especially for mass production.

Conduct simulation and testing

Circuit simulation software is used to verify the circuit design and ensure that the selection of components conforms to the expected behavior.

Make circuit prototypes and perform actual tests to verify the actual performance of the components.

Environmental considerations

For temperature-sensitive applications, select components with good temperature stability.

For devices used in moving or vibrating environments, select components with strong vibration resistance.

Meet safety standards

Ensure that selected components comply with relevant safety standards and regulatory requirements.

Consider the impact of components on electromagnetic compatibility (EMC) and electromagnetic interference (EMI).

Get expert advice

If you are unsure of certain parameters, you can consult the technical support of the component manufacturer.

Discuss design options with other engineers and get a second opinion.

Following the above steps can help you choose the right passive components more systematically, ensuring the performance and reliability of the final circuit design.

Where can I buy passive components?

If you need to buy passive components, you can visit the INFINITECH Electronic Components online mall. It is a professional electronic component procurement platform that offers a wide selection of passive components, including resistors, capacitors, inductors and more. Through the platform, you can easily query detailed specifications, prices and inventory information of the components you need, and make online purchases. INFINITECH is committed to providing customers with high quality passive components and services to ensure that your circuit design achieves the desired performance. Whether used for personal projects or commercial applications, INFINITECH meets your needs.

What is the difference between passive and active components?

Passive element

Passive components do not require an external power source to work, and they cannot amplify signals or perform logical operations. Passive components are primarily used to control, store, or consume energy. They can regulate current, voltage, store charge or magnetic field energy, and filter.

• Common types:

  • Resistors: Used to limit current, partial voltage and energy dissipation.

  • Capacitors: Used for storing charge, filtering and coupling signals.

  • Inductors: Used to store magnetic field energy, filter and oscillating circuits.

• Features: Passive components do not amplify the signal and do not require a power supply to maintain its function.

Active element

Active components require an external power source to work, and they are able to amplify signals, perform logical operations, and control current. Active components are mainly used for signal amplification, switch operation, logic processing and other functions.

Common types:

Transistor: Used for amplifying signals, switching operations.

Integrated circuit: Integrates multiple active and passive components for complex signal processing and logic operations.

Vacuum tube: An early amplifier element, now mainly used in specific audio amplification applications.

Features: Active components can amplify signals, perform logical operations, and usually require a power supply.

Major difference

Passive components do not require an external power supply to operate, while active components require an external power supply.

Passive components can not amplify the signal, mainly used for signal attenuation, storage and filtering; Active components can amplify signals, perform logical operations, and switch operations.

Passive components are simple in structure and easy to integrate. Active components are often more complex and require additional power management and stability considerations.

Application scenario

Passive components are widely used in filters, voltage dividers, coupling circuits, etc.

Active components are used in amplifiers, oscillators, digital logic circuits, etc.