Inductor Overview and Applications
Thought for 4 sec
This part is a generic fixed inductor: a passive two-terminal component that stores energy in a magnetic field when current flows through it.
Purpose
An inductor resists changes in current. In circuits, it is commonly used to:
- Store and transfer energy in switching power supplies
- Filter noise and ripple
- Block high-frequency signals while passing DC or low-frequency current
- Form resonant LC circuits with capacitors
- Provide impedance matching or RF tuning
The main electrical behavior is:
Where:
- V is the voltage across the inductor
- L is inductance
- di/dt is the rate of current change
This means a larger inductance produces more opposition to fast current changes.
Common functions include:
- Energy storage: especially in buck, boost, and buck-boost converters
- Filtering: smoothing current ripple in power rails
- Choking: suppressing high-frequency noise
- Resonance: tuning oscillator, RF, and filter circuits
- Current shaping: slowing transient current changes
When current starts increasing through the inductor, the magnetic field builds up and the inductor develops a voltage opposing that increase. When current decreases, the collapsing magnetic field releases stored energy and tries to keep current flowing.
In a switching regulator, for example:
- During the switch-on phase, current ramps up through the inductor
- Energy is stored in the magnetic field
- During the switch-off phase, the inductor releases energy into the load
- This creates a smoother output current when combined with capacitors
In a filter, the inductor’s impedance increases with frequency:
So higher-frequency noise sees more impedance and is attenuated.
Notable characteristics
Important inductor parameters include:
- Inductance value: e.g. nH, µH, or mH range
- Current rating: maximum continuous current before overheating or saturation
- Saturation current: current where inductance drops significantly
- DC resistance, DCR: winding resistance that causes voltage drop and power loss
- Q factor: important for RF and resonant applications
- Self-resonant frequency, SRF: above this, parasitic capacitance dominates
- Shielding: shielded inductors reduce magnetic field leakage
- Package size: affects current rating, resistance, and thermal performance
Typical use cases include:
- DC-DC buck converters
- Boost converters
- EMI filters
- LC low-pass filters
- RF matching networks
- Oscillators and resonant tanks
- Power rail noise suppression
- Audio crossover networks
- Sensor excitation circuits
- Motor and solenoid drive filtering
This part belongs to Flux’s generic passive component family, specifically the generic fixed inductor family. It is not one manufacturer-specific model; instead, it is a configurable generic component intended for rapid schematic and PCB development.
Its footprint adapts based on the selected package, supporting common SMD sizes and inductor package families such as:
- 0402 / 0603 / 0805: small chip inductors, usually for RF, signal filtering, and low-current applications
- SDR1806: larger power inductor format, suitable for switching regulators
- PA4320: high-current power inductor style
- SRN6028: shielded power inductor package, useful where EMI control matters
- SRR1260: larger shielded drum-core power inductor, suitable for higher-current DC-DC designs
The main configurable differences are:
Table
| Variation | Effect |
|---|---|
| Inductance value | Sets filtering, energy storage, or resonance behavior |
| Package size | Determines PCB area, current capability, and thermal performance |
| Shielded vs unshielded style | Affects EMI performance |
| DCR | Impacts efficiency and voltage drop |
| Saturation current | Determines maximum usable current |
| Self-resonant frequency | Important for RF/high-frequency filtering |
- 1 nH to 100 nH: RF matching, high-frequency filters, antennas
- 100 nH to 1 µH: high-speed filtering, compact DC-DC converters
- 1 µH to 100 µH: common switching regulator inductors
- 100 µH to 1 mH: lower-frequency filtering, energy storage, signal conditioning
- mH range: audio, sensor, and low-frequency filter applications
Compared with a real manufacturer-specific inductor, this generic part is best for early design work and topology capture. For final production, it should usually be replaced or configured to match a real inductor with known:
- Saturation current
- RMS current rating
- DCR
- tolerance
- shielding type
- thermal behavior
- availability and cost
In short: this part is a flexible placeholder/configurable inductor for building circuits quickly, while the final design should select a concrete inductor model based on current, frequency, efficiency, size, and EMI requirements.
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