SMD Inductor Code Calculator

1. Coding Systems

SMD inductors use various coding systems to indicate their inductance values and specifications. The most common systems include:

EIA (Electronic Industries Alliance) System
IEC (International Electrotechnical Commission) System
Manufacturer-specific codes
Direct value marking

2. EIA Code Format

The EIA coding system uses a three or four-character code:

First two digits: Significant figures
Third digit: Multiplier (power of 10)
Optional fourth character: Tolerance code
Example: "102K" = 1.0 × 10² μH ±10%

3. Package Sizes

Common SMD inductor package sizes include:

0402 (1.0mm × 0.5mm)
0603 (1.6mm × 0.8mm)
0805 (2.0mm × 1.25mm)
1008 (2.5mm × 2.0mm)
1210 (3.2mm × 2.5mm)

4. Selection Criteria

Key factors in SMD inductor selection:

Inductance value and tolerance
DC resistance (DCR)
Saturation current rating
Self-resonant frequency (SRF)
Operating temperature range
Shielding requirements

5. Applications

SMD inductors are widely used in:

Power supplies and voltage regulators
RF and wireless circuits
EMI/RFI filtering
Signal conditioning
Battery charging circuits

6. Design Considerations

Important aspects in SMD inductor implementation:

PCB layout optimization
Thermal management
EMI/EMC compliance
Cost and availability
Reliability requirements

7. Marking Systems

Detailed explanation of marking systems:

System	Format	Example	Notes
EIA-96	3-digit code	220 = 22μH	Most common
IEC	μH direct	22μ = 22μH	European std
JIS	Letter code	22K = 22μH	Japanese std

8. Performance Parameters

Critical performance specifications for SMD inductors:

Ferrite Cores

High permeability
Good EMI suppression
Low core losses
Temperature stable

Iron Powder Cores

High saturation
Good power handling
Cost effective
Stable inductance

9. Reliability Factors

Key reliability considerations:

Environmental Factors

Temperature cycling
Humidity resistance
Mechanical stress
Chemical exposure

Electrical Stress

Current derating
Voltage isolation
Surge handling
EMI immunity

10. Selection Guide

Step-by-step guide for selecting SMD inductors:

Step	Considerations	Critical Parameters
Initial Selection	Application requirements Space constraints	Inductance value Package size
Performance Review	Operating conditions Environmental factors	Current rating Temperature rise
Final Verification	Cost considerations Availability	Tolerance Reliability data

Additional selection considerations:

Cost and Availability:

Budget constraints
Supply chain reliability
Alternative sources
MOQ requirements

Manufacturing Considerations:

Assembly process compatibility
Reflow soldering profile
Moisture sensitivity level
Handling requirements

Quality and Reliability:

Manufacturer reputation
Qualification requirements
Expected lifetime
Failure rate specifications

12. Troubleshooting Guide

Common issues and solutions in SMD inductor applications:

Issue	Possible Causes	Solutions
Excessive Heating	Current exceeding rating Poor thermal design High ambient temperature	Verify current requirements Improve thermal management Consider larger package size
EMI Problems	Insufficient shielding Poor PCB layout Wrong core material	Use shielded inductors Optimize PCB layout Select appropriate core
Value Drift	Temperature effects Core saturation Mechanical stress	Use stable core material Check operating conditions Improve mounting method

Additional troubleshooting considerations:

Assembly Issues:

Solder joint reliability
Component placement accuracy
Thermal stress during reflow
Handling damage

Performance Issues:

Frequency response problems
Q factor degradation
Impedance matching issues
Core saturation effects

Reliability Issues:

Environmental stress failures
Long-term stability
Moisture sensitivity
Thermal cycling effects

Understanding SMD Inductor Codes