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:

8. Performance Parameters

Critical performance specifications for SMD inductors:

9. Core Materials

Common core materials and their characteristics:

• Ferrite Cores:
  • High permeability: 500-15000
  • Good for high frequency
  • Temperature stable
  • Cost effective
• Iron Powder Cores:
  • Lower permeability: 10-100
  • Better saturation handling
  • Suitable for power applications
  • Good cost/performance ratio

10. Reliability Factors

Key reliability considerations:

• Environmental Factors:
  • Temperature cycling resistance
  • Humidity resistance
  • Mechanical shock tolerance
  • Vibration resistance
• Electrical Stress:
  • Current derating
  • Voltage isolation
  • Surge handling
  • EMI immunity

11. Selection Guide

Systematic approach to SMD inductor selection:

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:

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