SG310 Inrush Current Limiter - Equivalent & Substitute Parts

Part Overview

The SG310 is an active inrush current limiter manufactured by Ametherm, part of the SURGE-GARD™ series. This component is designed to limit inrush current in power supply circuits, with a nominal resistance of 5 Ohms at ±15% tolerance and a maximum steady-state current rating of 4 A. The part is currently in active production status with 953 units in stock. Alternative components may be required due to inventory constraints, lead time considerations, or specific application requirements that demand different electrical or mechanical parameters.

Substiute Parts

SG310

AmethermIn Stock: 1034SG310 Datasheet

Current PartRFQ

B57213P0509M301

EPCOS - TDK ElectronicsIn Stock: 10312B57213P0509M301 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SG310 is based on the following critical electrical and mechanical parameters:

• Nominal resistance value: 5 Ohms
• Resistance tolerance: ±15% to ±20% (acceptable variance for inrush current limiting applications)
• Steady-state current rating: minimum 4 A (equal or higher ratings are acceptable)
• Physical form factor: cylindrical geometry with compatible lead spacing for PCB mounting
• Regulatory compliance: RoHS3 compliance and international approval certifications

The B57213P0509M301 qualifies as a substitute based on matching nominal resistance (5 Ohms), exceeding current rating (6 A vs. 4 A), and maintaining RoHS3 compliance. Tolerance variance (±20% vs. ±15%) remains within acceptable engineering margins for inrush current limiting circuits.

Parameter Comparison

Engineering Selection Recommendations

Both the SG310 and B57213P0509M301 are active production components with ROHS3 compliance. The SG310 carries CSA and UR approvals, while the B57213P0509M301 does not list specific approval agencies in the provided data. Selection between these parts should be based on:

• Circuit approval requirements: If CSA or UR certification is mandatory, the SG310 is the required choice.
• Current margin requirements: The B57213P0509M301 provides 50% additional steady-state current capacity (6 A vs. 4 A), suitable for applications requiring higher thermal headroom.
• Physical space constraints: The B57213P0509M301 has a slightly smaller diameter (0.571" vs. 0.600") and reduced lead spacing (0.295" vs. 0.310"), which may be advantageous in compact layouts.
• Tolerance specifications: The SG310's ±15% tolerance is tighter than the B57213P0509M301's ±20%, relevant for precision inrush current limiting circuits.

Frequently Asked Questions (FAQ)

Q: Can the B57213P0509M301 directly replace the SG310 in all applications?

A: Direct replacement is possible when circuit approval requirements do not mandate CSA or UR certification. The B57213P0509M301 meets the core electrical requirements (5 Ohm nominal resistance, 6 A steady-state current) and maintains RoHS3 compliance. Physical dimensions differ slightly; verify PCB layout compatibility before substitution.

Q: What is the significance of the tolerance difference (±15% vs. ±20%)?

A: Tolerance defines the acceptable resistance range at 25°C. The SG310's ±15% tolerance provides tighter control (4.25 Ohms to 5.75 Ohms) compared to the B57213P0509M301's ±20% range (4.0 Ohms to 6.0 Ohms). For inrush current limiting, this difference is typically acceptable; however, precision-critical applications may require the SG310.

Q: Why does the B57213P0509M301 have lower resistance at current (106 mOhms vs. 150 mOhms)?

A: Resistance at current reflects the component's thermal behavior under operating conditions. Lower resistance at current indicates better thermal stability and lower power dissipation, which is advantageous for extended operation at maximum current ratings.

Q: Are there mechanical compatibility concerns with the different lead spacings?

A: Lead spacing differs by 0.015" (0.37mm). Verify that the PCB footprint accommodates the B57213P0509M301's 0.295" spacing. If the original design requires 0.310" spacing, mechanical modification or footprint redesign may be necessary.

Q: What inventory considerations apply to these parts?

A: The SG310 has 953 units in stock, while the B57213P0509M301 has 10,226 units available. The B57213P0509M301 offers significantly higher inventory availability, which may reduce lead times for high-volume orders or urgent requirements.