SG308 Inrush Current Limiter - Equivalent & Substitute Parts

Part Overview

The SG308 is an inrush current limiter manufactured by Ametherm, part of the SURGE-GARD™ series. This component is designed to limit inrush current in power supply circuits and related applications. The SG308 features a resistance of 4 Ohms at 25°C with ±15% tolerance and supports a steady-state maximum current of 8 A. The part is currently active in production with full inventory availability (955 Pcs in stock). Finding equivalent or substitute parts may be necessary due to supply chain considerations, lead time requirements, or specific application constraints.

Substiute Parts

SG308

AmethermIn Stock: 1011SG308 Datasheet

Current PartRFQ

B57364S0409M000

EPCOS - TDK ElectronicsIn Stock: 5596B57364S0409M000 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for inrush current limiters is determined by the following critical parameters:

• Resistance value at 25°C (primary functional parameter)
• Tolerance specification (affects circuit performance margins)
• Steady-state maximum current rating (determines thermal and electrical limits)
• Physical dimensions and lead spacing (mechanical fit and PCB compatibility)
• Compliance certifications (RoHS, REACH, regulatory approvals)

The B57364S0409M000 qualifies as a substitute based on matching the primary resistance value of 4 Ohms. Both parts maintain ROHS3 compliance and REACH unaffected status. Tolerance differences (±15% vs ±20%) and physical dimensions (0.600" vs 0.827" diameter) represent the primary distinctions between these components.

Parameter Comparison

Engineering Selection Recommendations

Both the SG308 and B57364S0409M000 maintain active production status and full regulatory compliance (ROHS3 and REACH). Selection between these components should be based on:

• Tolerance requirements: The SG308 provides tighter tolerance (±15%) compared to the B57364S0409M000 (±20%)
• Physical space constraints: The SG308 has a smaller diameter (0.600") suitable for compact layouts; the B57364S0409M000 requires additional board space (0.827" diameter)
• Lead spacing compatibility: Verify PCB pad spacing matches the specified lead spacing for each component
• Inventory and lead time: Both parts are currently in stock with substantial quantities available

Frequently Asked Questions (FAQ)

Q: Can the B57364S0409M000 directly replace the SG308 in all applications?

A: Direct replacement depends on two factors: (1) PCB layout must accommodate the larger 0.827" diameter of the B57364S0409M000 versus the 0.600" diameter of the SG308, and (2) circuit design must tolerate the ±20% tolerance specification of the substitute versus the ±15% tolerance of the original part.

Q: What is the significance of the tolerance difference between these parts?

A: The SG308 tolerance of ±15% provides a tighter resistance specification, resulting in more predictable inrush current limiting performance. The B57364S0409M000 tolerance of ±20% introduces a wider resistance range, which may affect circuit performance in applications with strict inrush current control requirements.

Q: Are both parts suitable for the same environmental and compliance requirements?

A: Yes. Both the SG308 and B57364S0409M000 are ROHS3 compliant and REACH unaffected, meeting equivalent regulatory standards. The SG308 carries CSA and UR approvals; verify that the B57364S0409M000 meets any specific agency certifications required by your application.

Q: What should be verified before implementing a substitution?

A: Confirm (1) PCB mechanical fit with the larger diameter of the substitute part, (2) circuit tolerance to the ±20% specification, (3) steady-state current rating compatibility, and (4) any specific agency certifications or approvals required by your end application.