AHRF650S Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The AHRF650S is a polymeric PTC resettable fuse manufactured by Littelfuse, part of the PolySwitch® AHRF series. This component is rated for 16V maximum voltage with a 6.5A hold current and is designed for through-hole radial mounting in disc configuration. The AHRF650S is currently classified as obsolete, making identification of suitable substitute components essential for ongoing system support and new design implementations. The primary driver for substitution is product discontinuation, requiring engineers to identify functionally compatible alternatives from the active product portfolio.

Substiute Parts

AHRF650S

LittelfuseIn Stock: 997AHRF650S Datasheet

Current PartRFQ

AHRF600

Littelfuse Inc.In Stock: 1236AHRF600 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the AHRF650S is determined by the following critical parameters:

Voltage Compatibility: Maximum voltage rating must equal or exceed 16V. Both the main part and substitute must operate within the same voltage class to ensure circuit protection integrity.

Current Rating Alignment: The hold current (Ih) and trip current (It) define the protection threshold. Substitutes must maintain electrical characteristics within acceptable tolerance to preserve circuit protection function. The AHRF600 operates at 6A hold current versus the AHRF650S at 6.5A, representing a 7.7% reduction in hold current specification.

Mounting and Package Consistency: Through-hole radial disc configuration must be maintained to ensure mechanical compatibility with existing PCB layouts and component footprints.

Temperature Operating Range: The -40°C to 125°C range must be supported by substitute components to maintain performance across specified environmental conditions.

Compliance and Certifications: AEC-Q200 rating and ROHS3 compliance must be preserved in substitute selections to maintain automotive and environmental regulatory alignment.

The AHRF600 satisfies all substitution criteria as an active product within the same PolySwitch® AHRF series, sharing identical voltage rating, operating temperature range, mounting type, and compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

The AHRF600 is the qualified substitute for the obsolete AHRF650S based on the following engineering criteria:

Product Status and Availability: The AHRF600 maintains active product status with confirmed inventory availability (1193 pieces in stock), ensuring reliable procurement for both new designs and legacy system support. The AHRF650S obsolescence status eliminates it as a viable long-term sourcing option.

Compliance and Certification Alignment: Both components maintain identical AEC-Q200 automotive qualification and ROHS3 compliance certifications, preserving regulatory and environmental requirements across substitution.

Electrical Parameter Compatibility: Identical 16V maximum voltage rating and -40°C to 125°C operating temperature range ensure direct functional compatibility within existing circuit designs. The 7.7% reduction in hold current (6A versus 6.5A) and corresponding trip current reduction (12A versus 13.7A) represent tighter protection thresholds suitable for applications where the original 6.5A specification provides design margin.

Mechanical and Package Consistency: Radial disc through-hole configuration remains unchanged, maintaining PCB layout compatibility and component footprint alignment without requiring board redesign.

Selection of the AHRF600 as a substitute requires circuit-level analysis to confirm that the reduced hold and trip current specifications remain within acceptable protection parameters for the target application.

Frequently Asked Questions (FAQ)

Q: Can the AHRF600 be used as a direct replacement for the AHRF650S in existing designs?

A: The AHRF600 shares identical voltage rating, operating temperature range, mounting type, and compliance certifications with the AHRF650S. However, the hold current is reduced from 6.5A to 6A, and trip current is reduced from 13.7A to 12A. Direct substitution is mechanically and electrically feasible only if the circuit design accommodates these lower protection thresholds. Circuit analysis is required to confirm compatibility.

Q: What are the key differences between the AHRF650S and AHRF600?

A: The primary differences are product status (obsolete versus active), hold current specification (6.5A versus 6A), trip current (13.7A versus 12A), time to trip (7s versus 6.5s), and post-trip resistance (26 mOhms maximum versus 32 mOhms maximum). Voltage rating, temperature range, mounting configuration, and compliance certifications are identical.

Q: Are there any package or footprint differences between these components?

A: Both components use radial disc through-hole configuration. Physical dimensions differ slightly: the AHRF650S measures 0.500" L x 0.118" W with 0.874" seated height, while the AHRF600 measures 0.441" L x 0.118" W with 0.827" seated height. Lead spacing is nominally equivalent (0.200" versus 0.199"). These dimensional variations are within typical PCB layout tolerances for radial through-hole components.

Q: What compliance certifications apply to both parts?

A: Both the AHRF650S and AHRF600 maintain AEC-Q200 automotive qualification, ROHS3 compliance, and EAR99 export classification. REACH status is unaffected for both components.

Q: Why is the AHRF650S classified as obsolete?

A: Product obsolescence is determined by manufacturer discontinuation decisions. The AHRF600 represents the active alternative within the PolySwitch® AHRF series, providing equivalent functionality with tighter protection specifications.