RF4525-000 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The RF4525-000 is a Polymeric PTC (Positive Temperature Coefficient) resettable fuse manufactured by Littelfuse Inc. under the PolySwitch® ASMD series. This component functions as an automatic overcurrent protection device, resetting after fault conditions are cleared without requiring manual replacement. The part is rated for 16V maximum voltage with a 250 mA hold current and is designed for surface mount applications in the 1206 (3216 Metric) package format with concave geometry.

The RF4525-000 maintains Active product status with full AEC-Q200 automotive qualification and ROHS3 compliance. Identifying equivalent substitute parts is necessary to ensure supply chain continuity, optimize inventory management, and maintain design flexibility across manufacturing environments while preserving electrical and mechanical compatibility.

Substiute Parts

RF4525-000

Littelfuse Inc.In Stock: 1071RF4525-000 Datasheet

Current PartRFQ

NANOASMDC025F-2

Littelfuse Inc.In Stock: 33193NANOASMDC025F-2 Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the RF4525-000 are identified based on strict electrical and mechanical parameter matching within the Polymeric PTC resettable fuse category. The substitution logic is governed by the following critical parameters:

Electrical Parameters (Must Match Exactly):

• Voltage - Maximum: 16V
• Current - Hold (Ih) Maximum: 250 mA
• Current - Trip (It): 580 mA
• Time to Trip: 10 ms
• Resistance - Initial (Ri) Minimum: 400 mOhms
• Resistance - Post Trip (R1) Maximum: 2.1 Ohms
• Operating Temperature Range: -40°C to 85°C

Mechanical Parameters (Must Match Exactly):

• Package / Case: 1206 (3216 Metric), Concave
• Mounting Type: Surface Mount
• Size / Dimension: 0.126" L x 0.063" W (3.20mm x 1.59mm)
• Thickness Maximum: 0.032" (0.82mm)

Compliance & Certification Parameters:

• Type: Polymeric
• Series: PolySwitch® ASMD
• Ratings: AEC-Q200
• RoHS Status: ROHS3 Compliant

Only parts meeting all specified electrical, mechanical, and compliance criteria are classified as direct parametric equivalents. Deviations in any parameter disqualify a part from substitution eligibility.

Parameter Comparison

Engineering Selection Recommendations

The NANOASMDC025F-2 is a direct parametric equivalent to the RF4525-000 based on complete alignment of all electrical, mechanical, and compliance specifications. Both components are manufactured by Littelfuse Inc., belong to the PolySwitch® ASMD series, and carry identical AEC-Q200 automotive qualification and ROHS3 compliance certifications.

Selection between RF4525-000 and NANOASMDC025F-2 may be determined by:

Inventory Availability: The NANOASMDC025F-2 maintains higher stock levels (33,100 Pcs) compared to RF4525-000 (1,054 Pcs), supporting extended production runs and reducing lead time risk.

Packaging Specifications: Both parts are supplied in Tape & Reel (TR) format, ensuring compatibility with automated assembly equipment and standard pick-and-place operations.

Compliance Status: Both parts maintain Active product status with current manufacturer support, AEC-Q200 automotive-grade certification, and full ROHS3 environmental compliance.

Moisture Sensitivity: The NANOASMDC025F-2 specifies Moisture Sensitivity Level (MSL) 2A (4 Weeks), providing explicit handling and storage guidance for moisture-sensitive component management.

Either part is suitable for direct substitution in circuit designs requiring 16V, 250 mA hold current Polymeric PTC resettable fuses in 1206 surface mount packages.

Frequently Asked Questions (FAQ)

Q: Can NANOASMDC025F-2 be used as a direct replacement for RF4525-000 in existing designs?

A: Yes. The NANOASMDC025F-2 is a direct parametric equivalent with identical electrical ratings (16V, 250 mA Ih, 580 mA It), mechanical dimensions (1206 package, 3.20mm x 1.59mm x 0.82mm), and compliance certifications (AEC-Q200, ROHS3). No circuit modifications are required.

Q: Are there any differences in performance characteristics between these two parts?

A: No. Both parts share identical specifications for voltage rating, hold current, trip current, time to trip, initial resistance, post-trip resistance, and operating temperature range. Performance in circuit operation is equivalent.

Q: What is the significance of the Moisture Sensitivity Level (MSL) 2A specification on the NANOASMDC025F-2?

A: MSL 2A (4 Weeks) indicates the component can be exposed to ambient conditions (30°C, 60% relative humidity) for up to four weeks after packaging before soldering. This specification applies to the NANOASMDC025F-2 and should be observed during component storage and handling to prevent moisture absorption that could affect solderability.

Q: Are both parts suitable for automotive applications?

A: Yes. Both RF4525-000 and NANOASMDC025F-2 carry AEC-Q200 automotive qualification, confirming suitability for automotive-grade circuit protection applications.

Q: Can these parts be used interchangeably in pick-and-place assembly operations?

A: Yes. Both parts are supplied in Tape & Reel (TR) packaging format with identical 1206 (3216 Metric) concave package geometry, ensuring compatibility with standard automated surface mount assembly equipment.

Q: What is the functional difference between hold current (Ih) and trip current (It)?

A: Hold current (Ih) of 250 mA is the maximum continuous current the fuse conducts without tripping. Trip current (It) of 580 mA is the threshold at which the polymeric element begins heating and the device transitions to high-resistance state within 10 milliseconds, providing overcurrent protection.

Q: Are there supply chain advantages to selecting one part over the other?

A: The NANOASMDC025F-2 maintains significantly higher inventory (33,100 Pcs versus 1,054 Pcs for RF4525-000), potentially offering shorter lead times and reduced supply chain risk for high-volume production requirements.