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RLD30P185UFF Equivalent & Substitute Parts
Part Overview
The RLD30P185UFF is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., part of the POLY-FUSE® RLD30 series. This component is rated for 30V maximum voltage with a 1.85A hold current and is designed for through-hole radial disc mounting. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs requiring similar electrical protection characteristics.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Voltage - Max | 30V |
| Current - Hold (Ih) (Max) | 1.85 A |
| Current - Trip (It) | 3.7 A |
| Current - Max | 40 A |
| Time to Trip | 8.7 s |
| Resistance - Initial (Ri) (Min) | 30 mOhms |
| Resistance - Post Trip (R1) (Max) | 90 mOhms |
| Operating Temperature | -40°C ~ 85°C |
| Mounting Type | Through Hole |
| Package / Case | Radial, Disc |
| Lead Spacing | 0.201" (5.10mm) |
| Approval Agency | cURus, TUV |
| RoHS Status | ROHS3 Compliant |
Substitute Part Grouping Explanation
Substitution for the RLD30P185UFF is determined by strict electrical and mechanical compatibility. The following parameters must align for direct substitution:
- Voltage rating of 30V maximum
- Current hold (Ih) of 1.85A maximum
- Current trip (It) of 3.7A
- Time to trip of 8.7 seconds
- Initial resistance (Ri) minimum of 30 mOhms
- Post-trip resistance (R1) maximum of 90 mOhms
- Through-hole radial disc mounting configuration
- Lead spacing of 0.201" (5.10mm)
- Operating temperature range of -40°C to 85°C
- cURus and TUV approval certifications
Substitute parts are grouped into two categories: parametric equivalents (identical electrical specifications) and manufacturer-recommended alternatives (functionally compatible with minor parameter variations).
Parameter Comparison
| Part Number | Manufacturer | Voltage (Max) | Ih (Max) | It | Ri (Min) | R1 (Max) | Time to Trip | Product Status | Packaging |
|---|---|---|---|---|---|---|---|---|---|
| RLD30P185UFF | Littelfuse Inc. | 30V | 1.85 A | 3.7 A | 30 mOhms | 90 mOhms | 8.7 s | Obsolete | Radial, Disc |
| 30R185UPR | Littelfuse Inc. | 30V | 1.85 A | 3.7 A | 30 mOhms | 90 mOhms | 8.7 s | Active | Cut Tape (CT) |
| 0ZRB0185FF1E | Bel Fuse Inc. | 30V | 1.85 A | 3.7 A | 30 mOhms | 90 mOhms | 8.7 s | Active | Box |
| 0ZRB0185FF2E | Bel Fuse Inc. | 30V | 1.85 A | 3.7 A | 30 mOhms | 90 mOhms | 8.7 s | Active | Cut Tape (CT) |
| PFRA.110.2 | SCHURTER Inc. | 30V | — | 2.2 A | 100 mOhms | 270 mOhms | 6.6 s | Active | Cut Tape (CT) |
| PFRA.135 | SCHURTER Inc. | 30V | 1.35 A | 2.7 A | 65 mOhms | 170 mOhms | 7.3 s | Active | Bulk |
| PFRA.135.2 | SCHURTER Inc. | 30V | 1.35 A | 2.7 A | 65 mOhms | 170 mOhms | 7.3 s | Active | Cut Tape (CT) |
| PFRA.160 | SCHURTER Inc. | 30V | 1.6 A | 3.2 A | 55 mOhms | 150 mOhms | 8 s | Active | Bulk |
| PFRA.160.2 | SCHURTER Inc. | 30V | 1.6 A | 3.2 A | 55 mOhms | 150 mOhms | 8 s | Active | Cut Tape (CT) |
| PFRA.185 | SCHURTER Inc. | 30V | 1.85 A | 3.7 A | 40 mOhms | 110 mOhms | 8.7 s | Active | Bulk |
| PFRA.185.2 | SCHURTER Inc. | 30V | 1.85 A | 3.7 A | 40 mOhms | 110 mOhms | 8.7 s | Active | Cut Tape (CT) |
Engineering Selection Recommendations
Direct Parametric Equivalents (Identical Electrical Specifications)
The 30R185UPR (Littelfuse Inc.) and 0ZRB0185FF1E / 0ZRB0185FF2E (Bel Fuse Inc.) are direct parametric equivalents to the RLD30P185UFF. These parts maintain identical voltage, hold current, trip current, time to trip, and resistance specifications. All three manufacturers' parts carry cURus and TUV certifications. The primary difference is product status: the RLD30P185UFF is obsolete, while the equivalent parts are active. The 30R185UPR and 0ZRB0185FF series are recommended for new designs and ongoing production requiring the exact electrical protection profile of the original component.
Functionally Compatible Alternatives (Parameter Variations)
The SCHURTER PFRA series parts (PFRA.110.2, PFRA.135, PFRA.135.2, PFRA.160, PFRA.160.2, PFRA.185, PFRA.185.2) are manufacturer-recommended alternatives. These parts share the 30V voltage rating and through-hole radial disc mounting but differ in hold current, trip current, and resistance characteristics. The PFRA.185 and PFRA.185.2 maintain the 1.85A hold current and 3.7A trip current but feature slightly higher initial resistance (40 mOhms minimum versus 30 mOhms) and post-trip resistance (110 mOhms maximum versus 90 mOhms). All SCHURTER parts are active products with cURus and TUV certifications.
Packaging Considerations
The RLD30P185UFF was supplied in radial disc format. Equivalent parts are available in multiple packaging options: Cut Tape (CT), Box, and Bulk. Selection should align with production requirements and inventory management practices.
Frequently Asked Questions (FAQ)
Q: Can the 30R185UPR directly replace the RLD30P185UFF?
A: Yes. The 30R185UPR is a parametric equivalent with identical electrical specifications: 30V maximum voltage, 1.85A hold current, 3.7A trip current, 8.7-second time to trip, and matching resistance values. Both are polymeric PTC resettable fuses with through-hole radial disc mounting and identical lead spacing. The primary difference is that the RLD30P185UFF is obsolete while the 30R185UPR is an active product from Littelfuse Inc.
Q: What is the difference between the Littelfuse 30R185UPR and Bel Fuse 0ZRB0185FF series?
A: Both are parametric equivalents to the RLD30P185UFF with identical electrical specifications. The difference is manufacturer: Littelfuse Inc. produces the 30R185UPR, while Bel Fuse Inc. produces the 0ZRB0185FF1E and 0ZRB0185FF2E. The 0ZRB0185FF1E is supplied in Box packaging, while the 0ZRB0185FF2E is supplied in Cut Tape (CT). Both carry AEC-Q200 ratings in addition to cURus and TUV certifications.
Q: Can SCHURTER PFRA.185 parts substitute for the RLD30P185UFF?
A: The PFRA.185 and PFRA.185.2 are functionally compatible alternatives. They maintain the 1.85A hold current, 3.7A trip current, and 8.7-second time to trip. However, they differ in resistance specifications: initial resistance is 40 mOhms minimum (versus 30 mOhms for the RLD30P185UFF) and post-trip resistance is 110 mOhms maximum (versus 90 mOhms). These differences may affect circuit behavior in applications with tight resistance tolerances.
Q: What are the key parameters that determine substitution compatibility?
A: Direct substitution requires matching voltage rating (30V), hold current (1.85A), trip current (3.7A), time to trip (8.7 seconds), initial resistance (30 mOhms minimum), post-trip resistance (90 mOhms maximum), mounting type (through-hole radial disc), and lead spacing (0.201" / 5.10mm). Deviations in any of these parameters indicate functional compatibility rather than direct equivalence.
Q: Are all substitute parts RoHS3 compliant?
A: Yes. The RLD30P185UFF and all listed substitute parts are ROHS3 compliant. All carry cURus and TUV certifications. The Bel Fuse 0ZRB series additionally carries AEC-Q200 ratings.
Q: What packaging options are available for equivalent parts?
A: The 30R185UPR is supplied in Cut Tape (CT). The Bel Fuse 0ZRB0185FF1E is supplied in Box, while the 0ZRB0185FF2E is supplied in Cut Tape (CT). SCHURTER PFRA.185 is available in Bulk, and PFRA.185.2 is available in Cut Tape (CT). Selection depends on production volume and inventory management requirements.
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