RLD30P250UFF Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The RLD30P250UFF is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 30V maximum voltage with a 2.5A hold current. This component is classified as Obsolete, which necessitates identification of active equivalent parts for ongoing design support and procurement. The RLD30 series POLY-FUSE® provides overcurrent protection in through-hole radial disc configuration with cURus and TUV approval. Direct substitutes maintain identical electrical ratings and mechanical form factors while offering active product status and improved availability.

Key Parameters

Parameter	RLD30P250UFF
Voltage - Max	30V
Current - Hold (Ih) (Max)	2.5 A
Current - Trip (It)	5 A
Current - Max	40 A
Time to Trip	10.3 s
Resistance - Initial (Ri) (Min)	20 mOhms
Resistance - Post Trip (R1) (Max)	70 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Size / Dimension	0.449" L x 0.118" W (11.40mm x 3.00mm)
Height - Seated (Max)	0.720" (18.30mm)
Lead Spacing	0.201" (5.10mm)
Approval Agency	cURus, TUV
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following critical parameters:

Primary Equivalence Criteria:

Voltage - Max: 30V (exact match required)
Current - Hold (Ih) (Max): 2.5 A (exact match required)
Current - Trip (It): 5 A (exact match required)
Resistance - Initial (Ri) (Min): 20 mOhms (exact match required)
Resistance - Post Trip (R1) (Max): 70 mOhms (exact match required)
Operating Temperature: -40°C ~ 85°C (exact match required)
Mounting Type: Through Hole (exact match required)
Package / Case: Radial, Disc (exact match required)

Direct Substitutes (Full Electrical & Mechanical Equivalence):

30R250UPR (Littelfuse Inc., POLY-FUSE® 30R series) – Active product status, identical electrical specifications, lead spacing 0.118" (3.00mm)
RUEF250-AP (Littelfuse Inc., PolySwitch® RUEF series) – Active product status, identical electrical specifications, lead spacing 0.199" (5.05mm), extended current rating to 100A
0ZRB0250FF1E (Bel Fuse Inc., 0ZRB series) – Active product status, AEC-Q200 rated, identical electrical specifications, lead spacing 0.201" (5.10mm)
0ZRB0250FF2E (Bel Fuse Inc., 0ZRB series) – Active product status, AEC-Q200 rated, identical electrical specifications, lead spacing 0.201" (5.10mm)

Non-Equivalent Parts (Different Current Ratings):

The following SCHURTER PFRA series parts do not meet primary equivalence criteria due to different hold current ratings and are listed for reference only:

PFRA.110.2 (1.1A hold current, 2.2A trip current)
PFRA.135 (1.35A hold current, 2.7A trip current)
PFRA.135.2 (1.35A hold current, 2.7A trip current)
PFRA.160 (1.6A hold current, 3.2A trip current)
PFRA.160.2 (1.6A hold current, 3.2A trip current)
PFRA.185 (1.85A hold current, 3.7A trip current)

Parameter Comparison

Parameter	RLD30P250UFF	30R250UPR	RUEF250-AP	0ZRB0250FF1E	0ZRB0250FF2E
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Bel Fuse Inc.	Bel Fuse Inc.
Series	POLY-FUSE® RLD30	POLY-FUSE® 30R	PolySwitch® RUEF	0ZRB	0ZRB
Product Status	Obsolete	Active	Active	Active	Active
Voltage - Max	30V	30V	30V	30V	30V
Current - Hold (Ih) (Max)	2.5 A	2.5 A	2.5 A	2.5 A	2.5 A
Current - Trip (It)	5 A	5 A	5 A	5 A	5 A
Current - Max	40 A	40 A	100 A	40 A	40 A
Time to Trip	10.3 s	10.3 s	10.3 s	10.3 s	10.3 s
Resistance - Initial (Ri) (Min)	20 mOhms	20 mOhms	20 mOhms	20 mOhms	20 mOhms
Resistance - Post Trip (R1) (Max)	70 mOhms	70 mOhms	70 mOhms	70 mOhms	70 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc
Size / Dimension	0.449" L x 0.118" W (11.40mm x 3.00mm)	0.449" L x 0.118" W (11.40mm x 3.00mm)	0.449" L x 0.118" W (11.40mm x 3.00mm)	0.449" L x 0.118" W (11.40mm x 3.00mm)	0.449" L x 0.118" W (11.40mm x 3.00mm)
Height - Seated (Max)	0.720" (18.30mm)	0.720" (18.30mm)	0.720" (18.30mm)	0.720" (18.30mm)	0.720" (18.30mm)
Lead Spacing	0.201" (5.10mm)	0.118" (3.00mm)	0.199" (5.05mm)	0.201" (5.10mm)	0.201" (5.10mm)
Approval Agency	cURus, TUV	cURus, TUV	CQC, CSA, TUV, UL	cURus, TUV	cURus, TUV
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Packaging	-	Cut Tape (CT)	Cut Tape (CT)	Box	Cut Tape (CT)

Engineering Selection Recommendations

Primary Recommendation: 30R250UPR

The 30R250UPR from Littelfuse Inc. is the preferred direct substitute. It maintains active product status within the POLY-FUSE® 30R series and provides identical electrical and mechanical specifications to the obsolete RLD30P250UFF. This part is available in Cut Tape packaging with 2580 units in stock. The lead spacing of 0.118" (3.00mm) differs from the original 0.201" (5.10mm), requiring PCB layout verification.

Secondary Recommendation: RUEF250-AP

The RUEF250-AP from Littelfuse Inc. offers equivalent electrical performance with extended current rating capability (100A maximum versus 40A). This PolySwitch® series component carries broader approval agency certifications (CQC, CSA, TUV, UL) compared to the original part. Lead spacing of 0.199" (5.05mm) closely matches the original 0.201" (5.10mm), minimizing PCB layout modifications. Inventory availability is 8614 units.

Tertiary Recommendations: 0ZRB0250FF1E and 0ZRB0250FF2E

Both Bel Fuse Inc. 0ZRB series parts provide full electrical equivalence with AEC-Q200 automotive qualification. Lead spacing of 0.201" (5.10mm) matches the original specification exactly. The 0ZRB0250FF1E is supplied in Box packaging (6600 units available), while 0ZRB0250FF2E is supplied in Cut Tape packaging (6791 units available). Selection between these variants depends on procurement and assembly requirements.

Frequently Asked Questions (FAQ)

Q: Can PFRA series parts from SCHURTER substitute for the RLD30P250UFF?

A: No. PFRA series parts (PFRA.110.2, PFRA.135, PFRA.135.2, PFRA.160, PFRA.160.2, PFRA.185) have different hold current ratings ranging from 1.1A to 1.85A, which do not meet the 2.5A requirement of the original part. These are not equivalent substitutes.

Q: What is the significance of lead spacing differences between substitute parts?

A: Lead spacing affects PCB footprint compatibility. The original RLD30P250UFF specifies 0.201" (5.10mm) lead spacing. The 30R250UPR has 0.118" (3.00mm) spacing, requiring PCB redesign. The RUEF250-AP (0.199" / 5.05mm) and both 0ZRB variants (0.201" / 5.10mm) require minimal or no layout modification.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All four direct substitute parts (30R250UPR, RUEF250-AP, 0ZRB0250FF1E, 0ZRB0250FF2E) are ROHS3 compliant, matching the environmental compliance of the original RLD30P250UFF.

Q: What approval agencies certify these substitute parts?

A: The 30R250UPR, 0ZRB0250FF1E, and 0ZRB0250FF2E carry cURus and TUV approvals, identical to the original part. The RUEF250-AP carries broader certifications: CQC, CSA, TUV, and UL, providing additional regulatory coverage for certain applications.

Q: Does the extended current rating of RUEF250-AP (100A vs. 40A) affect circuit compatibility?

A: No. The extended maximum current rating does not affect circuit operation. The critical parameters—hold current (2.5A), trip current (5A), and trip time (10.3s)—remain identical. The higher maximum current rating provides additional safety margin without changing functional behavior.

Q: What packaging options are available for these substitutes?

A: 30R250UPR is available in Cut Tape (CT). RUEF250-AP is available in Cut Tape (CT). 0ZRB0250FF1E is available in Box. 0ZRB0250FF2E is available in Cut Tape (CT). Selection depends on assembly process requirements and procurement volume.

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