PFRA.185 Polymeric PTC Resettable Fuse 30V 1.85A Radial

Part Overview

The PFRA.185 is a polymeric PTC resettable fuse manufactured by SCHURTER Inc., rated for 30V maximum voltage with a 1.85A hold current (Ih). This component is designed for through-hole radial mounting in disc configuration and is currently in active product status. The PFRA.185 operates across a temperature range of -40°C to 85°C and carries cURus and TUV approvals with ROHS3 compliance.

Equivalent and substitute parts are identified based on matching electrical characteristics (voltage rating, current hold rating, trip current, and resistance parameters) and mechanical compatibility (through-hole radial disc mounting, lead spacing, and package dimensions). Substitute selection ensures functional interchangeability within specified operating parameters.

Key Parameters

Parameter	Value
Manufacturer Part Number	PFRA.185
Manufacturer	SCHURTER Inc.
Series	PFRA
Product Type	Polymeric PTC Resettable Fuse
Voltage - Max	30V
Current - Hold (Ih) (Max)	1.85A
Current - Trip (It)	3.7A
Current - Max	40A
Time to Trip	8.7s
Resistance - Initial (Ri) (Min)	40 mOhms
Resistance - Post Trip (R1) (Max)	110 mOhms
Operating Temperature	-40°C to 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Lead Spacing	0.201" (5.10mm)
Approval Agency	cURus, TUV
RoHS Status	ROHS3 Compliant
Product Status	Active

Substitute Part Grouping Explanation

Substitute parts for the PFRA.185 are identified from the Littelfuse POLY-FUSE® 30R series based on the following substitution criteria:

Primary Substitution Criteria:

Voltage rating: 30V maximum (exact match required)
Mounting type: Through hole radial disc configuration (exact match required)
Lead spacing: 0.201" (5.10mm) (exact match required)
Approval agencies: cURus and TUV certifications (maintained across all substitutes)
RoHS compliance: ROHS3 compliant (maintained across all substitutes)

Secondary Electrical Parameters (Allow Variation Within Functional Range):

Current hold (Ih): Substitutes range from 900mA to 1.85A
Current trip (It): Proportional to hold current (2:1 ratio maintained)
Time to trip: 5.9s to 8.7s
Initial resistance (Ri): 30 to 70 mOhms
Post-trip resistance (R1): 90 to 220 mOhms

The PFRA.185 is directly equivalent to Littelfuse 30R185UPR and 30R185UU (identical electrical and mechanical specifications). Additional substitutes with lower current ratings (30R090UPR/UU, 30R110UPR/UU, 30R135UPR/UU, 30R160UPR/UU) are available for applications requiring reduced hold current while maintaining 30V voltage rating and mechanical compatibility.

Parameter Comparison

Parameter	PFRA.185	30R090UPR / 30R090UU	30R110UPR / 30R110UU	30R135UPR / 30R135UU	30R160UPR / 30R160UU	30R185UPR / 30R185UU
Manufacturer	SCHURTER Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.
Series	PFRA	POLY-FUSE®, 30R	POLY-FUSE®, 30R	POLY-FUSE®, 30R	POLY-FUSE®, 30R	POLY-FUSE®, 30R
Voltage - Max	30V	30V	30V	30V	30V	30V
Current - Hold (Ih) (Max)	1.85A	900mA	1.1A	1.35A	1.6A	1.85A
Current - Trip (It)	3.7A	1.8A	2.2A	2.7A	3.2A	3.7A
Current - Max	40A	40A	40A	40A	40A	40A
Time to Trip	8.7s	5.9s	6.6s	7.3s	8.0s	8.7s
Resistance - Initial (Ri) (Min)	40 mOhms	70 mOhms	50 mOhms	40 mOhms	30 mOhms	30 mOhms
Resistance - Post Trip (R1) (Max)	110 mOhms	220 mOhms	170 mOhms	130 mOhms	110 mOhms	90 mOhms
Operating Temperature	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc
Lead Spacing	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)
Approval Agency	cURus, TUV	cURus, TUV	cURus, TUV	cURus, TUV	cURus, TUV	cURus, TUV
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

Direct Equivalent (Recommended for 1:1 Replacement):

30R185UPR (Littelfuse, Cut Tape packaging)
30R185UU (Littelfuse, Bulk packaging)

Both parts match the PFRA.185 exactly in electrical specifications (1.85A hold current, 3.7A trip current, 8.7s trip time) and mechanical configuration. All three parts carry identical approvals (cURus, TUV) and ROHS3 compliance. Selection between these options depends on packaging requirements: Cut Tape (CT) for automated assembly or Bulk for manual assembly.

Lower Current Alternatives (Application-Dependent): When circuit design permits reduced hold current, the following substitutes maintain 30V voltage rating, through-hole radial mounting, and regulatory compliance:

30R160UPR/UU: 1.6A hold current (closest to PFRA.185)
30R135UPR/UU: 1.35A hold current
30R110UPR/UU: 1.1A hold current
30R090UPR/UU: 900mA hold current

All substitute parts are active products with confirmed inventory availability and maintain the required thermal operating range (-40°C to 85°C).

Frequently Asked Questions (FAQ)

Q: Can 30R185UPR and 30R185UU be used interchangeably with PFRA.185? A: Yes. Both Littelfuse parts are electrically and mechanically identical to the PFRA.185. The difference is packaging: 30R185UPR is supplied in Cut Tape format for automated pick-and-place assembly, while 30R185UU is supplied in Bulk for manual handling. Select based on assembly process requirements.

Q: What is the difference between the 30R series substitutes with different current ratings? A: The 30R series maintains consistent 30V voltage rating and mechanical compatibility across all current ratings (900mA through 1.85A). The primary differences are hold current (Ih), trip current (It), and time-to-trip characteristics. Lower current ratings trip faster and at lower current thresholds. Selection depends on the specific circuit protection requirement.

Q: Are all substitute parts ROHS3 compliant? A: Yes. The PFRA.185 and all listed Littelfuse 30R substitutes are ROHS3 compliant. All carry cURus and TUV approvals, meeting the same regulatory standards.

Q: Can I use a lower current rating (e.g., 30R160UU instead of PFRA.185) in my circuit? A: Only if your circuit design permits operation at the lower hold current threshold. The 30R160UU holds at 1.6A versus the PFRA.185 at 1.85A. This means the fuse will trip at a lower current level. Verify that normal circuit operation does not exceed 1.6A continuous current before substitution.

Q: What is the significance of the lead spacing specification? A: Lead spacing (0.201" / 5.10mm) determines PCB hole pattern compatibility. All listed substitutes maintain identical lead spacing, ensuring direct PCB footprint compatibility without layout modifications.

Q: How do initial resistance (Ri) and post-trip resistance (R1) affect substitution? A: Initial resistance affects voltage drop during normal operation; post-trip resistance affects the fuse's holding voltage after thermal trip. The PFRA.185 specifies Ri minimum of 40 mOhms and R1 maximum of 110 mOhms. Substitutes with lower R1 values (30R160UPR/UU and 30R185UPR/UU at 90-110 mOhms) provide better post-trip performance. Higher R1 values in lower-current parts (30R090UPR/UU at 220 mOhms) may require circuit evaluation.

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