RUSBF135-AP Equivalent & Substitute Parts

Part Overview

The RUSBF135-AP is a polymeric PTC resettable fuse manufactured by Littelfuse, part of the PolySwitch® series. This through-hole radial disc component provides overcurrent protection at 16V with a 1.35A hold current rating. The part is actively produced and stocked, with full compliance to RoHS3 and international safety certifications (CSA, TUV, UL). Substitute parts are identified when electrical and mechanical parameters remain within the specified tolerances for this product category.

Key Parameters

Parameter	Value
Voltage - Max	16V
Current - Hold (Ih) (Max)	1.35 A
Current - Trip (It)	2.7 A
Current - Max	40 A
Time to Trip	4.5 s
Resistance - Initial (Ri) (Min)	40 mOhms
Resistance - Post Trip (R1) (Max)	112 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Lead Spacing	0.199" (5.05mm)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the RUSBF135-AP is determined by strict equivalence across the following critical parameters:

Voltage rating (16V maximum)
Current hold specification (1.35A maximum)
Current trip threshold (2.7A)
Resistance characteristics (initial and post-trip)
Thermal operating range (-40°C to 85°C)
Physical form factor (through-hole radial disc)
Lead spacing (0.199" / 5.05mm)
Regulatory compliance (RoHS3, CSA, TUV, UL)

The RUSBF135-2 meets all specified parameters and is classified as a direct equivalent within the PolySwitch® RUSBF series.

Parameter Comparison

Parameter	RUSBF135-AP	RUSBF135-2	Match
Voltage - Max	16V	16V	✓
Current - Hold (Ih) (Max)	1.35 A	1.35 A	✓
Current - Trip (It)	2.7 A	2.7 A	✓
Current - Max	40 A	40 A	✓
Time to Trip	4.5 s	4.5 s	✓
Resistance - Initial (Ri) (Min)	40 mOhms	40 mOhms	✓
Resistance - Post Trip (R1) (Max)	112 mOhms	112 mOhms	✓
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	✓
Mounting Type	Through Hole	Through Hole	✓
Package / Case	Radial, Disc	Radial, Disc	✓
Lead Spacing	0.199" (5.05mm)	0.199" (5.05mm)	✓
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	✓
Approval Agency	CSA, TUV, UL	CSA, TUV, UL	✓

Engineering Selection Recommendations

Both RUSBF135-AP and RUSBF135-2 are active production components from Littelfuse with identical electrical and mechanical specifications. Selection between these parts may be based on inventory availability and packaging format (both supplied in Cut Tape). The RUSBF135-2 currently maintains higher stock levels (3207 pcs vs. 2202 pcs). Both parts carry full regulatory approvals (CSA, TUV, UL) and RoHS3 compliance, making them functionally interchangeable for applications requiring 16V, 1.35A hold current PTC resettable fuse protection in through-hole radial disc configuration.

Frequently Asked Questions (FAQ)

Q: Can RUSBF135-2 be used as a direct replacement for RUSBF135-AP?

A: Yes. Both parts are electrically and mechanically identical across all specified parameters, including voltage rating, current characteristics, resistance values, operating temperature range, and physical dimensions. They are interchangeable in circuit design and PCB layout.

Q: What determines substitution eligibility for this part category?

A: Substitution requires exact matching of voltage rating, hold current (Ih), trip current (It), resistance characteristics, operating temperature range, mounting type, package form factor, and lead spacing. All regulatory certifications must also align.

Q: Are there any packaging differences between RUSBF135-AP and RUSBF135-2?

A: Both parts are supplied in Cut Tape (CT) packaging. No packaging differentiation exists between these equivalents.

Q: Do both parts meet the same regulatory standards?

A: Yes. Both RUSBF135-AP and RUSBF135-2 carry CSA, TUV, and UL approvals and are ROHS3 compliant.

Q: What is the lead spacing for these components?

A: Lead spacing is 0.199 inches (5.05mm) for both parts, ensuring identical PCB footprint compatibility.

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