RLD60P185XF Equivalent & Substitute Parts

Part Overview

The RLD60P185XF is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., part of the POLY-FUSE® RLD60 series. This component is rated for 60V maximum voltage with a 1.85A hold current and is designed for through-hole radial mounting in disc configuration. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs requiring similar protection characteristics.

Key Parameters

Parameter	Value
Voltage - Max	60V
Current - Hold (Ih) (Max)	1.85 A
Current - Trip (It)	3.7 A
Current - Max	40 A
Time to Trip	12.6 s
Resistance - Initial (Ri) (Min)	80 mOhms
Resistance - Post Trip (R1) (Max)	190 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

Substitute Part Grouping Explanation

Substitution for the RLD60P185XF is determined by the following critical parameters:

Primary Substitution Criteria:

Voltage rating (60V or higher)
Current hold rating (1.85A)
Current trip rating (3.7A)
Resistance characteristics (Ri ≥ 80 mOhms, R1 ≤ 190 mOhms)
Through-hole radial mounting configuration
Lead spacing compatibility (0.201" / 5.10mm)
Operating temperature range (-40°C ~ 85°C)

Substitute Categories:

Category 1: Direct Electrical Equivalents (60V Rating)

60R185XF (Littelfuse, POLY-FUSE® 60R series, Active status)
60R185XMR (Littelfuse, POLY-FUSE® 60R series, Active status)

Category 2: Higher Voltage Equivalents (72V Rating)

RXEF185-AP (Littelfuse, PolySwitch® RXEF series, Active status)
MF-RX185/72-0 (Bourns Inc., Multifuse® MF-RX/72 series, Active status)

The 72V-rated alternatives provide enhanced voltage margin while maintaining identical current and resistance specifications, suitable for applications requiring higher voltage headroom.

Parameter Comparison

Parameter	RLD60P185XF	60R185XF	60R185XMR	RXEF185-AP	MF-RX185/72-0
Manufacturer	Littelfuse Inc.	Littelfuse	Littelfuse Inc.	Littelfuse Inc.	Bourns Inc.
Series	POLY-FUSE® RLD60	POLY-FUSE® 60R	POLY-FUSE® 60R	PolySwitch® RXEF	Multifuse® MF-RX/72
Product Status	Obsolete	Active	Active	Active	Active
Voltage - Max	60V	60V	60V	72V	72V
Current - Hold (Ih) (Max)	1.85 A	1.85 A	1.85 A	1.85 A	1.85 A
Current - Trip (It)	3.7 A	3.7 A	3.7 A	3.7 A	3.7 A
Current - Max	40 A	40 A	40 A	40 A	40 A
Time to Trip	12.6 s	12.6 s	12.6 s	12.6 s	12.6 s
Resistance - Initial (Ri) (Min)	80 mOhms	80 mOhms	80 mOhms	80 mOhms	80 mOhms
Resistance - Post Trip (R1) (Max)	190 mOhms	190 mOhms	190 mOhms	190 mOhms	190 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
Lead Spacing	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)	0.199" (5.05mm)	0.201" (5.10mm)
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	cURus, TUV	cURus, TUV	cURus, TUV	CQC, CSA, TUV, UL	cURus, TUV

Engineering Selection Recommendations

For Direct Replacement (60V Systems): Select 60R185XF or 60R185XMR. Both are active products from Littelfuse with identical electrical specifications to the obsolete RLD60P185XF. The 60R185XF is available in bulk packaging, while 60R185XMR is supplied in cut tape format. Both meet ROHS3 compliance and carry cURus and TUV certifications.

For Enhanced Voltage Margin (72V Systems): Select RXEF185-AP (Littelfuse PolySwitch® series) or MF-RX185/72-0 (Bourns Multifuse® series). These components provide 12V additional voltage rating while maintaining all current and resistance specifications. RXEF185-AP carries expanded certifications including CQC, CSA, TUV, and UL. MF-RX185/72-0 is supplied in bulk packaging.

Compliance Considerations: All substitute parts are ROHS3 compliant, addressing the non-compliance status of the obsolete RLD60P185XF. All alternatives carry recognized safety certifications suitable for industrial and consumer applications.

Frequently Asked Questions (FAQ)

Q: Can 60R185XF directly replace RLD60P185XF in existing designs? A: Yes. The 60R185XF maintains identical voltage, current, resistance, and thermal specifications. Physical dimensions are compatible with standard through-hole radial mounting. The primary difference is product status (active vs. obsolete) and improved RoHS3 compliance.

Q: What is the difference between 60R185XF and 60R185XMR? A: Both parts are electrically and mechanically identical. The difference is packaging: 60R185XF is supplied in bulk, while 60R185XMR is supplied in cut tape format. Selection depends on assembly process requirements.

Q: When should I use the 72V-rated alternatives (RXEF185-AP or MF-RX185/72-0)? A: Use 72V-rated parts when your circuit operates at voltages approaching 60V or when additional voltage margin is required for system reliability. All other electrical characteristics remain identical to the 60V versions.

Q: Are there mechanical compatibility concerns with RXEF185-AP? A: RXEF185-AP has a lead spacing of 0.199" (5.05mm) compared to 0.201" (5.10mm) for other alternatives. This 0.02mm difference is within standard PCB tolerance and does not affect through-hole mounting compatibility.

Q: Which substitute offers the broadest certification coverage? A: RXEF185-AP carries the most comprehensive certifications: CQC, CSA, TUV, and UL, compared to cURus and TUV for other alternatives.

Q: Is the RLD60P185XF still available for purchase? A: The RLD60P185XF is obsolete but remains in inventory (1019 pcs). However, for new designs and long-term supply assurance, active alternatives such as 60R185XF, 60R185XMR, RXEF185-AP, or MF-RX185/72-0 are recommended.

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