RHE650 Equivalent & Substitute Parts

Part Overview

The RHE650 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 16V maximum voltage and 6.5A hold current. This component is classified as obsolete, which necessitates identification of equivalent substitute parts for ongoing design support and procurement. The RHE650 operates as a thermal protection device with a 12A trip current and 5.5 second trip time, designed for through-hole radial mounting in disc configuration.

Key Parameters

Parameter	Value
Voltage - Max	16V
Current - Hold (Ih) (Max)	6.5 A
Current - Trip (It)	12 A
Current - Max	100 A
Time to Trip	5.5 s
Resistance - Initial (Ri) (Min)	11 mOhms
Mounting Type	Through Hole
Package / Case	Radial, Disc
Size / Dimension	0.500" L x 0.118" W (12.70mm x 3.00mm)
Lead Spacing	0.199" (5.05mm)

Substitute Part Grouping Explanation

Substitute parts for the RHE650 are identified based on electrical parameter equivalence and mechanical compatibility. The critical parameters determining substitution eligibility are:

Voltage rating: 16V maximum
Hold current: 6.5A
Trip current: 12A
Trip time: 5.5 seconds
Initial resistance: 11 mOhms minimum
Mounting configuration: Through hole radial disc
Physical dimensions: 0.500" L x 0.118" W with 0.199" lead spacing

The RHEF650 (Littelfuse) and MF-RHT650-0 (Bourns) meet these electrical and mechanical specifications. Both parts maintain identical voltage, hold current, trip current, and trip time characteristics. Physical dimensions and mounting type are equivalent across all three parts.

Parameter Comparison

Parameter	RHE650	RHEF650	MF-RHT650-0
Manufacturer	Littelfuse Inc.	Littelfuse	Bourns Inc.
Product Status	Obsolete	Active	Active
Voltage - Max	16V	16V	16V
Current - Hold (Ih) (Max)	6.5 A	6.5 A	6.5 A
Current - Trip (It)	12 A	12 A	12 A
Current - Max	100 A	100 A	100 A
Time to Trip	5.5 s	5.5 s	5.5 s
Resistance - Initial (Ri) (Min)	11 mOhms	11 mOhms	11 mOhms
Resistance - Post Trip (R1) (Max)	4.3 Ohms	26 mOhms	26 mOhms
Operating Temperature	Not specified	-40°C ~ 125°C	-40°C ~ 125°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Disc	Radial, Disc	Radial, Disc
Size / Dimension	0.500" L x 0.118" W (12.70mm x 3.00mm)	0.500" L x 0.118" W (12.70mm x 3.00mm)	0.500" L x 0.118" W (12.70mm x 3.00mm)
Height - Seated (Max)	0.874" (22.20mm)	0.874" (22.20mm)	0.874" (22.20mm)
Lead Spacing	0.199" (5.05mm)	0.199" (5.05mm)	0.114" (2.90mm)
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, TUV, UR	CSA, TUV, UL	Not specified

Engineering Selection Recommendations

The RHEF650 is the primary substitute for the obsolete RHE650. Both parts are manufactured by Littelfuse and share identical electrical characteristics and physical dimensions. The RHEF650 carries active product status and achieves ROHS3 compliance, addressing regulatory requirements that the original RHE650 does not meet. Approval agencies include CSA, TUV, and UL certification.

The MF-RHT650-0 (Bourns Multifuse®) provides an alternative substitute with equivalent electrical performance and ROHS3 compliance. This part includes AEC-Q200 automotive qualification rating and MSL 1 moisture sensitivity classification. The lead spacing differs at 0.114" (2.90mm) compared to 0.199" (5.05mm) on the RHE650 and RHEF650, requiring PCB layout verification before implementation.

Both substitute parts demonstrate post-trip resistance of 26 mOhms, which differs from the RHE650 specification of 4.3 Ohms maximum. This parameter change reflects modern PTC fuse design and does not affect functional substitution for the specified electrical ratings.

Frequently Asked Questions (FAQ)

Q: Can the RHEF650 directly replace the RHE650 without PCB modification?

A: Yes. The RHEF650 maintains identical electrical ratings, physical dimensions, and lead spacing (0.199") as the RHE650, enabling direct PCB substitution.

Q: What is the impact of the different post-trip resistance values?

A: The RHE650 specifies 4.3 Ohms maximum post-trip resistance, while both RHEF650 and MF-RHT650-0 specify 26 mOhms maximum. This represents improved performance in modern PTC fuse design and does not compromise functional equivalence for the specified 6.5A hold current and 12A trip current ratings.

Q: Does the MF-RHT650-0 require PCB layout changes?

A: Yes. The MF-RHT650-0 has lead spacing of 0.114" (2.90mm) compared to 0.199" (5.05mm) on the RHE650. PCB footprint verification is required before implementation.

Q: What are the compliance differences between substitute parts?

A: The RHE650 is RoHS non-compliant. Both RHEF650 and MF-RHT650-0 achieve ROHS3 compliance. The MF-RHT650-0 additionally carries AEC-Q200 automotive qualification.

Q: Are operating temperature ranges specified for all parts?

A: Operating temperature is not specified for the RHE650. Both RHEF650 and MF-RHT650-0 operate across -40°C to 125°C.

Q: What packaging formats are available?

A: RHE650 is supplied in standard packaging. RHEF650 is available in bag packaging. MF-RHT650-0 is supplied in bulk packaging.

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