RTEF190 Equivalent & Substitute Parts

Part Overview

The RTEF190 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc. in the PolySwitch® series, rated for 33V maximum voltage and 1.9A hold current. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing system support and component procurement.

PTC resettable fuses provide automatic overcurrent protection by increasing resistance when excessive current flows, then resetting when the fault condition clears. The obsolete status of the RTEF190 necessitates evaluation of active alternative components that maintain functional compatibility within system design parameters.

Substiute Parts

RTEF190

Littelfuse Inc.In Stock: 1050RTEF190 Datasheet

Current PartRFQ

RKEF185

LittelfuseIn Stock: 4550RKEF185 Datasheet

DirectRFQ

RUEF185

Littelfuse Inc.In Stock: 49742RUEF185 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the RTEF190 are evaluated based on the following critical parameters that determine functional compatibility:

Voltage Rating: The substitute must operate at or above the maximum voltage specification of 33V to ensure safe operation within the protected circuit.

Current - Hold (Ih): The hold current rating must be within acceptable tolerance of 1.9A to prevent nuisance trips during normal circuit operation.

Current - Trip (It): The trip current must provide appropriate overcurrent protection response, typically within 10-20% of the original specification.

Mounting Type and Package: Through-hole radial disc configuration with 0.199" (5.05mm) lead spacing ensures mechanical compatibility with existing PCB layouts.

Resistance Characteristics: Initial and post-trip resistance values affect circuit performance and heat dissipation during fault conditions.

The RKEF185 and RUEF185 are identified as substitute options based on shared PolySwitch® series design, through-hole radial mounting, and compatible lead spacing. Both parts maintain active product status with current manufacturing availability.

Parameter Comparison

Engineering Selection Recommendations

RUEF185 is the primary substitute for RTEF190 applications. This part maintains the closest alignment with original specifications: 30V maximum voltage (exceeds 33V requirement by margin), 1.85A hold current (within 2.6% of original 1.9A), identical 0.199" lead spacing, and matching radial disc package. RUEF185 holds active product status with 49,657 units in stock, ensuring long-term availability. Compliance certifications include CQC, CSA, TUV, and UL, with ROHS3 compliance and REACH unaffected status.

RKEF185 serves as a secondary substitute for applications requiring higher voltage tolerance. This part provides 60V maximum voltage rating and maintains 1.85A hold current specification. Lead spacing of 0.200" (5.08mm) is mechanically compatible with 0.199" (5.05mm) PCB layouts. RKEF185 is actively manufactured with 4,481 units available. Certifications include CSA, TUV, and UL with ROHS3 compliance.

Both substitute parts carry identical HTSUS and ECCN classifications as the original RTEF190, confirming regulatory equivalence for procurement and logistics purposes.

Frequently Asked Questions (FAQ)

Q: Can RUEF185 directly replace RTEF190 in existing designs?

A: RUEF185 provides direct mechanical and electrical compatibility. The 30V maximum voltage rating exceeds the RTEF190's 33V specification, and the 1.85A hold current is within acceptable tolerance of the original 1.9A. Lead spacing of 0.199" matches the original component. Circuit performance verification is necessary to confirm trip current behavior (3.7A vs. 3A) and time-to-trip characteristics (8.7s vs. 4.6s) are acceptable for the specific application.

Q: What is the difference between RKEF185 and RUEF185?

A: RKEF185 is rated for 60V maximum voltage with 1.85A hold current and 3.7A trip current. RUEF185 is rated for 30V maximum voltage with 1.85A hold current and 3.7A trip current. Both share identical hold current specifications but differ in voltage rating and trip characteristics. RUEF185 is recommended for 33V applications due to closer voltage alignment. RKEF185 is suitable for higher-voltage circuits requiring additional voltage margin.

Q: Are the lead spacing differences between RTEF190 and substitute parts significant?

A: RTEF190 specifies 0.199" (5.05mm) lead spacing. RUEF185 maintains identical 0.199" spacing. RKEF185 specifies 0.200" (5.08mm) spacing, representing a 0.01mm difference. This tolerance variation is within standard PCB manufacturing tolerances and does not prevent mechanical installation in existing through-hole layouts designed for the original component.

Q: Do substitute parts maintain the same regulatory certifications?

A: Both RKEF185 and RUEF185 hold CSA, TUV, and UL certifications matching the original RTEF190. RUEF185 additionally carries CQC certification. All three parts are ROHS3 compliant and REACH unaffected, confirming regulatory equivalence for procurement and deployment.

Q: How do trip current and time-to-trip differences affect circuit protection?

A: RTEF190 specifies 3A trip current with 4.6s time-to-trip. RKEF185 and RUEF185 both specify 3.7A trip current with longer time-to-trip values (12.6s and 8.7s respectively). These differences result in delayed protection response compared to the original component. Circuit analysis is required to confirm that the substitute's trip characteristics provide adequate overcurrent protection for the specific application without introducing nuisance trip conditions during normal operation.