MDCG-4-17-38 Equivalent & Substitute Parts

Part Overview

The MDCG-4-17-38 is a glass body reed switch manufactured by Littelfuse, configured as a single-pole single-throw normally open (SPST-NO) device. This through-hole mounted component operates within a 17–38 AT (Ampere-Turn) range and is rated for 350mA AC / 500mA DC switching at 140V AC and 200V DC, with a maximum power dissipation of 10W. The part is currently active in production with ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1).

Equivalent and substitute parts are identified when component availability is limited, supply chain disruptions occur, or design flexibility permits functional alternatives that meet or exceed the electrical and mechanical requirements of the original specification.

Substiute Parts

MDCG-4-17-38

LittelfuseIn Stock: 795MDCG-4-17-38 Datasheet

Current PartRFQ

KSK-1A35-1015

Standex-Meder ElectronicsIn Stock: 3690KSK-1A35-1015 Datasheet

MFR RecommendedRFQ

KSK-1A66/3-2030

Standex-Meder ElectronicsIn Stock: 1307KSK-1A66/3-2030 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MDCG-4-17-38 is determined by the following critical parameters:

Circuit Configuration: All substitutes must maintain SPST-NO topology to preserve switching logic and control function.

Voltage Rating: Substitute parts must support minimum 140V AC and 200V DC switching voltage to ensure safe operation within the original design envelope.

Current Capacity: Substitute parts must accommodate minimum 350mA AC and 500mA DC switching current without exceeding rated power dissipation.

Power Rating: Substitute parts must support minimum 10W rated power to handle the electrical load of the original application.

Mounting Compatibility: Substitutes may differ in mounting type (through-hole vs. surface mount) provided the circuit board layout and assembly process can accommodate the alternative form factor.

Operating Temperature: Substitute parts must cover the full −40°C to 125°C operating range or a superset thereof.

Compliance: All substitutes must maintain ROHS3 compliance and MSL 1 rating to satisfy regulatory and environmental requirements.

Two substitute parts are identified: KSK-1A35-1015 and KSK-1A66/3-2030, both manufactured by Standex-Meder Electronics. These parts meet or exceed the electrical specifications of the MDCG-4-17-38 while offering alternative form factors and enhanced performance characteristics.

Parameter Comparison

Engineering Selection Recommendations

KSK-1A35-1015 Suitability:

This substitute exceeds the electrical specifications of the MDCG-4-17-38 in switching current (1A vs. 350mA AC / 500mA DC) and power rating (20W vs. 10W). The voltage ratings (200V AC/DC) meet or exceed the original specification. The operating temperature range extends to 130°C, providing additional thermal margin. However, this part is configured for surface mount assembly, requiring circuit board redesign and revalidation of the assembly process. This substitute is suitable for new designs or redesigned boards where surface mount technology is preferred.

KSK-1A66/3-2030 Suitability:

This substitute maintains through-hole mounting compatibility with the MDCG-4-17-38, eliminating the need for board redesign. Switching current (500mA AC/DC) meets the DC specification of the original part and exceeds the AC specification (350mA). Voltage ratings (200V AC/DC) exceed the original specification. Power rating (10W) matches the original specification. The operating temperature range extends to 130°C. This substitute is suitable for direct replacement in existing through-hole designs without circuit board modification.

Both substitutes maintain ROHS3 compliance and MSL 1 rating, satisfying regulatory and environmental requirements equivalent to the original part.

Frequently Asked Questions (FAQ)

Q: Can KSK-1A35-1015 be used as a direct replacement for MDCG-4-17-38 on existing circuit boards?

A: No. KSK-1A35-1015 is configured for surface mount assembly, while MDCG-4-17-38 uses through-hole mounting. Direct substitution requires circuit board redesign and assembly process modification. KSK-1A66/3-2030 is the appropriate choice for through-hole applications without board modification.

Q: What are the key electrical differences between the substitute parts?

A: KSK-1A35-1015 provides higher switching current capacity (1A) and power rating (20W) compared to the original part. KSK-1A66/3-2030 matches the original power rating (10W) while providing equivalent or superior switching current and voltage specifications. Both substitutes support 200V AC/DC switching voltage, exceeding the original 140V AC specification.

Q: Are both substitute parts compliant with the same regulatory standards as the original part?

A: Yes. Both KSK-1A35-1015 and KSK-1A66/3-2030 maintain ROHS3 compliance and MSL 1 (unlimited) moisture sensitivity rating, matching the regulatory and environmental profile of MDCG-4-17-38.

Q: What is the operate range specification, and how does it affect substitution?

A: Operate range, measured in Ampere-Turns (AT), defines the magnetic field strength required to activate the reed switch. MDCG-4-17-38 operates at 17–38 AT, KSK-1A35-1015 at 10–15 AT, and KSK-1A66/3-2030 at 20–30 AT. Substitution is valid when the magnetic field source in the application falls within the operate range of the substitute part. Verify magnetic field specifications before substitution.

Q: Can these substitutes handle higher current loads than the original part?

A: Yes. Both substitutes support equal or higher switching current ratings. KSK-1A35-1015 supports 1A (AC/DC) compared to the original 350mA AC / 500mA DC. KSK-1A66/3-2030 supports 500mA (AC/DC), matching the original DC specification and exceeding the AC specification. Verify that the application load does not exceed the rated specifications of the selected substitute.

Q: What is the impact of different release times on circuit performance?

A: Release time defines the delay between magnetic field removal and switch opening. MDCG-4-17-38 has a 0.2 ms release time. KSK-1A35-1015 has 0.1 ms, and KSK-1A66/3-2030 has 0.05 ms. Faster release times may improve circuit response in timing-sensitive applications but do not affect basic switching functionality. Verify timing requirements before substitution.