MDCG-4-12-38 Equivalent & Substitute Parts

Part Overview

The MDCG-4-12-38 is a glass body reed switch manufactured by Littelfuse Inc., configured as a SPST-NO (Single Pole Single Throw - Normally Open) device. This through-hole mounted component operates within a 12 ~ 38AT actuation range and is rated for 350mA AC / 500mA DC switching at 140V AC and 200V DC. The part is currently active in production with 1,158 units in stock. Substitute parts are identified when equivalent electrical performance and mechanical compatibility can be maintained within the specified parameter tolerances for this reed switch category.

Substiute Parts

MDCG-4-12-38

Littelfuse Inc.In Stock: 1206MDCG-4-12-38 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

Substitute parts for the MDCG-4-12-38 are qualified based on the following electrical and mechanical criteria:

Primary Substitution Criteria:

• Circuit configuration must remain SPST-NO
• Switching voltage ratings must meet or exceed the original specification (140V AC / 200V DC minimum)
• Switching current capacity must support the application requirements
• Rated power must be sufficient for the intended load
• Operating temperature range must encompass the application environment
• RoHS3 compliance and REACH unaffected status must be maintained
• Mounting type compatibility with the circuit board design

Identified Substitute Parts:

1. KSK-1A35-1015 (Standex-Meder Electronics) — Qualified for applications where surface mount technology is acceptable and higher current capacity (1A AC/DC) is beneficial. Operates within 10 ~ 15AT range with 20W rated power.

2. KSK-1A66/3-2030 (Standex-Meder Electronics) — Qualified for through-hole mounting applications requiring 500mA AC/DC switching capacity. Operates within 20 ~ 30AT range with 10W rated power.

Parameter Comparison

Engineering Selection Recommendations

KSK-1A66/3-2030 Selection: This substitute is the primary recommendation for through-hole mounting applications. It maintains identical mounting technology, rated power (10W), and DC switching current (500mA) as the MDCG-4-12-38. Both parts are ROHS3 compliant and REACH unaffected. The KSK-1A66/3-2030 provides 200V AC/DC switching capability, exceeding the original 140V AC specification. The operate range (20 ~ 30AT) differs from the original (12 ~ 38AT), requiring verification that the application's magnetic field strength aligns with this narrower actuation window.

KSK-1A35-1015 Selection: This substitute is applicable only when surface mount technology can replace through-hole mounting in the circuit board design. It provides superior current capacity (1A AC/DC) and higher rated power (20W), with extended operating temperature range (-40°C ~ 130°C). The operate range (10 ~ 15AT) is significantly different from the original specification and requires confirmation of magnetic field compatibility.

Both substitutes maintain full regulatory compliance (ROHS3, REACH unaffected, EAR99 ECCN classification).

Frequently Asked Questions (FAQ)

Q: Can KSK-1A35-1015 directly replace MDCG-4-12-38 on the same PCB?

A: No. KSK-1A35-1015 uses surface mount termination, while MDCG-4-12-38 uses through-hole axial termination. PCB layout and footprint modifications are required. Additionally, the operate range differs (10 ~ 15AT vs. 12 ~ 38AT), requiring magnetic field verification.

Q: What is the primary difference between the two substitute options?

A: KSK-1A66/3-2030 maintains through-hole mounting compatibility with the original part, while KSK-1A35-1015 requires surface mount capability. KSK-1A35-1015 offers higher current capacity (1A vs. 500mA) and power rating (20W vs. 10W).

Q: Are the operate range differences critical?

A: Yes. The operate range (measured in Ampere-Turns, AT) determines the magnetic field strength required to actuate the switch. MDCG-4-12-38 operates at 12 ~ 38AT, KSK-1A66/3-2030 at 20 ~ 30AT, and KSK-1A35-1015 at 10 ~ 15AT. The application's magnetic actuator must be compatible with the selected substitute's actuation range.

Q: Do all parts meet the same regulatory requirements?

A: Yes. MDCG-4-12-38, KSK-1A66/3-2030, and KSK-1A35-1015 are all ROHS3 compliant, REACH unaffected, and classified as EAR99 for export control purposes.

Q: What is the switching voltage difference between MDCG-4-12-38 and the substitutes?

A: MDCG-4-12-38 is rated for 140V AC / 200V DC. Both KSK substitutes are rated for 200V AC / 200V DC, providing higher AC voltage capability. This makes them suitable for applications requiring higher AC switching voltages.

Q: Can I use KSK-1A66/3-2030 in all applications where MDCG-4-12-38 is currently installed?

A: Substitution requires verification of three factors: (1) magnetic field strength compatibility with the 20 ~ 30AT operate range, (2) circuit board layout compatibility with through-hole mounting, and (3) confirmation that 500mA DC / 500mA AC switching current meets application requirements.