CT139 Solid State Relay - Equivalent & Substitute Parts

Part Overview

The CT139 is a solid-state relay (SSR) manufactured by Coto Technology, configured as a SPST-NO (1 Form A) switching device in a 6-DIP package. This component is rated for 50 mA load current across 0–1000 V and features a 1.17 VDC input control voltage. The CT139 is classified as obsolete, making identification of compatible substitute parts essential for system redesign, inventory replenishment, and long-term design continuity. The CT140, manufactured by the same supplier, provides a direct alternative meeting similar form-factor and functional requirements.

Substiute Parts

CT139

Coto TechnologyIn Stock: 905CT139 Datasheet

Current PartRFQ

CT140

Coto TechnologyIn Stock: 1583CT140 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the CT139 are identified based on mechanical and electrical compatibility within the COTOMOS™ solid-state relay family. The critical substitution parameters are:

• Form Factor & Mounting: 6-DIP (0.300", 7.62mm) package with PC pin termination and through-hole mounting
• Control Input: 1.17 VDC input voltage
• Circuit Type: SPST-NO (1 Form A) configuration
• Output Capability: AC and DC switching support
• Compliance Standards: ROHS3 compliance and REACH unaffected status

The CT140 qualifies as a substitute based on identical mechanical packaging, control voltage, circuit configuration, and compliance certifications. Differences in load voltage rating (1500 V vs. 1000 V), load current (45 mA vs. 50 mA), and on-state resistance do not disqualify it as a substitute when the application operating parameters fall within the CT140's specification envelope.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: CT140

The CT140 is the preferred substitute for obsolete CT139 applications. Both devices share identical input control voltage (1.17 VDC), circuit configuration (SPST-NO 1 Form A), package dimensions (6-DIP 0.300"), and pin termination (PC Pin). Both comply with ROHS3 standards and carry unaffected REACH status.

The CT140 is currently in active production status, ensuring long-term availability and supply chain stability. This contrasts directly with the CT139's obsolete classification. The CT140 offers enhanced load voltage capability (1500 V vs. 1000 V), providing greater headroom in applications requiring maximum voltage rating flexibility.

Applications operating at or below 1000 V load voltage with current demands of 45 mA or less experience no functional constraint when migrating from CT139 to CT140. Pin-for-pin compatibility and identical control voltage specifications eliminate redesign requirements for PCB layouts and control circuitry.

Frequently Asked Questions (FAQ)

Q: Can the CT140 directly replace the CT139 in existing designs?

A: Yes. Both parts are housed in 6-DIP (0.300", 7.62mm) packages with PC pin termination and identical pinout. Control voltage is 1.17 VDC for both devices. No PCB layout or schematic modifications are required. The CT140 is a pin-for-pin and functionally compatible substitute.

Q: What are the key differences between CT139 and CT140?

A: Load voltage rating differs (CT139: 0–1000 V; CT140: 0–1500 V). Load current rating differs (CT139: 50 mA; CT140: 45 mA). On-state resistance differs (CT139: 150 Ω max; CT140: 200 Ω max). Product status differs (CT139: Obsolete; CT140: Active). All other parameters—input voltage, circuit type, packaging, mounting, and compliance—remain identical.

Q: Is the CT140's lower current rating (45 mA vs. 50 mA) a design limitation?

A: Substitution is suitable when your application requires 45 mA or less. If your design requires the full 50 mA capability of the original CT139, the CT140 does not provide adequate current headroom and should not be used.

Q: Are both parts RoHS3 compliant and REACH-affected?

A: Yes. Both CT139 and CT140 are ROHS3 compliant and REACH unaffected. Both carry Moisture Sensitivity Level (MSL) 2 rating with a 1-year shelf life. No compliance-based barriers exist to substitution.

Q: What is the advantage of the CT140's higher voltage rating?

A: The CT140 supports load voltages up to 1500 V, compared to 1000 V for the CT139. This provides 50% additional voltage margin, beneficial for applications approaching the original 1000 V limit or requiring future design flexibility. Applications safely operating within 1000 V receive no functional benefit but gain design margin.

Q: Can I substitute the CT139 with the CT140 in high-volume production?

A: Yes. The CT140 is in active production with 1552 pieces in current inventory, ensuring supply chain reliability. The CT139, classified as obsolete with 833 pieces available, presents long-term procurement risk. The CT140 substitution eliminates obsolescence risk for future production runs.