SMCJ78CA-TP Transient Voltage Suppressor (TVS) Diode – Equivalent & Substitute Parts

Part Overview

The SMCJ78CA-TP is a unidirectional Zener-type transient voltage suppressor manufactured by Micro Commercial Co, designed for general-purpose overvoltage protection in surface-mount applications. This DO-214AB (SMC) package TVS diode operates across a junction temperature range of -55°C to 175°C and is ROHS3 compliant with unlimited moisture sensitivity rating (MSL 1). The part is currently active in production with 3,869 units in stock. Equivalent and substitute parts are identified based on matching or superior electrical performance within the same mechanical package footprint, enabling direct or near-direct board-level replacement when supply constraints or design optimization require alternative sourcing.

Key Parameters

Parameter	Value	Unit
Voltage – Reverse Standoff (Typ)	78	V
Voltage – Breakdown (Min)	86.7	V
Voltage – Clamping (Max) @ Ipp	126	V
Current – Peak Pulse (10/1000µs)	11.9	A
Power – Peak Pulse	1500	W
Operating Temperature Range	-55 to 175	°C (TJ)
Package / Case	DO-214AB, SMC	—
Mounting Type	Surface Mount	—
Type	Zener	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the SMCJ78CA-TP is determined by the following criteria:

Electrical Parameters (Critical):

Voltage – Reverse Standoff: 78V (nominal)
Voltage – Breakdown (Min): 86.7V
Voltage – Clamping (Max) @ Ipp: 126V
Current – Peak Pulse (10/1000µs): ≥11.9A (equal or higher acceptable)
Power – Peak Pulse: ≥1500W (equal or higher acceptable)

Mechanical Parameters (Critical):

Package / Case: DO-214AB or SMC equivalent
Mounting Type: Surface Mount
Bidirectional Channels: 1

Compliance & Environmental (Required):

Type: Zener
RoHS Status: ROHS3 Compliant
Operating Temperature: Must support minimum -55°C to 150°C range

Substitute parts are classified as Direct (identical electrical and mechanical specifications) or Similar (matching voltage and package with equal or superior current/power ratings). All listed substitutes maintain the same clamping voltage (126V) and reverse standoff voltage (78V) to ensure functional equivalence in circuit protection applications.

Parameter Comparison

Part Number	Manufacturer	Voltage – Reverse Standoff (V)	Voltage – Clamping (Max) @ Ipp (V)	Current – Peak Pulse (A)	Power – Peak Pulse (W)	Operating Temp Range (°C)	Package	RoHS Status
SMCJ78CA-TP	Micro Commercial Co	78	126	11.9	1500	-55 to 175	DO-214AB (SMC)	ROHS3
SMCJ78CA	MDD	78	126	11.9	1500	-50 to 150	DO-214AB (SMC)	ROHS3
SMCJ78CA-E3/57T	Vishay General Semiconductor – Diodes Division	78	126	11.9	1500	-55 to 150	DO-214AB (SMC)	ROHS3
5.0SMDJ78CA	MDE Semiconductor Inc	78	126	39.7	5000	-55 to 150	DO-214AB (SMC)	ROHS3
5.0SMDJ78CA-T7	Littelfuse Inc.	78	126	39.7	5000	-65 to 150	DO-214AB (SMC)	ROHS3
SMCJ78CA-13-F	Diodes Incorporated	78	126	11.4	1500	-55 to 150	DO-214AB (SMC)	ROHS3
SMDJ78CA	Alpha & Omega Semiconductor Inc.	78	126	23.9	3000	-55 to 150	DO-214AB (SMC)	ROHS3
SMDJ78CA-T7	Littelfuse Inc.	78	126	23.8	3000	-65 to 150	DO-214AB (SMC)	ROHS3
SMLJ78CA	Bourns Inc.	78	126	22.8	3000	-55 to 150	DO-214AB (SMC)	ROHS3

Engineering Selection Recommendations

Direct Substitutes (Identical Specifications): SMCJ78CA (MDD) and SMCJ78CA-E3/57T (Vishay) are direct electrical equivalents with matching 11.9A peak pulse current and 1500W power dissipation. Both maintain the 78V reverse standoff and 126V clamping voltage. SMCJ78CA-E3/57T is qualified to the TransZorb® series standard and carries Vishay's established reliability record. Selection between these options depends on supply availability and preferred manufacturer qualification.

Higher Current Capacity Substitutes (Superior Performance): Parts with elevated peak pulse current ratings (23.8A–39.7A) and corresponding power ratings (3000W–5000W) provide enhanced transient suppression margin. SMDJ78CA-T7 (Littelfuse, 23.8A, 3000W) and 5.0SMDJ78CA-T7 (Littelfuse, 39.7A, 5000W) extend the operating temperature range to -65°C, beneficial for harsh environments. These are suitable for applications requiring additional surge protection headroom without circuit redesign.

Temperature Range Considerations: The original SMCJ78CA-TP operates to 175°C junction temperature. Most substitutes are rated to 150°C maximum. Applications requiring the full 175°C capability should prioritize SMCJ78CA-E3/57T (Vishay, -55°C to 150°C) or confirm thermal design margins with lower-rated alternatives.

Compliance & Availability: All listed substitutes are ROHS3 compliant and carry active product status. Inventory levels vary: SMLJ78CA (Bourns) offers the highest stock (13,454 units), while SMCJ78CA-E3/57T (Vishay) provides 34,200 units. SMDJ78CA-T7 (Littelfuse) carries REACH Affected status; verify regulatory requirements for your application region.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with higher peak pulse current (e.g., 5.0SMDJ78CA-T7 at 39.7A instead of 11.9A)?

A: Yes. Higher current ratings provide superior transient suppression capability without affecting circuit protection function. The clamping voltage (126V) and reverse standoff voltage (78V) remain identical, ensuring equivalent overvoltage protection. Higher current capacity reduces thermal stress during surge events and extends component life in high-transient environments.

Q: What is the difference between SMCJ78CA and SMDJ78CA part numbers?

A: Both are 78V TVS diodes in DO-214AB (SMC) packages with identical clamping voltage (126V). The primary difference is peak pulse current: SMCJ78CA is rated 11.9A (1500W), while SMDJ78CA is rated 23.9A (3000W). SMDJ78CA provides double the surge capacity and is suitable for higher-energy transient environments. Both are electrically interchangeable at the circuit level.

Q: Are all substitute parts available in Tape & Reel (TR) packaging?

A: Most substitutes are supplied in Tape & Reel format for automated assembly. SMDJ78CA (Alpha & Omega) does not specify packaging format in available data. Confirm packaging availability with your supplier before design release, particularly for high-volume production requiring reel quantities.

Q: Does operating temperature range affect substitution eligibility?

A: Operating temperature range affects application suitability but not electrical substitution. The original SMCJ78CA-TP operates -55°C to 175°C. Most substitutes are rated -55°C to 150°C, which is acceptable for standard industrial applications (-40°C to 85°C ambient). Applications requiring junction temperatures above 150°C should retain the original part or confirm thermal margins with the substitute manufacturer.

Q: Can I substitute SMCJ78CA-TP with SMCJ78CA-13-F (Diodes Incorporated)?

A: Yes. SMCJ78CA-13-F is a direct substitute with matching 78V reverse standoff, 126V clamping voltage, and 11.4A peak pulse current (within 4.2% of the original 11.9A specification). Both are rated 1500W peak pulse power and operate across -55°C to 150°C. The slight current variation is within normal manufacturing tolerance and does not affect circuit protection performance.

Q: What does "ROHS3 Compliant" mean for TVS diode selection?

A: ROHS3 Compliant indicates the part meets Restriction of Hazardous Substances Directive 3 requirements, restricting lead, cadmium, mercury, and other hazardous materials. All listed substitutes carry ROHS3 compliance, ensuring compatibility with modern electronics manufacturing standards and regulatory requirements in EU and equivalent markets.

Q: Is the DO-214AB package identical to SMC package?

A: Yes. DO-214AB and SMC refer to the same surface-mount package outline. Both designations describe a two-lead surface-mount diode package with identical footprint, lead spacing, and soldering requirements. Parts listed as "DO-214AB (SMC)" or "SMC (DO-214AB)" are mechanically and electrically interchangeable at the PCB level.

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