SMAJ51C Equivalent & Substitute Parts

Part Overview

The SMAJ51C is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This bidirectional zener diode operates at a 51V reverse standoff voltage with an 86.52V maximum clamping voltage and 4.9A peak pulse current rating in a DO-214AC (SMA) package.

The SMAJ51C is classified as obsolete. Equivalent and substitute parts are available from multiple active manufacturers, offering comparable or enhanced electrical performance while maintaining the same package footprint and core functional specifications.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	51	V
Voltage - Breakdown (Min)	53.73	V
Voltage - Clamping (Max) @ Ipp	86.52	V
Current - Peak Pulse (10/1000µs)	4.9	A
Power - Peak Pulse	400	W
Package / Case	DO-214AC, SMA	—
Operating Temperature Range	-65 to 150	°C (TJ)
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the SMAJ51C is determined by the following critical parameters:

Reverse Standoff Voltage: 51V (all substitutes match this specification)
Package Type: DO-214AC / SMA surface mount (all substitutes use identical package)
Bidirectional Channels: 1 (all substitutes are single-channel bidirectional devices)
Type: Zener TVS diode (all substitutes are zener-type TVS diodes)
RoHS Compliance: ROHS3 Compliant (all substitutes meet this requirement)
Moisture Sensitivity: MSL 1 (all substitutes rated MSL 1)

Substitute parts are grouped into two categories based on clamping voltage performance:

Group A (Lower Clamping Voltage): SMAJ51CA, SMAJ51CA-13-F, SMAJ51CA-TP, TV04A510JB-G, TV04A510JB-HF — all feature 82.4V maximum clamping voltage with 4.85–4.9A peak pulse current.

Group B (Higher Clamping Voltage): SMAJ51CE3/TR13 — features 91.1V maximum clamping voltage with 5.5A peak pulse current and 500W power rating.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (V)	Voltage - Clamping (Max) @ Ipp (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Operating Temperature (°C)	Product Status	Package
SMAJ51C	Littelfuse Inc.	51	86.52	4.9	400	-65 to 150	Obsolete	DO-214AC (SMA)
SMAJ51CA	Good-Ark Semiconductor	51	82.4	4.9	400	-55 to 150	Active	DO-214AC (SMA)
SMAJ51CA-13-F	Diodes Incorporated	51	82.4	4.9	400	-55 to 150	Active	DO-214AC (SMA)
SMAJ51CA-TP	Micro Commercial Co	51	82.4	4.9	400	-55 to 175	Active	DO-214AC (SMA)
SMAJ51CE3/TR13	Microchip Technology	51	91.1	5.5	500	-65 to 150	Active	DO-214AC (SMA)
TV04A510JB-G	Comchip Technology	51	82.4	4.85	400	-55 to 150	Active	DO-214AC (SMA)
TV04A510JB-HF	Comchip Technology	51	82.4	4.85	400	-55 to 150	Active	DO-214AC (SMA)

Engineering Selection Recommendations

For Direct Replacement (Group A Substitutes)

SMAJ51CA, SMAJ51CA-13-F, SMAJ51CA-TP, TV04A510JB-G, and TV04A510JB-HF are direct functional equivalents with lower clamping voltages (82.4V vs. 86.52V). All are active products with ROHS3 compliance and MSL 1 rating. These parts are suitable for applications where the lower clamping voltage provides adequate protection margin.

SMAJ51CA-TP offers the widest operating temperature range (-55 to 175°C), making it preferable for high-temperature environments.

For Enhanced Performance (Group B Substitute)

SMAJ51CE3/TR13 from Microchip Technology provides higher clamping voltage (91.1V) and increased peak pulse current (5.5A) with 500W power rating. This part matches the original SMAJ51C operating temperature range (-65 to 150°C) and is suitable for applications requiring higher transient energy absorption. Product status is active with full ROHS3 and REACH compliance.

Compliance Considerations

All substitute parts are ROHS3 compliant and carry MSL 1 moisture sensitivity rating, matching the original specification. All are available from active manufacturers with established supply chains.

Frequently Asked Questions (FAQ)

Q: Can I use SMAJ51CA as a direct replacement for SMAJ51C?

A: Yes. SMAJ51CA maintains the same 51V reverse standoff voltage, DO-214AC package, and 4.9A peak pulse current. The clamping voltage is lower (82.4V vs. 86.52V), which is acceptable for most general-purpose overvoltage protection applications. SMAJ51CA is an active product from Good-Ark Semiconductor with full compliance certifications.

Q: What is the difference between Group A and Group B substitutes?

A: Group A substitutes (SMAJ51CA, SMAJ51CA-13-F, SMAJ51CA-TP, TV04A510JB-G, TV04A510JB-HF) feature 82.4V clamping voltage and 400W power rating. Group B (SMAJ51CE3/TR13) features 91.1V clamping voltage and 500W power rating. Group B provides higher transient energy absorption capacity.

Q: Does the lower clamping voltage of Group A parts affect circuit protection?

A: Lower clamping voltage reduces the peak voltage seen by protected circuitry during transient events. For most applications, this is beneficial. Selection depends on the specific voltage tolerance of downstream components.

Q: Are all substitutes available in the same package?

A: Yes. All substitute parts use the DO-214AC (SMA) surface-mount package, ensuring mechanical and electrical compatibility with the original SMAJ51C footprint.

Q: Which substitute has the best temperature performance?

A: SMAJ51CA-TP supports -55 to 175°C operating range, the widest upper temperature limit among all substitutes. SMAJ51CE3/TR13 matches the original -65 to 150°C range.

Q: Are all substitutes RoHS compliant?

A: Yes. All substitute parts are ROHS3 compliant with MSL 1 moisture sensitivity rating, matching the original specification.

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