SMAJ300C Transient Voltage Suppressor Equivalent & Substitute Parts

Part Overview

The SMAJ300C is a bidirectional Zener transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. The device features a 300V reverse standoff voltage with a 510.3V maximum clamping voltage and 800mA peak pulse current capability in a DO-214AC (SMA) package.

The SMAJ300C is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this component.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	300	V
Voltage - Breakdown (Min)	317.7	V
Voltage - Clamping (Max) @ Ipp	510.3	V
Current - Peak Pulse (10/1000µs)	800	mA
Power - Peak Pulse	400	W
Operating Temperature Range	-65 to 150	°C
Package / Case	DO-214AC (SMA)	—
Mounting Type	Surface Mount	—
Type	Zener	—
Bidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitution of the SMAJ300C is determined by strict alignment of the following electrical and mechanical parameters:

Reverse standoff voltage: 300V (nominal)
Package / Case: DO-214AC (SMA) surface mount
Bidirectional channel configuration: 1 channel
Device type: Zener TVS diode
Peak pulse power rating: 400W
Mounting type: Surface mount

Substitute parts must maintain compatibility across these core parameters. Variations in clamping voltage (within the specified range), peak pulse current, and operating temperature range are permissible provided the part remains functionally equivalent for the intended application category (general purpose or telecom overvoltage protection).

Parameter Comparison

Parameter	SMAJ300C (Littelfuse)	SMAJ300CA (Meritek)	P4SMA350CA (Eaton)	SMAJ300CA-TP (Micro Commercial Co)
Voltage - Reverse Standoff (Typ)	300V	300V	300V	300V
Voltage - Breakdown (Min)	317.7V	335V	332V	335V
Voltage - Clamping (Max) @ Ipp	510.3V	486V	482V	486V
Current - Peak Pulse (10/1000µs)	800mA	820mA	900mA	800mA
Power - Peak Pulse	400W	400W	400W	400W
Operating Temperature Range	-65 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 175°C
Package / Case	DO-214AC (SMA)	DO-214AC (SMA)	DO-214AC (SMA)	DO-214AC (SMA)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active

Engineering Selection Recommendations

All three substitute parts (SMAJ300CA, P4SMA350CA, and SMAJ300CA-TP) are classified as active products with current manufacturing status, ensuring long-term supply chain availability compared to the obsolete SMAJ300C.

SMAJ300CA (Meritek) and SMAJ300CA-TP (Micro Commercial Co) maintain the closest electrical alignment to the original SMAJ300C, with clamping voltages of 486V and peak pulse currents of 820mA and 800mA respectively. Both are ROHS3 compliant.

P4SMA350CA (Eaton - Electronics Division) offers the highest peak pulse current capability at 900mA with a clamping voltage of 482V, providing enhanced transient suppression margin. This part is designated for telecom applications and carries RoHS compliance certification.

All substitute parts are packaged in DO-214AC (SMA) surface-mount configuration and maintain the 300V reverse standoff voltage specification. Selection should be based on specific application requirements, supply chain availability, and thermal operating range constraints.

Frequently Asked Questions (FAQ)

Q: Can SMAJ300CA be used as a direct replacement for SMAJ300C?

A: Yes. SMAJ300CA maintains the same 300V reverse standoff voltage, DO-214AC (SMA) package, and 400W peak pulse power rating. The clamping voltage is 486V compared to 510.3V in the original part, representing a 4.8% reduction within acceptable substitution tolerance for general-purpose TVS applications.

Q: What is the difference between SMAJ300CA and SMAJ300CA-TP?

A: Both parts share identical electrical specifications (300V standoff, 486V clamping, 400W power rating) and DO-214AC (SMA) packaging. SMAJ300CA-TP is supplied in Tape & Reel (TR) packaging format and supports an extended operating temperature range of -55 to 175°C compared to -55 to 150°C for SMAJ300CA. SMAJ300CA-TP is manufactured by Micro Commercial Co.

Q: Is P4SMA350CA suitable for the same applications as SMAJ300C?

A: P4SMA350CA is functionally compatible for general overvoltage protection applications. It maintains the 300V reverse standoff voltage and DO-214AC (SMA) package. The part offers higher peak pulse current (900mA vs. 800mA) and slightly lower clamping voltage (482V vs. 510.3V). P4SMA350CA is designated for telecom applications and carries RoHS compliance.

Q: What are the key parameters that determine substitution compatibility?

A: Substitution compatibility is determined by: reverse standoff voltage (300V), package type (DO-214AC/SMA), mounting configuration (surface mount), bidirectional channel count (1), and peak pulse power rating (400W). Variations in clamping voltage and peak pulse current are permissible within the specified electrical operating range.

Q: Are all substitute parts RoHS compliant?

A: Yes. SMAJ300CA and SMAJ300CA-TP are ROHS3 compliant. P4SMA350CA is RoHS compliant. All three substitute parts meet environmental compliance requirements for modern manufacturing and deployment.

Q: What is the operating temperature range difference between substitutes?

A: SMAJ300CA and P4SMA350CA support -55 to 150°C operating range. SMAJ300CA-TP extends this to -55 to 175°C, providing enhanced thermal margin for high-temperature applications. The original SMAJ300C supports -65 to 150°C; substitutes have a minimum temperature floor of -55°C.

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