SMAJ120 Equivalent & Substitute Parts

Part Overview

The SMAJ120 is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse, rated for 120V reverse standoff voltage with a 202.65V maximum clamping voltage. This component is designed for general-purpose transient voltage protection in surface-mount applications using the DO-214AC (SMA) package. The SMAJ120 is currently listed as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	120V
Voltage - Breakdown (Min)	126V
Voltage - Clamping (Max) @ Ipp	202.65V
Current - Peak Pulse (10/1000µs)	2.1A
Power - Peak Pulse	400W
Package / Case	DO-214AC, SMA
Operating Temperature Range	-65°C ~ 150°C (TJ)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the SMAJ120 are qualified based on the following critical parameters:

Voltage - Reverse Standoff: Must be 120V (±0V tolerance for direct substitution)
Package / Case: Must be DO-214AC, SMA (identical footprint and pinout)
Unidirectional Channels: Must be 1 (single channel configuration)
Type: Must be Zener TVS diode
Mounting Type: Must be Surface Mount
RoHS Status: Must maintain ROHS3 compliance

All identified substitute parts meet these core electrical and mechanical requirements. Variations in clamping voltage (193V to 214V range), peak pulse current (2.0A to 2.6A), and power dissipation (400W to 500W) remain within acceptable operating margins for general-purpose transient suppression applications while maintaining the same reverse standoff voltage and package footprint.

Parameter Comparison

Parameter	SMAJ120 (Littelfuse)	SMAJ120A (MDD)	SMAJ120A-13-F (Diodes Inc.)	SMAJ120AE3/TR13 (Microchip)	SMAJ120E3/TR13 (Microchip)	TV04A121J-G (Comchip)
Voltage - Reverse Standoff (Typ)	120V	120V	120V	120V	120V	120V
Voltage - Breakdown (Min)	126V	133V	133V	133V	133V	133V
Voltage - Clamping (Max) @ Ipp	202.65V	193V	193V	193V	214V	193V
Current - Peak Pulse (10/1000µs)	2.1A	2.1A	2.0A	2.6A	2.3A	2.07A
Power - Peak Pulse	400W	400W	400W	500W	500W	400W
Package / Case	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA	DO-214AC, SMA
Operating Temperature Range	-65°C ~ 150°C	-50°C ~ 150°C	-55°C ~ 150°C	-65°C ~ 150°C	-65°C ~ 150°C	-55°C ~ 150°C
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

All substitute parts listed are active production components with ROHS3 compliance and MSL 1 rating, ensuring long-term availability and regulatory compliance. The SMAJ120A (MDD) and TV04A121J-G (Comchip) provide direct electrical equivalence with 193V clamping voltage and 2.0A to 2.07A peak pulse current. The SMAJ120AE3/TR13 (Microchip) offers enhanced power dissipation at 500W with 2.6A peak pulse current. The SMAJ120E3/TR13 (Microchip) provides 214V clamping voltage, suitable for applications requiring higher transient suppression margins. The SMAJ120A-13-F (Diodes Incorporated) includes automotive-grade qualification and is rated for -55°C to 150°C operation.

Selection should prioritize active-status components based on supply chain availability, lead time requirements, and specific application temperature range needs. All substitute parts maintain identical package footprint and pinout compatibility with the original SMAJ120.

Frequently Asked Questions (FAQ)

Q: Can SMAJ120 substitutes be used interchangeably in existing designs?

A: Yes, all listed substitute parts share identical reverse standoff voltage (120V), package type (DO-214AC, SMA), and unidirectional channel configuration. Direct PCB footprint compatibility is maintained. Variations in clamping voltage and peak pulse current remain within acceptable operating parameters for general-purpose transient suppression.

Q: What is the difference between the Microchip SMAJ120AE3/TR13 and SMAJ120E3/TR13 variants?

A: Both are Microchip products with identical reverse standoff voltage and package. The SMAJ120AE3/TR13 provides 193V clamping voltage with 2.6A peak pulse current and 500W power dissipation. The SMAJ120E3/TR13 provides 214V clamping voltage with 2.3A peak pulse current and 500W power dissipation. Selection depends on required transient suppression voltage margin.

Q: Does the SMAJ120A-13-F automotive grade affect general-purpose applications?

A: No. Automotive-grade qualification indicates additional testing and reliability standards. This part is fully compatible with general-purpose applications and offers enhanced reliability margins.

Q: Are there temperature range limitations when substituting the SMAJ120?

A: The original SMAJ120 operates from -65°C to 150°C. Most substitutes operate from -50°C to -55°C minimum. For applications requiring -65°C operation, select SMAJ120AE3/TR13 or SMAJ120E3/TR13 (both Microchip, -65°C rated).

Q: What packaging format is available for these substitutes?

A: All substitute parts are supplied in Tape & Reel (TR) packaging for automated assembly. The DO-214AC (SMA) package remains consistent across all variants.

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