CD214A-T18ALF Equivalent & Substitute Parts

Part Overview

The CD214A-T18ALF is a transient voltage suppressor (TVS) diode manufactured by Bourns Inc., designed for general-purpose overvoltage protection in surface-mount applications. This unidirectional Zener diode operates with an 18V reverse standoff voltage and provides 29.2V clamping at peak pulse current. The part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain electrical and mechanical compatibility for new designs or production continuity.

Key Parameters

Parameter	Value
Manufacturer Part Number	CD214A-T18ALF
Manufacturer	Bourns Inc.
Category	Transient Voltage Suppressors (TVS)
Package / Case	DO-214AC, SMA
Mounting Type	Surface Mount
Type	Zener
Unidirectional Channels	1
Voltage - Reverse Standoff (Typ)	18V
Voltage - Breakdown (Min)	20V
Voltage - Clamping (Max) @ Ipp	29.2V
Current - Peak Pulse (10/1000µs)	13.7A
Power - Peak Pulse	400W
Operating Temperature	-55°C ~ 150°C (TJ)
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the CD214A-T18ALF is determined by strict electrical and mechanical parameter alignment:

Critical Matching Parameters:

Voltage - Reverse Standoff (Typ): 18V
Voltage - Breakdown (Min): 20V minimum
Package / Case: DO-214AC (SMA)
Mounting Type: Surface Mount
Unidirectional Channels: 1
Type: Zener

Direct Equivalents maintain identical electrical specifications (18V standoff, 20V breakdown minimum, 29.2V clamping, 13.7A peak pulse current) and are sourced from active manufacturers. These parts are pin-compatible and electrically interchangeable without circuit modification.

Similar Alternatives share the same voltage class (18V standoff, 20V breakdown) and package but differ in clamping voltage, peak pulse current, or power dissipation. These parts are mechanically compatible but require circuit-level verification of performance parameters.

Voltage-Adjacent Parts (15V and 16V standoff) are listed for reference only and are not direct substitutes due to different voltage ratings.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Operating Temperature	Product Status	Package / Case
CD214A-T18ALF	Bourns Inc.	18V	20V	29.2V	13.7A	400W	-55°C ~ 150°C (TJ)	Obsolete	DO-214AC, SMA
SMAJ18A	MDD	18V	20V	29.2V	13.7A	400W	-50°C ~ 150°C (TJ)	Active	DO-214AC, SMA
SM4T21AY	STMicroelectronics	18V	20V	39.3V	59A (8/20µs)	400W	-55°C ~ 150°C (TJ)	Active	DO-214AC, SMA
SMA6J18A-E3/5A	Vishay General Semiconductor - Diodes Division	18V	20V	33.2V	102A (8/20µs)	4000W	-55°C ~ 150°C (TJ)	Active	DO-214AC, SMA
SMA6J18A-TP	Micro Commercial Co	18V	20V	29.2V	20.5A	600W	-55°C ~ 175°C (TA)	Active	DO-214AC, SMA
SMA6J18A-TR	STMicroelectronics	18V	20V	33.2V	102A (8/20µs)	600W	-55°C ~ 175°C (TJ)	Active	DO-214AC, SMA

Engineering Selection Recommendations

Direct Equivalent (Recommended for Pin-for-Pin Replacement): SMAJ18A (MDD) is the primary direct equivalent, matching all critical electrical parameters (18V standoff, 20V breakdown, 29.2V clamping, 13.7A peak pulse). Product status is active with 15,522 units in stock. Operating temperature range is -50°C to 150°C, which covers the original -55°C to 150°C specification for most applications above -50°C. RoHS3 compliance and MSL 1 rating are maintained.

Alternative Direct Equivalent: SMA6J18A-TP (Micro Commercial Co) provides identical clamping voltage (29.2V) with enhanced peak pulse current (20.5A) and power dissipation (600W). Operating temperature extends to 175°C. This part is suitable where higher transient current handling or extended temperature operation is beneficial.

Higher Performance Alternatives: SMA6J18A-E3/5A (Vishay) and SMA6J18A-TR (STMicroelectronics) both provide 18V standoff with higher clamping voltage (33.2V) and significantly higher peak pulse current (102A). These are appropriate for applications requiring enhanced transient suppression capability. SMA6J18A-TR offers extended temperature range to 175°C.

Compliance Verification: All recommended substitutes maintain ROHS3 compliance, MSL 1 rating, and EAR99 export classification. REACH status varies; verify against specific supply chain requirements.

Frequently Asked Questions (FAQ)

Q: Can SMAJ18A directly replace CD214A-T18ALF without circuit modification? A: Yes. SMAJ18A matches all critical electrical parameters (18V standoff, 20V breakdown, 29.2V clamping, 13.7A peak pulse) and uses identical DO-214AC (SMA) packaging. The operating temperature range (-50°C to 150°C) is compatible with most applications. Verify your circuit's minimum operating temperature requirement.

Q: What is the difference between direct equivalents and similar alternatives? A: Direct equivalents (SMAJ18A, SMA6J18A-TP) maintain identical clamping voltage and peak pulse current specifications. Similar alternatives (SMA6J18A-E3/5A, SMA6J18A-TR) share the same voltage class but provide higher clamping voltage and peak pulse current, requiring circuit-level performance verification.

Q: Are all substitute parts in the same package? A: Yes. All listed substitutes use DO-214AC (SMA) surface-mount packaging, ensuring mechanical compatibility with existing PCB layouts and assembly processes.

Q: Why are SMAJ15A and SMAJ16A parts listed if they are not direct substitutes? A: These parts are included for reference only. They represent voltage-adjacent alternatives (15V and 16V standoff) and are not electrically compatible with the 18V standoff requirement of CD214A-T18ALF.

Q: What compliance certifications should I verify for my application? A: All recommended substitutes are ROHS3 compliant and carry MSL 1 (unlimited moisture sensitivity). Verify REACH status and ECCN classification against your supply chain and export requirements. STMicroelectronics SM4T21AY and SMA6J18A-TR carry AEC-Q101 automotive qualification if automotive-grade components are required.

Q: Can I use parts with higher peak pulse current ratings as direct replacements? A: Yes, from an electrical compatibility standpoint. Parts with higher peak pulse current (such as SMA6J18A-TP at 20.5A or SMA6J18A-E3/5A at 102A) provide enhanced transient suppression without degrading circuit performance. Verify that your PCB layout and thermal management accommodate any increased power dissipation.

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