SRDA05-4R2 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SRDA05-4R2 is a steering (rail-to-rail) transient voltage suppressor diode manufactured by onsemi, designed for general-purpose power line protection applications. This 8-SOIC surface-mount device features a 5V reverse standoff voltage with a 12V maximum clamping voltage and 10A peak pulse current rating (8/20µs).

The SRDA05-4R2 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
Manufacturer	onsemi
Category	Transient Voltage Suppressors (TVS)
Type	Steering (Rail to Rail)
Unidirectional Channels	4
Voltage - Reverse Standoff (Typ)	5V
Voltage - Breakdown (Min)	6V
Voltage - Clamping (Max) @ Ipp	12V
Current - Peak Pulse (10/1000µs)	10A (8/20µs)
Power - Peak Pulse	500W
Mounting Type	Surface Mount
Package / Case	8-SOIC (0.154", 3.90mm Width)
Operating Temperature	-55°C ~ 150°C (TJ)
Capacitance @ Frequency	10pF @ 1MHz
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the SRDA05-4R2 are classified based on the following substitution criteria:

Direct Equivalent (Identical Electrical & Mechanical Parameters):

Reverse standoff voltage: 5V
Breakdown voltage (Min): 6V
Clamping voltage (Max): 12V
Peak pulse current: 10A (8/20µs)
Package: 8-SOIC
Mounting type: Surface Mount
Unidirectional channels: 4

Similar Substitutes (Compatible Electrical Parameters with Deviations):

Reverse standoff voltage: 5V or 3.3V
Package: 8-SOIC or 8-SO
Mounting type: Surface Mount
Unidirectional channels: 4
Clamping voltage (Max): 12V to 21V range
Peak pulse current: 10A to 30A range

The SRDA05-4R2G represents a direct equivalent with improved product status (Active vs. Obsolete) and enhanced RoHS compliance. The SRDA05-4.TBT, SRDA05-4BTG, and SRDA3.3-4BTG are similar substitutes with higher current and clamping voltage ratings, suitable for applications requiring enhanced transient protection margins.

Parameter Comparison

Parameter	SRDA05-4R2 (Main)	SRDA05-4R2G (Direct)	SRDA05-4.TBT (Similar)	SRDA05-4BTG (Similar)	SRDA3.3-4BTG (Similar)
Manufacturer	onsemi	onsemi	Semtech Corporation	Littelfuse Inc.	Littelfuse Inc.
Type	Steering (Rail to Rail)	Steering (Rail to Rail)	Steering (Rail to Rail)	Steering (Rail to Rail)	Steering (Rail to Rail)
Unidirectional Channels	4	4	4	4	4
Voltage - Reverse Standoff (Typ)	5V	5V	5V (Max)	5V (Max)	3.3V (Max)
Voltage - Breakdown (Min)	6V	6V	6V	6V	4.6V
Voltage - Clamping (Max) @ Ipp	12V	12V	20V	21V	17.7V (Typ)
Current - Peak Pulse (10/1000µs)	10A (8/20µs)	10A (8/20µs)	25A (8/20µs)	25A (8/20µs)	30A (8/20µs)
Power - Peak Pulse	500W	500W	500W	600W	600W
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	8-SOIC	8-SOIC	8-SO	8-SOIC	8-SOIC
Operating Temperature	-55°C ~ 150°C (TJ)	-55°C ~ 150°C (TJ)	-55°C ~ 125°C (TJ)	-40°C ~ 125°C (TJ)	-40°C ~ 125°C (TJ)
Capacitance @ Frequency	10pF @ 1MHz	10pF @ 1MHz	8pF @ 1MHz	—	—
Product Status	Obsolete	Active	Not For New Designs	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

SRDA05-4R2G (Direct Equivalent - Recommended Primary Choice): The SRDA05-4R2G is the preferred direct substitute for the obsolete SRDA05-4R2. This part maintains identical electrical specifications (5V standoff, 12V clamping, 10A peak pulse current) and mechanical compatibility (8-SOIC package). The SRDA05-4R2G is classified as Active with ROHS3 compliance, providing superior supply chain availability and regulatory alignment compared to the obsolete original part. Inventory availability is significantly higher (17,070 pcs vs. 969 pcs).

SRDA05-4BTG (Active Alternative with Enhanced Ratings): The SRDA05-4BTG, manufactured by Littelfuse Inc., is an active product with higher current (25A vs. 10A) and clamping voltage (21V vs. 12V) ratings. This part is suitable for applications requiring increased transient protection margins while maintaining the same 5V standoff voltage and 8-SOIC package footprint. ROHS3 compliance and active product status support long-term availability.

SRDA05-4.TBT (Similar Substitute - Limited Recommendation): The SRDA05-4.TBT, manufactured by Semtech Corporation, offers higher current (25A) and clamping voltage (20V) ratings with a slightly lower capacitance (8pF vs. 10pF). This part is classified as "Not For New Designs," limiting its suitability for new applications. The 8-SO package variant may require PCB layout verification for compatibility with 8-SOIC footprints.

SRDA3.3-4BTG (Different Voltage Class - Not Recommended for Direct Substitution): The SRDA3.3-4BTG operates at a different voltage class (3.3V standoff vs. 5V) and is not suitable as a direct substitute for the SRDA05-4R2. This part is applicable only to designs specifically requiring 3.3V protection levels.

Frequently Asked Questions (FAQ)

Q: Can the SRDA05-4R2G be used as a direct replacement for the SRDA05-4R2?

A: Yes. The SRDA05-4R2G is a direct equivalent with identical electrical parameters (5V standoff, 12V clamping, 10A peak pulse current) and mechanical compatibility (8-SOIC package). The primary differences are product status (Active vs. Obsolete) and RoHS compliance (ROHS3 vs. non-compliant), both favoring the SRDA05-4R2G for new and ongoing production.

Q: What are the key differences between the SRDA05-4R2 and SRDA05-4BTG?

A: The SRDA05-4BTG maintains the same 5V standoff voltage and 8-SOIC package but provides higher peak pulse current (25A vs. 10A) and clamping voltage (21V vs. 12V). The SRDA05-4BTG is manufactured by Littelfuse Inc. and is classified as Active with ROHS3 compliance. These higher ratings provide enhanced transient protection capability.

Q: Is the SRDA05-4.TBT compatible with the SRDA05-4R2 PCB footprint?

A: The SRDA05-4.TBT uses an 8-SO package variant, while the SRDA05-4R2 uses 8-SOIC. Although both are 8-pin surface-mount packages with similar dimensions (0.154" width, 3.90mm), PCB layout verification is required to confirm footprint compatibility. The SRDA05-4.TBT is classified as "Not For New Designs," limiting its applicability.

Q: Why is the SRDA3.3-4BTG not recommended as a substitute?

A: The SRDA3.3-4BTG operates at a 3.3V reverse standoff voltage with a 4.6V minimum breakdown voltage, compared to the SRDA05-4R2's 5V standoff and 6V breakdown. This voltage class difference makes it unsuitable for direct substitution in 5V protection circuits. The SRDA3.3-4BTG is applicable only to designs requiring 3.3V transient protection.

Q: What is the impact of operating temperature range differences?

A: The SRDA05-4R2 operates from -55°C to 150°C (TJ), while the SRDA05-4BTG and SRDA3.3-4BTG operate from -40°C to 125°C (TJ). Applications requiring operation below -40°C or above 125°C must retain the SRDA05-4R2 or SRDA05-4R2G. For standard industrial temperature ranges (-40°C to 125°C), the SRDA05-4BTG is fully compatible.

Q: How do capacitance specifications affect substitution?

A: The SRDA05-4R2 and SRDA05-4R2G both specify 10pF @ 1MHz capacitance. The SRDA05-4.TBT specifies 8pF @ 1MHz, a minor reduction. For most general-purpose applications, this difference is not significant. Applications with strict capacitance requirements should verify compatibility with the specific substitute part's datasheet.

Q: What is the significance of RoHS compliance in selecting a substitute?

A: The SRDA05-4R2 is RoHS non-compliant, while all substitute parts (SRDA05-4R2G, SRDA05-4.TBT, SRDA05-4BTG, SRDA3.3-4BTG) are ROHS3 compliant. For applications subject to RoHS regulations or customer requirements, ROHS3-compliant substitutes are mandatory. The SRDA05-4R2G is the preferred choice for regulatory compliance while maintaining identical electrical specifications.

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