Equivalent & Substitute Parts for Diodes Incorporated S3A

Part Overview

The Diodes Incorporated S3A is a general-purpose rectifier diode rated for 50 V DC reverse voltage and 3 A average rectified current in a Surface Mount SMC (DO-214AB) package. This component is classified as obsolete, which necessitates identification of equivalent and substitute parts for ongoing design requirements and procurement needs. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges while considering current product availability and active manufacturing status.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	50	V
Current - Average Rectified (Io)	3	A
Voltage - Forward (Vf) (Max) @ If	1.15	V @ 3 A
Reverse Recovery Time (trr)	2	µs
Current - Reverse Leakage @ Vr	10	µA @ 50 V
Capacitance @ Vr, F	40	pF @ 4V, 1MHz
Package / Case	DO-214AB, SMC	—
Operating Temperature - Junction	-65 to 150	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the S3A are selected based on the following criteria:

Mandatory Compatibility Parameters:

Current - Average Rectified (Io): 3 A (exact match required)
Package / Case: DO-214AB, SMC (identical mounting and form factor)
Mounting Type: Surface Mount (identical assembly method)
Operating Temperature Range: Minimum -65°C to 150°C junction temperature capability
RoHS3 Compliance: Required for regulatory alignment

Voltage Rating Consideration: Substitute parts may have equal or higher DC reverse voltage ratings (Vr). The S3A operates at 50 V; substitutes with higher voltage ratings (200 V, 1000 V) are electrically compatible in circuits designed for 50 V operation, as they provide additional voltage margin and reverse polarity protection.

Recovery Characteristics: Standard recovery diodes (>500 ns) and fast recovery diodes (≤500 ns) are both acceptable substitutes, as recovery speed does not degrade circuit performance in general-purpose rectification applications.

Parameter Comparison

Parameter	S3A (Main Part)	S3M_HF (Substitute)	STTH302S (Substitute)
Manufacturer	Diodes Incorporated	Diodes Incorporated	STMicroelectronics
Product Status	Obsolete	Active	Active
Voltage - DC Reverse (Vr) (Max)	50 V	1000 V	200 V
Current - Average Rectified (Io)	3 A	3 A	3 A
Voltage - Forward (Vf) (Max) @ If	1.15 V @ 3 A	1.15 V @ 3 A	950 mV @ 3 A
Speed	Standard Recovery >500ns	Standard Recovery >500ns	Fast Recovery ≤500ns
Reverse Recovery Time (trr)	2 µs	Not specified	35 ns
Current - Reverse Leakage @ Vr	10 µA @ 50 V	10 µA @ 1000 V	3 µA @ 200 V
Capacitance @ Vr, F	40 pF @ 4V, 1MHz	40 pF @ 4V, 1MHz	Not specified
Package / Case	DO-214AB, SMC	DO-214AB, SMC	DO-214AB, SMC
Operating Temperature - Junction	-65 to 150°C	-65 to 150°C	175°C (Max)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

S3M_HF (Diodes Incorporated): The S3M_HF is the manufacturer-recommended substitute. It maintains identical current rating (3 A), forward voltage characteristics (1.15 V @ 3 A), and package form factor (DO-214AB, SMC). The elevated voltage rating (1000 V) provides enhanced reverse voltage margin. Active product status ensures ongoing availability and supply chain continuity. ROHS3 compliance and identical operating temperature range (-65 to 150°C) confirm full regulatory and thermal compatibility.

STTH302S (STMicroelectronics): The STTH302S is an alternative substitute from a different manufacturer. It matches the 3 A current requirement and DO-214AB, SMC package specification. The 200 V voltage rating provides adequate margin above the 50 V design requirement. Fast recovery characteristics (35 ns trr) represent an improvement over standard recovery. Lower forward voltage (950 mV @ 3 A) reduces power dissipation. Active product status and ROHS3 compliance confirm availability and regulatory alignment. Maximum junction temperature of 175°C exceeds the S3A specification, providing additional thermal headroom.

Both substitutes are electrically and mechanically compatible with the obsolete S3A and support continued circuit implementation without redesign.

Frequently Asked Questions (FAQ)

Q: Can the S3M_HF replace the S3A in all applications? A: Yes. The S3M_HF maintains the 3 A current rating, identical forward voltage (1.15 V @ 3 A), and DO-214AB, SMC package. The higher voltage rating (1000 V vs. 50 V) provides additional reverse voltage protection without affecting circuit operation in 50 V applications.

Q: What is the difference between the S3M_HF and STTH302S? A: Both are compatible substitutes with identical 3 A current ratings and SMC packages. The S3M_HF is from Diodes Incorporated (same manufacturer as the S3A) with 1000 V rating and standard recovery. The STTH302S is from STMicroelectronics with 200 V rating and fast recovery (35 ns). The STTH302S has lower forward voltage (950 mV) and higher maximum junction temperature (175°C).

Q: Does the fast recovery characteristic of STTH302S affect compatibility? A: No. Fast recovery (≤500 ns) is a performance enhancement over standard recovery (>500 ns). It does not degrade circuit function and may improve efficiency in switching applications.

Q: Are all substitutes available in the same package? A: Yes. All parts (S3A, S3M_HF, STTH302S) use the DO-214AB, SMC surface mount package with identical mechanical dimensions and land patterns.

Q: Which substitute has the best availability? A: The STTH302S has the highest inventory (25,200 pcs), followed by S3M_HF (1,061 pcs). Both are active products with ongoing manufacturing support.

Q: Are there any compliance differences between substitutes? A: No. All parts are ROHS3 compliant and REACH unaffected, meeting identical regulatory requirements.

Q: Can I use STTH302S in place of S3M_HF? A: Yes. Both meet the 3 A current requirement and SMC package specification. Selection between them depends on voltage rating preference (200 V vs. 1000 V), recovery speed requirements, and forward voltage characteristics for the specific application.

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