SS34L Schottky Diode Equivalent & Substitute Parts

Part Overview

The SS34L is a 40 V, 3 A Schottky rectifier diode manufactured by Taiwan Semiconductor Corporation in Sub SMA (DO-219AB) surface mount package. This component is classified as "Not For New Designs," indicating it has reached end-of-life status. The part operates across a junction temperature range of -55°C to 150°C and exhibits fast recovery characteristics suitable for high-frequency rectification applications.

Due to its obsolescence status, identification of equivalent and substitute parts is necessary for design continuity, production support, and legacy system maintenance. Substitute parts must maintain electrical compatibility while accommodating potential package or performance variations.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	40	V
Current - Average Rectified (Io)	3	A
Voltage - Forward (Vf) (Max) @ If	500 mV @ 3 A	mV
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	500 µA @ 40 V	µA
Package / Case	DO-219AB	—
Operating Temperature - Junction	-55 to 150	°C
Technology	Schottky	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the SS34L is determined by the following electrical and mechanical parameters:

Primary Substitution Criteria:

Voltage rating: 40 V DC reverse voltage (Vr) minimum
Current rating: 3 A average rectified current (Io) minimum
Technology: Schottky diode
Package compatibility: Surface mount configurations
Speed classification: Fast recovery ≤ 500ns

Substitution Categories:

Category 1: Direct Electrical Equivalent (Active Status) The SS34LW (Taiwan Semiconductor Corporation) maintains identical electrical specifications (40 V, 3 A) with active product status. Package variation (SOD-123W vs. Sub SMA) requires PCB layout modification but preserves electrical performance.

Category 2: Parametric Equivalents with Current Derating The Vishay eSMP® series parts (SS1FL4-M3/H, SS1FL4-M3/I, SS1FL4HM3/H, SS1FL4HM3/I) operate at 40 V reverse voltage with 1 A average rectified current. These parts are suitable for applications where the 3 A current requirement can be met through parallel configuration or where actual circuit current demand is ≤ 1 A. All Vishay parts maintain DO-219AB package compatibility and active product status. The SS1FL4HM3/H and SS1FL4HM3/I variants include automotive-grade qualification (AEC-Q101).

Parameter Comparison

Parameter	SS34L (Main)	SS34LW	SS1FL4-M3/H	SS1FL4-M3/I	SS1FL4HM3/H	SS1FL4HM3/I
Manufacturer	Taiwan Semiconductor	Taiwan Semiconductor	Vishay	Vishay	Vishay	Vishay
Voltage - DC Reverse (Vr) (Max)	40 V	40 V	40 V	40 V	40 V	40 V
Current - Average Rectified (Io)	3 A	3 A	1 A	1 A	1 A	1 A
Voltage - Forward (Vf) (Max) @ If	500 mV @ 3 A	550 mV @ 3 A	500 mV @ 1 A	500 mV @ 1 A	500 mV @ 1 A	500 mV @ 1 A
Speed	Fast Recovery ≤ 500ns	Fast Recovery ≤ 500ns	Fast Recovery ≤ 500ns	Fast Recovery ≤ 500ns	Fast Recovery ≤ 500ns	Fast Recovery ≤ 500ns
Current - Reverse Leakage @ Vr	500 µA @ 40 V	200 µA @ 40 V	200 µA @ 40 V	200 µA @ 40 V	200 µA @ 40 V	200 µA @ 40 V
Package / Case	DO-219AB (Sub SMA)	SOD-123W	DO-219AB (SMF)	DO-219AB (SMF)	DO-219AB (SMF)	DO-219AB (SMF)
Operating Temperature - Junction	-55 to 150°C	-55 to 125°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C
Product Status	Not For New Designs	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Automotive Grade	—	—	—	—	AEC-Q101	AEC-Q101

Engineering Selection Recommendations

For Direct Replacement (Preferred): Select SS34LW when PCB layout modification is acceptable. This part maintains identical electrical specifications (40 V, 3 A) and active product status. The SOD-123W package is smaller than Sub SMA, requiring footprint redesign but offering improved thermal performance and space efficiency. Operating temperature range is reduced to -55°C to 125°C; verify compatibility with application requirements.

For Package-Compatible Substitution: The Vishay eSMP® series (SS1FL4-M3/H, SS1FL4-M3/I, SS1FL4HM3/H, SS1FL4HM3/I) maintains DO-219AB package compatibility with the original SS34L, eliminating PCB layout changes. These parts are rated for 1 A average rectified current. Selection depends on actual circuit current requirements:

If circuit current demand is ≤ 1 A: Direct substitution is acceptable.
If circuit current demand exceeds 1 A: Parallel configuration of multiple devices is required.

All Vishay parts carry active product status and ROHS3 compliance. The SS1FL4HM3/H and SS1FL4HM3/I variants include AEC-Q101 automotive qualification, suitable for automotive and high-reliability applications.

Compliance Considerations: All substitute parts maintain ROHS3 compliance and REACH unaffected status, matching the original SS34L. Moisture sensitivity level (MSL) is 1 (Unlimited) across all options, indicating no special storage or handling requirements.

Frequently Asked Questions (FAQ)

Q: Can SS34LW be used as a direct replacement for SS34L? A: Electrically, yes. The SS34LW maintains 40 V reverse voltage and 3 A current ratings. However, the package differs (SOD-123W vs. Sub SMA DO-219AB), requiring PCB footprint modification. Operating temperature range is reduced from -55°C to 150°C to -55°C to 125°C; verify this meets application requirements.

Q: Why are the Vishay eSMP® parts rated for only 1 A when the SS34L is rated for 3 A? A: The Vishay SS1FL4 series is a different product line with lower current rating. These parts are suitable for applications where circuit current is ≤ 1 A or where multiple devices can be paralleled to achieve higher current capacity.

Q: Can I parallel multiple SS1FL4 devices to achieve 3 A capacity? A: Parallel configuration is a circuit design decision outside the scope of this component equivalency reference. Consult application-specific design guidelines and thermal analysis.

Q: What is the difference between SS1FL4-M3/H, SS1FL4-M3/I, SS1FL4HM3/H, and SS1FL4HM3/I? A: All four parts share identical electrical specifications (40 V, 1 A, fast recovery Schottky). The SS1FL4HM3/H and SS1FL4HM3/I variants include AEC-Q101 automotive qualification. The suffix designations (M3/H, M3/I, HM3/H, HM3/I) indicate manufacturing or qualification variants; consult Vishay documentation for specific differences.

Q: Are all substitute parts RoHS compliant? A: Yes. All listed substitute parts (SS34LW, SS1FL4-M3/H, SS1FL4-M3/I, SS1FL4HM3/H, SS1FL4HM3/I) are ROHS3 compliant, matching the original SS34L.

Q: What is the reverse leakage difference between SS34L and the substitute parts? A: The SS34L exhibits 500 µA reverse leakage at 40 V. All Vishay eSMP® substitutes and the SS34LW show 200 µA reverse leakage at 40 V, representing improved leakage performance.

Q: Which substitute part should I select for automotive applications? A: For automotive applications requiring AEC-Q101 qualification, select SS1FL4HM3/H or SS1FL4HM3/I. Both maintain DO-219AB package compatibility and 40 V rating. Current rating is 1 A; verify circuit requirements.

Q: Is the SS34L still available for purchase? A: The SS34L is classified as "Not For New Designs" and carries 300,400 pieces in inventory. However, active alternatives (SS34LW, Vishay eSMP® series) are recommended for new designs and ongoing production.

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