SS34LH Equivalent & Substitute Parts

Part Overview

The SS34LH is a 3A, 40V Schottky rectifier diode manufactured by Taiwan Semiconductor Corporation in SOD-123 surface mount packaging. This component is classified as "Not For New Designs," indicating it has been superseded in the manufacturer's product line. The SS34LH remains in inventory and continues to function within its specified electrical and thermal parameters. Identifying equivalent substitute parts is necessary for applications requiring continued supply, design updates, or inventory optimization while maintaining electrical compatibility.

Substiute Parts

SS34LH

Taiwan Semiconductor CorporationIn Stock: 839SS34LH Datasheet

Current PartRFQ

SS34LWH

Taiwan Semiconductor CorporationIn Stock: 31418SS34LWH Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SS34LH is determined by strict equivalence across the following electrical and mechanical parameters:

Critical Matching Parameters:

• Voltage - DC Reverse (Vr) (Max): 40 V
• Current - Average Rectified (Io): 3 A
• Technology: Schottky
• Operating Temperature - Junction: -55°C to 125°C
• RoHS Status: ROHS3 Compliant
• Surface Mount configuration

Package Compatibility Consideration: The SS34LH uses SOD-123 packaging. Substitute parts may use alternative surface mount packages (such as SOD-123W) provided the electrical parameters remain within specification and the physical footprint is compatible with the target application's PCB layout.

Forward Voltage Tolerance: Forward voltage specifications may vary between equivalent parts within acceptable operating ranges. The SS34LH specifies 500 mV maximum at 3 A; substitute parts with higher forward voltage ratings (such as 550 mV) remain functionally equivalent provided the application design accommodates this variance.

Reverse Leakage Current: Reverse leakage current may differ between equivalent parts. The SS34LH specifies 500 µA at 40 V; substitute parts with lower leakage specifications (such as 200 µA) provide improved performance characteristics and are directly substitutable.

Parameter Comparison

Engineering Selection Recommendations

SS34LWH as Primary Substitute:

The SS34LWH is the manufacturer-recommended substitute for the SS34LH. Both components share identical electrical specifications for reverse voltage (40 V), average rectified current (3 A), fast recovery speed (≤ 500ns), and operating temperature range (-55°C to 125°C). Both are manufactured by Taiwan Semiconductor Corporation and maintain ROHS3 compliance.

Compliance and Qualification:

The SS34LH carries AEC-Q101 automotive qualification. The SS34LWH is listed as an active product with Moisture Sensitivity Level (MSL) 1 (Unlimited), indicating superior handling characteristics and continued manufacturer support.

Package Transition Consideration:

The primary difference between these parts is packaging: SS34LH uses SOD-123, while SS34LWH uses SOD-123W. This package change requires PCB layout verification to ensure footprint compatibility. The SOD-123W package is a wider variant of the standard SOD-123 form factor.

Forward Voltage Differential:

The SS34LWH specifies a maximum forward voltage of 550 mV at 3 A, compared to 500 mV for the SS34LH. This 50 mV increase is within typical Schottky diode manufacturing tolerances and does not preclude substitution. Circuit designs must accommodate this variance through thermal analysis or voltage margin verification.

Reverse Leakage Improvement:

The SS34LWH exhibits lower reverse leakage current (200 µA at 40 V) compared to the SS34LH (500 µA at 40 V). This represents an improvement in leakage characteristics and provides enhanced performance in low-current applications.

Inventory and Supply:

The SS34LH is available in limited inventory (809 pieces). The SS34LWH is available in significantly higher inventory (31,352 pieces) with active product status, ensuring long-term supply continuity.

Frequently Asked Questions (FAQ)

Q: Can the SS34LWH directly replace the SS34LH in existing designs?

A: Electrical substitution is valid provided the application accommodates the package change from SOD-123 to SOD-123W and the forward voltage increase from 500 mV to 550 mV. PCB layout verification is required to confirm footprint compatibility.

Q: What is the significance of the forward voltage difference (500 mV vs. 550 mV)?

A: The 50 mV difference falls within normal Schottky diode manufacturing variation. Applications with tight voltage margin requirements must verify that the higher forward voltage does not exceed circuit design limits. Thermal analysis may be necessary for high-current applications.

Q: Does the lower reverse leakage current of the SS34LWH affect compatibility?

A: No. Lower reverse leakage current (200 µA vs. 500 µA) represents improved performance and does not create compatibility issues. Applications benefit from reduced leakage in low-current or high-impedance circuits.

Q: Are both parts automotive-qualified?

A: The SS34LH carries AEC-Q101 qualification. The SS34LWH is listed as an active product but does not explicitly reference AEC-Q101 in the provided specifications. Automotive applications requiring AEC-Q101 certification must verify the SS34LWH's qualification status with the manufacturer.

Q: What is the difference between SOD-123 and SOD-123W packaging?

A: SOD-123W is a wider variant of the standard SOD-123 surface mount package. Both are small-outline diode packages suitable for surface mount assembly. PCB footprint dimensions differ; layout compatibility must be confirmed before substitution.

Q: Why is the SS34LH marked "Not For New Designs"?

A: This designation indicates the manufacturer has superseded the SS34LH with newer products (such as the SS34LWH). Existing designs may continue using the SS34LH; new designs should transition to active products like the SS34LWH to ensure long-term supply and manufacturer support.

Q: Are both parts RoHS compliant?

A: Yes. Both the SS34LH and SS34LWH are ROHS3 compliant and REACH unaffected, meeting environmental regulatory requirements.

Q: What is Moisture Sensitivity Level (MSL) 1?

A: MSL 1 (Unlimited) indicates the component has unlimited shelf life without moisture bake-out requirements. The SS34LWH's MSL 1 rating provides superior handling flexibility compared to higher MSL ratings.