BAT54ST Equivalent & Substitute Parts

Part Overview

The BAT54ST is a Schottky diode array in a 1 Pair Series Connection configuration, rated for 30 V DC reverse voltage and 100 mA average rectified current per diode. This component is designed for surface mount applications in the SOT-523 package. The BAT54ST is classified as obsolete, necessitating identification of active equivalent parts to maintain design continuity and ensure long-term component availability for new production and legacy system support.

Substiute Parts

BAT54ST

onsemiIn Stock: 95315BAT54ST Datasheet

Current PartRFQ

BAT54SWT1G

onsemiIn Stock: 605271BAT54SWT1G Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BAT54ST is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

• Diode Configuration: Must maintain 1 Pair Series Connection topology
• Technology: Must be Schottky type
• Voltage - DC Reverse (Vr) (Max): Must equal or exceed 30 V
• Reverse Recovery Time (trr): Must equal 5 ns
• Current - Reverse Leakage @ Vr: Must equal 2 µA @ 25 V
• Operating Temperature - Junction: Must support maximum 125°C

Mechanical Compatibility Criteria:

• Mounting Type: Must be Surface Mount
• Base Product Number: Must be BAT54 family

Current Rating Consideration: The BAT54ST is rated for 100 mA average rectified current per diode. Substitute parts with equal or higher current ratings maintain functional compatibility within the original design envelope.

The BAT54SWT1G qualifies as a direct substitute, meeting all electrical parameters while offering enhanced current capacity (200 mA) and active product status.

Parameter Comparison

Engineering Selection Recommendations

BAT54SWT1G as Primary Substitute:

The BAT54SWT1G is the qualified substitute for the obsolete BAT54ST. This selection is based on the following engineering factors:

1. Product Status: The BAT54SWT1G maintains active product status with onsemi, ensuring continued availability and manufacturing support. The BAT54ST is obsolete, creating supply chain risk.

2. Electrical Equivalence: All critical electrical parameters match the BAT54ST specification: 30 V reverse voltage rating, 5 ns reverse recovery time, and 2 µA reverse leakage current. The BAT54SWT1G exceeds the current requirement (200 mA versus 100 mA), providing design margin without compromising performance.

3. Forward Voltage Improvement: The BAT54SWT1G exhibits lower forward voltage (800 mV @ 100 mA) compared to the BAT54ST (1 V @ 100 mA), resulting in reduced power dissipation and improved thermal performance.

4. Temperature Range Enhancement: The BAT54SWT1G supports an extended operating temperature range (-55°C to 125°C) versus the BAT54ST maximum of 125°C, enabling broader application scope.

5. Compliance and Certifications: Both parts maintain identical REACH and ECCN classifications (REACH Unaffected, EAR99). The BAT54SWT1G includes RoHS3 compliance certification.

6. Package Consideration: The BAT54SWT1G uses SC-70 (SOT-323) packaging, which differs from the BAT54ST SOT-523 package. PCB layout modification is required for physical integration.

Frequently Asked Questions (FAQ)

Q: Can the BAT54SWT1G directly replace the BAT54ST without circuit modification?

A: Electrical substitution is valid. The BAT54SWT1G meets all electrical specifications of the BAT54ST. However, physical PCB layout modification is required due to package differences (SC-70/SOT-323 versus SOT-523). Footprint redesign is necessary for component placement and soldering.

Q: What is the significance of the higher current rating (200 mA) in the BAT54SWT1G?

A: The BAT54SWT1G 200 mA rating exceeds the BAT54ST 100 mA requirement, providing operational margin. This higher rating does not affect circuit performance when the design current remains at or below 100 mA. The component operates safely within its rated envelope.

Q: How does the lower forward voltage of the BAT54SWT1G affect circuit performance?

A: The BAT54SWT1G forward voltage of 800 mV @ 100 mA is lower than the BAT54ST specification of 1 V @ 100 mA. This reduction decreases power dissipation and heat generation. For circuits with tight voltage budgets, this improvement may require verification of downstream component performance, particularly in low-voltage applications.

Q: Are there any compliance or regulatory differences between these parts?

A: Both parts maintain identical REACH and ECCN classifications. The BAT54SWT1G includes RoHS3 compliance certification, which the BAT54ST does not specify. Both parts have MSL 1 (Unlimited) moisture sensitivity ratings, indicating no special handling requirements.

Q: What is the impact of the extended temperature range in the BAT54SWT1G?

A: The BAT54SWT1G supports -55°C to 125°C operation, compared to the BAT54ST maximum of 125°C. This extended lower temperature limit enables use in cold environment applications. For designs operating only at or above 0°C, this difference has no practical impact.

Q: Is the SOT-523 to SC-70 package transition a significant design change?

A: Yes. Package transition requires PCB footprint redesign, trace routing adjustment, and potential changes to assembly processes. The SC-70 package is smaller than SOT-523, which may provide board space benefits. Assembly and soldering parameters differ between packages and must be validated according to manufacturer guidelines.

Q: Can the BAT54ST be sourced as an alternative to the BAT54SWT1G?

A: No. The BAT54ST is classified as obsolete. While inventory may exist in distribution channels, obsolete parts present supply chain risk and lack manufacturing support. The BAT54SWT1G is the recommended active substitute.