onsemi BAW56

Overview

The onsemi BAW56 is a dual silicon switching diode containing two high-speed diode elements in a common-anode configuration. The legacy device combines an 85 V repetitive reverse-voltage rating, 200 mA average forward-current capability per diode, 6 ns maximum reverse-recovery time, and low junction capacitance in a three-lead SOT-23 package.

For engineers reviewing the BAW56 datasheet, BAW56 pinout, BAW56 application, or BAW56 equivalent, the common-anode connection is the defining circuit characteristic: pins 1 and 2 are separate cathodes, while pin 3 joins both anodes. The original Fairchild/onsemi BAW56 is obsolete; the active onsemi BAW56LT1G is a related replacement candidate but carries a lower 70 V reverse-voltage rating.

Technical Context

BAW56 integrates two matched-function switching diodes around one shared anode, reducing component count and routing length in dual-channel clamps and signal-steering networks. It must not be confused with BAV70, which uses a common-cathode connection, or BAV99, which connects two diodes in series. Those devices may share an SOT-23 outline but are not pin-function equivalents.

The 6 ns recovery time and approximately 2 pF diode capacitance support fast signal operation, while the 2.5 µA maximum reverse leakage at 70 V limits static error in many control circuits. BAW56 is a signal diode rather than a high-energy TVS device; external current limiting and transient-energy analysis are required when it is used for input or inductive-load protection.

Key Specifications

Pinout & Package

BAW56 uses SOT-23 circuit style 12, with two cathodes on pins 1 and 2 and the common anode on pin 3. A footprint-compatible device with a common cathode or series-connected internal circuit will not perform the same function even if its package dimensions are identical.

Key Features

• Two silicon switching diodes in one SOT-23 package
• Common-anode internal configuration
• 85 V repetitive reverse-voltage rating per diode
• 200 mA average forward-current capability per diode
• 6 ns maximum reverse-recovery time
• Approximately 2 pF diode capacitance
• 2.5 µA maximum reverse leakage at 70 V
• 350 mW total package power dissipation
• Compact three-lead surface-mount construction
• A1 legacy device marking
• Suitable for high-speed switching, dual-channel clamping, and signal steering

Applications

Equivalent & Alternatives

Quality

Quality review of legacy onsemi BAW56 inventory should include Fairchild/onsemi traceability, date and lot codes, tape-and-reel condition, SOT-23 dimensions, terminal finish, and A1 marking inspection. Because the bare BAW56 designation is obsolete, material should be matched to the original packaging and manufacturing records rather than authenticated from top marking alone.

Electrical sampling can verify the common-anode pin configuration, forward voltage at a controlled test current, reverse leakage at high reverse bias, and isolation between the two cathodes. Applications using both diodes simultaneously should also confirm total package dissipation because the two junctions share one small SOT-23 thermal path.

Availability

The original onsemi BAW56 is obsolete and is generally available only from remaining Fairchild/onsemi legacy inventory. BAW56 may be available at Aetrix Electronics for maintenance, repair, and existing-production requirements, subject to stock, date-code acceptance, traceability, and electrical verification. For new designs, BAW56LT1G, Nexperia BAW56,215, and Diotec Semiconductor BAW56 should be evaluated against the required reverse-voltage margin.

Manufacturer

BAW56 originated in the Fairchild Semiconductor small-signal diode portfolio, which became part of onsemi following the acquisition of Fairchild. The original bare BAW56 is discontinued, while onsemi continues to support the related common-anode switching function through devices such as BAW56LT1G in its discrete semiconductor portfolio.

FAQ

What type of component is onsemi BAW56?

onsemi BAW56 is a dual silicon switching diode containing two diode elements in a common-anode SOT-23 package. BAW56 was designed for high-speed signal switching, steering, paired clamping, and low-current transient routing, with separate cathodes and one shared anode connection.

What is the correct pinout for BAW56?

BAW56 pin 1 is cathode K1, pin 2 is cathode K2, and pin 3 is the common anode shared by both diodes. The BAW56 pinout is different from common-cathode BAV70 and series-connected BAV99 devices despite all three commonly using SOT-23 packages.

What are the maximum voltage and current ratings of BAW56?

The original onsemi BAW56 has an 85 V repetitive reverse-voltage rating and a 200 mA average forward-current rating per diode. BAW56 also supports brief non-repetitive forward-current pulses, but simultaneous diode loading and total package dissipation must remain within the 350 mW thermal limit.

How fast is BAW56 and what capacitance does it add?

BAW56 has a maximum reverse-recovery time of 6 ns and approximately 2 pF maximum diode capacitance. These characteristics make BAW56 suitable for high-speed switching and pulse steering, although source impedance, PCB parasitics, and package placement still influence actual circuit bandwidth.

What are the forward voltage and reverse leakage of BAW56?

BAW56 has a maximum forward voltage of 1.25 V at 150 mA and maximum reverse leakage of 2.5 µA at 70 V. BAW56 leakage increases with junction temperature, so high-impedance circuits should be evaluated at their maximum operating temperature rather than only at room temperature.

Can BAW56 be replaced by BAV70 or BAV99?

BAW56 cannot normally be replaced by BAV70 or BAV99 without changing the circuit. BAW56 has a common-anode configuration, BAV70 has a common-cathode configuration, and BAV99 connects its two diodes in series. Their identical package style does not make their pin functions interchangeable.

Is onsemi BAW56 obsolete and what is the recommended replacement?

The original bare onsemi BAW56 is obsolete. onsemi BAW56LT1G is the related active continuation, but its 70 V rating is lower than the original BAW56 rating of 85 V. Nexperia BAW56,215 and Diotec Semiconductor BAW56 provide higher reverse-voltage margins and should be considered when preserving the original rating is necessary.