onsemi BD1356S

Overview

BD1356S from Fairchild Semiconductor is an NPN epitaxial silicon transistor in TO-126 package, rated for 45 V V_CEO, 1.5 A DC collector current, and 12.5 W collector dissipation at T_C = 25°C, commonly used in medium-power linear amplification and switching applications such as audio output stages and power supply regulators.

For engineers reviewing the BD1356S datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO/V_CBO rating, h_FE classification (40–100), V_CE(sat) @ 500 mA/50 mA, thermal derating behavior, and complementary pairing with BD136.

Technical Context

The BD1356S operates as a medium-power bipolar junction transistor optimized for linear and switching use with fixed-base drive configurations. Its h_FE is specified across three test conditions-25–250 at I_C = 5 mA, 25–160 at I_C = 0.5 A, and 40–100 at I_C = 150 mA-enabling predictable gain control in Class AB audio stages and regulated DC-DC feedback paths.

Thermal performance is defined by two dissipation limits: 12.5 W at case temperature T_C = 25°C and only 1.25 W at ambient T_A = 25°C, requiring heatsinking for sustained operation above ~250 mW. Safe operating area curves confirm pulsed capability up to 3.0 A with 10 µs–1 ms pulse widths.

Key Specifications

Pinout & Package

BD1356S uses the TO-126 package: molded plastic case with three leads, 16.10 mm length, 13.06 mm width, and 4.2 mm height; mounting hole Ø3.20 mm; intended for PCB through-hole mounting with heatsink contact via tab (lead #2).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power transistor applications.

Compared with BD135 and MJD13005, the BD1356S offers exact legacy compatibility with BD135 designs while providing lower cost and smaller footprint than TO-220 alternatives-ideal for space-constrained 12–15 V linear and switching applications where 45 V rating suffices.

Availability

BD1356S is available at Aetrix Electronics and suitable for audio amplifiers, linear voltage regulators, DC motor drivers, and relay interfaces requiring stable component supply and long-term obsolescence management.

Supply support for BD1356S includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The BD1356S belongs to Fairchild's legacy medium-power bipolar transistor family designed for cost-sensitive, thermally constrained linear and switching applications in consumer, industrial, and automotive auxiliary systems.

FAQ

What is the pin configuration of BD1356S?

The BD1356S uses TO-126 package with standardized pinout: lead #1 is Emitter, lead #2 is Collector (connected to metal tab), and lead #3 is Base. This matches JEDEC TO-126 mechanical specification and is identical to BD135. Mounting orientation must ensure collector tab contact with heatsink for thermal compliance.

Is BD1356S electrically identical to BD135?

Yes, BD1356S is functionally and electrically identical to BD135 per Fairchild's Rev. A datasheet: same V_CEO = 45 V, I_C = 1.5 A, h_FE classification 40–100, and TO-126 package. The "6S" suffix reflects a manufacturing lot or marking variant-not a parametric revision.

What is the maximum safe continuous power dissipation for BD1356S?

The BD1356S has P_C = 12.5 W at case temperature T_C = 25°C, but only 1.25 W at ambient temperature T_A = 25°C. For continuous operation, thermal design must maintain T_C ≤ 25°C using a heatsink; otherwise, power must be derated linearly above 25°C at 0.1 W/°C per the datasheet curve.

Can BD1356S replace BD137 or BD139 in a circuit?

No-BD1356S is rated for V_CEO = 45 V, whereas BD137 and BD139 are rated for 60 V and 80 V respectively. Substituting BD1356S in circuits designed for higher voltage rails risks premature breakdown; it is only interchangeable with BD135, not higher-voltage variants in the same family.

Does BD1356S require a base resistor in switching applications?

Yes, BD1356S requires an external base resistor to limit I_B and ensure saturation. For 500 mA collector current, datasheet specifies I_B = 50 mA; with V_BE(on) ≈ 1 V, a 70–100 Ω resistor is typical when driven from 5 V logic. Omitting this resistor risks excessive base current and thermal failure.