onsemi FSB560

Overview

FSB560 from Fairchild Semiconductor is an NPN low-saturation transistor in SuperSOT-3 (SOT-23) package, rated for 60 V V_CEO, 2 A continuous collector current, and 300 mV V_CE(sat) at I_C = 1 A / I_B = 100 mA. It delivers high DC current gain (h_FE = 100–300 at I_C = 500 mA) and operates across –55°C to +150°C, supporting compact switching in DC-DC converters and load-switching circuits.

For engineers reviewing the FSB560 datasheet, pinout, applications, or equivalent options, key selection criteria include verified low V_CE(sat) performance at 1–2 A, thermal resistance of 250°C/W on standard FR-4 PCB, and confirmed SuperSOT-3 footprint compatibility with space-constrained board layouts.

Technical Context

The FSB560 is a discrete silicon NPN bipolar junction transistor optimized for low-voltage saturation operation in medium-current switching applications. Its design emphasizes high h_FE (min. 70 at 100 mA, min. 80 at 1 A) and tight V_CE(sat) control (max. 350 mV at 2 A), enabling efficient power stage operation without active gate drive complexity.

It features a maximum collector-emitter breakdown voltage of 60 V and emitter-base breakdown of 5 V, with output capacitance (C_obo) of 30 pF at 10 V and transition frequency (f_T) of 75 MHz - confirming suitability for switching frequencies up to several MHz in non-resonant topologies.

Key Specifications

Pinout & Package

FSB560 uses the SuperSOT-3 (SOT-23) package: 3-pin, surface-mount, plastic-molded, with standard lead pitch of 0.95 mm and body dimensions 2.9 × 1.3 × 1.0 mm. Thermal pad is not present; power dissipation relies on trace conduction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN low-saturation transistor applications.

Compared with NSS12500UW3T1G and DXT75100MPQ-13, the FSB560 offers balanced trade-offs: moderate voltage/current ratings, proven thermal performance on standard FR-4, and direct compatibility with legacy SOT-23 footprints - making it optimal for cost-sensitive, space-constrained 24–48 V industrial switching where 1–2 A capability suffices.

Availability

FSB560 is available at Aetrix Electronics and suitable for DC-DC converter design, LED driver implementation, and industrial load switching requiring stable component supply and long-term production continuity.

Supply support for FSB560 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, acquired by ON Semiconductor in 2016.

The FSB560 belongs to Fairchild's SuperSOT-3 low-saturation transistor family, designed specifically for high-efficiency, medium-current switching in space-constrained industrial and automotive power stages.

FAQ

What is the maximum continuous collector current rating for the FSB560?

The FSB560 is rated for 2 A continuous collector current (I_C) at T_A = 25°C with derating above that temperature. This rating assumes proper PCB copper area per Fairchild's thermal test condition (FR-4, 76 mm × 114 mm). At 100°C ambient, usable current drops to approximately 1.2 A due to 4 mW/°C derating from its 500 mW P_D limit. The FSB560 must be operated within these boundaries to avoid junction overheating and premature failure.

Does the FSB560 have a built-in base resistor?

No, the FSB560 does not include an integrated base resistor. It is a bare-die NPN transistor requiring external base current limiting - typically via a series resistor sized to deliver I_B = I_C / h_FE (e.g., ~10–20 mA for 1–2 A collector current). This distinguishes it from digital transistors like the NSBC114EPDXV6T1G and confirms the need for discrete bias network design when using the FSB560 in switching applications.

What is the typical V_CE(sat) of the FSB560 at 2 A collector current?

The typical V_CE(sat) of the FSB560 at I_C = 2 A and I_B = 200 mA is 300 mV, with a maximum specification of 350 mV. This value is measured under pulsed conditions (≤300 μs, ≤2% duty cycle) per datasheet Note 4. In continuous DC operation, thermal self-heating may raise V_CE(sat) by up to 15% depending on PCB layout and ambient temperature - a factor critical to efficiency modeling in the FSB560's target applications.

Is the FSB560 pin-compatible with the FSB560A variant?

Yes, the FSB560 and FSB560A share identical pinout, package (SuperSOT-3), and absolute maximum ratings. Their key difference lies in DC current gain: FSB560 specifies h_FE = 100–300 at I_C = 500 mA, while FSB560A specifies 250–550 under identical conditions. Both parts are interchangeable in circuits where gain variation is acceptable, but designs requiring guaranteed minimum h_FE ≥ 250 should specify FSB560A. The FSB560 remains valid where lower gain tolerance is acceptable.

What is the thermal resistance (R_θJA) of the FSB560 on a standard PCB?

The FSB560 has a specified R_θJA of 250°C/W when mounted on a standard FR-4 PCB measuring 76 mm × 114 mm × 1.57 mm with minimum land pattern size. This value assumes no additional copper pour or thermal vias. Adding 10–20 mm² of exposed copper connected to the collector pad via ≥4 thermal vias can reduce R_θJA by 30–40%, directly improving the FSB560's sustainable current capability and reliability in thermally demanding applications.