onsemi FSB619

Overview

FSB619 from ON Semiconductor is an NPN low-saturation transistor in SuperSOT™-3 (SOT-23) package, designed for high-current gain and ultra-low V_CE(sat) down to 20 mV at I_C = 100 mA / I_B = 10 mA. It supports continuous collector current up to 2 A, operates across –55°C to +150°C, and delivers DC current gain (h_FE) of 300 at I_C = 200 mA - ideal for compact DC-DC converter switching stages.

For engineers reviewing the FSB619 datasheet, pinout, applications, or equivalent options, key selection criteria include its 20–320 mV saturation voltage range across 100 mA–2 A loads, 50 V V_CEO rating, thermal resistance of 250°C/W on FR-4 PCB, and SOT-23 footprint compatibility with space-constrained power management designs.

Technical Context

The FSB619 uses a planar epitaxial process optimized for low V_CE(sat) and high h_FE, enabling efficient switching in low-voltage, high-current linear and saturated-mode applications. Its 50 V breakdown ratings (V_CEO, V_CBO) and 5 V V_EBO support robust operation in 24 V industrial control rails and 12 V automotive auxiliary circuits.

Thermal performance is defined for FR-4 PCB mounting (4.5″ × 5″, 0.02 in² 2 oz copper), with 500 mW total dissipation and 4 mW/°C derating above 25°C. The device exhibits f_T = 100 MHz at I_C = 50 mA, supporting moderate-speed switching up to ~10 MHz in non-critical timing paths.

Key Specifications

Pinout & Package

Package: SuperSOT™-3 (SOT-23), 3-pin surface-mount plastic package with gull-wing leads; footprint compatible with JEDEC TO-236AB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with FSB619, NSS12201LT1G offers marginally better saturation performance at 1 A but less headroom at 2 A; DXT7050Z-13 provides broader h_FE tolerance but sacrifices 500 mA current capacity and adds 15 mV conduction loss - making FSB619 optimal for 2 A, low-drop, high-gain saturated switching.

Availability

FSB619 is available at Aetrix Electronics and suitable for DC-DC converter switching stages, automotive body control module load drivers, and industrial PLC output stages requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for FSB619 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The FSB619 belongs to ON Semiconductor's legacy Fairchild low-saturation bipolar transistor family, engineered specifically for high-current, low-V_CE(sat) switching in space-constrained power management and load-driving applications.

FAQ

What is the maximum continuous collector current rating for the FSB619?

The FSB619 has a maximum continuous collector current (I_C) rating of 2 A at T_A = 25°C, as specified in the Absolute Maximum Ratings table. This rating assumes proper PCB thermal management per the recommended land pattern and 2 oz copper pad area. At elevated ambient temperatures, derating applies at 4 mW/°C above 25°C, limiting usable current in high-temperature environments. The FSB619 maintains functional saturation up to this 2 A level, confirmed by h_FE = 100 and V_CE(sat) = 320 mV at I_C = 2 A / I_B = 50 mA in the Electrical Characteristics table.

Does the FSB619 have a documented pinout compatible with standard SOT-23 footprints?

Yes, the FSB619 uses the SuperSOT™-3 package, which is mechanically and electrically compatible with the JEDEC TO-236AB outline and standard SOT-23 footprint. Pin 1 is Emitter, Pin 2 is Base, and Pin 3 is Collector - matching the common SOT-23 pin assignment used by ON Semiconductor, Diodes Inc., and other major suppliers. The device marking "619" appears adjacent to Pin 1, and the land pattern recommendation in the datasheet confirms alignment with industry-standard SOT-23 solder pads.

What is the typical V_CE(sat) of the FSB619 at 1 A collector current?

The typical V_CE(sat) of the FSB619 at I_C = 1 A and I_B = 10 mA is 235 mV, as stated in the Electrical Characteristics table under "Collector-Emitter Saturation Voltage." This value is measured at T_A = 25°C and reflects the device's low-saturation design. The datasheet also specifies a maximum of 320 mV at I_C = 2 A / I_B = 50 mA, confirming consistent low-drop behavior across its rated current range. The FSB619 achieves this performance via optimized doping and geometry in its planar epitaxial structure.

Can the FSB619 be used in automotive applications?

Yes, the FSB619 is suitable for automotive applications due to its extended operating junction temperature range of –55°C to +150°C and qualification under AEC-Q101 stress test conditions as part of the Fairchild/ON Semiconductor portfolio. Its 50 V V_CEO rating provides sufficient margin for 12 V and 24 V vehicle electrical systems, and its low V_CE(sat) minimizes heat generation in body control modules, lighting drivers, and auxiliary power switches. The FSB619 has been deployed in production automotive modules including door latch actuators and HVAC fan controls.

How does the FSB619's DC current gain (h_FE) vary with collector current?

The FSB619's h_FE varies with collector current as follows: minimum 200 at I_C = 10 mA, 300 at I_C = 200 mA, 200 at I_C = 1 A, and 100 at I_C = 2 A - all measured at V_CE = 2 V and T_A = 25°C. This profile indicates peak gain near 200 mA, supporting efficient base drive optimization for mid-range loads. The gain remains sufficient for reliable saturation at 2 A (h_FE = 100 implies I_B = 20 mA required), ensuring robust switching in high-current applications without excessive base drive overhead. The FSB619's gain curve is documented in Figure 3 of its datasheet.