STMicroelectronics STN790A

Overview

STN790A from STMicroelectronics is a medium-current, high-performance PNP bipolar junction transistor in SOT-223 package, featuring V(BR)CER = −40 V, IC = −3 A continuous, hFE > 100 at IC = −1 A, and VCE(sat) = −0.15 V at IC = −0.5 A/IB = −5 mA - used as a heavy-load switch in battery charger switching regulators.

For engineers reviewing the STN790A datasheet, STN790A pinout, STN790A application, or STN790A equivalent, key selection criteria include low saturation voltage under high current, robust thermal resistance (Rthj-amb = 78 °C/W on 1 cm² PCB), DC gain stability across load range, and SOT-223 surface-mount compatibility for portable power management layouts.

Technical Context

This PNP transistor uses "Base Island" planar technology to achieve simultaneous high hFE (>100 at IC = −1 A) and ultra-low VCE(sat) (−0.15 V typical at IC = −0.5 A). Its RBE = 47 Ω test condition enables stable breakdown rating of −40 V (V(BR)CER), distinguishing it from standard VCEO-rated devices.

Switching performance is characterized with resistive load: td = 180 ns, tr = 160 ns, ts = 250 ns, tf = 80 ns at IC = −3 A, supporting efficient operation in battery charger PWM stages where storage time minimization reduces conduction loss during turn-off.

Key Specifications

Pinout & Package

SOT-223 plastic surface-mount package with integrated heat sink tab (pin 3); footprint compatible with JEDEC MO-178AB, lead-free per ECOPACK® specification.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP switching transistor applications.

Compared with STN790A, NSS12201LT1G trades voltage/current headroom for footprint reduction, while DXT3904P-7 retains voltage rating but sacrifices current capability and hFE consistency - both require redesign of base drive and thermal layout to maintain system reliability.

Availability

STN790A is available at Aetrix Electronics and suitable for battery charger switching regulators, portable equipment power management, and industrial sensor load drivers requiring stable component supply with consistent parametric performance across production batches.

Supply support for STN790A 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The STN790A belongs to ST's high-performance discrete transistor product line, engineered specifically for high-current, low-saturation-voltage switching in space-constrained portable and battery-powered systems.

FAQ

What is the maximum safe operating temperature for STN790A?

The STN790A has a maximum operating junction temperature (TJ) of 150 °C. To sustain this limit, the device must be mounted on a PCB with ≥1 cm² copper area to achieve the specified Rthj-amb of 78 °C/W. Ambient temperature plus power dissipation × thermal resistance must remain below 150 °C - e.g., at 1.6 W dissipation, ambient must not exceed 32 °C without additional cooling.

Can STN790A replace an NPN transistor in the same circuit?

No - STN790A is a PNP transistor and cannot directly substitute for an NPN device without inverting the entire bias network. Its emitter connects to the higher potential rail, and base requires negative control relative to emitter. Replacing an NPN would require redesigning drive polarity, power rail orientation, and protection circuitry - it is not a drop-in functional replacement.

Is STN790A RoHS-compliant and lead-free?

Yes - STN790A is manufactured in ST's ECOPACK® package with lead-free second-level interconnect, compliant with RoHS Directive 2011/65/EU. The inner box label and package marking indicate the lead-free status per JEDEC Standard JESD97, and soldering profiles follow Pb-free reflow guidelines (peak temperature ≤ 260 °C).

Does STN790A require a base resistor, and how is its value calculated?

Yes - a base resistor is required to limit IB and ensure saturation. For IC = −3 A and minimum hFE = 90 (per datasheet at IC = −3 A), IB ≥ −33 mA is needed. With VEB(on) ≈ −0.8 V and controller output of 0 V (active low), a 120 Ω resistor yields IB ≈ −33 mA from a −5 V rail. Derating to 100 Ω ensures margin across temperature and unit variation.