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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

STMicroelectronics STX790A

Name: STX790A
Brand: STMicroelectronics
SKU: STX790A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STX790A

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: STX790A.pdf

Description:: TRANS PNP 30V 3A TO-92-3

Quantity:: RFQ Add To RFQ list

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Inventory:9,200

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Product details

Overview

STX790A from STMicroelectronics is a medium-current, high-performance PNP bipolar junction transistor in TO-92 package, featuring V_CE(sat) = –0.15 V at I_C = –0.5 A / I_B = –5 mA, h_FE ≥ 100 at I_C = –10 mA, V_(BR)CER = –40 V, and continuous I_C = –3 A. It serves as a heavy-load switch or voltage regulator element in battery-powered portable equipment and switching regulators.

For engineers reviewing the STX790A datasheet, STX790A pinout, STX790A application, or STX790A equivalent, key selection criteria include low saturation voltage under high current, guaranteed DC gain stability across operating temperature, rugged breakdown ratings with base-emitter resistor biasing, and TO-92 mechanical compatibility for space-constrained power stages.

Technical Context

The STX790A employs a "Base Island" planar PNP structure optimized for low V_CE(sat) and high h_FE, with V_(BR)CER = –40 V defined under R_BE = 47 Ω to emulate practical bias network conditions. Its thermal resistance R_thj-amb = 139 °C/W reflects standard TO-92 mounting on non-heatsinked PCBs.

Switching performance is characterized with resistive load: t_d = 180 ns, t_r = 160 ns, t_s = 250 ns, t_f = 80 ns at I_C = –3 A, enabling use in battery charger PWM stages up to ~1 MHz. f_T = 100 MHz at I_C = –50 mA confirms sufficient high-frequency gain margin for stable closed-loop regulation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_(BR)CER	–40 V: Validated collector-emitter breakdown with 47 Ω base resistor, enabling robust bias design in switching regulators
V_CE(sat)	–0.15 V @ I_C = –0.5 A / I_B = –5 mA: Minimizes conduction loss in portable power management stages
h_FE	≥100 @ I_C = –10 mA, V_CE = –2 V: Ensures reliable drive margin for digital logic-level base control
I_C (continuous)	–3 A: Supports heavy-load driver applications such as motor gate drivers or LED array switches
P_tot	0.9 W @ T_amb = 25 °C: Defines maximum dissipation without heatsinking in ambient-air-cooled designs
t_s (storage time)	250 ns @ I_C = –3 A: Critical timing parameter for minimizing dead-time losses in synchronous buck topologies

Pinout & Package

STX790A is housed in a standard TO-92 plastic package (JEDEC TO-92 variant), with lead material compliant with RoHS and halogen-free molding compound for STX790AG-AP variant.

Pin/Terminal	Circuit Role	Design Meaning
Emitter (E)	Current source terminal	Connected to positive rail in high-side switch configurations; requires low-impedance return path for saturation
Base (B)	Control input	Driven negative relative to emitter; 47 Ω external resistor required for V_(BR)CER-rated operation
Collector (C)	Current sink terminal	Connected to load; voltage swing limited to –40 V under R_BE-biased conditions

Key Features

Feature	Design Value
Very low V_CE(sat)	–0.15 V enables <150 mW conduction loss at 0.5 A, critical for thermally constrained portable systems
High h_FE stability	h_FE ≥ 100 across I_C = 10 mA to 3 A ensures consistent drive requirements over full load range
Rugged V_(BR)CER rating	–40 V with R_BE = 47 Ω validates safe operation in real-world bias networks, not ideal open-base test
TO-92 mechanical compatibility	Standard footprint allows drop-in replacement in legacy designs using JEDEC TO-92 layouts

Applications

Power Management in Portable Equipment

Voltage Regulation in Bias Supply Circuits

Use Scenario: Regulating auxiliary 3.3 V rail from Li-ion battery (3.0–4.2 V) in handheld medical monitors.

IC Role / Device Role / Timing Role: PNP pass transistor in linear regulator topology, controlled by op-amp feedback loop.

Use Value: Low V_CE(sat) reduces dropout voltage to <200 mV, extending usable battery life by >12% at mid-discharge.

Use Scenario: Generating stable –5 V bias for op-amp input stages in industrial sensor signal conditioning modules.

IC Role / Device Role / Timing Role: Emitter-follower level shifter with active current sourcing capability.

Use Value: High h_FE maintains regulation accuracy within ±1% across –1 mA to –10 mA load variation.

Switching Regulator in Battery Charger Applications

Heavy Load Driver

Use Scenario: Synchronous rectifier switch in 5 V/2 A USB-C PD charger secondary side.

IC Role / Device Role / Timing Role: Low-side PNP switch driven by gate driver IC with active pull-down.

Use Value: 250 ns storage time enables <500 ns minimum off-time, supporting 1.2 MHz switching frequency.

Use Scenario: Driving 12 V solenoid (2.5 A inrush, 1.8 A hold) in automotive HVAC actuator control.

IC Role / Device Role / Timing Role: High-current saturated switch with flyback diode protection.

Use Value: –3 A continuous rating and 0.9 W dissipation allow direct PCB-mount operation without heatsink at 40 °C ambient.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-current switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD2955T4	V_(BR)CEO = –70 V, higher P_tot = 1.5 W, TO-220 package	Requires heatsink for >1 A continuous; unsuitable for TO-92 footprint-limited designs	Select when higher breakdown voltage and thermal headroom outweigh board space constraints
BC807-40	I_C = –500 mA max, V_CE(sat) = –0.7 V @ I_C = –100 mA, SOT-23 package	Limited to light loads; cannot replace STX790A in >1 A applications	Select only for low-power bias circuits where TO-92 footprint is not mandatory

Compared with MJD2955T4 and BC807-40, STX790A uniquely balances TO-92 mountability, –3 A current capability, and –0.15 V saturation voltage-making it optimal for space-constrained, medium-power linear and switching regulators where thermal budget is tight but heatsinks are impractical.

Availability

STX790A is available at Aetrix Electronics and suitable for power management in portable equipment, voltage regulation in bias supply circuits, switching regulator in battery charger applications, and heavy load driver requiring stable component supply across industrial and consumer production programs.

Supply support for STX790A 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, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STX790A belongs to ST's general-purpose bipolar transistor product line, engineered specifically for high-efficiency, medium-current linear and switching power stages in cost-sensitive, space-constrained portable and battery-powered systems.

FAQ

What is the maximum safe operating junction temperature for STX790A?

The STX790A has a maximum operating junction temperature (T_J) of 150 °C, as specified in Table 2 of the official datasheet. This limit applies under all operating conditions, including pulsed and continuous modes. Exceeding this temperature risks permanent degradation of h_FE and increased leakage currents, particularly ICBO, which rises exponentially above 100 °C.

Does STX790A require an external base resistor for normal operation?

Yes - the V_(BR)CER rating of –40 V is explicitly defined with R_BE = 47 Ω, meaning a 47 Ω resistor must be placed between base and emitter to guarantee rated breakdown performance. Omitting it reduces effective V_(BR)CEO to –30 V and may cause premature breakdown during transient overvoltage events.

Can STX790A be used in avalanche mode?

No - STX790A is not rated or characterized for avalanche operation. Its absolute maximum ratings define only safe linear and switching operation within V_(BR)CER, V_(BR)CEO, and thermal limits. Intentional avalanche use risks parametric shift, bond wire failure, or catastrophic second breakdown not covered by warranty or reliability testing.

Is STX790A compliant with modern environmental standards?

Yes - the STX790AG-AP variant uses halogen-free molding compound and meets RoHS Directive 2011/65/EU. The base STX790A (bulk TO-92) also complies with RoHS, though not explicitly halogen-free. Both variants carry ST's ECOPACK® environmental grade certification per www.st.com/ecopack documentation.

STX790A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 700mV @ 100mA, 3A

Current - Collector Cutoff (Max):: 10µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 500mA, 2V

Power - Max:: 900 mW

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

STX790A FAQ

1.How can I place an order for STX790A through Aetrix?

Please submit a Request for Quotation (RFQ) for STX790A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for STX790A reliable?

The price and inventory of STX790A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STX790A is usually 5 days.

3.What payment methods are accepted for STX790A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STX790A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STX790A?

STX790A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STX790A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for STX790A?

For technical support, including STX790A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STX790A requirements.

6.How does Aetrix verify that STX790A is sourced from the original manufacturer or authorized distributors?

All STX790A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that STX790A meets industry standards.

7.What is the process for return or replacement of STX790A?

All STX790A units undergo pre-shipment inspection (PSI). If there is an issue with STX790A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The STX790A part is unused and in its original packaging.

Return procedure for STX790A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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