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

STMicroelectronics 2N5657

Name: 2N5657
Brand: STMicroelectronics
SKU: 2N5657
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N5657

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: 2N5657.pdf

Description:: TRANS NPN 350V 0.5A SOT-32-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N5657 from STMicroelectronics is a silicon epitaxial-base NPN transistor in SOT-32 (TO-126) package, rated for 350 V V_CEO, 0.5 A I_C, and 20 W P_tot at T_c ≤ 25 °C. It serves as a high-voltage switching element in AC line relays and low-current DC-DC converters.

For engineers reviewing the 2N5657 datasheet, 2N5657 pinout, 2N5657 application, or 2N5657 equivalent, key selection criteria include V_CEO(sus) = 350 V at I_C = 100 mA with 50 mH inductive load, h_FE ≥ 25 at I_C = 50 mA, and R_thj-case = 6.25 °C/W for thermal design in relay driver stages.

Technical Context

This NPN power transistor features an epitaxial base structure optimized for high-voltage blocking and controlled switching in inductive load circuits. Its safe operating area supports pulsed operation up to 1 A I_CM with 300 µs pulse width and 1.5% duty cycle.

The device exhibits V_CE(sat) ≤ 2.5 V at I_C = 0.25 A / I_B = 25 mA and f_T = 10 MHz at I_C = 50 mA, enabling use in medium-frequency switching applications where gain stability and saturation voltage are critical.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	350 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines maximum off-state blocking capability in relay drivers.
I_C	0.5 A continuous - Rated collector current at T_c = 25 °C; sets steady-state load current limit without derating.
P_tot	20 W - Total power dissipation at case temperature ≤ 25 °C; requires heatsinking for sustained operation above ~5 W.
h_FE	25–250 - DC current gain range across I_C = 50 mA to 0.5 A; enables predictable base drive sizing in linear and saturated switch modes.
R_thj-case	6.25 °C/W - Junction-to-case thermal resistance; determines temperature rise per watt dissipated when mounted on heatsink.
V_CE(sat)	1–10 V - Collector-emitter saturation voltage across I_C = 0.1–0.5 A; directly impacts conduction loss and thermal load in switching applications.
f_T	10 MHz - Transition frequency at I_C = 50 mA; indicates usable bandwidth for small-signal amplification or fast switching control loops.

Pinout & Package

SOT-32 (TO-126) plastic package with three leads: emitter (lead 1), base (lead 2), collector (lead 3). Mounting tab is electrically connected to collector and must be isolated from chassis unless referenced to collector potential.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Low-impedance return path; connects to ground or load common in high-side switch configurations.
2 (Base)	Control input	Receives current-limited drive signal; requires series resistor to limit I_B ≤ 0.25 A peak.
3 (Collector)	High-voltage output node	Connected to inductive load (e.g., relay coil) and supply rail; tab provides thermal path and electrical connection to collector.

Key Features

Feature	Design Value
High-voltage sustaining capability	V_CEO(sus) = 350 V at I_C = 100 mA with 50 mH inductive load - ensures reliable turn-off under reactive load conditions.
Controlled saturation behavior	V_CE(sat) ≤ 2.5 V at I_C = 0.25 A / I_B = 25 mA - minimizes conduction loss and self-heating during active switching.
Thermal performance	R_thj-case = 6.25 °C/W - enables compact heatsink design for 10–15 W continuous dissipation with <100 °C junction rise.
Gain consistency	h_FE ≥ 25 at I_C = 50 mA - supports stable biasing in linear amplifier and constant-current source topologies.

Applications

AC Line Relay Drivers

High-Voltage DC-DC Converters

Use Scenario: Driving 120/240 VAC relay coils with inductive energy storage and flyback voltage spikes.

IC Role / Device Role / Timing Role: High-voltage NPN switch controlling coil current; handles 350 V transient clamping via V_CEO(sus).

Use Value: Eliminates need for external snubbers in many designs due to robust SOA and 350 V sustaining rating.

Use Scenario: Low-current, high-input-voltage flyback or forward converter primary switches.

IC Role / Device Role / Timing Role: Main power switch in isolated DC-DC topologies operating from 200–300 VDC bus.

Use Value: Enables compact, cost-effective converters up to ~15 W output with minimal gate drive complexity.

Industrial Control Interface Cards

High-Voltage Signal Amplifiers

Use Scenario: Isolating PLC outputs to drive solenoids, contactors, or indicator lamps from 24–240 V systems.

IC Role / Device Role / Timing Role: Level-shifting interface transistor translating logic-level signals to high-voltage loads.

Use Value: Provides galvanic separation between microcontroller I/O and field-side voltages without optocoupler overhead.

Use Scenario: Linear amplification of sensor signals requiring high common-mode rejection in HV test equipment.

IC Role / Device Role / Timing Role: Common-emitter amplifier stage biased for high V_CE swing and moderate gain stability.

Use Value: Delivers >300 V peak-to-peak output swing with h_FE ≥ 15 at I_C = 0.25 A for precision HV signal conditioning.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N5551	V_CEO = 160 V, I_C = 0.6 A, P_tot = 0.625 W - lower voltage rating, much lower power handling	Not suitable for AC line relay or >200 V DC-DC applications; limited to low-power signal switching	Select only for sub-100 V, <100 mW applications where gain-bandwidth tradeoff favors f_T = 100 MHz
MJE13003	V_CEO = 400 V, I_C = 1.5 A, P_tot = 40 W - higher voltage, current, and power ratings; TO-126 package	Supports heavier inductive loads and higher power converters; requires larger heatsink	Choose when >0.5 A load current or >20 W dissipation is required; verify base drive compatibility

Compared with 2N5657, 2N5551 lacks sufficient voltage margin for AC line use, while MJE13003 offers headroom in all key ratings but demands greater drive and thermal management - making 2N5657 optimal for 0.2–0.5 A, 250–350 V switching where thermal and layout constraints favor its 20 W rating.

Availability

2N5657 is available at Aetrix Electronics and suitable for AC line relay drivers, high-voltage DC-DC converters, and industrial control interface cards requiring stable component supply and long-term manufacturability.

Supply support for 2N5657 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, digital, and mixed-signal ICs and discrete devices for industrial, automotive, and consumer markets.

The 2N5657 belongs to ST's legacy high-voltage bipolar transistor product line, engineered specifically for robust, cost-effective switching in AC mains-connected industrial controls and power conversion systems.

FAQ

Is the 2N5657 RoHS compliant?

Yes, the 2N5657 manufactured by STMicroelectronics meets RoHS Directive 2011/65/EU requirements. Lead-free soldering is supported with peak reflow temperatures up to 260 °C for 10 seconds, consistent with JEDEC J-STD-020 standards for SOT-32 packages.

What is the maximum safe inductive load energy the 2N5657 can interrupt?

Based on the SOA curve and V_CEO(sus) = 350 V at I_C = 100 mA with L = 50 mH, the device safely interrupts up to ~250 mJ stored energy (½ × L × I²) in properly clamped relay coil circuits without secondary breakdown.

Can the 2N5657 be used in avalanche mode?

No - the 2N5657 is not characterized or guaranteed for repetitive avalanche operation. Its absolute maximum ratings define single-pulse limits only; sustained operation beyond V_CEO risks irreversible degradation. External clamping is required for inductive flyback protection.

How does base current limitation affect reliability?

Exceeding I_B = 0.25 A peak causes localized heating at the base-emitter junction, accelerating degradation. Designers must limit base drive using series resistors and ensure I_B ≤ 0.1 A for continuous operation to maintain h_FE stability and prevent thermal runaway.

2N5657 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 350 V

Vce Saturation (Max) @ Ib, Ic:: 10V @ 100mA, 500mA

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 30 @ 100mA, 10V

Power - Max:: 20 W

Frequency - Transition:: 10MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: SOT-32-3

2N5657 FAQ

1.How can I place an order for 2N5657 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N5657 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 2N5657 reliable?

The price and inventory of 2N5657 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N5657 is usually 5 days.

3.What payment methods are accepted for 2N5657?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N5657 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N5657?

2N5657 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N5657 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 2N5657?

For technical support, including 2N5657 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N5657 requirements.

6.How does Aetrix verify that 2N5657 is sourced from the original manufacturer or authorized distributors?

All 2N5657 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 2N5657 meets industry standards.

7.What is the process for return or replacement of 2N5657?

All 2N5657 units undergo pre-shipment inspection (PSI). If there is an issue with 2N5657, 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 2N5657 part is unused and in its original packaging.

Return procedure for 2N5657:

1.Submit a request within 90 days.

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

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