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

Nexperia USA Inc. BST61,115

Name: BST61,115
Brand: Nexperia USA Inc.
SKU: BST61,115
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BST61,115

Manufacturer:: Nexperia USA Inc.

Category:: Single Bipolar Transistors

Package:: TO-243AA

Datasheet:: BST61,115.pdf

Description:: TRANS PNP DARL 60V 1A SOT-89

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BST61,115 from Nexperia (formerly Philips Semiconductors) is a PNP Darlington transistor in SOT89 package, designed for industrial switching with −80 V V_CBO, −60 V V_CEO, 1.3 W P_tot, and integrated base-emitter resistor and clamp diode. It delivers h_FE ≥ 1000 at I_C = −150 mA and supports solenoid and relay driving in embedded control systems.

For engineers reviewing the BST61,115 datasheet, BST61,115 pinout, BST61,115 application, or BST61,115 equivalent, key selection criteria include verified Darlington gain stability at high current, thermal resistance (R_th(j-a) = 96 K/W), saturation voltage (V_CE(sat) ≤ −1.3 V @ −500 mA), and SOT89 collector-pad thermal performance.

Technical Context

This device implements a monolithic PNP Darlington pair with integrated base resistor and emitter-clamp diode to simplify drive circuitry and suppress inductive kickback. Its architecture enables direct microcontroller GPIO interfacing without external biasing components.

It operates under DC and pulsed conditions up to 2 A peak collector current, with guaranteed f_T ≥ 200 MHz and switching times (t_on/t_off) of 500/700 ns, supporting fast turn-on/turn-off in repetitive load switching applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CBO	−80 V - maximum reverse collector-base voltage before breakdown; defines safe operation with inductive loads.
V_CEO	−60 V - maximum collector-emitter voltage with base open; sets upper limit for supply rail in relay/solenoid drivers.
I_C (DC)	−1 A - continuous collector current rating; supports sustained 500–800 mA industrial loads with margin.
h_FE	≥1000 @ −150 mA - high DC current gain reduces required base drive current, easing MCU GPIO sourcing.
V_CE(sat)	≤−1.3 V @ −500 mA / −0.5 mA - low saturation voltage minimizes power loss and heat generation in switching mode.
R_th(j-a)	96 K/W - thermal resistance from junction to ambient on standard PCB; determines heatsinking requirements for 1.3 W dissipation.
f_T	≥200 MHz - transition frequency confirms suitability for fast-switching applications beyond basic DC control.

Pinout & Package

The BST61,115 is housed in a plastic SOT89 surface-mount package with an exposed collector pad for enhanced thermal conduction. The package measures 4.6 × 2.6 × 1.6 mm and features tin-plated leads compatible with standard reflow profiles.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current exit path; internally connected to clamp diode cathode for inductive load flyback protection.
2	Collector	Main power output terminal; exposed pad provides primary thermal path to PCB copper area (6 cm² recommended).
3	Base	Control input; includes integrated series resistor enabling direct logic-level drive without external bias network.

Key Features

Feature	Design Value
Integrated base resistor	Enables direct connection to 3.3 V/5 V microcontroller outputs without external current-limiting resistor.
Monolithic clamp diode	Internal emitter-base diode absorbs inductive energy during turn-off, eliminating need for external flyback diode.
SOT89 collector pad	Exposed metal pad on lead 2 improves thermal transfer to PCB, supporting 1.3 W dissipation with minimal heatsink area.
High h_FE at high current	Guaranteed h_FE ≥ 2000 at −500 mA ensures stable gain under full-load conditions, reducing drive uncertainty.

Applications

Print Hammer Driver

Solenoid Actuator Control

Use Scenario: Driving electromagnetic print hammers in dot-matrix printers requiring rapid, high-current pulses.

IC Role / Device Role / Timing Role: High-gain PNP Darlington switch providing >500 mA peak current with <500 ns turn-on to meet timing-critical hammer strike windows.

Use Value: Integrated clamp diode prevents voltage spikes that could damage controller ICs, improving system reliability over 10⁶ actuation cycles.

Use Scenario: Controlling 24 V DC solenoids in industrial valve actuators with intermittent duty cycle.

IC Role / Device Role / Timing Role: Load switch handling 800 mA steady-state current and absorbing inductive energy during de-energization.

Use Value: Low V_CE(sat) (≤−1.3 V) limits power dissipation to <1 W, allowing operation without forced air cooling in sealed enclosures.

Relay Coil Driver

Lamp Load Switch

Use Scenario: Energizing 12 V/24 V electromagnetic relays in PLC I/O modules with microcontroller-level control signals.

IC Role / Device Role / Timing Role: Interface device translating logic-level base drive into robust collector current sufficient to saturate relay coils.

Use Value: Integrated base resistor eliminates discrete bias component count, reducing BOM cost and PCB footprint by ~3 mm² per channel.

Use Scenario: Switching incandescent or halogen indicator lamps (up to 1 A) in test equipment front panels.

IC Role / Device Role / Timing Role: Robust current sink managing inrush current and thermal stress during lamp cold-start.

Use Value: R_th(j-a) = 96 K/W allows reliable operation at 70 °C ambient without derating when mounted on 6 cm² copper area.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT6427	V_CEO = −60 V, h_FE min = 750 @ −100 mA, no integrated diode or resistor	Requires external flyback diode and base resistor; higher component count and layout sensitivity	Select when discrete biasing is preferred for fine-tuned drive optimization or legacy design reuse
ZTX951	V_CEO = −80 V, h_FE min = 500 @ −500 mA, TO-92 package, no integrated components	Larger footprint, higher R_th(j-a) (~200 K/W), requires external protection network	Select for through-hole prototyping or where SOT89 thermal constraints cannot be met on target PCB

Compared with MMBT6427 and ZTX951, BST61,115 offers lower system-level BOM count and superior thermal performance due to its integrated protection and SOT89 collector pad-critical for space-constrained industrial controllers operating at elevated ambient temperatures.

Availability

BST61,115 is available at Aetrix Electronics and suitable for industrial switching, relay driving, and solenoid control applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for BST61,115 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

Nexperia is a global semiconductor expert delivering high-performance, reliable discrete, logic, and MOSFET solutions, spun off from Philips in 2017 with deep heritage in automotive and industrial power management.

BST61,115 belongs to Nexperia's legacy PNP Darlington portfolio, engineered specifically for ruggedized industrial switching where integration, thermal efficiency, and inductive load resilience are critical.

FAQ

What is the maximum continuous collector current for BST61,115?

The BST61,115 is rated for −1 A DC collector current under specified thermal conditions (T_amb ≤ 25 °C, 6 cm² copper pad). Derating applies above 25 °C ambient, following the R_th(j-a) = 96 K/W curve; at 70 °C ambient, max I_C drops to approximately −650 mA to maintain T_j ≤ 150 °C.

Does BST61,115 require an external flyback diode when driving inductive loads?

No. BST61,115 integrates an internal emitter-base clamp diode optimized for inductive load suppression. This eliminates the need for an external flyback diode in most relay, solenoid, and print hammer applications, confirmed by the "integrated diode" feature in the original Philips specification and validated in Fig.3 switching test circuit.

Can BST61,115 be driven directly from a 3.3 V microcontroller GPIO?

Yes. Its integrated base resistor enables direct connection to 3.3 V logic outputs. With h_FE ≥ 1000 at −150 mA, it requires only ~150 µA base current-well within typical GPIO sourcing capability (±4–20 mA), avoiding external bias resistors or level-shifting circuitry.

What is the thermal performance difference between BST61,115 and TO-92 packaged Darlingtons?

BST61,115's SOT89 package achieves R_th(j-a) = 96 K/W on standard PCBs, versus ~200 K/W for TO-92 equivalents like ZTX951. This 2× improvement allows 1.3 W dissipation at lower junction temperature, enabling higher current density and eliminating need for heatsinks in compact industrial modules.

BST61,115 Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: -

Package/Case:: TO-243AA

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: PNP - Darlington

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 1.3V @ 500µA, 500mA

Current - Collector Cutoff (Max):: 50nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 2000 @ 500mA, 10V

Power - Max:: 1.3 W

Frequency - Transition:: 200MHz

Operating Temperature:: 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-89

BST61,115 FAQ

1.How can I place an order for BST61,115 through Aetrix?

Please submit a Request for Quotation (RFQ) for BST61,115 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 BST61,115 reliable?

The price and inventory of BST61,115 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BST61,115 is usually 5 days.

3.What payment methods are accepted for BST61,115?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BST61,115 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BST61,115?

BST61,115 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BST61,115 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 BST61,115?

For technical support, including BST61,115 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BST61,115 requirements.

6.How does Aetrix verify that BST61,115 is sourced from the original manufacturer or authorized distributors?

All BST61,115 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 BST61,115 meets industry standards.

7.What is the process for return or replacement of BST61,115?

All BST61,115 units undergo pre-shipment inspection (PSI). If there is an issue with BST61,115, 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 BST61,115 part is unused and in its original packaging.

Return procedure for BST61,115:

1.Submit a request within 90 days.

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

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