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

onsemi 2SB1121T-TD-E

Name: 2SB1121T-TD-E
Brand: onsemi
SKU: 2SB1121T-TD-E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SB1121T-TD-E

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-243AA

Datasheet:: 2SB1121T-TD-E.pdf

Description:: TRANS PNP 25V 2A PCP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2SB1121T-TD-E from onsemi is a PNP bipolar junction transistor (BJT) designed for medium-power switching and linear amplification in compact hybrid ICs. It delivers -25 V V_CEO, -2 A I_C, low -0.35 V typical V_CE(sat) at -1.5 A, 150 MHz f_T, and operates within -55°C to +150°C T_stg. It is used in relay drivers, lamp drivers, and voltage regulators where high current density and fast switching are required.

For engineers reviewing the 2SB1121T-TD-E datasheet, pinout, applications, or equivalent options, key selection criteria include verified SOA performance at -1.5 A, SC-62 (SOT-89/TO-243) package thermal resistance on ceramic substrate, and h_FE rank T (200–400 at -100 mA), critical for stable biasing in industrial control circuits.

Technical Context

This PNP BJT employs FBET and MBIT fabrication processes to achieve low saturation voltage and wide safe operating area (SOA). Its structure supports continuous -2 A collector current with 1.3 W power dissipation when mounted on a 250 mm² ceramic substrate, enabling robust operation under pulsed loads up to -5 A.

The device exhibits fast switching dynamics: 60 ns turn-on time, 350 ns storage time, and 25 ns fall time under specified test conditions. Its 32 pF output capacitance and 150 MHz gain-bandwidth product support reliable performance in mid-frequency switching applications up to several megahertz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-25 V - Maximum allowable collector-emitter voltage before breakdown; defines upper limit for voltage regulator or relay driver rail compatibility.
I_C	-2 A - Continuous DC collector current rating; supports medium-power load switching without forced cooling on ceramic substrates.
V_CE(sat)	-0.35 V (typ) at -1.5 A / -75 mA - Low saturation voltage reduces conduction loss and self-heating in high-duty-cycle switching.
f_T	150 MHz - Gain-bandwidth product confirms suitability for audio-frequency and low-MHz signal amplification and switching.
h_FE Rank	T (200–400 at -100 mA) - Tighter DC current gain binning ensures predictable base drive requirements in production designs.
Package	PCP (JEITA SC-62 / JEDEC SOT-89 / TO-243) - Surface-mount, 3-pin thermally enhanced outline with exposed emitter tab for PCB heat sinking.
t_on/t_f	60 ns / 25 ns - Verified switching speed enables efficient operation in PWM-driven lamp and solenoid control up to ~2 MHz.

Pinout & Package

Package: PCP - thermally optimized surface-mount plastic package (JEITA SC-62, JEDEC SOT-89, TO-243), featuring an exposed emitter pad for enhanced thermal conduction to PCB copper.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal; requires -75 mA base current to saturate at -1.5 A collector load; connected via current-limiting resistor in driver stages.
2	Collector	High-side switching node; connects to negative supply rail in high-side PNP configurations or load return path in low-side arrangements.
3	Emitter	Power reference terminal; electrically and thermally tied to PCB ground plane or heatsink via exposed metal pad; carries full load current.

Key Features

Feature	Design Value
Low V_CE(sat)	-0.35 V typical at -1.5 A enables <1 W conduction loss in 24 V relay drivers, reducing thermal stress on adjacent components.
Wide SOA	Rated for -2 A continuous and -5 A pulsed operation with defined derating curves; supports surge-tolerant lamp ignition and motor stall conditions.
Fast switching	60 ns t_on, 25 ns t_f allow clean square-wave drive of inductive loads without excessive ringing or shoot-through risk in H-bridge pre-drivers.
Ultrasmall PCP footprint	3.0 × 4.5 mm outline with 1.6 mm height fits dense hybrid IC layouts; compatible with standard SOT-89 pick-and-place tooling.

Applications

Relay Drivers	Lamp Drivers
Use Scenario: Driving 12–24 V electromagnetic relays in PLC I/O modules and industrial control panels. IC Role / Device Role / Timing Role: High-current PNP switch controlling relay coil current path to ground; handles inductive kickback via inherent SOA margin. Use Value: -0.35 V V_CE(sat) minimizes power loss during sustained coil energization, enabling compact thermal design without auxiliary snubbers.	Use Scenario: Switching incandescent or halogen lamps in automotive interior lighting and building management systems. IC Role / Device Role / Timing Role: Medium-power load switch managing lamp inrush and steady-state current up to 2 A. Use Value: Wide SOA and -5 A pulse rating accommodate cold-filament surge currents exceeding 3× steady-state, preventing premature failure.
Voltage Regulators	Electrical Equipment Control
Use Scenario: Pass transistor in discrete linear voltage regulators supplying ±15 V analog circuitry in test equipment. IC Role / Device Role / Timing Role: Series pass element regulating output by modulating collector-emitter voltage drop under feedback control. Use Value: 150 MHz f_T and stable h_FE ensure adequate loop bandwidth and transient response for sub-1% regulation accuracy.	Use Scenario: Output stage in programmable logic controller (PLC) digital output cards driving solenoids and small actuators. IC Role / Device Role / Timing Role: Final-stage interface transistor translating microcontroller GPIO signals into isolated, current-boosted load control. Use Value: SC-62 package's exposed emitter pad allows direct thermal coupling to metal-core PCB, sustaining -2 A loads at 70°C ambient without derating.

Relay Drivers

Lamp Drivers

Use Scenario: Driving 12–24 V electromagnetic relays in PLC I/O modules and industrial control panels.

IC Role / Device Role / Timing Role: High-current PNP switch controlling relay coil current path to ground; handles inductive kickback via inherent SOA margin.

Use Value: -0.35 V V_CE(sat) minimizes power loss during sustained coil energization, enabling compact thermal design without auxiliary snubbers.

Use Scenario: Switching incandescent or halogen lamps in automotive interior lighting and building management systems.

IC Role / Device Role / Timing Role: Medium-power load switch managing lamp inrush and steady-state current up to 2 A.

Use Value: Wide SOA and -5 A pulse rating accommodate cold-filament surge currents exceeding 3× steady-state, preventing premature failure.

Voltage Regulators

Electrical Equipment Control

Use Scenario: Pass transistor in discrete linear voltage regulators supplying ±15 V analog circuitry in test equipment.

IC Role / Device Role / Timing Role: Series pass element regulating output by modulating collector-emitter voltage drop under feedback control.

Use Value: 150 MHz f_T and stable h_FE ensure adequate loop bandwidth and transient response for sub-1% regulation accuracy.

Use Scenario: Output stage in programmable logic controller (PLC) digital output cards driving solenoids and small actuators.

IC Role / Device Role / Timing Role: Final-stage interface transistor translating microcontroller GPIO signals into isolated, current-boosted load control.

Use Value: SC-62 package's exposed emitter pad allows direct thermal coupling to metal-core PCB, sustaining -2 A loads at 70°C ambient without derating.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SB1218T-TD-E	V_CEO = -30 V, I_C = -1.5 A, V_CE(sat) = -0.4 V (typ) at -1 A	Higher voltage rating but lower current capacity; better for 28 V automotive systems with lower load demands	Select when system rail exceeds -25 V but load current remains ≤1.5 A
MJD2955RLG	V_CEO = -60 V, I_C = -10 A, TO-220 package, slower switching (t_f = 100 ns)	Higher power and voltage capability, but larger footprint and reduced frequency response	Choose for high-reliability industrial power supplies requiring >5 W dissipation and mechanical mounting

Compared with 2SB1121T-TD-E, 2SB1218T-TD-E trades current headroom for higher voltage tolerance in space-constrained designs, while MJD2955RLG offers greater ruggedness and thermal mass at the cost of PCB area and switching speed-making the 2SB1121T-TD-E optimal for compact, medium-speed, medium-power hybrid ICs.

Availability

2SB1121T-TD-E is available at Aetrix Electronics and suitable for relay drivers, lamp drivers, and voltage regulators requiring stable component supply across industrial automation, building controls, and test instrumentation programs.

Supply support for 2SB1121T-TD-E 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.

The 2SB1121 series belongs to onsemi's general-purpose bipolar transistor portfolio, engineered for high-density hybrid IC integration in industrial control and power management systems where low V_CE(sat), fast switching, and thermal efficiency are prioritized.

FAQ

What is the h_FE range for 2SB1121T-TD-E?

The 2SB1121T-TD-E is binned to h_FE Rank T, specifying a DC current gain of 200–400 at V_CE = -2 V and I_C = -100 mA. This tighter binning improves predictability in base-drive calculations for production-grade relay and lamp driver circuits compared to the broader S-rank variant (140–280).

Is 2SB1121T-TD-E RoHS compliant and lead-free?

Yes, 2SB1121T-TD-E is Pb-Free and RoHS compliant, as confirmed by the "Pb-Free" marking in the Ordering Information section and packaging designation "TD-E" per onsemi documentation. The device meets JEDEC J-STD-609 Category 1 moisture sensitivity level (MSL-1) for standard SMT assembly.

What is the maximum power dissipation for 2SB1121T-TD-E on a standard PCB?

When mounted on a 250 mm² ceramic substrate (0.8 mm thick), 2SB1121T-TD-E achieves 1.3 W maximum power dissipation. On standard FR-4 PCBs without thermal vias or copper pour, derating is required-typically ≤500 mW continuous-due to higher thermal resistance; layout must follow the provided land pattern example for optimal performance.

How does the PCP package of 2SB1121T-TD-E differ from standard SOT-89?

The PCP package used for 2SB1121T-TD-E is identical in outline and pin assignment to JEDEC SOT-89 (TO-243), but features process-optimized mold compound and internal leadframe geometry for improved thermal conductivity and mechanical reliability in hybrid IC assembly. Dimensions and land pattern match SOT-89, ensuring full footprint compatibility.

Can 2SB1121T-TD-E replace 2SB1121S-TD-E in existing designs?

Yes, 2SB1121T-TD-E can directly replace 2SB1121S-TD-E where higher h_FE is beneficial, as both share identical package, pinout, absolute maximum ratings, and electrical characteristics except for h_FE binning (T: 200–400 vs. S: 140–280). No layout or schematic changes are needed, though base resistor values may be adjusted to optimize bias stability.

2SB1121T-TD-E Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-243AA

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 2 A

Voltage - Collector Emitter Breakdown (Max):: 25 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 75mA, 1.5A

Current - Collector Cutoff (Max):: 100nA (ICBO)

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

Power - Max:: 500 mW

Frequency - Transition:: 150MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: PCP

2SB1121T-TD-E FAQ

1.How can I place an order for 2SB1121T-TD-E through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SB1121T-TD-E 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 2SB1121T-TD-E reliable?

The price and inventory of 2SB1121T-TD-E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SB1121T-TD-E is usually 5 days.

3.What payment methods are accepted for 2SB1121T-TD-E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SB1121T-TD-E transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SB1121T-TD-E?

2SB1121T-TD-E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SB1121T-TD-E 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 2SB1121T-TD-E?

For technical support, including 2SB1121T-TD-E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SB1121T-TD-E requirements.

6.How does Aetrix verify that 2SB1121T-TD-E is sourced from the original manufacturer or authorized distributors?

All 2SB1121T-TD-E 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 2SB1121T-TD-E meets industry standards.

7.What is the process for return or replacement of 2SB1121T-TD-E?

All 2SB1121T-TD-E units undergo pre-shipment inspection (PSI). If there is an issue with 2SB1121T-TD-E, 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 2SB1121T-TD-E part is unused and in its original packaging.

Return procedure for 2SB1121T-TD-E:

1.Submit a request within 90 days.

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

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