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

onsemi 2SB1205T-E

Name: 2SB1205T-E
Brand: onsemi
SKU: 2SB1205T-E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SB1205T-E

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-251-3 Short Leads, IPAK, TO-251AA

Datasheet:: 2SB1205T-E.pdf

Description:: TRANS PNP 20V 5A TP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2SB1205T-E from onsemi is a PNP bipolar junction transistor (BJT) optimized for medium-power switching applications, featuring –20 V V_CEO, –5 A I_C, –250 mV typical V_CE(sat) at –3 A/–60 mA, 320 MHz f_T, and SC-64 (TO-251) TP package. It serves as a high-current, low-saturation switch in flash circuits, relay drivers, and lamp drivers.

For engineers reviewing the 2SB1205T-E datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CE(sat) at high I_C, h_FE rank T (200–400 at 500 mA), fast switching (t_on = 40 ns, t_f = 10 ns), thermal performance under DC operation, and TP package footprint compatibility with TO-251 layouts.

Technical Context

The 2SB1205T-E uses FBET and MBIT fabrication processes to achieve low saturation voltage and fast switching. Its PNP structure supports common-emitter switching with base-controlled turn-on, and its rated –5 A continuous collector current requires careful thermal management-PC = 1 W at T_a = 25°C, rising to 10 W at T_c = 25°C.

Electrical behavior is characterized across temperature (–25°C to +75°C) and bias conditions: h_FE maintains ≥60 at –4 A, V_CE(sat) stays ≤ –500 mV, and Cob = 60 pF at –10 V V_CB, supporting stable high-frequency switching in discrete driver stages without oscillation risk.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	–20 V - Maximum allowable collector-to-emitter voltage before breakdown in common-emitter configuration.
I_C	–5 A - Continuous DC collector current rating; defines maximum steady-state load drive capability.
V_CE(sat)	–250 mV (typ) at –3 A/–60 mA - Low conduction loss enables efficient power switching with minimal heat generation.
f_T	320 MHz - Sufficient gain-bandwidth for reliable operation in pulse-width modulated (PWM) lamp/relay control up to ~100 kHz.
h_FE Rank	T (200–400 at 500 mA) - Higher DC gain improves base drive efficiency and reduces required base current in saturated-switch designs.
t_f	10 ns - Fast fall time minimizes switching transition losses and supports high-duty-cycle operation without thermal runaway.
C_ob	60 pF at –10 V - Low output capacitance reduces Miller effect, enabling stable high-speed switching with minimal gate/base drive overshoot.

Pinout & Package

2SB1205T-E is housed in the TP package (JEITA/SC-64, JEDEC/TO-251), a surface-mount variant of TO-251 with three leads and an exposed collector tab for thermal dissipation. The package measures 7.0 × 5.0 × 2.3 mm (L × W × H) and weighs 0.315 g.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control input terminal; requires –60 mA base current to saturate at –3 A collector current.
2	Collector	Main current sink path; electrically connected to exposed metal tab for thermal conduction to PCB copper.
3	Emitter	Common reference node; tied to system ground or positive rail depending on circuit topology (common-emitter or common-base).
4	Collector	Second collector connection-internally bonded to Pin 2-to enhance current handling and thermal spreading.

Key Features

Feature	Design Value
Low V_CE(sat)	–250 mV typ at –3 A ensures <150 mW conduction loss, reducing heatsink requirements in compact lamp drivers.
Fast switching	40 ns t_on/10 ns t_f enables clean PWM edges and supports >100 kHz switching frequencies without excessive EMI.
High current capacity	–5 A I_C and –8 A I_CP support direct driving of automotive relays and LED arrays without external current boosting.
TP package (TO-251)	Surface-mount SC-64 footprint offers mechanical robustness and thermal performance comparable to through-hole TO-92 but with higher power density.

Applications

Automotive Relay Drivers	DC-DC Converter Switching Stages
Use Scenario: Driving 12 V automotive electromagnetic relays (e.g., headlight, horn, starter control) in body control modules. IC Role / Device Role / Timing Role: PNP BJT configured as low-side switch with base resistor network; provides full saturation at 500 mA–3 A loads. Use Value: –250 mV V_CE(sat) minimizes power loss during sustained coil energization, preventing thermal derating in sealed enclosures.	Use Scenario: High-side synchronous rectifier or auxiliary switch in non-isolated buck converters for industrial sensors. IC Role / Device Role / Timing Role: Discrete PNP switch controlling feedback loop timing or enabling/disabling converter sections via base pulse. Use Value: 320 MHz f_T and 10 ns t_f ensure accurate pulse fidelity and minimal dead-time distortion in 50–100 kHz control loops.
LED Flash Circuits	Voltage Regulator Pass Elements
Use Scenario: High-intensity camera flash discharge control in portable imaging systems requiring short (<10 ms), high-current pulses. IC Role / Device Role / Timing Role: PNP switch placed between battery and xenon/LED array; triggered by microcontroller GPIO with current-limited base drive. Use Value: –8 A I_CP rating safely handles 5–7 A flash pulses, while fast t_f prevents afterglow and enables precise exposure timing.	Use Scenario: Series pass element in linear voltage regulators delivering up to 3 A at 3.3 V/5 V for FPGA I/O banks or analog subsystems. IC Role / Device Role / Timing Role: PNP emitter-follower configured as adjustable current source; base driven by error amplifier output. Use Value: h_FE ≥60 at –4 A ensures stable regulation under full load, and low V_BE(sat) (–1.0 V typ) reduces dropout voltage overhead.

Automotive Relay Drivers

DC-DC Converter Switching Stages

Use Scenario: Driving 12 V automotive electromagnetic relays (e.g., headlight, horn, starter control) in body control modules.

IC Role / Device Role / Timing Role: PNP BJT configured as low-side switch with base resistor network; provides full saturation at 500 mA–3 A loads.

Use Value: –250 mV V_CE(sat) minimizes power loss during sustained coil energization, preventing thermal derating in sealed enclosures.

Use Scenario: High-side synchronous rectifier or auxiliary switch in non-isolated buck converters for industrial sensors.

IC Role / Device Role / Timing Role: Discrete PNP switch controlling feedback loop timing or enabling/disabling converter sections via base pulse.

Use Value: 320 MHz f_T and 10 ns t_f ensure accurate pulse fidelity and minimal dead-time distortion in 50–100 kHz control loops.

LED Flash Circuits

Voltage Regulator Pass Elements

Use Scenario: High-intensity camera flash discharge control in portable imaging systems requiring short (<10 ms), high-current pulses.

IC Role / Device Role / Timing Role: PNP switch placed between battery and xenon/LED array; triggered by microcontroller GPIO with current-limited base drive.

Use Value: –8 A I_CP rating safely handles 5–7 A flash pulses, while fast t_f prevents afterglow and enables precise exposure timing.

Use Scenario: Series pass element in linear voltage regulators delivering up to 3 A at 3.3 V/5 V for FPGA I/O banks or analog subsystems.

IC Role / Device Role / Timing Role: PNP emitter-follower configured as adjustable current source; base driven by error amplifier output.

Use Value: h_FE ≥60 at –4 A ensures stable regulation under full load, and low V_BE(sat) (–1.0 V typ) reduces dropout voltage overhead.

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
2SB1204T-E	V_CEO = –15 V, V_CE(sat) = –300 mV (typ) at –2 A, h_FE rank T (140–280)	Limited to lower-voltage rails (≤12 V); less margin for transient spikes in automotive environments.	Select when cost sensitivity outweighs need for –20 V rating and higher current headroom.
MJD2955T4G	TO-252 (DPAK), V_CEO = –60 V, I_C = –10 A, V_CE(sat) = –1.2 V (max) at –8 A	Higher voltage tolerance but significantly higher saturation loss; requires larger PCB area and heatsinking.	Choose for legacy TO-252 layouts or where –60 V surge immunity is mandatory, accepting higher conduction loss.

Compared with 2SB1205T-E, 2SB1204T-E trades voltage headroom for tighter h_FE consistency at lower currents, while MJD2955T4G prioritizes ruggedness over efficiency-making 2SB1205T-E optimal for space-constrained, thermally sensitive 12–20 V switching where low V_CE(sat) and fast t_f are critical.

Availability

2SB1205T-E is available at Aetrix Electronics and suitable for automotive relay drivers, LED flash circuits, and voltage regulator pass elements requiring stable component supply, consistent h_FE ranking, and TO-251-compatible thermal performance.

Supply support for 2SB1205T-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 2SB1205T-E belongs to onsemi's general-purpose bipolar transistor family engineered for high-reliability discrete switching in power management and interface circuits where low saturation voltage and fast response are essential.

FAQ

What is the h_FE range for 2SB1205T-E at 500 mA?

The 2SB1205T-E is ranked T, meaning its DC current gain h_FE falls between 200 and 400 when measured at V_CE = –2 V and I_C = 500 mA. This rank is laser-marked on the device (e.g., "B1205" plus rank code) and confirmed in the EN2114C datasheet. Designers should use h_FE = 200 (min) for worst-case base drive calculations in the 2SB1205T-E.

Is 2SB1205T-E pin-compatible with 2SB1205S-E?

Yes-both 2SB1205T-E and 2SB1205S-E share identical TP (TO-251/SC-64) packaging, pinout (Base–Collector–Emitter–Collector), and mechanical dimensions. The only difference is h_FE rank: S (140–280) vs. T (200–400). No PCB layout change is needed when substituting 2SB1205T-E for 2SB1205S-E in existing designs.

What is the maximum pulsed collector current for 2SB1205T-E?

The 2SB1205T-E supports a peak collector current I_CP of –8 A under pulse conditions, as specified in the Absolute Maximum Ratings table. This rating applies to single pulses with defined duty cycle and thermal conditions (e.g., t_p ≤ 100 ms, T_c ≤ 25°C). For sustained operation, the –5 A DC limit must be observed to prevent junction overheating in the 2SB1205T-E.

Does 2SB1205T-E require a heatsink in standard PCB mounting?

At ambient temperatures ≤40°C and DC I_C ≤2 A, the 2SB1205T-E typically operates within safe junction limits using only 1–2 cm² of 2-oz copper pour connected to the collector tab-no external heatsink required. However, at –5 A DC with limited copper area or elevated ambient, thermal simulation using the 2SB1205T-E's θ_JA ≈ 120°C/W (typ) is recommended to avoid exceeding 150°C T_j.

How does the TP package of 2SB1205T-E differ from TP-FA?

The TP package used in 2SB1205T-E is the standard leaded version (SC-64/TO-251), while TP-FA (used in 2SB1205T-TL-E) adds a molded resin overmold and tape-and-reel packaging. Both share identical electrical specs and pinout, but TP-FA offers enhanced moisture resistance and automated placement compatibility. The 2SB1205T-E's TP variant is supplied in 500 pcs./bag and is optimized for manual or semi-automated assembly.

2SB1205T-E Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-251-3 Short Leads, IPAK, TO-251AA

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 5 A

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 60mA, 3A

Current - Collector Cutoff (Max):: 500nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 500mA, 2V

Power - Max:: 1 W

Frequency - Transition:: 320MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TP

2SB1205T-E FAQ

1.How can I place an order for 2SB1205T-E through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SB1205T-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 2SB1205T-E reliable?

The price and inventory of 2SB1205T-E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SB1205T-E is usually 5 days.

3.What payment methods are accepted for 2SB1205T-E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SB1205T-E transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SB1205T-E?

2SB1205T-E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SB1205T-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 2SB1205T-E?

For technical support, including 2SB1205T-E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SB1205T-E requirements.

6.How does Aetrix verify that 2SB1205T-E is sourced from the original manufacturer or authorized distributors?

All 2SB1205T-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 2SB1205T-E meets industry standards.

7.What is the process for return or replacement of 2SB1205T-E?

All 2SB1205T-E units undergo pre-shipment inspection (PSI). If there is an issue with 2SB1205T-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 2SB1205T-E part is unused and in its original packaging.

Return procedure for 2SB1205T-E:

1.Submit a request within 90 days.

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

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