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

onsemi 2SB1205S-E

Name: 2SB1205S-E
Brand: onsemi
SKU: 2SB1205S-E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SB1205S-E

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2SB1205S-E.pdf

Description:: TRANS PNP 20V 5A TP

Quantity:: RFQ Add To RFQ list

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Inventory:4,724

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Product details

Overview

2SB1205S-E from onsemi is a PNP bipolar junction transistor (BJT) rated for –20 V V_CEO, –5 A I_C, and low –250 mV typical V_CE(sat) at –3 A/–60 mA drive, optimized for high-current switching in flash circuits, relay drivers, and lamp drivers using TP package.

For engineers reviewing the 2SB1205S-E datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CE(sat) ≤ –500 mV max, f_T = 320 MHz, h_FE range (100–400), TO-251 (SC-64) package compatibility, and Pb-free TP bag packaging.

Technical Context

This PNP BJT employs FBET and MBIT processes to achieve low saturation voltage and fast switching (t_on = 40 ns, t_f = 10 ns). It supports DC and pulse operation up to –8 A I_CP, with thermal design enabled by 10 W P_C at T_c = 25°C and 150°C T_j rating.

Its electrical behavior is defined across temperature (–25°C to +75°C) and bias conditions: h_FE varies with I_C (100@500 mA, 60@–4 A), while V_BE(sat) remains –1.0 to –1.3 V at –3 A/–60 mA - critical for base drive sizing in saturated-switch applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	–20 V - maximum safe collector-emitter voltage under open-base condition; defines off-state blocking capability in relay/lamp driver circuits
I_C	–5 A - continuous DC collector current; supports high-power load switching without forced cooling at ambient temperatures
V_CE(sat)	–250 mV (typ), –500 mV (max) at –3 A/–60 mA - enables low conduction loss and minimal heat generation in saturated switch mode
f_T	320 MHz - usable gain-bandwidth for moderate-speed digital switching (e.g., strobe control in flash units)
h_FE	100–400 (rank-dependent) - determines required base drive current; e.g., 60 mA IB suffices for 3 A IC at h_FE ≥ 50
C_ob	60 pF at –10 V V_CB - impacts turn-off speed and high-frequency noise coupling in switching node layout

Pinout & Package

2SB1205S-E uses the TP package (JEDEC TO-251 / JEITA SC-64), a 4-pin single-ended surface-mount variant with exposed collector tabs for thermal relief. Pin 1 = Base, Pin 2 = Collector, Pin 3 = Emitter, Pin 4 = Collector (dual-collector configuration).

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control input requiring ~60 mA drive for full saturation at 3 A; low V_BE(sat) reduces base resistor power dissipation
2 & 4	Collector	Dual-collector terminals electrically connected - used for parallel current paths or enhanced thermal conduction to PCB copper
3	Emitter	Common emitter node; tied to system ground or negative rail in high-side switch configurations

Key Features

Feature	Design Value
Low V_CE(sat)	–250 mV typical at –3 A ensures <150 mW conduction loss, reducing heatsink requirements in compact lamp drivers
Fast switching	t_on/t_f = 40 ns/10 ns enables clean 100 kHz+ PWM control in flash charging circuits without excessive ringing
Dual-collector TP package	Pins 2 and 4 both connect to collector - improves current sharing and thermal spreading over standard TO-251 footprint
High h_FE range	Rank S (100–200) and T (200–400) options allow precise base drive optimization across production lots and temperature ranges

Applications

Flash Circuit Driver	Voltage Regulator Pass Element
Use Scenario: High-current discharge path for camera flash capacitor banks requiring rapid turn-on and low-loss conduction. IC Role / Device Role / Timing Role: Main PNP switching transistor controlling flash tube anode connection to ground during discharge phase. Use Value: Low V_CE(sat) minimizes energy loss in flash pulse; 320 MHz f_T supports clean edge fidelity for sub-100 µs strobe timing.	Use Scenario: Series pass element in linear voltage regulators delivering up to 5 A output current with tight ripple control. IC Role / Device Role / Timing Role: Adjustable current-sinking pass device operating in active region to regulate output voltage via feedback loop. Use Value: High h_FE reduces base drive burden on error amplifier; 10 W P_C at T_c = 25°C supports sustained operation without derating.
Relay Driver	Lamp Driver
Use Scenario: Driving 12 V/24 V electromagnetic relays with coil currents up to 4 A in industrial control panels. IC Role / Device Role / Timing Role: Saturated-switch interface between microcontroller GPIO and relay coil, providing galvanic isolation via optocoupler or direct drive. Use Value: Fast t_f = 10 ns limits relay contact arcing; dual-collector pins improve reliability under repetitive surge stress.	Use Scenario: On/off control of automotive or signage incandescent lamps drawing 3–5 A at 12 V nominal supply. IC Role / Device Role / Timing Role: High-side or low-side switch managing lamp current path, often paired with current-sense resistor for overcurrent protection. Use Value: –20 V V_CEO withstands load-dump transients; –500 mV max V_CE(sat) keeps lamp dimming negligible during full-on state.

Flash Circuit Driver

Voltage Regulator Pass Element

Use Scenario: High-current discharge path for camera flash capacitor banks requiring rapid turn-on and low-loss conduction.

IC Role / Device Role / Timing Role: Main PNP switching transistor controlling flash tube anode connection to ground during discharge phase.

Use Value: Low V_CE(sat) minimizes energy loss in flash pulse; 320 MHz f_T supports clean edge fidelity for sub-100 µs strobe timing.

Use Scenario: Series pass element in linear voltage regulators delivering up to 5 A output current with tight ripple control.

IC Role / Device Role / Timing Role: Adjustable current-sinking pass device operating in active region to regulate output voltage via feedback loop.

Use Value: High h_FE reduces base drive burden on error amplifier; 10 W P_C at T_c = 25°C supports sustained operation without derating.

Relay Driver

Lamp Driver

Use Scenario: Driving 12 V/24 V electromagnetic relays with coil currents up to 4 A in industrial control panels.

IC Role / Device Role / Timing Role: Saturated-switch interface between microcontroller GPIO and relay coil, providing galvanic isolation via optocoupler or direct drive.

Use Value: Fast t_f = 10 ns limits relay contact arcing; dual-collector pins improve reliability under repetitive surge stress.

Use Scenario: On/off control of automotive or signage incandescent lamps drawing 3–5 A at 12 V nominal supply.

IC Role / Device Role / Timing Role: High-side or low-side switch managing lamp current path, often paired with current-sense resistor for overcurrent protection.

Use Value: –20 V V_CEO withstands load-dump transients; –500 mV max V_CE(sat) keeps lamp dimming negligible during full-on state.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SB1197K-TL-E	V_CEO = –25 V, I_C = –3 A, V_CE(sat) = –350 mV (max) at –2 A - higher voltage rating but lower current capacity	Better suited for 24 V systems with lower load current; less margin for 5 A lamp/relay loads	Select when V_CEO > –20 V is mandatory and peak current stays below 3 A
MJD2955RLG	TO-252 (DPAK), V_CEO = –60 V, I_C = –10 A, V_CE(sat) = –1.1 V (max) at –8 A - higher voltage/current but higher saturation loss	Used in higher-voltage industrial motor controls; requires larger PCB area and more base drive power	Choose for 48 V+ systems or where thermal mass allows higher V_CE(sat) penalty

Compared with 2SB1205S-E, 2SB1197K-TL-E trades current headroom for voltage margin, while MJD2955RLG offers greater ruggedness at the cost of efficiency and board space - making 2SB1205S-E optimal for compact 12–20 V, 3–5 A switching where low-loss saturation is critical.

Availability

2SB1205S-E is available at Aetrix Electronics and suitable for flash circuit drivers, relay drivers, and lamp drivers requiring stable component supply, RoHS-compliant packaging, and consistent parametric performance across production batches.

Supply support for 2SB1205S-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 intelligent devices.

The 2SB1205S-E belongs to onsemi's general-purpose bipolar transistor product line, engineered specifically for high-reliability, high-current switching in consumer and industrial power interfaces.

FAQ

What is the package type and lead count for 2SB1205S-E?

The 2SB1205S-E uses the TP package (JEDEC TO-251 / JEITA SC-64), a 4-lead surface-mount outline with dual collector terminals (pins 2 and 4), base (pin 1), and emitter (pin 3). It is supplied in 500 pcs./bag Pb-free packaging per ordering information.

Does 2SB1205S-E support pulse current operation beyond its DC rating?

Yes, the 2SB1205S-E supports I_CP = –8 A under pulsed conditions, as specified in its Absolute Maximum Ratings. This enables short-duration surge handling in relay coil de-energization or flash capacitor discharge, provided duty cycle and thermal management remain within limits defined in the PC–Ta derating curve.

How does the hFE ranking affect 2SB1205S-E performance in circuit design?

The 2SB1205S-E is ranked by h_FE: Rank S = 100–200, Rank T = 200–400. This affects base drive sizing - for example, achieving –3 A I_C requires only ~15 mA I_B in Rank T vs. ~30 mA in Rank S. Designers must select rank based on drive capability and temperature stability requirements.

Can 2SB1205S-E be used in linear regulator applications?

Yes, the 2SB1205S-E is rated for 10 W collector dissipation at T_c = 25°C and operates reliably in the active region. Its h_FE stability and low V_BE(sat) support use as a series pass element in adjustable linear regulators delivering up to 5 A, provided adequate heatsinking and SOA compliance are maintained.

What is the maximum operating junction temperature for 2SB1205S-E?

The 2SB1205S-E has a maximum junction temperature (T_j) rating of 150°C, as stated in its Absolute Maximum Ratings. This allows operation in demanding environments such as under-hood automotive modules or enclosed industrial enclosures, provided PCB thermal design maintains T_j ≤ 150°C under worst-case power dissipation.

2SB1205S-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:: 140 @ 500mA, 2V

Power - Max:: 1 W

Frequency - Transition:: 320MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TP

2SB1205S-E FAQ

1.How can I place an order for 2SB1205S-E through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SB1205S-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 2SB1205S-E reliable?

The price and inventory of 2SB1205S-E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SB1205S-E is usually 5 days.

3.What payment methods are accepted for 2SB1205S-E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SB1205S-E transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SB1205S-E?

2SB1205S-E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SB1205S-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 2SB1205S-E?

For technical support, including 2SB1205S-E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SB1205S-E requirements.

6.How does Aetrix verify that 2SB1205S-E is sourced from the original manufacturer or authorized distributors?

All 2SB1205S-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 2SB1205S-E meets industry standards.

7.What is the process for return or replacement of 2SB1205S-E?

All 2SB1205S-E units undergo pre-shipment inspection (PSI). If there is an issue with 2SB1205S-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 2SB1205S-E part is unused and in its original packaging.

Return procedure for 2SB1205S-E:

1.Submit a request within 90 days.

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

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