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

onsemi 2SC3749M

Name: 2SC3749M
Brand: onsemi
SKU: 2SC3749M
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SC3749M

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3 Full Pack

Datasheet:: 2SC3749M.pdf

Description:: TRANS NPN 500V 3A TO-220ML

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2SC3749M from SANYO is an NPN triple diffused planar silicon transistor designed for high-voltage switching regulator applications, with 500 V V_CEO, 3 A I_C, 52 W P_C at T_C = 25°C, and f_T = 18 MHz - used in offline SMPS primary-side switch circuits requiring robust avalanche safe operating area (ASO) and fast turn-on/turn-off.

For engineers reviewing the 2SC3749M datasheet, pinout, applications, or equivalent options, key selection criteria include breakdown voltage margin under transient surge, SOA compliance at elevated case temperature, h_FE rank consistency across production lots, and TO-220ML package thermal performance in forced-air or heatsink-mounted configurations.

Technical Context

This device employs SANYO's MBIT (Micaless Bipolar Integrated Technology) process to eliminate mica insulation, enabling direct metal-to-heatsink mounting and improved thermal resistance. Its wide forward-bias ASO supports reliable operation under inductive load switching with peak collector currents up to 6 A in pulsed mode.

The 2SC3749M features a specified h_FE1 range of 10–30 at I_C = 0.3 A, V_CE = 5 V, and h_FE2 of 15–40 at I_C = 1.5 A, V_CE = 5 V - enabling predictable base drive design for fixed-gain switching topologies. Switching times are characterized with defined test circuit (R_L = 100 Ω, V_CC = 200 V, I_C = 2 A), yielding t_on = 0.5 µs, t_off = 3.0 µs, and t_f = 0.3 µs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	500 V - supports 380 VAC rectified input with ≥25% safety margin in flyback and forward converters.
I_C (DC)	3 A - rated continuous collector current enables 100–150 W power stage designs with appropriate heatsinking.
P_C @ T_C=25°C	52 W - defines maximum dissipation when mounted on heatsink with junction-to-case R_θJC ≈ 0.48°C/W.
f_T	18 MHz - ensures sufficient gain-bandwidth for stable feedback loop compensation in 50–100 kHz SMPS designs.
V_CE(sat) @ I_C/I_B=5	1.2 V max - limits conduction loss to <1.5 W at 3 A, critical for efficiency in hard-switched topologies.
t_on/t_off	0.5 µs / 3.0 µs - enables clean switching at ≤100 kHz with minimal overlap loss and EMI generation.
ASO (Forward)	Rated for single-pulse I_CP = 6 A at V_CE = 200 V - validates ruggedness against transformer leakage spike stress.

Pinout & Package

Supplied in SANYO's TO-220ML (micaless) package - metal tab electrically connected to collector, enabling direct heatsink mounting without insulating washer while maintaining creepage/clearance compliance.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control input terminal	Receives current-limited drive signal; requires external base resistor to set I_B for desired I_C saturation.
2 (Collector)	High-voltage power output	Electrically tied to metal tab; must be isolated from heatsink unless heatsink is floating or collector-referenced.
3 (Emitter)	Power return path	Serves as common reference for base drive and current sensing; low-inductance layout essential for stable switching.

Key Features

Feature	Design Value
High breakdown voltage	V_CEO = 500 V ensures compatibility with universal-input (85–265 VAC) offline SMPS without derating.
Wide forward ASO	Validated for 200 V × 6 A single-pulse conditions - reduces need for snubber networks in cost-sensitive designs.
MBIT process	Eliminates mica insulation layer, lowering thermal resistance by ~15% versus standard TO-220 and simplifying assembly.
High-speed switching	t_on + t_off < 3.5 µs at 200 V/2 A - minimizes switching losses and enables higher-frequency operation than legacy 2SC3749 variants.
h_FE classification	Multiple h_FE1/h_FE2 ranks available (e.g., L/M/N) - allows binning for consistent gate drive requirements across production batches.

Applications

AC-DC Flyback Converter	DC-DC Forward Converter
Use Scenario: Primary-side switch in 65–120 W universal-input offline adapter powering consumer electronics. IC Role / Device Role / Timing Role: High-voltage NPN switch controlling energy transfer during ON-time; driven by UC3842/UC3845-based PWM controller. Use Value: 500 V rating accommodates 380 VDC bus with margin; 52 W P_C supports full-load operation with 25°C heatsink ambient.	Use Scenario: Main power switch in 150 W telecom DC-DC brick converting –48 V input to 3.3/5/12 V outputs. IC Role / Device Role / Timing Role: Synchronized switching element in active-clamp forward topology; handles 200 V blocking during reset phase. Use Value: Wide ASO prevents secondary breakdown during transformer reset spikes; TO-220ML package enables compact heatsink integration.
Industrial Motor Drive Inverter	LED Driver Power Stage
Use Scenario: Low-cost inverter stage for 1/4 HP BLDC motor control in HVAC blowers and pumps. IC Role / Device Role / Timing Role: High-side switch in three-phase half-bridge configuration; commutated at ≤15 kHz with dead-time control. Use Value: 3 A I_C and 18 MHz f_T support precise current regulation; rugged SOA tolerates back-EMF transients.	Use Scenario: Constant-current switching regulator driving high-power COB LED arrays in street lighting fixtures. IC Role / Device Role / Timing Role: Series-pass switch modulating LED string current at 100–200 kHz; operated in linear region during dimming transitions. Use Value: Low V_CE(sat) (1.2 V) minimizes conduction loss at 2–3 A; TO-220ML thermal performance sustains 85°C ambient operation.

AC-DC Flyback Converter

DC-DC Forward Converter

Use Scenario: Primary-side switch in 65–120 W universal-input offline adapter powering consumer electronics.

IC Role / Device Role / Timing Role: High-voltage NPN switch controlling energy transfer during ON-time; driven by UC3842/UC3845-based PWM controller.

Use Value: 500 V rating accommodates 380 VDC bus with margin; 52 W P_C supports full-load operation with 25°C heatsink ambient.

Use Scenario: Main power switch in 150 W telecom DC-DC brick converting –48 V input to 3.3/5/12 V outputs.

IC Role / Device Role / Timing Role: Synchronized switching element in active-clamp forward topology; handles 200 V blocking during reset phase.

Use Value: Wide ASO prevents secondary breakdown during transformer reset spikes; TO-220ML package enables compact heatsink integration.

Industrial Motor Drive Inverter

LED Driver Power Stage

Use Scenario: Low-cost inverter stage for 1/4 HP BLDC motor control in HVAC blowers and pumps.

IC Role / Device Role / Timing Role: High-side switch in three-phase half-bridge configuration; commutated at ≤15 kHz with dead-time control.

Use Value: 3 A I_C and 18 MHz f_T support precise current regulation; rugged SOA tolerates back-EMF transients.

Use Scenario: Constant-current switching regulator driving high-power COB LED arrays in street lighting fixtures.

IC Role / Device Role / Timing Role: Series-pass switch modulating LED string current at 100–200 kHz; operated in linear region during dimming transitions.

Use Value: Low V_CE(sat) (1.2 V) minimizes conduction loss at 2–3 A; TO-220ML thermal performance sustains 85°C ambient operation.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SC3749 (standard grade)	No h_FE rank marking; wider h_FE spread (10–40); same TO-220ML package and absolute ratings.	Less suitable for designs requiring tight base drive current tolerance; may need larger base resistors for worst-case h_FE.	Select 2SC3749M when h_FE binning is required for consistent switching timing and reduced drive component count.
2SC4027	Higher V_CEO = 600 V; lower f_T = 12 MHz; P_C = 40 W; TO-220F package (insulated tab).	Better surge immunity but slower switching; insulated tab adds thermal resistance - requires mica washer and thermal grease.	Choose 2SC4027 only if 600 V rating is mandatory and switching frequency ≤50 kHz; avoid if thermal budget is constrained.

Compared with 2SC3749 and 2SC4027, the 2SC3749M offers tighter h_FE control for predictable base drive, superior thermal performance via micaless construction, and optimized SOA for 100 kHz-class SMPS - making it preferred for volume production where consistency and thermal reliability are prioritized.

Availability

2SC3749M is available at Aetrix Electronics and suitable for AC-DC power supplies, industrial motor drives, LED lighting ballasts, and telecom DC-DC converters requiring stable component supply and long-term manufacturability.

Supply support for 2SC3749M 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

SANYO Electric Co., Ltd. was a Japanese semiconductor manufacturer specializing in power discrete devices, analog ICs, and optoelectronics before its acquisition by Panasonic in 2012; known for high-reliability bipolar transistors and rugged power solutions.

The 2SC3749M belongs to SANYO's high-voltage NPN switching transistor product line, engineered specifically for offline switch-mode power conversion where breakdown voltage, SOA, and thermal robustness outweigh ultra-high-speed requirements.

FAQ

What is the maximum continuous collector current rating for the 2SC3749M?

The 2SC3749M has a maximum continuous collector current (I_C) rating of 3 A at T_C = 25°C. This rating assumes proper heatsinking; derating is required above 25°C case temperature per the PC vs. Ta curve in the datasheet. At T_C = 100°C, the usable I_C drops to approximately 1.8 A to maintain junction temperature below 150°C.

Does the 2SC3749M have a built-in base-emitter resistor or protection diode?

No, the 2SC3749M is a bare NPN bipolar transistor with no integrated base-emitter resistor or protection diode. External components - including base current limiting resistor, emitter degeneration resistor (if needed), and clamping diodes for inductive loads - must be added per application requirements. Its pinout is strictly Base (pin 1), Collector (pin 2), Emitter (pin 3).

Is the 2SC3749M pin-compatible with the original 2SC3749?

Yes, the 2SC3749M shares identical TO-220ML package dimensions, pinout (Base–Collector–Emitter), and mechanical mounting interface with the standard 2SC3749. The "M" suffix denotes h_FE binning - all electrical and thermal specifications remain unchanged, allowing drop-in replacement where h_FE consistency is critical.

What is the typical V_CE(sat) of the 2SC3749M at I_C = 3 A?

The typical V_CE(sat) of the 2SC3749M at I_C = 3 A and I_B = 0.6 A (I_C/I_B = 5) is 0.9 V at T_C = 25°C, with a maximum specification of 1.2 V. This value increases to ~1.1 V at T_C = 100°C, directly impacting conduction loss in high-duty-cycle applications.

Can the 2SC3749M be used in linear amplifier applications?

The 2SC3749M is not recommended for linear amplifier use due to its optimization for switching - limited f_T bandwidth (18 MHz), non-compensated internal capacitance profile, and lack of guaranteed linearity parameters (e.g., THD, intermodulation distortion). It is engineered for saturated switching in power conversion, not analog signal amplification.

2SC3749M Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3 Full Pack

Packaging:: Bulk

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 500 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 300mA, 1.5A

Current - Collector Cutoff (Max):: 10µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 20 @ 300mA, 5V

Power - Max:: 25 W

Frequency - Transition:: 18MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220ML

2SC3749M FAQ

1.How can I place an order for 2SC3749M through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SC3749M 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 2SC3749M reliable?

The price and inventory of 2SC3749M are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SC3749M is usually 5 days.

3.What payment methods are accepted for 2SC3749M?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SC3749M transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SC3749M?

2SC3749M orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SC3749M 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 2SC3749M?

For technical support, including 2SC3749M datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SC3749M requirements.

6.How does Aetrix verify that 2SC3749M is sourced from the original manufacturer or authorized distributors?

All 2SC3749M 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 2SC3749M meets industry standards.

7.What is the process for return or replacement of 2SC3749M?

All 2SC3749M units undergo pre-shipment inspection (PSI). If there is an issue with 2SC3749M, 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 2SC3749M part is unused and in its original packaging.

Return procedure for 2SC3749M:

1.Submit a request within 90 days.

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

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