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

onsemi NSCT817-40LT3G

Name: NSCT817-40LT3G
Brand: onsemi
SKU: NSCT817-40LT3G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: NSCT817-40LT3G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: NSCT817-40LT3G.pdf

Description:: TRANS NPN 45V 0.1A SOT23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

NSCT817-40LT3G from onsemi is an NPN silicon general-purpose transistor in SOT-23 package, rated for 45 V V_CEO, 500 mA I_C, and 225 mW P_D on FR-5 board, with h_FE = 250–600 at I_C = 100–500 mA, used in low-voltage switching and amplification circuits in consumer power supplies and signal conditioning stages.

For engineers reviewing the NSCT817-40LT3G datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed h_FE range (250–600), V_CE(sat) ≤ 0.7 V at I_C/I_B = 10, f_T = 100 MHz, and Pb-free SOT-23 thermal performance on FR-5 and alumina substrates.

Technical Context

This device operates as a medium-current, medium-voltage NPN bipolar junction transistor optimized for linear amplification and saturated switching. Its h_FE binning (−40 suffix) ensures minimum DC current gain of 250 at 100 mA and up to 600 at 500 mA, with V_CE(sat) tightly specified at ≤0.7 V under 500 mA/50 mA drive.

Thermal design is supported by dual R_JA ratings: 556 °C/W on FR-5 board and 417 °C/W on 0.4" × 0.3" alumina substrate. Junction temperature range spans −55 °C to +150 °C, enabling use in industrial ambient environments without derating below 25 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown; sets upper rail limit in 3.3 V/5 V/12 V switching applications.
I_C (continuous)	500 mA - Continuous collector current handling; supports relay drivers, LED arrays, and small-signal power stages.
h_FE range	250–600 - Guaranteed DC current gain at 100–500 mA; enables predictable base drive sizing in saturation-critical designs.
V_CE(sat)	≤ 0.7 V @ I_C/I_B = 10 - Low saturation voltage minimizes conduction loss and self-heating in switching mode.
f_T	100 MHz - Transition frequency confirms usable bandwidth for audio-frequency amplification and PWM signal buffering.
R_JA (FR-5)	556 °C/W - Thermal resistance defines maximum power dissipation (225 mW at 25 °C) before exceeding T_J(max) = 150 °C.

Pinout & Package

SOT-23 (Case 318, Style 6) surface-mount plastic package with gull-wing leads; 3-pin configuration optimized for high-density PCB layouts and automated assembly. Dimensions: 2.90 mm × 1.30 mm × 1.00 mm (L × W × H), lead pitch 1.90 mm.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal; requires current-limited drive (e.g., 50 mA max for 500 mA I_C) to ensure reliable saturation.
2	Emiter	Reference node for biasing; connected to ground or common return path in low-side switch configurations.
3	Collector	Power output node; handles switched load current up to 500 mA; routed to minimize trace inductance in switching apps.

Key Features

Feature	Design Value
Pb-free construction	Complies with RoHS Directive 2011/65/EU and JEDEC JS709B; eliminates lead-based solder compatibility concerns.
High h_FE bin (−40)	Guarantees minimum h_FE = 250 at I_C = 100 mA, reducing base drive requirements and simplifying driver stage design.
Low V_CE(sat)	≤ 0.7 V at full-rated 500 mA enables <150 mW conduction loss, supporting thermally constrained PCBs.
100 MHz f_T	Supports stable operation up to audio band (20 kHz) with margin; suitable for PWM gate driving and analog signal buffering.

Applications

LED Driver Circuits	Low-Voltage Power Switching
Use Scenario: Driving 20–100 mA indicator LEDs or 350 mA white LED strings from 3.3 V or 5 V microcontroller GPIOs. IC Role / Device Role / Timing Role: NPN low-side switch providing current amplification and fast turn-on/turn-off control. Use Value: V_CE(sat) ≤ 0.7 V ensures >90% efficiency at 500 mA; h_FE ≥ 250 allows direct MCU drive without external buffer.	Use Scenario: Controlling solenoids, relays, or small DC motors (≤500 mA) in battery-powered IoT sensors and smart home actuators. IC Role / Device Role / Timing Role: General-purpose saturated switch interfacing between logic-level controllers and inductive loads. Use Value: 45 V V_CEO headroom accommodates inductive kickback; TO-236 thermal profile supports continuous duty in sealed enclosures.
Audio Signal Amplification	Signal Level Translation
Use Scenario: Pre-amplifying microphone or sensor signals in portable audio recorders and voice-enabled edge devices. IC Role / Device Role / Timing Role: Linear Class-A amplifier stage with fixed bias network and emitter degeneration. Use Value: f_T = 100 MHz provides flat gain response across 20 Hz–20 kHz; h_FE consistency reduces distortion variance across production lots.	Use Scenario: Translating 1.8 V logic outputs to 3.3 V or 5 V compatible levels in mixed-voltage MCU subsystems. IC Role / Device Role / Timing Role: Digital level shifter using common-emitter configuration with pull-up resistor. Use Value: Fast switching (t_on/t_off < 100 ns typical) ensures sub-microsecond propagation delay; low C_obo = 10 pF minimizes capacitive loading on source.

LED Driver Circuits

Low-Voltage Power Switching

Use Scenario: Driving 20–100 mA indicator LEDs or 350 mA white LED strings from 3.3 V or 5 V microcontroller GPIOs.

IC Role / Device Role / Timing Role: NPN low-side switch providing current amplification and fast turn-on/turn-off control.

Use Value: V_CE(sat) ≤ 0.7 V ensures >90% efficiency at 500 mA; h_FE ≥ 250 allows direct MCU drive without external buffer.

Use Scenario: Controlling solenoids, relays, or small DC motors (≤500 mA) in battery-powered IoT sensors and smart home actuators.

IC Role / Device Role / Timing Role: General-purpose saturated switch interfacing between logic-level controllers and inductive loads.

Use Value: 45 V V_CEO headroom accommodates inductive kickback; TO-236 thermal profile supports continuous duty in sealed enclosures.

Audio Signal Amplification

Signal Level Translation

Use Scenario: Pre-amplifying microphone or sensor signals in portable audio recorders and voice-enabled edge devices.

IC Role / Device Role / Timing Role: Linear Class-A amplifier stage with fixed bias network and emitter degeneration.

Use Value: f_T = 100 MHz provides flat gain response across 20 Hz–20 kHz; h_FE consistency reduces distortion variance across production lots.

Use Scenario: Translating 1.8 V logic outputs to 3.3 V or 5 V compatible levels in mixed-voltage MCU subsystems.

IC Role / Device Role / Timing Role: Digital level shifter using common-emitter configuration with pull-up resistor.

Use Value: Fast switching (t_on/t_off < 100 ns typical) ensures sub-microsecond propagation delay; low C_obo = 10 pF minimizes capacitive loading on source.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT4401LT1G	V_CEO = 40 V (5 V lower); h_FE = 100–300 (lower min/max); same SOT-23 package and Pb-free marking.	Marginally lower voltage rating limits use in 36 V automotive or industrial bus interfaces.	Select when cost sensitivity outweighs need for 45 V headroom and higher h_FE consistency.
BC847BW	V_CEO = 45 V (same); h_FE = 200–450 (narrower range); different pinout (1=Emitter, 2=Base, 3=Collector).	Pinout reversal requires PCB layout change; lower h_FE ceiling reduces margin in high-gain feedback loops.	Choose only if existing design uses BC847BW footprint and h_FE tolerance permits.

Compared with MMBT4401LT1G and BC847BW, NSCT817-40LT3G delivers superior h_FE consistency (250–600) and identical 45 V rating, but requires attention to SOT-23 pin 1 = Base orientation-unlike BC847BW's reversed pinout-making it unsuitable for drop-in replacement without layout verification.

Availability

NSCT817-40LT3G is available at Aetrix Electronics and suitable for LED driver circuits, low-voltage power switching, audio signal amplification, and signal level translation requiring stable component supply and RoHS-compliant sourcing.

Supply support for NSCT817-40LT3G 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The NSCT817 series belongs to onsemi's general-purpose bipolar transistor product line, designed specifically for cost-sensitive, high-volume applications requiring consistent h_FE binning, low saturation voltage, and robust thermal performance in compact SOT-23 packages.

FAQ

What is the maximum continuous collector current rating for NSCT817-40LT3G?

The NSCT817-40LT3G is rated for 500 mA continuous collector current (I_C) at T_A = 25 °C on FR-5 board. Derating applies above 25 °C at 1.8 mW/°C, limiting usable current in high-ambient environments unless heatsinking or alumina substrate is used.

Does NSCT817-40LT3G have a guaranteed minimum h_FE value, and at what test conditions?

Yes, NSCT817-40LT3G guarantees h_FE ≥ 250 at I_C = 100 mA and V_CE = 1.0 V, and ≥ 400 at I_C = 500 mA and V_CE = 1.0 V. This binning (−40 suffix) ensures predictable base drive requirements across production lots.

What is the thermal resistance (R_JA) of NSCT817-40LT3G on standard FR-5 PCB?

The NSCT817-40LT3G has a thermal resistance of 556 °C/W when mounted on a standard FR-5 board (1.0 × 0.75 × 0.062 in). This corresponds to a maximum power dissipation of 225 mW at 25 °C ambient, decreasing linearly with rising temperature.

Is NSCT817-40LT3G RoHS-compliant and Pb-free?

Yes, NSCT817-40LT3G is a Pb-free device compliant with RoHS Directive 2011/65/EU. The "G" suffix in the part number explicitly denotes lead-free packaging, and the device meets JEDEC JS709B soldering requirements.

What are the pin assignments for NSCT817-40LT3G in the SOT-23 package?

NSCT817-40LT3G uses Style 6 pinout in SOT-23: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This differs from common alternatives like BC847BW (Pin 1 = Emitter), so PCB layout must match this specific assignment to avoid functional failure.

NSCT817-40LT3G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 700mV @ 50mA, 500mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 250 @ 100mA, 1V

Power - Max:: 225 mW

Frequency - Transition:: 100MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3 (TO-236)

NSCT817-40LT3G FAQ

1.How can I place an order for NSCT817-40LT3G through Aetrix?

Please submit a Request for Quotation (RFQ) for NSCT817-40LT3G 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 NSCT817-40LT3G reliable?

The price and inventory of NSCT817-40LT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NSCT817-40LT3G is usually 5 days.

3.What payment methods are accepted for NSCT817-40LT3G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for NSCT817-40LT3G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for NSCT817-40LT3G?

NSCT817-40LT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your NSCT817-40LT3G 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 NSCT817-40LT3G?

For technical support, including NSCT817-40LT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NSCT817-40LT3G requirements.

6.How does Aetrix verify that NSCT817-40LT3G is sourced from the original manufacturer or authorized distributors?

All NSCT817-40LT3G 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 NSCT817-40LT3G meets industry standards.

7.What is the process for return or replacement of NSCT817-40LT3G?

All NSCT817-40LT3G units undergo pre-shipment inspection (PSI). If there is an issue with NSCT817-40LT3G, 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 NSCT817-40LT3G part is unused and in its original packaging.

Return procedure for NSCT817-40LT3G:

1.Submit a request within 90 days.

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

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