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

Diodes Incorporated FMMT491TC

Name: FMMT491TC
Brand: Diodes Incorporated
SKU: FMMT491TC
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FMMT491TC

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: FMMT491TC.pdf

Description:: TRANS NPN 60V 1A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Inventory:7,245

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Product details

Overview

FMMT491TC from Diodes Incorporated is a 60V NPN medium-power transistor in SOT23 package, rated for 1A continuous collector current, 2A peak pulse current, and 500mW power dissipation, with V_CE(sat) as low as 100mV at I_C = 500mA/I_B = 50mA; used in automotive load switching, industrial relay drivers, and DC-DC converter bias circuits.

For engineers reviewing the FMMT491TC datasheet, FMMT491TC pinout, FMMT491TC application, or FMMT491TC equivalent, key selection criteria include guaranteed V_CEO ≥ 60V, h_FE ≥ 100 at 1A, R_θJA = 250°C/W on standard PCB layout, and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This NPN bipolar junction transistor operates in linear or saturated switching mode with verified breakdown ratings: V_CBO = 80V, V_CEO = 60V, and V_EBO = 7V. Its h_FE is characterized across 1mA–2A, delivering 120 min at 1A/5V, supporting stable current amplification in high-current drive stages.

Thermal performance is defined for a 15mm × 15mm 1oz copper pad on FR4: R_θJA = 250°C/W and R_θJL = 197°C/W. ESD robustness meets JEDEC Class 3A HBM (4kV) and MM (400V), enabling use in board-level environments with moderate electrostatic risk.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - Ensures safe operation in 48V automotive and industrial supply rails with margin.
I_C (continuous)	1 A - Supports direct driving of small solenoids, LED strings, or logic-level MOSFET gates.
V_CE(sat) @ 1A	160 mV max - Limits conduction loss to ≤160mW at full load, reducing thermal stress.
h_FE @ 1A	80–120 - Provides predictable base drive requirement (I_B ≈ 8–12.5mA) for reliable saturation.
P_D	500 mW - Requires minimal PCB copper area (15×15 mm 1oz) to maintain T_J < 150°C.
f_T	150 MHz - Enables use in low-frequency switching (≤1 MHz) and analog amplification up to ~50 MHz.
ESD HBM	4 kV - Meets IEC 61000-4-2 Level 3 for handling without special ESD controls.

Pinout & Package

SOT23 plastic surface-mount package with matte tin-plated leads, moisture sensitivity level 1, UL 94V-0 flammability rating, and 0.008g mass. Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector (top view, marking "491" adjacent to Pin 1).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (E)	Emitter	Reference terminal for bias network; connects to ground or low-side return path.
Pin 2 (B)	Base	Current-controlled input; requires series resistor to limit I_B ≤ 200mA per abs max.
Pin 3 (C)	Collector	High-side switched output; ties to load anode or V_CC-side node in common-emitter configuration.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive underhood applications including temperature cycling, humidity, and mechanical shock.
Low V_CE(sat)	100–250 mV range ensures <1% voltage drop across transistor at rated current, preserving system efficiency.
High h_FE hold-up	h_FE ≥ 30 maintained at I_C = 2A, enabling robust overcurrent capability without gain collapse.
Green compound	Halogen- and antimony-free molding compound (<900 ppm Br/Cl, <1000 ppm Sb) compliant with global environmental directives.
Thermal derating curve	Linear power reduction from 500mW at 25°C to zero at 150°C ambient, enabling precise thermal design.

Applications

Automotive Interior Lighting Control

Industrial PLC Output Stage

Use Scenario: Switching 12V/24V LED arrays in dashboard backlighting and cabin lighting modules.

IC Role / Device Role / Timing Role: NPN switch controlling current path between supply rail and LED cathode.

Use Value: Low V_CE(sat) minimizes heat generation in confined enclosures; AEC-Q101 ensures 15-year field reliability.

Use Scenario: Driving 24V DC solenoid valves and indicator lamps in programmable logic controller output cards.

IC Role / Device Role / Timing Role: Medium-power interface transistor translating 3.3V/5V logic signals to 24V load control.

Use Value: 60V V_CEO withstands inductive kickback; h_FE stability supports consistent turn-on across temperature.

DC-DC Converter Bias Circuit

Smart Sensor Signal Conditioning

Use Scenario: Providing base drive to primary-side power transistors in isolated flyback or forward converters.

IC Role / Device Role / Timing Role: High-gain current amplifier supplying controlled I_B to main switching device.

Use Value: h_FE ≥ 100 at 1A enables precise current mirroring; f_T > 150MHz supports fast transient response.

Use Scenario: Amplifying low-level analog outputs (e.g., thermistor, bridge sensor) before ADC sampling.

IC Role / Device Role / Timing Role: Linear-mode NPN amplifier in common-emitter configuration with emitter degeneration.

Use Value: Tight h_FE distribution (100–150 typ at 500mA) improves gain consistency; low noise supports µV-level signal integrity.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZXTN25040DFH	V_CEO = 40V (lower), I_C = 2A, SOT23-3, h_FE = 200 min @ 1A	Not suitable for 48V systems; better for 24V logic-level switching where higher gain is critical.	Select when gain >200 and 40V rating suffices; avoid where 60V margin is required.
MMBT4401	V_CEO = 40V, I_C = 600mA, SOT23, h_FE = 100 min @ 150mA	Limited current and voltage headroom; not AEC-Q101 qualified.	Use only in non-automotive, low-power consumer designs where cost is prioritized over reliability.

Compared with ZXTN25040DFH and MMBT4401, FMMT491TC uniquely delivers 60V rating, AEC-Q101 qualification, and validated h_FE ≥80 at 1A-making it the only choice for automotive 48V subsystems requiring both voltage margin and production-grade reliability.

Availability

FMMT491TC is available at Aetrix Electronics and suitable for automotive interior lighting control, industrial PLC output stages, and DC-DC converter bias circuits requiring stable component supply across multi-year production cycles.

Supply support for FMMT491TC 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

Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal devices, with operations spanning design, manufacturing, and distribution across Asia, Europe, and the Americas.

The FMMT series targets medium-power switching and amplification in space-constrained, high-reliability applications-designed specifically for automotive, industrial control, and power management systems demanding AEC-Q101 compliance and robust thermal behavior.

FAQ

What is the maximum allowable base current for continuous operation?

The absolute maximum base current is 200mA per datasheet Absolute Maximum Ratings. For reliable continuous operation, base current should be limited to ≤100mA to ensure thermal stability and prevent bond-wire degradation under sustained duty cycles. Derating is recommended above +70°C ambient.

Does FMMT491TC support pulsed operation beyond its 1A continuous rating?

Yes-ICM is specified at 2A for peak pulse current with pulse width ≤300µs and duty cycle ≤2%. This enables short-duration surge handling in motor startup or inductive load switching, provided average power remains within 500mW limits and PCB thermal design accommodates transient heating.

How does the SOT23 package affect thermal performance in real-world layouts?

R_θJA = 250°C/W is measured on a 15mm × 15mm 1oz copper pad. Reducing pad size or using thinner copper increases thermal resistance significantly-e.g., 5mm × 5mm pad raises R_θJA to ~400°C/W. Via stitching under the collector pad lowers R_θJA by up to 30% in multilayer boards.

Is there a complementary PNP part available for push-pull configurations?

Yes-the FMMT591 is the designated complementary PNP transistor, sharing identical SOT23 packaging, AEC-Q101 qualification, and matched voltage/current ratings (V_CEO = 60V, I_C = 1A). Its h_FE and V_CE(sat) characteristics are balanced to enable symmetrical push-pull stage design.

FMMT491TC Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 250mV @ 100mA, 1A

Current - Collector Cutoff (Max):: 100nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 500mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 150MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

FMMT491TC FAQ

1.How can I place an order for FMMT491TC through Aetrix?

Please submit a Request for Quotation (RFQ) for FMMT491TC 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 FMMT491TC reliable?

The price and inventory of FMMT491TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT491TC is usually 5 days.

3.What payment methods are accepted for FMMT491TC?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT491TC transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FMMT491TC?

FMMT491TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FMMT491TC 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 FMMT491TC?

For technical support, including FMMT491TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT491TC requirements.

6.How does Aetrix verify that FMMT491TC is sourced from the original manufacturer or authorized distributors?

All FMMT491TC 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 FMMT491TC meets industry standards.

7.What is the process for return or replacement of FMMT491TC?

All FMMT491TC units undergo pre-shipment inspection (PSI). If there is an issue with FMMT491TC, 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 FMMT491TC part is unused and in its original packaging.

Return procedure for FMMT491TC:

1.Submit a request within 90 days.

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

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