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

Diodes Incorporated FMMT634TA

Name: FMMT634TA
Brand: Diodes Incorporated
SKU: FMMT634TA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FMMT634TA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: FMMT634TA.pdf

Description:: TRANS NPN DARL 100V 0.9A SOT23-3

Quantity:: RFQ Add To RFQ list

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Inventory:47,610

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Product details

Overview

FMMT634TA from Diodes Incorporated is a 100V NPN Darlington transistor in SOT23 package, delivering 900mA continuous collector current, 5A peak pulse current, and >5k hFE at 2A for high-gain switching. It serves as a high-voltage interface driver in relay, solenoid, and lamp control circuits where low-base-drive requirements and robust voltage blocking are essential.

For engineers reviewing the FMMT634TA datasheet, FMMT634TA pinout, FMMT634TA application, or FMMT634TA equivalent, key selection criteria include V_CEO = 100V, I_C = 900mA, hFE ≥ 5k at 2A, V_CE(sat) ≤ 0.85V at 900mA/5mA drive, and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

The FMMT634TA integrates two cascaded NPN transistors in a monolithic Darlington configuration to achieve high DC current gain while maintaining 100V V_CEO rating. Its base-emitter turn-on voltage is 1.33–1.50V at 1A, and saturation is optimized with V_CE(sat) ≤ 0.75V at IC = 500mA/IB = 5mA.

Thermal performance is defined for SOT23 mounting on 25mm × 25mm 1oz copper (R_θJA = 155°C/W at t ≤ 5s), supporting pulsed operation up to 1W transient power. ESD ratings meet 2kV HBM and 200V MM per JEDEC JESD22-A114/A115.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	100 V - Enables direct switching of 24–48V industrial loads without external snubbing.
I_C (continuous)	900 mA - Supports sustained relay coil or small solenoid actuation without thermal derating at 25°C.
hFE	≥5k at IC = 2A - Reduces required base drive current to ≤400µA for full conduction, easing MCU GPIO sourcing.
V_CE(sat)	0.75 V max at IC = 500mA/IB = 5mA - Limits conduction loss to <375mW, minimizing self-heating in compact layouts.
Power dissipation (P_D)	625 mW (steady-state) - Matches thermal limits of standard SOT23 PCB land patterns with 1oz copper.
ESD HBM	2000 V - Provides robust handling during automated assembly and board-level integration.

Pinout & Package

Package: SOT23 - Surface-mount plastic case, 0.008g weight, UL 94V-0 rated, moisture sensitivity level 1, matte tin-plated leads solderable per MIL-STD-202 Method 208.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink output node	Connected to load return path; requires low-impedance ground reference for stable saturation.
2 (Base)	Control input terminal	Accepts TTL/CMOS-compatible drive; 5mA IB ensures full saturation at 900mA IC.
3 (Collector)	High-side switch node	Interfaces directly with 100V-rated loads; exposed pad (if present) must be tied to collector for thermal relief.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive under-hood applications including temperature cycling, humidity bias, and mechanical shock.
Lead-free & Halogen-free	Meets RoHS 2 (2011/65/EU) and "Green" definition: Br+Cl <1500ppm, Sb <1000ppm.
High BV_CBO	120V min - Prevents premature breakdown during inductive flyback transients in relay/solenoid switching.
f_T = 140MHz	Supports fast turn-on (290ns) and controlled switching in PWM-driven loads up to ~10kHz.

Applications

Lamp Driving

Relay Control

Use Scenario: Switching 12–48V incandescent or LED indicator lamps in automotive dashboards and industrial HMIs.

IC Role / Device Role / Timing Role: High-gain NPN Darlington switch providing low-base-current on/off control with minimal MCU resource usage.

Use Value: Eliminates need for external base resistors or driver stages; V_CE(sat) ≤ 0.75V ensures >95% lamp voltage delivery at full brightness.

Use Scenario: Driving 24V/1A electromagnetic relays in PLC I/O modules and motor starter panels.

IC Role / Device Role / Timing Role: Load-switching transistor handling inductive kickback with built-in V_CEO = 100V margin.

Use Value: Withstands 100V flyback spikes without clamping diode; hFE ≥ 5k allows direct microcontroller GPIO drive.

Solenoid Actuation

Industrial Sensor Interface

Use Scenario: Energizing 24V/500mA pneumatic solenoid valves in factory automation and HVAC control systems.

IC Role / Device Role / Timing Role: High-current gain switch enabling rapid valve response with minimal base drive overhead.

Use Value: 5A I_CM supports 10ms startup surges; thermal R_θJA = 155°C/W sustains repeated duty cycles without heatsinking.

Use Scenario: Level-shifting and isolating digital outputs from 3.3V/5V MCUs to 24V field sensors in industrial IO-Link nodes.

IC Role / Device Role / Timing Role: Voltage-tolerant interface buffer translating logic signals to higher-voltage load domains.

Use Value: 100V V_CEO prevents latch-up during sensor cable ESD events; AEC-Q101 grade ensures long-term field reliability.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN Darlington transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZXTN07012F	V_CEO = 100V, I_C = 1A, hFE = 200–1000 (standard gain), no AEC-Q101 rating	Lower gain requires higher base drive; suitable for non-automotive cost-sensitive designs	Select when gain >5k is unnecessary and automotive qualification is not required.
FMMT618TA	V_CEO = 80V, I_C = 1A, hFE = 100–800, same SOT23 package and AEC-Q101 qualification	Lower voltage rating limits use to ≤48V systems; higher I_C but lower gain than FMMT634TA	Choose for 48V nominal systems where reduced voltage margin is acceptable and higher continuous current is prioritized.

Compared with ZXTN07012F and FMMT618TA, the FMMT634TA uniquely combines AEC-Q101 qualification, 100V blocking, and ≥5k hFE-making it optimal for automotive and industrial high-gain, high-voltage switching where base drive efficiency and reliability are critical.

Availability

FMMT634TA is available at Aetrix Electronics and suitable for lamp driving, relay control, solenoid actuation, and industrial sensor interface applications requiring stable component supply across automotive, factory automation, and building management systems.

Supply support for FMMT634TA 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for automotive, industrial, and computing markets.

The FMMT634TA belongs to Diodes' AEC-Q101-qualified discrete transistor product line, engineered specifically for high-voltage, high-gain switching in harsh-environment control applications.

FAQ

What is the maximum safe operating voltage for FMMT634TA in continuous DC applications?

The FMMT634TA is rated for 100V collector-emitter voltage (V_CEO) under DC conditions at 25°C ambient. For reliable long-term operation, design margins should limit steady-state V_CE to ≤80V in environments exceeding 85°C or where inductive transients may occur. Derating curves in the datasheet confirm 60V max at 125°C junction temperature.

Can FMMT634TA replace a standard single NPN transistor in existing designs?

Yes, but only if the circuit accounts for its Darlington-specific characteristics: higher V_BE(on) (~1.33–1.50V), slower turn-off time (2400ns), and higher saturation voltage at low currents. It is not a drop-in replacement for general-purpose NPNs like BC817, but excels where high hFE and 100V blocking are mandatory.

Does FMMT634TA require an external flyback diode when driving inductive loads?

No external diode is strictly required due to its 100V V_CEO rating, which exceeds typical 24–48V relay/solenoid flyback spikes. However, a 1N4007 or similar diode is recommended for long-term reliability in high-cycle or high-energy applications to reduce junction stress and extend lifetime beyond 100k operations.

How does the AEC-Q101 qualification impact FMMT634TA's use in non-automotive applications?

AEC-Q101 qualification ensures enhanced robustness against thermal cycling, mechanical shock, and humidity exposure-benefiting any mission-critical industrial application. While not mandatory outside automotive, it provides measurable reliability advantages in factory automation, energy infrastructure, and outdoor equipment where extended service life and field failure avoidance are priorities.

FMMT634TA 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 - Darlington

Current - Collector (Ic) (Max):: 900 mA

Voltage - Collector Emitter Breakdown (Max):: 100 V

Vce Saturation (Max) @ Ib, Ic:: 960mV @ 5mA, 1A

Current - Collector Cutoff (Max):: 100nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 20000 @ 100mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: 140MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

FMMT634TA FAQ

1.How can I place an order for FMMT634TA through Aetrix?

Please submit a Request for Quotation (RFQ) for FMMT634TA 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 FMMT634TA reliable?

The price and inventory of FMMT634TA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT634TA is usually 5 days.

3.What payment methods are accepted for FMMT634TA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT634TA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FMMT634TA?

FMMT634TA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FMMT634TA 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 FMMT634TA?

For technical support, including FMMT634TA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT634TA requirements.

6.How does Aetrix verify that FMMT634TA is sourced from the original manufacturer or authorized distributors?

All FMMT634TA 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 FMMT634TA meets industry standards.

7.What is the process for return or replacement of FMMT634TA?

All FMMT634TA units undergo pre-shipment inspection (PSI). If there is an issue with FMMT634TA, 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 FMMT634TA part is unused and in its original packaging.

Return procedure for FMMT634TA:

1.Submit a request within 90 days.

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

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