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

Diodes Incorporated FMMT549ATC

Name: FMMT549ATC
Brand: Diodes Incorporated
SKU: FMMT549ATC
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FMMT549ATC

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: FMMT549ATC.pdf

Description:: TRANS PNP 30V 1A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Inventory:2,250

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Product details

Overview

FMMT549ATC from Diodes Incorporated is a 30V PNP silicon planar high-voltage transistor in SOT23 package, rated for -1A continuous collector current, -30V V_CEO, and 500mW power dissipation; used in low-power switching and linear amplification circuits in automotive body control modules and industrial sensor interfaces.

For engineers reviewing the FMMT549ATC datasheet, FMMT549ATC pinout, FMMT549ATC application, or FMMT549ATC equivalent, key selection criteria include verified V_CEO ≥ -30V, h_FE = 150–200 at I_C = -500mA, V_CE(sat) ≤ -300mV, thermal resistance R_θJA = 250°C/W, and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This PNP bipolar junction transistor operates with emitter-grounded configuration, supporting DC and pulse switching up to 100MHz (f_T). Its -35V V_CBO and -5V V_EBO ratings enable robust operation in negative-rail biasing networks and level-shifting stages.

Designed for surface-mount use on FR4 PCBs with minimum copper pad layout, it delivers stable gain (h_FE = 150–500) across I_C = -100mA to -500mA at V_CE = -2V, with switching times t_on = 50ns and t_off = 300ns under defined load conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-30 V - Maximum allowable collector-emitter voltage before breakdown in common-emitter configuration
I_C (cont.)	-1 A - Continuous collector current rating defining safe DC conduction capability
P_D	500 mW - Power dissipation limit on FR4 board with 1 oz copper, determining thermal derating envelope
h_FE	150–200 - DC current gain at I_C = -500mA, V_CE = -2V, enabling predictable base drive sizing
V_CE(sat)	-300 mV - Saturation voltage at I_C = -100mA, I_B = -1mA, defining low-loss switching state
f_T	100 MHz - Transition frequency indicating usable bandwidth for RF or fast-switching applications
R_θJA	250 °C/W - Junction-to-ambient thermal resistance under standard mounting, guiding heatsinking decisions

Pinout & Package

Package: SOT23 - Surface-mount plastic case, UL 94V-0 rated, 0.008g weight, moisture sensitivity level 1 per J-STD-020.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current source terminal	Connected to higher potential rail in PNP switching; sets reference for base bias and current flow direction
2 (Base)	Control input	Receives negative-going drive signal to turn on; requires ~-1mA for full saturation at I_C = -100mA
3 (Collector)	Current sink terminal	Connected to load and lower-potential node; carries full switched current with minimal V_CE(sat) loss

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive applications including engine control units and lighting drivers requiring high-reliability stress testing
Lead-free & halogen-free	Complies with RoHS Directive 2011/65/EU and Diodes Inc.'s "Green" policy, eliminating antimony and brominated flame retardants
V_CEO = -30V	Enables use in 24V automotive systems with margin against transients up to ±30V without clamping
h_FE = 150–200 @ I_C = -500mA	Reduces required base drive current and simplifies driver circuit design in medium-current switching
t_off = 300 ns	Supports PWM frequencies up to ~300 kHz in DC-DC pre-regulators and LED dimming circuits

Applications

Automotive Body Control Module

Industrial Sensor Signal Conditioning

Use Scenario: Driving resistive loads such as door lock actuators and HVAC damper motors in 12V/24V vehicle subsystems.

IC Role / Device Role / Timing Role: PNP switch controlling ground-return path; operates in saturation mode with <300ns turn-off for precise pulse-width control.

Use Value: -30V V_CEO withstands load-dump transients; AEC-Q101 qualification ensures field reliability over 15-year vehicle life.

Use Scenario: Level-shifting and current amplification for analog output stages of pressure and temperature transducers.

IC Role / Device Role / Timing Role: Linear amplifier configured in common-emitter mode with fixed bias network for stable DC gain.

Use Value: h_FE = 150–200 at I_C = -500mA enables accurate 4–20mA loop drive with <1% gain drift over -40°C to +125°C.

Low-Power DC-DC Pre-regulator

LED Current Sink Driver

Use Scenario: Active pre-regulation stage in isolated flyback converters to reduce input ripple before main controller IC.

IC Role / Device Role / Timing Role: High-speed switching transistor operating in hard-switched mode with 50ns t_on and 300ns t_off.

Use Value: f_T = 100MHz supports clean square-wave edge integrity; 500mW rating allows compact layout without external heatsink.

Use Scenario: Constant-current sink for indicator LEDs and status backlighting in medical diagnostic equipment panels.

IC Role / Device Role / Timing Role: Linear current regulator using emitter-follower configuration with precision sense resistor feedback.

Use Value: V_BE(on) = -850 to -1000mV at I_C = -1A ensures stable reference for current-setting op-amp feedback loop.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX653	V_CEO = -30V, I_C = -1A, h_FE = 100–300, but R_θJA = 300°C/W and not AEC-Q101 qualified	Suitable for commercial-grade consumer electronics only; lacks automotive stress validation	Select when cost sensitivity outweighs automotive qualification requirements
MMBT5401	V_CEO = -60V, I_C = -200mA, h_FE = 60–250, lower current rating and higher V_CE(sat) (-400mV @ I_C = -100mA)	Applicable where higher voltage margin is needed but load current remains below 200mA	Choose for designs requiring >-30V breakdown headroom with reduced thermal load

Compared with ZTX653 and MMBT5401, FMMT549ATC uniquely combines AEC-Q101 qualification, -1A current handling, and 250°C/W thermal resistance-making it optimal for space-constrained, thermally demanding automotive and industrial switching nodes where reliability and power density are co-prioritized.

Availability

FMMT549ATC is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor interfaces, low-power DC-DC pre-regulators, and LED current sink drivers requiring stable component supply across production lifecycles.

Supply support for FMMT549ATC 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, headquartered in Plano, Texas, serving automotive, industrial, computing, and consumer markets with high-reliability components.

FMMT549ATC belongs to Diodes' FMMT series of high-voltage bipolar transistors designed specifically for AEC-Q101-compliant automotive switching and amplification functions in compact SOT23 form factor.

FAQ

What is the maximum operating temperature range for FMMT549ATC?

The FMMT549ATC is rated for junction and storage temperatures from -55°C to +150°C. This wide range supports deployment in under-hood automotive environments and industrial enclosures exposed to ambient extremes, provided PCB layout maintains thermal resistance within the 250°C/W specification under actual operating power dissipation.

Is FMMT549ATC pin-compatible with FMMT549TA?

Yes - both FMMT549ATC and FMMT549TA use identical SOT23 package and pinout (Emitter-Base-Collector on pins 1-2-3), with identical electrical specifications except for marking code (59A vs. 549) and minor h_FE binning differences; they are mechanically and electrically interchangeable in existing designs.

Does FMMT549ATC require external protection against ESD or voltage transients?

No dedicated ESD protection diode is integrated; however, its -5V V_EBO and -35V V_CBO provide inherent transient tolerance. For ISO 7637-2 pulse 5a/b compliance in automotive systems, external TVS clamping on base and collector lines is recommended per system-level test requirements.

How does the h_FE variation affect base drive design?

With h_FE ranging from 150 to 200 at I_C = -500mA, base current must be sized for worst-case gain (150) to ensure saturation across process and temperature. For I_C = -500mA, minimum I_B = 3.33mA guarantees V_CE(sat) ≤ -300mV, allowing robust margin against gain degradation at high temperature.

FMMT549ATC 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:: Obsolete

Transistor Type:: PNP

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

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 300mV @ 1mA, 100mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 150 @ 500mA, 2V

Power - Max:: 500 mW

Frequency - Transition:: 100MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

FMMT549ATC FAQ

1.How can I place an order for FMMT549ATC through Aetrix?

Please submit a Request for Quotation (RFQ) for FMMT549ATC 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 FMMT549ATC reliable?

The price and inventory of FMMT549ATC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT549ATC is usually 5 days.

3.What payment methods are accepted for FMMT549ATC?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT549ATC transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FMMT549ATC?

FMMT549ATC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FMMT549ATC 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 FMMT549ATC?

For technical support, including FMMT549ATC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT549ATC requirements.

6.How does Aetrix verify that FMMT549ATC is sourced from the original manufacturer or authorized distributors?

All FMMT549ATC 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 FMMT549ATC meets industry standards.

7.What is the process for return or replacement of FMMT549ATC?

All FMMT549ATC units undergo pre-shipment inspection (PSI). If there is an issue with FMMT549ATC, 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 FMMT549ATC part is unused and in its original packaging.

Return procedure for FMMT549ATC:

1.Submit a request within 90 days.

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

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