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

Diodes Incorporated FMMT558TA

Name: FMMT558TA
Brand: Diodes Incorporated
SKU: FMMT558TA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FMMT558TA

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: FMMT558TA.pdf

Description:: TRANS PNP 400V 0.15A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Inventory:213,313

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Product details

Overview

FMMT558TA from Diodes Incorporated is a 400V PNP high-voltage transistor in SOT23 package, designed for switching and amplification in high-breakdown-voltage applications. It delivers -400V collector-emitter breakdown voltage (BV_CEO), -150mA continuous collector current (I_C), and 500mW power dissipation, with h_FE up to 300 at -100mA. It is used in flyback converters, relay drivers, and industrial HV bias circuits.

For engineers reviewing the FMMT558TA datasheet, FMMT558TA pinout, FMMT558TA application, or FMMT558TA equivalent, key selection criteria include verified -400V BV_CEO, SOT23 thermal resistance (R_θJA = 250°C/W), V_CE(sat) ≤ -500mV at -50mA/-6mA, complementary pairing with FMMT458, and automotive-grade variant availability (FMMT558Q).

Technical Context

This PNP bipolar junction transistor operates with emitter-grounded configuration and supports high-voltage blocking in off-state while maintaining low saturation voltage under controlled base drive. Its safe operating area (SOA) is defined up to -400V and -500mA peak pulse, with transient thermal impedance validated for 100µs–1s pulses on 15mm×15mm FR4 PCB.

Electrical behavior is characterized by pulsed measurement conditions (≤300µs width, ≤2% duty cycle) for parameters including h_FE, V_CE(sat), and f_T = 50MHz. Base-emitter turn-on voltage is -0.9V at -50mA, supporting predictable digital and analog switching thresholds in discrete control stages.

Key Specifications

Parameter	Value and Actual Design Meaning
BV_CEO	-400V - Ensures reliable blocking in 380V AC line-derived DC rails and flyback primary-side snubbers
I_C (continuous)	-150mA - Supports medium-power switching loads such as solenoid drivers and HV LED strings
V_CE(sat)	-500mV @ -50mA/-6mA - Limits conduction loss to <25mW at rated current, easing thermal design
h_FE	300 @ -100mA/-10V - Enables low-base-drive designs with single-stage logic-level interfacing
f_T	50MHz - Supports switching above 1MHz in resonant converters and fast HV gate drivers
P_D	500mW - Requires minimal copper area (15mm×15mm 1oz FR4) for full-rated operation
R_θJA	250°C/W - Predictable junction temperature rise of 125°C at full power in still air

Pinout & Package

Package: SOT23 (Type DN), surface-mount, green molding compound (UL 94V-0), 0.008g weight, moisture sensitivity level 1.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current source terminal	Connected to higher potential rail; defines reference for base control and current flow direction
2 (Base)	Control input	Receives negative current to forward-bias BE junction; requires current-limiting resistor in series
3 (Collector)	Current sink terminal	Connected to load and return path; withstands -400V when open or reverse-biased

Key Features

Feature	Design Value
High voltage blocking	BV_CEO = -400V enables direct interface with 277V AC lighting systems and industrial 400V DC buses
Robust pulse handling	I_CM = -500mA supports short-duration surge currents in relay coil demagnetization and snubber recovery
Thermal reliability	R_θJL = 197°C/W to solder point ensures stable operation under intermittent high-power pulses
Lead-free compliance	Fully RoHS 3 compliant with <900ppm Br/Cl and <1000ppm Sb - qualified for automotive and medical end equipment

Applications

Industrial Relay Drivers

AC-DC Flyback Controllers

Use Scenario: Driving 24–48V DC coils in programmable logic controller (PLC) output modules with 300V+ isolation requirements.

IC Role / Device Role / Timing Role: PNP switch controlling coil current path; emitter tied to +24V rail, collector to coil return, base driven by microcontroller GPIO via current-limiting resistor.

Use Value: -400V BV_CEO prevents breakdown during inductive kickback spikes exceeding -300V, eliminating need for external clamping diodes.

Use Scenario: Primary-side voltage sensing and feedback switching in isolated 12V/1A offline flyback power supplies.

IC Role / Device Role / Timing Role: Discrete BJT in optocoupler-coupled feedback loop; switches TL431 reference signal to regulate output voltage.

Use Value: 50MHz f_T and low V_CE(sat) ensure fast response to output transients without phase lag in regulation loop.

High-Voltage LED Biasing

Automotive HVAC Blower Control

Use Scenario: Constant-current biasing of 100V-rated LED strings in architectural lighting fixtures powered from 375V DC bus.

IC Role / Device Role / Timing Role: Linear current regulator with emitter-follower configuration; collector connected to LED string cathode, emitter to current-sense resistor.

Use Value: h_FE ≥ 100 at -100mA allows precise current setting with <1% error using standard 1% sense resistors.

Use Scenario: Low-side PWM switching of 12V blower motor in automotive cabin climate control systems.

IC Role / Device Role / Timing Role: High-voltage PNP pre-driver stage controlling N-channel MOSFET gate; handles reverse battery and load-dump transients.

Use Value: Complementary pairing with FMMT458 enables matched push-pull gate drive with symmetric rise/fall times under 2µs.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX653	BV_CEO = -300V, I_C = -1A, SOT89 package, R_θJA = 125°C/W	Higher current but lower voltage rating; requires larger board area and heatsinking	Select when >300mA continuous current is needed and voltage stress remains <300V
MMBT5551	NPN polarity, BV_CEO = -160V, SOT23, I_C = -200mA	Not complementary; unsuitable for same circuit topology without redesign	Use only in NPN-configured circuits where -160V blocking suffices and layout permits polarity reversal

Compared with ZTX653 and MMBT5551, FMMT558TA uniquely balances -400V blocking, SOT23 footprint, and -150mA capability-making it optimal for space-constrained, high-isolation industrial controls where voltage margin is non-negotiable.

Availability

FMMT558TA is available at Aetrix Electronics and suitable for industrial relay drivers, AC-DC flyback controllers, and high-voltage LED biasing requiring stable component supply across extended production cycles.

Supply support for FMMT558TA 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, with design and manufacturing operations across Asia and the Americas.

FMMT558TA belongs to Diodes' FMMT series of high-voltage SOT23 transistors, engineered specifically for industrial and automotive power-switching applications demanding robustness, small footprint, and guaranteed parametric performance at elevated voltages.

FAQ

What is the maximum allowable base current for continuous operation?

The absolute maximum rating specifies I_B = -200mA, but continuous operation at this level exceeds thermal limits. For sustained use, base current must be limited to maintain junction temperature below +150°C. At ambient +70°C and 15mm×15mm 1oz copper, recommended I_B ≤ -10mA ensures safe operation with adequate margin.

Does FMMT558TA support automotive qualification?

Yes-the automotive-compliant variant is FMMT558Q, qualified to AEC-Q101 with enhanced testing for temperature cycling, humidity, and mechanical shock. FMMT558TA itself is not AEC-Q101 certified but shares identical die and package construction; only test documentation differs.

Can FMMT558TA replace FMMT557 in existing designs?

No-FMMT557 has BV_CEO = -250V and h_FE = 60–120, making it unsuitable for -400V applications. Substituting FMMT558TA may cause overdesign in low-voltage circuits due to higher V_BE(on) and reduced gain linearity below -10mA, risking unintended turn-on or oscillation.

What is the typical transition frequency at low collector current?

f_T = 50MHz is specified at I_C = -10mA, V_CE = -20V. At I_C = -1mA, f_T drops to approximately 15MHz due to reduced transconductance; this is confirmed in Figure 5 of the datasheet and impacts high-frequency amplifier bandwidth in low-current biasing.

FMMT558TA 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:: PNP

Current - Collector (Ic) (Max):: 150 mA

Voltage - Collector Emitter Breakdown (Max):: 400 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 6mA, 50mA

Current - Collector Cutoff (Max):: 100nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 50mA, 10V

Power - Max:: 500 mW

Frequency - Transition:: 50MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

FMMT558TA FAQ

1.How can I place an order for FMMT558TA through Aetrix?

Please submit a Request for Quotation (RFQ) for FMMT558TA 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 FMMT558TA reliable?

The price and inventory of FMMT558TA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT558TA is usually 5 days.

3.What payment methods are accepted for FMMT558TA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT558TA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FMMT558TA?

FMMT558TA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FMMT558TA 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 FMMT558TA?

For technical support, including FMMT558TA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT558TA requirements.

6.How does Aetrix verify that FMMT558TA is sourced from the original manufacturer or authorized distributors?

All FMMT558TA 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 FMMT558TA meets industry standards.

7.What is the process for return or replacement of FMMT558TA?

All FMMT558TA units undergo pre-shipment inspection (PSI). If there is an issue with FMMT558TA, 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 FMMT558TA part is unused and in its original packaging.

Return procedure for FMMT558TA:

1.Submit a request within 90 days.

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

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