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

Diodes Incorporated FMMT558TC

Name: FMMT558TC
Brand: Diodes Incorporated
SKU: FMMT558TC
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: FMMT558TC

Manufacturer:: Diodes Incorporated

Category:: Single Bipolar Transistors

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

Datasheet:: FMMT558TC.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:9,685

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Product details

Overview

FMMT558TC from Diodes Incorporated is a 400V PNP high-voltage transistor in SOT23 package, designed for high-breakdown voltage switching and linear amplification in off-line power supplies and industrial controls. It delivers -400V V_CEO, -150mA continuous collector current, 500mW power dissipation, and h_FE up to 300 at -100mA, supporting robust operation in flyback snubber and relay driver circuits.

For engineers reviewing the FMMT558TC datasheet, FMMT558TC pinout, FMMT558TC application, or FMMT558TC equivalent, key selection criteria include verified -400V BV_CEO, SOT23 thermal resistance (R_θJA = 250°C/W), pulse current capability (-500mA I_CM), and complementary pairing with FMMT458 for push-pull topologies.

Technical Context

This PNP bipolar junction transistor operates in active, saturation, and cutoff regions with guaranteed breakdown ratings up to -400V across both collector-base and collector-emitter terminals. Its h_FE remains stable from -1mA to -100mA (100–300), enabling predictable DC gain control in high-side switch drivers.

V_CE(sat) is specified at -200mV (I_C = -20mA, I_B = -2mA) and -500mV (I_C = -50mA, I_B = -6mA), confirming low conduction loss in saturated switching. Transition frequency f_T of 50MHz supports moderate-speed switching up to ~100kHz in SMPS feedback paths.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-400V - Enables direct use in 380V AC rectified bus switching without external clamping
I_C (cont.)	-150mA - Supports medium-power load switching in industrial I/O modules
P_D	500mW - Requires minimal heatsinking on 15mm×15mm FR4 PCB with 1oz copper
h_FE	100–300 - Ensures reliable base drive margin across production lots and temperature range
f_T	50MHz - Allows stable operation in error amplifier compensation networks up to 100kHz
V_CE(sat)	-200mV @ -20mA - Minimizes power loss in high-side gate driving applications
R_θJA	250°C/W - Defines thermal derating slope: max power drops to 300mW at +85°C ambient

Pinout & Package

Package: SOT23 (Type DN), surface-mount plastic package with matte tin-plated leads, UL 94V-0 rated molding compound, and moisture sensitivity level 1 per J-STD-020.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current source terminal	Connected to positive rail in high-side switch configuration; must handle full load current
2 (Base)	Control input	Receives negative bias current to turn on; requires current-limiting resistor for safe drive
3 (Collector)	Output terminal	Switches negative current to ground or low-side load; exposed to full V_CEO stress

Key Features

Feature	Design Value
High voltage blocking	Guaranteed -400V V_CEO and V_CBO enables direct interface with 277V/380V DC bus lines
Robust pulse handling	-500mA I_CM supports short-duration surge currents in relay coil discharge and snubber circuits
Stable DC gain	h_FE ≥100 at -1mA and ≥150 at -100mA ensures consistent switching thresholds across operating range
Green compliance	Halogen- and antimony-free, fully RoHS-compliant construction meets automotive and industrial environmental mandates

Applications

Industrial Relay Drivers

Off-Line Flyback Snubbers

Use Scenario: Driving 24–48VDC industrial relays with inductive kick energy exceeding 100mJ.

IC Role / Device Role / Timing Role: High-side PNP switch absorbing reverse EMF during de-energization.

Use Value: -400V V_CEO withstands transient spikes without clamping diodes; -500mA I_CM handles peak coil current.

Use Scenario: Clamp voltage overshoot across primary winding in 10–50W flyback converters.

IC Role / Device Role / Timing Role: Fast-turn-off PNP clamp transistor triggered by RCD network.

Use Value: 1600ns t_off ensures rapid recovery; -200mV V_CE(sat) minimizes clamp power loss.

High-Voltage Level Shifters

AC Mains-Sensing Circuits

Use Scenario: Translating logic-level signals to control 100–400V loads in programmable logic controllers.

IC Role / Device Role / Timing Role: Inverting level shifter with isolated base drive and emitter-referenced output.

Use Value: -7V V_EBO allows safe base-emitter biasing; SOT23 footprint enables compact isolation barriers.

Use Scenario: Zero-cross detection and voltage monitoring in smart meter front-ends connected to 230V AC mains.

IC Role / Device Role / Timing Role: High-impedance, high-breakdown sensing transistor in resistive divider interface.

Use Value: -100nA I_CES at -320V ensures negligible leakage current; -400V rating provides safety margin over peak line voltage.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ZTX653	V_CEO = -300V, h_FE = 100–250, SOT23 package	Limited to ≤265V DC bus; lower voltage margin in 380V systems	Select when cost sensitivity outweighs need for 400V headroom
MMBT5551	NPN type, V_CEO = -160V, not complementary; different polarity and voltage class	Requires circuit redesign for high-side switching; unsuitable as drop-in replacement	Only consider in new designs where NPN topology is preferred and voltage stress <160V

Compared with ZTX653 and MMBT5551, FMMT558TC provides unique 400V blocking capability in a standard SOT23 footprint, making it the only option among the three qualified for direct use in 380V rectified supply interfaces without additional protection components.

Availability

FMMT558TC is available at Aetrix Electronics and suitable for industrial relay drivers, off-line flyback snubbers, high-voltage level shifters, and AC mains-sensing circuits requiring stable component supply and long-term manufacturability.

Supply support for FMMT558TC 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.

FMMT558TC belongs to Diodes' FMMT series of high-voltage transistors, engineered specifically for ruggedized switching in industrial power conversion, motor control, and mains-connected equipment where reliability under sustained high-voltage stress is critical.

FAQ

What is the maximum allowable collector-emitter voltage for FMMT558TC?

The absolute maximum V_CEO is -400V at T_A = +25°C, verified per DS33101 Rev. 7-2. Derating applies above +25°C: R_θJA = 250°C/W limits usable voltage swing under power dissipation. Operation beyond -400V risks irreversible avalanche failure even with brief pulses.

Can FMMT558TC be used as a direct replacement for FMMT458?

No - FMMT458 is an NPN complement with identical package and voltage rating but opposite polarity. Swapping them without circuit revision causes inversion of control logic and potential latch-up. They are paired in push-pull or complementary symmetry designs, not interchanged.

Is FMMT558TC qualified for automotive applications?

The standard FMMT558TC is not AEC-Q101 qualified. Diodes offers the automotive-grade variant FMMT558Q, which undergoes extended temperature cycling, HTOL, and ESD testing per AEC-Q101. Use FMMT558Q for under-hood or infotainment power stages requiring automotive qualification.

What is the recommended PCB layout for thermal performance?

Mount FMMT558TC on a 15mm × 15mm × 1.6mm FR4 board with ≥1 oz copper on the component side. Use the SOT23 (Type DN) pad layout from Diodes' package outline document: 2.0mm × 0.8mm pads, 1.35mm X1, 2.9mm Y1. Avoid thermal relief on collector pad to maximize heat transfer to copper plane.

FMMT558TC 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):: 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

FMMT558TC FAQ

1.How can I place an order for FMMT558TC through Aetrix?

Please submit a Request for Quotation (RFQ) for FMMT558TC 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 FMMT558TC reliable?

The price and inventory of FMMT558TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT558TC is usually 5 days.

3.What payment methods are accepted for FMMT558TC?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT558TC transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for FMMT558TC?

FMMT558TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your FMMT558TC 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 FMMT558TC?

For technical support, including FMMT558TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT558TC requirements.

6.How does Aetrix verify that FMMT558TC is sourced from the original manufacturer or authorized distributors?

All FMMT558TC 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 FMMT558TC meets industry standards.

7.What is the process for return or replacement of FMMT558TC?

All FMMT558TC units undergo pre-shipment inspection (PSI). If there is an issue with FMMT558TC, 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 FMMT558TC part is unused and in its original packaging.

Return procedure for FMMT558TC:

1.Submit a request within 90 days.

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

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