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Diodes Incorporated FMMT558QTA
- Part No.:
- FMMT558QTA
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Bipolar Transistors
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
FMMT558QTA.pdf
- Description:
- TRANS PNP 400V 0.15A SOT-23-3
- Quantity:
- Payment:
- Shipping:
Inventory:19,213
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Product details
Overview
FMMT558QTA from Diodes Incorporated is a 400V PNP high-voltage transistor in SOT23 package, designed for off-line switching and high-side switching applications requiring robust voltage blocking. It delivers -150mA continuous collector current, -400V VCEO, and 500mW power dissipation, with hFE up to 300 at -100mA - used in flyback snubber circuits, relay drivers, and industrial power supply hold-up stages.
For engineers reviewing the FMMT558QTA datasheet, FMMT558QTA pinout, FMMT558QTA application, or FMMT558QTA equivalent, key selection criteria include verified -400V breakdown rating, SOT23 thermal performance under pulsed loads, complementary pairing with FMMT458, and automotive-grade variant availability (FMMT558Q).
Technical Context
This PNP bipolar junction transistor operates in linear or saturated switching mode with guaranteed -400V collector-emitter breakdown and -7V emitter-base limit. Its fT of 50MHz supports fast turn-off in high-frequency snubbers, while VCE(sat) ≤ -500mV at -50mA/-6mA ensures low conduction loss in high-side driver configurations.
Thermal design relies on RθJA = 250°C/W (15mm × 15mm FR4, 1oz Cu), and transient capability is defined by SOA curves up to 100μs pulses. The device uses matte tin-plated leads and complies with RoHS 3, halogen-free, and antimony-free "Green" standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | -400V - Enables direct use in 380V DC bus and 230V AC line-referenced circuits without external clamping. |
| IC (cont.) | -150mA - Supports relay coils, small solenoids, and auxiliary power rail switching in compact designs. |
| PD | 500mW - Requires minimal PCB copper area (15mm × 15mm) for thermal management in space-constrained SOT23 layouts. |
| hFE | 100–300 - Ensures reliable base drive margin across -1mA to -100mA operating range for stable saturation control. |
| VCE(sat) | ≤ -500mV @ -50mA/-6mA - Minimizes power loss and self-heating during sustained on-state operation. |
| fT | 50MHz - Allows clean switching in flyback snubbers and resonant gate drivers up to ~5MHz effective frequency. |
| toff | 1600ns - Defines maximum usable switching frequency in hard-switched topologies with controlled fall time. |
Pinout & Package
Package: SOT23 (Type DN), surface-mount, molded green plastic, UL 94V-0 rated, 0.008g weight. Moisture sensitivity level 1 per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | E | High-side reference node; connects to positive rail in common-emitter switch configuration. |
| 2 (Base) | B | Current-controlled input; requires negative bias relative to emitter to turn on. |
| 3 (Collector) | C | Switched output node; sinks current to load when saturated, referenced to ground or lower potential. |
Key Features
| Feature | Design Value |
|---|---|
| High voltage blocking | Guaranteed -400V VCEO enables direct interface with rectified mains without external TVS or Zener clamping. |
| Robust pulse handling | ICM = -500mA peak allows short-duration surge tolerance in inductive load switching and ESD protection paths. |
| Stable gain over current range | hFE ≥ 100 at -1mA and ≥ 15 at -100mA ensures predictable base drive sizing across full load range. |
| Lead-free & green compliance | Fully RoHS 3 compliant, halogen- and antimony-free, meeting automotive and industrial environmental mandates. |
Applications
| Industrial Power Supply Snubber | AC Line Voltage Monitor |
|---|---|
|
Use Scenario: Absorbs leakage inductance energy in flyback transformer secondary during MOSFET turn-off. IC Role / Device Role / Timing Role: PNP switch clamping voltage spike across secondary winding using RC network and transistor conduction path. Use Value: Prevents secondary-side overvoltage exceeding -400V rating while maintaining <1600ns turn-off timing for synchronous recovery. |
Use Scenario: Detects zero-crossing and overvoltage events on 230V AC mains via resistive divider and comparator interface. IC Role / Device Role / Timing Role: High-voltage level shifter translating AC-derived logic signals to isolated microcontroller inputs. Use Value: Leverages -400V VCEO to withstand transients >1.5kVpk without additional protection components. |
| Relay Driver Circuit | Hold-Up Capacitor Discharge Switch |
|
Use Scenario: Drives 12V/24V relay coil in programmable logic controller (PLC) output modules. IC Role / Device Role / Timing Role: High-side PNP switch sourcing current to relay coil anode, controlled by microcontroller GPIO. Use Value: Delivers -150mA continuous current with VCE(sat) ≤ -500mV, minimizing heat rise in sealed enclosure environments. |
Use Scenario: Safely discharges bulk capacitor after system shutdown in medical power supplies. IC Role / Device Role / Timing Role: Controlled bleed switch activated only during fault or standby, preventing uncontrolled discharge. Use Value: Uses -400V rating to tolerate residual DC bus voltage up to 375V, ensuring safe discharge without arcing or failure. |
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 | VCEO = -300V, IC = -1A, SOT89 package | Higher current but lower voltage rating; requires larger footprint and heatsinking | Select when >-150mA load current is needed and -300V suffices; not suitable for 380V DC bus. |
| FMMT558Q | Automotive-grade AEC-Q101 qualified, identical electrical specs, same SOT23 package | Validated for automotive temperature cycling (-40°C to +150°C) and humidity testing | Choose for automotive body electronics or industrial systems requiring extended reliability validation. |
Compared with ZTX653 and FMMT558Q, the FMMT558QTA provides optimal balance of -400V rating, SOT23 compactness, and industrial-grade reliability - making it preferred for space-constrained off-line power interfaces where voltage margin is critical and automotive qualification is unnecessary.
Availability
FMMT558QTA is available at Aetrix Electronics and suitable for industrial power supply snubbers, AC line monitoring circuits, relay driver modules, and hold-up capacitor discharge switches requiring stable component supply and consistent SOT23 assembly compatibility.
Supply support for FMMT558QTA 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.
The FMMT series targets high-voltage, high-reliability discrete switching applications in industrial, computing, and consumer power systems - emphasizing ruggedness, thermal efficiency, and regulatory compliance in miniature packages.
FAQ
What is the maximum safe operating voltage for FMMT558QTA in continuous DC conditions?
The absolute maximum collector-emitter voltage (VCEO) is -400V at TA = +25°C. Derating applies above 25°C: RθJA = 250°C/W limits junction temperature rise, so continuous DC operation above -320V requires active cooling or reduced ambient temperature to maintain TJ ≤ +150°C.
Can FMMT558QTA replace FMMT558 in existing designs?
Yes - FMMT558QTA is the tape-and-reel packaged version of FMMT558 with identical electrical specifications, SOT23 (Type DN) mechanical outline, and marking code "558". The "QTA" suffix denotes 3000-unit reel packaging; no circuit or layout changes are required for drop-in replacement.
How does FMMT558QTA's hFE behave at high collector currents?
hFE is specified as minimum 15 at -100mA and -10V VCE. At -150mA, hFE drops further but remains sufficient for forced beta ≥ 10 with appropriate base drive. Figure 7 in DS33101 shows hFE degrades gradually beyond -100mA, supporting predictable saturation design up to rated IC.
Is FMMT558QTA suitable for automotive applications?
The standard FMMT558QTA is not AEC-Q101 qualified. For automotive use, Diodes offers the FMMT558Q variant - identical electrically and mechanically but subjected to extended temperature cycling, humidity testing, and failure analysis per AEC-Q101. Use FMMT558Q for under-hood or infotainment power modules.
FMMT558QTA 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
FMMT558QTA FAQ
1.How can I place an order for FMMT558QTA through Aetrix?
Please submit a Request for Quotation (RFQ) for FMMT558QTA 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 FMMT558QTA reliable?
The price and inventory of FMMT558QTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FMMT558QTA is usually 5 days.
3.What payment methods are accepted for FMMT558QTA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FMMT558QTA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FMMT558QTA?
FMMT558QTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FMMT558QTA 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 FMMT558QTA?
For technical support, including FMMT558QTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FMMT558QTA requirements.
6.How does Aetrix verify that FMMT558QTA is sourced from the original manufacturer or authorized distributors?
All FMMT558QTA 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 FMMT558QTA meets industry standards.
7.What is the process for return or replacement of FMMT558QTA?
All FMMT558QTA units undergo pre-shipment inspection (PSI). If there is an issue with FMMT558QTA, 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 FMMT558QTA part is unused and in its original packaging.
Return procedure for FMMT558QTA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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