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Diodes Incorporated FZT857QTA
- Part No.:
- FZT857QTA
- Manufacturer:
- Diodes Incorporated
- Category:
- Single Bipolar Transistors
- Package:
- TO-261-4, TO-261AA
- Datasheet:
-
FZT857QTA.pdf
- Description:
- TRANS NPN 300V 3.5A SOT-223-3
- Quantity:
- Payment:
- Shipping:
Inventory:1,893
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Product details
Overview
FZT857QTA from Diodes Incorporated is a 300V NPN medium-power transistor in SOT223 package, designed for high-voltage switching in automotive and industrial power supplies. It delivers 3.5A continuous collector current, 300V VCEO, <155mV VCE(sat) at 1A, 87mΩ RCE(sat), and AEC-Q101 qualification for under-hood applications.
For engineers reviewing the FZT857QTA datasheet, FZT857QTA pinout, FZT857QTA application, or FZT857QTA equivalent, key selection criteria include high-voltage blocking capability, low saturation resistance for thermal efficiency, gain stability up to 3A, automotive-grade reliability, and SOT223 thermal performance on PCB copper areas.
Technical Context
This NPN bipolar junction transistor operates as a high-voltage switch with BVCEO = 300V and BVCBO = 350V, enabling use in flyback, boost, and offline SMPS primary-side switching where voltage transients exceed 250V. Its hFE remains ≥15 at 3A (VCE = 10V), supporting stable base drive design across load range.
Thermal performance is defined for two mounting conditions: RθJA = 42°C/W on 52mm × 52mm 2oz Cu, and 78°C/W on 25mm × 25mm 1oz Cu. Safe operating area (SOA) supports single-pulse operation up to 300V/3.5A with 100µs–1s pulse widths, validated per JEDEC JESD22-A114/A115 ESD ratings (8kV HBM, 400V MM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 300 V - Enables direct replacement of legacy 250–300V transistors in AC-DC front-end and LED driver primary switches. |
| IC (continuous) | 3.5 A - Supports ≥30W output in compact SOT223-based converters without forced air cooling. |
| VCE(sat) @ 1A | <155 mV - Reduces conduction loss to <155 mW at 1A, critical for thermally constrained automotive modules. |
| RCE(sat) | 87 mΩ - Equivalent on-resistance enables accurate SOA modeling and thermal derating calculations. |
| hFE @ 3A | ≥15 - Ensures sufficient current gain at full rated current for reliable base drive margin in high-side configurations. |
| fT | 80 MHz - Supports switching frequencies up to ~500 kHz with adequate gain margin in hard-switched topologies. |
| ESD HBM | 8,000 V - Meets IEC 61000-4-2 Level 4 system-level ESD immunity requirements for automotive ECUs. |
Pinout & Package
Package: SOT223 (Type DN), surface-mount, 4-terminal molded plastic housing with exposed collector tab for thermal conduction. Weight: 0.112 g. Moisture sensitivity level: J-STD-020 Level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Collector (Tab) | Main current path and thermal interface | Exposed metal tab serves as both high-current terminal and primary heat sink; must be soldered to ≥52 mm² 2oz Cu for rated 3.0 W dissipation. |
| Emitter | Current return node | Low-inductance emitter connection essential for minimizing switching overshoot in high-dI/dt applications like flyback snubbers. |
| Base | Control input | Requires ≤600 mA peak drive for full 3.5A switching; VBE(sat) = 1.02–1.25 V ensures predictable base resistor sizing. |
| Collector (Lead) | Secondary collector connection | Redundant collector lead improves mechanical robustness and current sharing; electrically tied to tab internally. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive under-hood use (-40°C to +150°C ambient), PPAP-capable with IATF16949 manufacturing traceability. |
| Low RCE(sat) = 87 mΩ | Enables >92% efficiency in 24V-input DC-DC converters at 2A output, reducing heatsink volume by 35% vs. standard SOT223 transistors. |
| hFE specified up to 3A | Eliminates extrapolation uncertainty in base drive design-guaranteed minimum gain supports fixed-bias circuits without feedback compensation. |
| Green, halogen-free construction | Meets EU RoHS 3 (2015/863/EU) and Diodes' "Green" definition (<900 ppm Br, <900 ppm Cl, <1000 ppm Sb), compliant for global automotive Tier 1 supply chains. |
Applications
| Automotive LED Headlamp Driver | Industrial Flyback Power Supply |
|---|---|
Use Scenario: Primary-side switch in constant-current LED driver for adaptive front lighting systems (AFS), operating from 12–24V battery with 300V reflected transients. IC Role / Device Role / Timing Role: High-voltage NPN switch controlling energy transfer into transformer primary; handles repetitive 300V spikes during MOSFET gate drive coupling. Use Value: 300V VCEO and 8kV HBM withstand capability prevent field failures due to load dump or alternator ripple-induced overvoltage. |
Use Scenario: 24V-input, 12V/3A isolated flyback converter powering PLC I/O modules in factory automation cabinets. IC Role / Device Role / Timing Role: Primary-side BJT switch replacing MOSFETs in cost-sensitive designs where gate drive complexity must be minimized. Use Value: 3.5A IC and <155mV VCE(sat) enable 91% peak efficiency at full load without external heatsink on 25mm×25mm 1oz Cu PCB. |
| AC-DC Auxiliary Power Supply | High-Voltage DC-DC Bias Supply |
Use Scenario: Standby auxiliary supply in 3kW server PSU, deriving 12V/0.5A from rectified mains using discrete transistor-based flyback. IC Role / Device Role / Timing Role: Low-cost, high-reliability primary switch operating in discontinuous conduction mode (DCM) at 65 kHz. Use Value: AEC-Q101 qualification ensures long-term reliability in 24/7 operation; RθJA = 42°C/W allows 3.0W dissipation with minimal board area. |
Use Scenario: Isolated bias supply for SiC gate drivers in EV traction inverters, generating ±15V from 400V DC bus. IC Role / Device Role / Timing Role: High-voltage NPN in self-oscillating Royer topology, switching at ~200 kHz with resonant turn-off. Use Value: fT = 80 MHz and fast ton/toff (100 ns / 5.3 µs) support stable oscillation and low EMI in high-noise motor control environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage NPN transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ZXTN25050DFH | Higher VCEO = 500V but lower IC = 2.5A; SOT89 package limits thermal performance (RθJA = 100°C/W). | Better for ultra-high-voltage transient suppression (e.g., telecom surge protection), less suitable for sustained 3A loads. | Select when VCEO margin >200V is prioritized over continuous current capability and thermal density. |
| FZT849QTA | Complementary PNP version (BVECO = 300V, IC = –3.5A); identical SOT223 footprint and AEC-Q101 qualification. | Used in complementary emitter-follower or push-pull output stages requiring matched thermal and switching characteristics. | Choose for dual-transistor configurations where symmetry, matching, and shared qualification are required. |
Compared with ZXTN25050DFH and FZT849QTA, FZT857QTA uniquely balances 300V blocking, 3.5A current, and SOT223 thermal capability-making it optimal for cost-sensitive, space-constrained automotive and industrial SMPS where both voltage headroom and thermal density matter.
Availability
FZT857QTA is available at Aetrix Electronics and suitable for automotive LED drivers, industrial flyback power supplies, and AC-DC auxiliary supplies requiring stable component supply, AEC-Q101 compliance, and SOT223 thermal performance.
Supply support for FZT857QTA 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, manufacturing, and sales operations across Asia, Europe, and the Americas.
FZT857QTA belongs to Diodes' high-voltage power transistor product line, engineered specifically for automotive and industrial power conversion where reliability under thermal and electrical stress is non-negotiable.
FAQ
What is the maximum allowable junction temperature for FZT857QTA?
The absolute maximum junction temperature is +150°C, with storage temperature ranging from –55°C to +150°C. Derating begins at +25°C ambient, with linear reduction of power dissipation at 24 mW/°C for 52mm × 52mm 2oz Cu mounting. Thermal resistance junction-to-lead is 8.8°C/W, confirming the collector tab is the dominant thermal path.
Is FZT857QTA pin-compatible with older SOT223 NPN transistors like MJD31C?
No-FZT857QTA uses a 4-terminal SOT223 (collector-tab + collector-lead + base + emitter), whereas MJD31C is a 3-terminal SOT223 with collector-tab-only configuration. Pin assignment differs: FZT857QTA's base and emitter leads are reversed relative to MJD31C, requiring PCB layout revision for drop-in replacement.
Can FZT857QTA replace a MOSFET in a flyback converter primary side?
Yes, but with circuit adaptation: its bipolar nature requires base current drive (not voltage drive), and switching speed is slower (toff = 5.3 µs). It excels in low-frequency (<100 kHz), high-voltage, cost-sensitive designs where gate driver complexity and MOSFET price premium must be avoided.
Does FZT857QTA support pulsed operation beyond its DC ratings?
Yes-the Safe Operating Area (SOA) graph confirms single-pulse capability up to 300V/3.5A for durations from 100 µs to 1 s. At 10 ms pulse width, it supports up to 300V/2.5A; at 100 µs, up to 300V/5A (ICM = 5A), provided duty cycle remains ≤2% and pulse width ≤300 µs per test condition notes.
FZT857QTA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- TO-261-4, TO-261AA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 3.5 A
- Voltage - Collector Emitter Breakdown (Max):
- 300 V
- Vce Saturation (Max) @ Ib, Ic:
- 345mV @ 600mA, 3.5A
- Current - Collector Cutoff (Max):
- 50nA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 100 @ 500mA, 10V
- Power - Max:
- 1.6 W
- Frequency - Transition:
- 80MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-223-3
FZT857QTA FAQ
1.How can I place an order for FZT857QTA through Aetrix?
Please submit a Request for Quotation (RFQ) for FZT857QTA 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 FZT857QTA reliable?
The price and inventory of FZT857QTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FZT857QTA is usually 5 days.
3.What payment methods are accepted for FZT857QTA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FZT857QTA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FZT857QTA?
FZT857QTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FZT857QTA 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 FZT857QTA?
For technical support, including FZT857QTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FZT857QTA requirements.
6.How does Aetrix verify that FZT857QTA is sourced from the original manufacturer or authorized distributors?
All FZT857QTA 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 FZT857QTA meets industry standards.
7.What is the process for return or replacement of FZT857QTA?
All FZT857QTA units undergo pre-shipment inspection (PSI). If there is an issue with FZT857QTA, 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 FZT857QTA part is unused and in its original packaging.
Return procedure for FZT857QTA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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