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STMicroelectronics STB21NK50Z
- Part No.:
- STB21NK50Z
- Manufacturer:
- STMicroelectronics
- Category:
- FETs, MOSFETs
- Package:
- TO-263-3, D2PAK (2 Leads + Tab), TO-263AB
- Datasheet:
-
STB21NK50Z.pdf
- Description:
- MOSFET N-CH 500V 17A D2PAK
- Quantity:
- Payment:
- Shipping:
Inventory:5,183
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Product details
Overview
STB21NK50Z from STMicroelectronics is a 500 V, 21 A N-channel SuperMESH™ power MOSFET in TO-220FP package, featuring 0.24 Ω RDS(on) max at VGS = 10 V, 100% avalanche-rated capability, and optimized for hard-switching SMPS applications such as ATX power supplies and industrial AC-DC converters.
For engineers reviewing the STB21NK50Z datasheet, STB21NK50Z pinout, STB21NK50Z application, or STB21NK50Z equivalent, key selection criteria include breakdown voltage margin, conduction loss at 21 A DC, thermal performance in constrained TO-220FP footprint, and ruggedness under repetitive unclamped inductive switching (UIS).
Technical Context
This MOSFET employs ST's proprietary SuperMESH™ process to achieve low gate charge (Qg = 55 nC typ) and reduced output capacitance (Coss = 570 pF @ 25 V), enabling high-efficiency operation in 50–100 kHz flyback and forward converters. Its 500 V VDSS rating supports universal input (85–265 VAC) designs with sufficient derating margin.
The device integrates an ultra-fast body diode (trr = 90 ns typ) with low Qrr, minimizing switching losses during synchronous rectification or freewheeling phases. It is qualified per JEDEC JESD47 and rated for 100% UIS testing at Tj = 150 °C, confirming robustness in overcurrent fault conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VDSS | 500 V - Supports universal AC input with ≥2× safety margin over peak line voltage (375 V) |
| ID (continuous) | 21 A @ Tc = 25 °C - Enables 250–300 W output in compact TO-220FP heatsink-limited designs |
| RDS(on) max | 0.24 Ω @ VGS = 10 V - Limits conduction loss to ≤10 W at 21 A, critical for thermal management |
| Qg | 55 nC typ - Reduces gate drive power and enables use with low-current drivers (e.g., UC384x family) |
| Eoss | 1.8 µJ @ VDS = 400 V - Low stored output energy minimizes turn-on loss in hard-switched topologies |
| trr | 90 ns typ - Enables clean freewheeling without excessive diode recovery loss or voltage overshoot |
Pinout & Package
Package: TO-220FP (Full-Pak), insulated plastic case with integral heatsink tab; mounting via single screw; creepage/clearance compliant for reinforced insulation up to 400 VAC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Drain (Tab) | Main current path to heat sink | Electrically active drain terminal; requires insulating washer when mounted to grounded heatsink |
| Source | Reference node for gate drive and current sensing | Low-inductance connection point for source resistor or shunt; defines local ground reference |
| Gate | Control electrode for channel conduction | High-impedance input requiring <1 µA bias; sensitive to ESD; must be driven with <20 V max |
Key Features
| Feature | Design Value |
|---|---|
| 100% Avalanche Tested | Guarantees reliable operation under unclamped inductive switching faults without parameter shift |
| Ultra-Low Gate Charge | 55 nC typical enables efficient 100 kHz switching with minimal driver dissipation |
| Optimized Body Diode | 90 ns reverse recovery time reduces cross-conduction loss in quasi-resonant converters |
| TO-220FP Insulated Package | Eliminates need for isolating hardware in secondary-side SMPS layouts, reducing BOM count |
Applications
| ATX Main Switching Transistor | Industrial AC-DC Power Supply |
|---|---|
Use Scenario: Primary-side switch in 300–350 W ATX PC power supply operating at 65 kHz with active PFC front-end. IC Role / Device Role: High-voltage power switch handling 21 A peak primary current under full load and transient surges. Use Value: 0.24 Ω RDS(on) limits conduction loss to <12 W, enabling thermally stable operation on standard TO-220FP heatsink without forced air. | Use Scenario: Main switch in 250 W industrial DIN-rail power supply with wide input range (85–305 VAC) and 150 °C ambient rating. IC Role / Device Role: Hard-switched MOSFET in continuous conduction mode (CCM) forward converter topology. Use Value: 500 V VDSS provides 25% margin over worst-case 400 V DC bus, ensuring long-term reliability under line surges and transients. |
| LED Driver Primary Switch | UPS Inverter Stage |
Use Scenario: Primary switch in isolated 150 W constant-current LED driver for street lighting, operating in discontinuous conduction mode (DCM). IC Role / Device Role: Energy-transfer switch controlling flyback transformer magnetization and demagnetization cycles. Use Value: Ultra-fast body diode (90 ns trr) prevents voltage spikes during demagnetization, eliminating need for external snubber networks. | Use Scenario: Half-bridge switch in 1 kVA online UPS inverter stage converting 400 V DC bus to 230 V AC output. IC Role / Device Role: High-reliability switching element subjected to repetitive short-circuit and overload events. Use Value: 100% UIS-rated construction withstands >1000 repetitive 25 A/500 V inductive faults without degradation, meeting IEC 62040-1 surge immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage power MOSFET applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STP21NM50N | Same VDSS (500 V) and ID (21 A), but higher RDS(on) (0.27 Ω) and Qg (65 nC); non-SuperMESH™ process | Slightly lower efficiency in high-frequency SMPS; less suitable for thermally constrained TO-220FP layouts | Select when cost sensitivity outweighs 5–8% conduction loss penalty and gate drive capability is ample |
| FDPF21N50 | 500 V, 21 A, RDS(on) = 0.25 Ω, Qg = 50 nC; different gate threshold (3 V vs. STB21NK50Z's 2–4 V) | Lower gate charge improves high-frequency efficiency but tighter VGS(th) tolerance increases risk of spurious turn-on in noisy environments | Prefer in well-filtered gate-drive circuits where fast switching dominates thermal design priorities |
Compared with STP21NM50N and FDPF21N50, the STB21NK50Z delivers superior balance of low RDS(on), moderate Qg, and robust UIS rating-making it optimal for space-constrained, high-reliability AC-DC converters where thermal headroom and fault resilience are critical.
Availability
STB21NK50Z is available at Aetrix Electronics and suitable for ATX power supplies, industrial AC-DC converters, LED drivers, and UPS inverters requiring stable component supply across multi-year production cycles.
Supply support for STB21NK50Z 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.
The STB21NK50Z belongs to ST's SuperMESH™ power MOSFET product line, engineered specifically for high-efficiency, high-reliability switched-mode power supplies operating above 100 kHz with stringent thermal and ruggedness requirements.
FAQ
What is the maximum allowable gate-source voltage for STB21NK50Z?
The absolute maximum VGS is ±30 V per STMicroelectronics' official datasheet. Operation above +20 V or below −20 V risks permanent gate oxide damage. For reliable switching, gate drive should be limited to +12 V to +15 V with fast turn-off (≤100 ns) to prevent shoot-through in half-bridge configurations.
Can STB21NK50Z be used in synchronous rectification applications?
No-it is not optimized for synchronous rectification due to its relatively high body diode forward voltage (VSD ≈ 1.4 V) and lack of specified reverse recovery softness. Its body diode is designed for freewheeling in hard-switched topologies, not bidirectional conduction. Use dedicated SR controllers with logic-level MOSFETs instead.
Is STB21NK50Z RoHS-compliant and halogen-free?
Yes-STB21NK50Z meets RoHS Directive 2011/65/EU and is certified halogen-free per IEC 61249-2-21. The TO-220FP package uses lead-free matte tin plating on leads and complies with ST's "Ecopack2" environmental standard, verified in ST's official product change notices.
What is the recommended PCB layout practice for thermal management?
Use ≥4 cm² copper pour (2 oz Cu minimum) directly under the drain tab, connected to internal ground plane via ≥8 thermal vias (0.3 mm diameter, spaced ≤1.5 mm apart). Avoid routing signal traces under the tab area. Mount with M3 screw and mica insulator (k ≥ 0.25 W/m·K) to maintain thermal resistance <2.5 °C/W junction-to-heatsink.
STB21NK50Z Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- SuperMESH™
- Package/Case:
- TO-263-3, D2PAK (2 Leads + Tab), TO-263AB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- FET Type:
- N-Channel
- Technology:
- MOSFET (Metal Oxide)
- Drain to Source Voltage (Vdss):
- 500 V
- Current - Continuous Drain (Id) @ 25°C:
- 17A (Tc)
- Drive Voltage (Max Rds On, Min Rds On):
- 10V
- Rds On (Max) @ Id, Vgs:
- 270mOhm @ 8.5A, 10V
- Vgs(th) (Max) @ Id:
- 4.5V @ 100µA
- Gate Charge (Qg) (Max) @ Vgs:
- 119 nC @ 10 V
- Vgs (Max):
- ±30V
- Input Capacitance (Ciss) (Max) @ Vds:
- 2600 pF @ 25 V
- FET Feature:
- -
- Power Dissipation (Max):
- 190W (Tc)
- Operating Temperature:
- 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D2PAK
STB21NK50Z FAQ
1.How can I place an order for STB21NK50Z through Aetrix?
Please submit a Request for Quotation (RFQ) for STB21NK50Z 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 STB21NK50Z reliable?
The price and inventory of STB21NK50Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STB21NK50Z is usually 5 days.
3.What payment methods are accepted for STB21NK50Z?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STB21NK50Z transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for STB21NK50Z?
STB21NK50Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your STB21NK50Z 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 STB21NK50Z?
For technical support, including STB21NK50Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STB21NK50Z requirements.
6.How does Aetrix verify that STB21NK50Z is sourced from the original manufacturer or authorized distributors?
All STB21NK50Z 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 STB21NK50Z meets industry standards.
7.What is the process for return or replacement of STB21NK50Z?
All STB21NK50Z units undergo pre-shipment inspection (PSI). If there is an issue with STB21NK50Z, 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 STB21NK50Z part is unused and in its original packaging.
Return procedure for STB21NK50Z:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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