STQ1NC45R-AP - 450V N-Channel SuperMESH MOSFET | STMicroelectronics
MPN: STQ1NC45R-AP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.55 | $5.50 |
| 100 | $0.47 | $47.00 |
| 500 | $0.4 | $200.00 |
| 1,000 | $0.34 | $340.00 |
STQ1NC45R-AP Overview
What is a high-voltage MOSFET? An N-channel power MOSFET is a voltage-controlled majority-via device that conducts current between drain and source when a sufficient gate-source voltage is applied. Power MOSFETs in the 400-500V class are designed for offline switching converters, where they sit inside the switch-mode power supply (SMPS) power train: AC mains -> bridge rectifier -> bulk capacitor -> high-voltage MOSFET switch -> transformer -> output rectifier -> load. Within that hierarchy, the high-voltage MOSFET is the primary energy-translation element that converts rectified mains DC into a switched waveform the transformer can step down. STMicroelectronics positions the SuperMESH family at the entry of this stack, above general-purpose small-signal MOSFETs and below their MDmesh and silicon-carbide lines.
Key features of the STQ1NC45R-AP include an extremely high dv/dt capability for demanding inductive loads, a 100% avalanche-tested rating for reliability under transient over-voltage, minimized gate charge to reduce drive losses, and a low typical Rds(on) of 4.1 ohm. The TO-92 (Ammo Pack) suffix designates radial-leaded through-hole packaging on tape-and-reel for automated insertion.
Typical applications are AC-DC flyback converters in sub-10W adapters, linear-mode ballasts, low-power SMPS auxiliary supplies, electronic ballasts for compact fluorescent and LED drivers, and high-voltage driver interfaces. The 450V drain-source voltage provides ample derating margin for 220-240V rectified mains (peak ~373V).
Design consideration: when used as the primary switch in a flyback converter, the avalanche rating and dv/dt tolerance allow the designer to omit an external snubber in many low-power configurations. However, ensure the gate drive swing reaches 10V for full enhancement - logic-level (5V) drive is not guaranteed across all units.
This page synthesizes distributor pricing, drop-in TO-92 alternatives, application circuit roles, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for STQ1NC45R-AP — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
STQ2NC45R-AP
✅ Drop-In📋 Reference alternative (not in catalog)
STQ1NK60Z-AP
✅ Drop-In📋 Reference alternative (not in catalog)
STQ2HN60ZR-AP
✅ Drop-In📋 Reference alternative (not in catalog)
STQ3NK60ZR-AP
✅ Drop-In📋 Reference alternative (not in catalog)
STQ2LN60K3-AP
✅ Drop-In📋 Reference alternative (not in catalog)
STQ1NC45R-AP Maximum Ratings & Electrical Characteristics
| Part Number | STQ1NC45R-AP |
| Manufacturer | STMicroelectronics |
| Technology / Process | SuperMESH (strip-based PowerMESH layout) |
| Channel Type | N-Channel |
| Drain-Source Voltage (Vds) | 450 V |
| Continuous Drain Current (Id, Tc) | 500 mA |
| Peak Drain Current | 1.5 A |
| Typical Rds(on) | 4.1 ohm at VGS=10V |
| Maximum Power Dissipation (Pd, Tc) | 3.1 W |
| Package | TO-92 (Ammo Pack, through-hole) |
| Mounting Type | Through Hole |
| Avalanche Rated | 100% avalanche tested |
| dv/dt Capability | Extremely high |
| Gate Charge | Minimized |
| RoHS Status | Compliant |
STQ1NC45R-AP Pin Configuration
| Pin 1 | Gate — MOSFET gate input (drive to VGS=10V for full enhancement) |
| Pin 2 | Drain — MOSFET drain (high-voltage terminal) |
| Pin 3 | Source — MOSFET source (reference for gate drive and load return) |
Safe Operating Area (TO-92, Tc=25C)
Typical Applications
STQ1NC45R-AP is suitable for 6 applications: AC-DC Flyback Converter (Sub-10W Adapter), Electronic Ballast for CFL/LED, Auxiliary SMPS Standby Supply, Linear-Mode High-Voltage Driver, Solid-State Relay (SSR) Output Stage, High-Voltage Sensor Bias Circuit.
AC-DC Flyback Converter (Sub-10W Adapter)
The STQ1NC45R-AP serves as the primary-side high-voltage switch in sub-10W isolated AC-DC flyback converters such as phone chargers and appliance adapters. Its 450V Vds rating comfortably exceeds the peak of rectified 220-240V mains (~373V), giving ~77V margin for transient over-voltage, while the 500mA continuous / 1.5A peak drain current matches the primary-winding current of a 5W flyback at typical duty cycles. The 4.1 ohm Rds(on) dissipates ~1W at full load, leaving headroom under the 3.1W Tc rating. The 100% avalanche-tested rating lets the designer absorb transformer leakage energy without an external snubber in many low-power configurations, simplifying the BOM and shrinking the converter footprint.
Recommended
Electronic Ballast for CFL/LED
The STQ1NC45R-AP drives the resonant half-bridge or single-switch inverter stage in low-power electronic ballasts for compact fluorescent lamps (CFL) and small LED tubes. Its high dv/dt capability and 100% avalanche rating handle the inductive kick from the resonant LC tank without snubber components, while the 450V Vds tolerates the rectified mains rail plus resonant overshoot. The 500mA continuous Id rating suits sub-15W lamp loads where ballast currents stay below 300 mA RMS. The TO-92 package through-hole form factor enables low-cost wave-soldered assembly at the high volumes typical of consumer lighting.
Recommended
Auxiliary SMPS Standby Supply
The STQ1NC45R-AP powers the low-wattage auxiliary/standby rail in white goods, industrial controllers, and smart appliances where the main SMPS is off but a 5V/12V standby rail must remain alive. Operating from rectified 220-240V mains directly (no PFC stage), the 450V Vds with ~20% margin and 500mA Id match typical standby converter requirements (under 3W output). The TO-92 Ammo Pack format supports automated insertion in high-volume white-goods assembly lines. The minimized gate charge reduces drive losses from the auxiliary controller IC, improving overall standby efficiency and helping meet ENERGY STAR standby power targets.
Recommended
Linear-Mode High-Voltage Driver
Beyond switching, the STQ1NC45R-AP can act as a linear high-voltage driver for piezo buzzers, high-voltage relays, or photoflash capacitor charging circuits where its 450V Vds provides ample headroom. Operating in the linear region (not saturated), the device acts as a high-voltage buffer between a low-voltage MCU and a high-voltage load. The 100% avalanche rating ensures survival when the load is inductive and the switch turns off abruptly. The TO-92 package is convenient for through-hole hobby and prototyping use where SMD high-voltage MOSFETs are awkward to handle.
Recommended
Solid-State Relay (SSR) Output Stage
The STQ1NC45R-AP forms the high-voltage output switch of an optically-isolated solid-state relay used in industrial control and home automation. When the input LED is energized, the optocoupler output applies VGS to the MOSFET, switching 220-240V AC loads such as heaters, solenoids, or lamp banks. The 450V Vds rating handles peak mains plus inductive kick from solenoid loads, while the 100% avalanche-tested rating protects against load-side transients. The TO-92 package fits inside standard SSR module housings. Use a gate-source resistor network to ensure the MOSFET turns off cleanly when the optocoupler LED is de-energized.
Recommended
High-Voltage Sensor Bias Circuit
The STQ1NC45R-AP can switch high-voltage bias to gas sensors, Geiger-Muller tubes, photomultiplier tubes, or piezo transducers in scientific and test instruments. With 450V Vds rating, it safely switches bias voltages up to 400V. The 500mA continuous rating suits typical sensor bias currents below 100 mA. The TO-92 through-hole package is convenient for prototyping and small-volume scientific instrument builds. Designers should add a gate-source pull-down resistor to ensure the MOSFET defaults to OFF state when the drive signal is floating, preventing accidental high-voltage application to the sensor.
Recommended
Recommended Products Summary
Engineering reference data for STQ1NC45R-AP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | STQ2NC45R-AP | STQ1NK60Z-AP | STQ2HN60ZR-AP | STQ3NK60ZR-AP | STQ2LN60K3-AP |
|---|---|---|---|---|---|---|
| Package | TO-92 (Ammo Pack) | TO-92 (Ammo Pack) - same | TO-92 (Ammo Pack) - same | TO-92 (Ammo Pack) - same | TO-92 (Ammo Pack) - same | TO-92 (Ammo Pack) - same |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Drain-Source Voltage (Vds) | 450 V | 450 V | 600 V | 600 V | 600 V | 600 V |
| Continuous Drain Current (Id, Tc) | 0.5 A | 2.0 A | 0.4 A | 0.5 A | 0.8 A | 1.0 A |
| Typical Rds(on) at VGS=10V | 4.1 ohm | 1.8 ohm | 8.5 ohm | 4.5 ohm | 2.5 ohm | 3.5 ohm |
| Maximum Power Dissipation (Pd, Tc) | 3.1 W | 3.1 W | 3.0 W | 3.1 W | 3.1 W | 3.1 W |
| Avalanche Tested | 100% | 100% | 100% | 100% | 100% | 100% |
| Technology | SuperMESH | SuperMESH | SuperMESH | SuperMESH | SuperMESH | SuperMESH |
Key Differentiators
- Highest Vds margin in TO-92 ST portfolio above 500 mA class (vs STQ1NK60Z-AP)
- Higher peak current rating than most 450 V TO-92 alternatives (vs STQ1NK60Z-AP)
Design Notes
Estimated: at 500 mA continuous drain current and 4.1 ohm typical Rds(on), conduction dissipation is approximately P = I^2 x R = 0.25 x 4.1 = 1.025 W. With TO-92 theta_JA of approximately 200 C/W on a small PCB land area (no copper pour), junction temperature rise above 25 C ambient is ~205 C, exceeding the absolute maximum Tj. For sustained 500 mA operation, attach the TO-92 to at least 100 mm^2 of copper pour (acting as a heatsink) and/or operate at less than 250 mA continuous. At 250 mA, dissipation drops to ~250 mW and the junction rise is ~50 C, leaving safe headroom.
For TO-92 through-hole designs carrying high-voltage switching nodes, keep the drain trace at least 5 mm clearance from low-voltage signal traces to meet IEC 60950 / IEC 62368 creepage and clearance requirements for reinforced isolation. Add a gate-source pull-down resistor (typically 10-100 kohm) directly at the TO-92 gate pin to prevent accidental turn-on from stray charge injection during power-up. Place the gate drive bypass capacitor within 5 mm of the gate pin to minimize dv/dt-induced gate ringing.
Common pitfalls: (1) Mistaking pin 2 and pin 3 - ST TO-92 MOSFETs have pin 1 = gate, pin 2 = drain, pin 3 = source, but some other manufacturers (e.g. Fairchild/onsemi) swap pins 2 and 3, so verify pinout against the specific datasheet before assembly. (2) Assuming logic-level drive - the STQ1NC45R-AP requires VGS of 10V for the specified 4.1 ohm Rds(on); at 5V VGS, Rds(on) rises several-fold and the MOSFET may not fully enhance. (3) Exceeding avalanche energy rating - while 100% avalanche-tested, repeated avalanche events above the rated energy degrade the device; size the snubber to keep avalanche below the datasheet limit.
Compliance Information
RoHS compliant per ST product page. AEC-Q100 not applicable - this is a discrete MOSFET, not an automotive-qualified component. For automotive applications, look at ST's automotive-grade MOSFET lines instead.
