This guide is the entry point to the Good-Ark power MOSFET library: it maps the selection decisions—voltage class, polarity, loss budget, and package—and points to the dedicated articles that go deep on each step. Use it as the decision map before opening a datasheet; the linked articles carry the detail.
The Selection Map
Power MOSFET selection follows a four-step path, and each step has a dedicated article in this series:
- Polarity. Ground-referenced loads use N-channel; simple high-side loads can use P-channel; current-hungry high-side stages migrate to N-channel with a driver. The full decision path, the gate-drive arithmetic, and the MCU-drive truth table are in the N-channel vs P-channel article.
- Voltage class and structure. Below 150 V, trench technology dominates; above 200 V, super junction takes over; the structure comparison and the voltage-band map are in the trench vs planar article, and the super junction article covers the high-voltage side.
- Loss budget. The RDS(on)-versus-Qg trade, the conduction-switching crossover, and the die-size economics are the subject of the low RDS(on) article. The gate-charge timing and the drive requirements follow in the gate-drive guide.
- Package and thermal. The package’s thermal path, footprint, and current capability are covered by the TO-252 article and the QFN/DFN article, with the method centralized in the package-thermal guide.
The Voltage-Structure Map
| Voltage band | Dominant structure | Typical applications | Where to go next |
|---|---|---|---|
| Below 40 V | Trench, logic-level options | Load switches, POL, battery paths | N/P article, logic-level article |
| 40–100 V | Trench and shielded-gate | Buck converters, SR, motor bridges | SR article, trench article |
| 100–200 V | Trench or planar by application | Industrial loads, some drives | Trench article |
| 200 V and above | Super junction | PFC, flyback, LLC | Super junction article, SiC guide for the crossover |
The map is a screening heuristic; the final part number comes from the loss budget and the thermal design, not the structure alone.
The Key Numbers to Read
Every MOSFET datasheet answers the same five questions, and the dedicated articles explain how to read each:
- RDS(on) at temperature—the conduction number, specified at a gate voltage and measured hot (low RDS(on) article);
- Qg and the Miller plateau—the drive and switching number (gate-drive guide);
- Body diode—the recovery behavior that matters in bridges and synchronous stages (SR article);
- SOA and avalanche—the ruggedness numbers for faults and inductive loads (automotive article for the mission-profile view);
- Thermal resistance and package—the boundary that decides the real current (package-thermal guide).
Reading the Curves
The datasheet is read through its curves at the operating temperature and condition. The RDS(on)-temperature multiplier, the gate-charge curve, and the SOA curves are each explained in the articles that own them—the low RDS(on) article for the temperature behavior, the gate-drive guide for the gate-charge curve, and the automotive article for the SOA and mission-profile view. This guide only points to those pages; the reading method lives there.
Common Mistakes to Avoid
- Choosing by the 25 °C RDS(on). The hot value and the gate-voltage condition decide the loss ranking.
- Ignoring the gate-drive budget. A larger die needs more gate charge; the drive may not deliver it at the target frequency.
- Skipping the thermal path. The package is only as good as the copper and heatsink attached to it.
- Forgetting the body diode. In bridges and SR, the recovery behavior is a design input, not a footnote.
- Comparing parts at different test conditions. Voltage, current, temperature, and pulse width must match before the numbers mean anything.
Verifying the Datasheet
The five verification rows—RDS(on), gate charge, body-diode recovery, SOA and avalanche, and thermal resistance—are covered row by row in the cluster articles (low RDS(on), gate-drive guide, synchronous rectifier, automotive, and package-thermal). Use the map’s step 3 to apply them to two or three candidates; the reading method belongs to the sub-articles, not this hub.
Selection by Application
The map lands differently in each application, and the dedicated articles show the route:
- Load switching and power gating. Polarity and drive dominate; the N/P article and the logic-level article carry the decision, and a TO-252 handles most medium-power loads.
- DC-DC converters and POL. The loss budget and the SR decision dominate; the low RDS(on) article and the SR article apply, with the trench structure from the trench article.
- Offline PFC and flyback. The super junction article carries the high-voltage selection, and the SiC guide covers the crossover.
- Automotive and industrial. The mission profile, SOA, and qualification dominate; the automotive article carries the standards and documentation discipline.
Each route starts from the same four-step map; the application decides which step binds first.
Where to Go Next
- For the polarity and drive decision: N-Channel vs P-Channel Power MOSFETs (this series);
- For the loss economics: Low RDS(on) Power MOSFETs (this series);
- For the package: TO-252 (DPAK) Power MOSFETs and QFN vs DFN Packages (this series);
- For the thermal method: Power Package Thermal Design (this series);
- For the device families and datasheets, the product catalog and Documents sections are the starting points; for project-specific selection, contact Good-Ark.
Key Terms at a Glance
The hub’s vocabulary, with the owning article for each definition:
- RDS(on)—the on-state resistance, specified at a gate voltage and temperature; the low RDS(on) article owns the reading method and the temperature behavior.
- Qg and the Miller plateau—the gate charge and the flat region of the gate-charge curve that set the drive requirement; the gate-drive guide owns the sizing method.
- Body diode—the intrinsic reverse diode of the MOSFET, whose recovery behavior matters in bridges and synchronous stages; the synchronous rectifier article owns that view.
- SOA and avalanche—the safe-operating-area and energy ratings that decide fault survival; the automotive article owns the mission-profile view.
- Rth(j-a) and Rth(j-c)—the thermal resistances that set the junction temperature; the package-thermal guide owns the method.
The glossary is a pointer table, not a teaching section: each term’s full explanation lives in the article that owns it, and this page routes the reader there.
The Decision Tree in One View
- Low-side or ground-referenced load → N-channel; simple high-side load → P-channel; high-current or efficiency-critical high-side → N-channel with a driver. The N/P article carries the truth table.
- Below 150 V → trench structure; above 200 V → super junction; the voltage-band map is in the trench article.
- Conduction-dominated design → low RDS(on) matters; frequency-dominated design → Qg matters; the crossover method is in the low RDS(on) article.
- Board-mounted heat → TO-252 or leadless package; heatsink-mounted heat → TO-220/TO-247 class; the package articles and the thermal guide carry the detail.
Each branch of the tree ends at the article that owns the decision, keeping the hub to navigation.
Frequently Asked Questions
How do I start a MOSFET selection? Fix the operating point first—voltage, current, frequency, ambient—then follow the map: polarity, voltage class and structure, loss budget, and package. Each step narrows the list before the datasheet comparison, and each step’s article in this series carries the method for that decision.
What is the fastest differentiator between candidates? The RDS(on) × Qg figure of merit at the operating temperature separates parts within a voltage class; the package thermal path then decides the practical current. The figure of merit ranks die efficiency, and the thermal budget ranks the board; both must pass before the part number is final.
When should I move to SiC instead of silicon MOSFETs? When the voltage, frequency, temperature, or efficiency targets exceed what silicon can deliver economically—the crossover is covered in the SiC Power Device Design Guide in this series, and the map there starts where this guide ends.
The Map Beats the Datasheet
Power MOSFET selection is a decision map, not a search for the lowest number. Work the polarity, voltage, loss, and package steps in order, use the linked articles for the detail, and the shortlist builds itself before the datasheet comparison begins. The map is reusable: every new design starts at the same four questions, and the answers change with the application, not with the fashion. When the map is followed honestly, the datasheet comparison is the last step, not the first—and the result is a part chosen for the design, not for its front page.