IXYS Power MOSFET Selection Guide
Selecting the right power MOSFET is crucial for power electronics design success. This guide walks through the IXYS MOSFET portfolio and provides selection criteria based on application requirements.
MOSFET Technology Overview
IXYS offers both planar and trench MOSFET technologies:
Planar MOSFETs (X-Class Series)
Best for: High-voltage applications (>500V)
- Better avalanche ruggedness
- Superior body diode performance
- Higher voltage capability up to 1000V+
Trench MOSFETs (TrenchFET Series)
Best for: Low-voltage high-current applications (<200V)
- Ultra-low Rds(on)
- Fast switching characteristics
- Higher cell density
Key Selection Parameters
Contact LiTong's application engineering team for personalized selection assistance.
💡 FAE Insights
Professional Insight
MOSFET selection requires balancing electrical, thermal, and cost requirements.
⚠️ Common Pitfalls
- ✗ Using 25°C Rds(on) for thermal calculations
- ✗ Ignoring avalanche requirements
- ✗ Insufficient voltage margin
- ✗ Overlooking gate drive requirements
📋 Customer Cases
Motor Drive Manufacturer
Industrial Automation
Challenge
Selected MOSFETs with insufficient avalanche rating
Solution
Redesigned with IXYS X-Class MOSFETs with 500mJ avalanche rating
Customer Feedback
"LiTong FAE helped us understand avalanche requirements and select appropriate devices."
Results
Eliminated failures, improved reliability by 10x
Frequently Asked Questions
1. When should I choose planar vs trench MOSFET?
Choose planar MOSFETs for high-voltage applications (>500V) where avalanche ruggedness is important. Choose trench MOSFETs for low-voltage high-current applications (<200V) where low Rds(on) is critical. Planar devices have better body diode performance and avalanche capability, making them ideal for motor drives with inductive loads. Trench devices offer lower Rds(on) per die area, making them cost-effective for high-current DC-DC converters. IXYS X-Class series uses planar technology for 500V+ applications, while TrenchFET series uses trench technology for 40-200V applications.
2. How do I calculate required voltage rating?
Calculate MOSFET voltage rating with adequate margin: (1) Determine maximum DC bus voltage including tolerances; (2) Add voltage spikes from switching (typically 20-30% of bus voltage); (3) Include safety margin of 20-30%. Formula: Vds(min) = Vbus_max × 1.3 × 1.3. Example: For 400V bus with 10% tolerance, Vds(min) = 440V × 1.3 × 1.3 = 744V. Select standard rating above this, such as 800V or 1000V. For AC line applications, consider peak voltage (325V for 230VAC) plus transients. IXYS offers MOSFETs from 40V to 1000V+ to cover all application requirements.
3. What is the trade-off between Rds(on) and gate charge?
Rds(on) and gate charge (Qg) present a fundamental trade-off in MOSFET design: (1) Lower Rds(on) reduces conduction losses but typically increases die size and Qg; (2) Lower Qg enables faster switching and lower gate drive losses but may increase Rds(on); (3) High-frequency applications (>200kHz) benefit more from low Qg; (4) High-current applications benefit more from low Rds(on). Modern IXYS MOSFETs optimize both parameters through advanced cell design. For SMPS applications, prioritize Qg for high frequency. For motor drives, prioritize Rds(on) for lower conduction losses at moderate frequencies.