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As switching frequencies increase and SiC MOSFETs become more widely adopted, high-side gate driving presents an important design challenge. The floating source voltage of a high-side SiC MOSFET can reach several hundred volts, requiring the gate to be driven sufficiently above the source potential.

A bootstrap circuit provides a simple and cost-effective solution. At the heart of this circuit, however, is the bootstrap diode - and choosing the right diode is critical for achieving fast, reliable operation.

 

High-Voltage SiC Performance in a Compact Package

The SI02C120SMA from Diotec is a 2 A / 1200 V Silicon Carbide Schottky diode housed in the compact DO-214AA (SMA) package.

Designed for high-frequency switching applications, the SI02C120SMA combines:

• 1200 V reverse-voltage capability for demanding high-voltage applications
• 2 A forward-current rating with high repetitive peak-current capability
• Extremely low reverse-recovery charge for fast, efficient switching
• Low intrinsic junction capacitance to minimize unwanted capacitive coupling

These characteristics make the SI02C120SMA particularly well suited as a bootstrap diode for high-side SiC MOSFET gate drivers.

 

Faster Bootstrap Charging

High-frequency operation places demanding requirements on the bootstrap circuit. The bootstrap capacitor must be recharged rapidly during the available low-side conduction interval, while the diode must withstand repetitive peak charging currents.

The SI02C120SMA's robust peak-current capability can allow designers to reduce or eliminate the bootstrap resistor, depending on the application. This lowers the impedance of the charging path and enables faster bootstrap capacitor charging and discharging, resulting in a greater flexibility for high-frequency and high-duty-cycle operation.

 

Reduced Ringing and EMI

SiC MOSFETs deliver extremely fast switching transitions, but their high dv/dt can also introduce unwanted ringing and EMI into the gate-drive circuitry.

With its low junction capacitance and near-zero reverse-recovery charge, the SI02C120SMA helps minimize parasitic current paths and switching disturbances. This can contribute to cleaner gate-drive waveforms and reduce the risk of EMI-induced false Undervoltage Lockout (UVLO) triggering.

 

A Superior Alternative to Ultra-Fast Silicon Diodes

While standard recovery silicon diodes have traditionally been used in bootstrap circuits for high voltage applications, their reverse-recovery characteristics can become increasingly problematic as switching speed and voltage increase.

The SiC Schottky technology of the SI02C120SMA eliminates the need for minority-carrier charge removal during turn-off, providing extremely fast switching with minimal reverse-recovery effects.

For designers looking to maximize the performance of high-frequency SiC power converters, the SI02C120SMA provides a compact, high-voltage and high-speed solution for reliable bootstrap operation.

 

Features

• High reverse breakdown voltage
• Almost zero switching losses
• Low reverse leakage current
• High efficiency high frequency switching
• Compact SMA package
   

Applications

• Auxiliary Power Supply
• Solar inverters
• Telecom power supplies
• Power factor correction
   

Specifications

• 2 A average forward current at 160°C (IFAV)
• 1200 V repetitive reverse voltage (VRRM)
• Typical forward voltage 1.40 V V at 2 A and 25°C (VF)
• Typical reverse leakage 2 µA at 1200 V and 175°C (IR)
• Total capacitive charge 16 nC at 800 V, 2 A, 200 A/µs [QC)
• DO-214AC (SMA) case outline