Infineon BSC042N03LSG: Key Specifications and Application Circuit Design

The Infineon BSC042N03LSG is a state-of-the-art N-channel MOSFET utilizing Infineon's advanced OptiMOS™ 3 technology. Designed primarily for high-efficiency, low-voltage applications, this power transistor excels in scenarios demanding minimal switching losses and superior thermal performance. Its key specifications make it an ideal choice for switch-mode power supplies (SMPS), motor control, and high-frequency DC-DC converters.

Key Specifications:

Voltage and Current Ratings: The device boasts a drain-source voltage (VDS) of 30 V and a continuous drain current (ID) of 70 A at a case temperature (TC) of 25°C. This high current handling capability in a compact package is a significant advantage.

Low On-Resistance: A standout feature is its exceptionally low typical on-resistance (RDS(on)) of just 3.7 mΩ at a gate-source voltage (VGS) of 10 V. This low resistance directly translates to reduced conduction losses, higher efficiency, and lower heat generation.

Gate Charge: The total gate charge (Qg) is typically 22 nC, which is crucial for determining driving requirements. A lower gate charge allows for faster switching speeds and reduces the stress on the gate driver circuitry.

Package: It is housed in a PG-TSDSON-8 (SuperSO8) package. This surface-mount package offers an excellent footprint-to-performance ratio, providing low parasitic inductance and effective thermal characteristics for power-dense designs.

Application Circuit Design Considerations:

Implementing the BSC042N03LSG effectively requires careful attention to its driving and layout.

1. Gate Driving: To leverage its fast switching capabilities, a dedicated gate driver IC is highly recommended. The driver must be capable of sourcing and sinking sufficient peak current to quickly charge and discharge the MOSFET's gate. The recommended gate-source voltage (VGS) is 10 V for achieving the specified RDS(on). A small series resistor (e.g., 2-10 Ω) is often used in series with the gate to dampen ringing and prevent oscillations, but its value must be chosen as a trade-off between switching speed and EMI.

2. Synchronous Buck Converter Example: A primary application is in the synchronous buck converter circuit, where the BSC042N03LSG is perfectly suited for the low-side synchronous rectifier position.

In this topology, the low-side MOSFET's low RDS(on) is critical for minimizing losses during the freewheeling phase of the switching cycle, directly boosting overall converter efficiency.

The circuit requires a high-side switch (control MOSFET) and the BSC042N03LSG as the low-side switch. A PWM controller with integrated drivers for both MOSFETs is typically used.

Layout is paramount: The power loop, comprising the input capacitors, the high-side MOSFET, the low-side MOSFET (BSC042N03LSG), and the inductor, must be as small and tight as possible to minimize parasitic inductance, which causes voltage spikes and ringing. Use wide copper pours and multiple vias to reduce resistance and improve thermal dissipation.

3. Decoupling and Thermal Management: Place high-frequency ceramic decoupling capacitors very close to the drain and source pins of the MOSFET to provide a clean, low-inductance current path. Given the high current capability, effective thermal management through PCB layout is essential. A large copper area connected to the drain and source pins (using thermal reliefs if needed) acts as an effective heat sink. For high-power applications, additional cooling via a heatsink may be necessary.

ICGOODFIND Summary

The Infineon BSC042N03LSG stands out as an exceptional MOSFET for power conversion tasks, offering an optimal blend of very low on-resistance, high current capacity, and fast switching performance. Its advantages are fully realized in demanding low-voltage applications like DC-DC converters and motor drives, where efficiency and power density are critical. Proper circuit design, focusing on robust gate driving and meticulous PCB layout, is essential to unlock its full potential.

Keywords:

1. OptiMOS™ 3

2. Low RDS(on)

3. Synchronous Buck Converter

4. Gate Driver

5. Thermal Management