The TO-247 SiC MOSFET half-bridge gate driver evaluation board

Broadcom Inc

The Goal

In order to enable an easier transition toward SiC technology, Broadcom® is expanding its Isolated Gate Driver portfolio, accompanied with the appropriate evaluation boards for 1200V SiC MOSFETs. The new board coming from this series is the Isolated Gate Driver evaluation board made for discrete TO-247.

The main benefits of the SiC MOSFET are the improved efficiency and power density. Additionally, for low-power applications, the price is a very important driving factor. The aim of this evaluation board is to demonstrate that such high efficient but also cost-optimized design can be realized with the simple gate driver design.

The Challenge

The discrete package has the disadvantage of the high stray inductance. This becomes even more critical when such a package is used for the fast switching SiC MOSFET. PCB layout design needs to be carefully done in order to squeeze every possible watt out of the converter and minimize the EMI noise. An additional challenge is the precise switching loss characterization, and this requires a high-bandwidth measurement of the commutating current. 


The Solution

Evaluation board EB1200-3161 features Broadcom’s dual output isolated gate drive optocouplers ACFL-3161, used to drive SiC MOSFETs in a discrete TO-247 package. The board features an integrated capacitor DC Bus with the optimized layout that minimizes the commutation loop inductance. The high-bandwidth current switch current measurement is implemented and it is realized as the low inductive planar Shunt resistor.


  • Two isolated ACFL-3161 gate drive optocouplers with the following features: 
    •     UVLO (under-voltage lockout) protection  
    •     Dual output drive to control turning on and off transients  
  • Electrically and mechanically suitable for TO-247 4 pin packages 
  • With adjustment of the gate resistors and isolated auxiliary power supply, the evaluation board supports the following SiC MOSFETs: 
    •     SCTWA70N120G2V4
    •     C3M0021120K 
  • DC Bus and balancing/discharge resistors. 
  • Isolated SMPS for gate drivers. 
  • Resistor shunt based, low side switch current measurement over BNC interface 
  • Access to PWM input signals. 
  • Continuous operation in buck/boost configuration up to 3kW output power and 50kHz switching frequency. It is the end-user responsibility to provide and integrate appropriate heat sink in case of continuous operation.