SiC MOSFET Gate Driver Board for 62mm module

Broadcom Inc

The Goal

Isolated Gate Driver evaluation board for 1200V SiC MOSFET in 62mm power module package, based on the Broadcom ACPL-355JC gate driver IC.

The Challenge

62mm power module package is the most popular in industrial and traction applications. It gained popularity in the '90s with the first generations of IGBTs. Compared to the IGBT, SiC MOSFET tends to have much faster behavior during switching transients. This behavior induces higher overvoltage and oscillations when SiC is combined with traditional packages. Optimization of the switching performance in such a case is the main challenge. The second most important challenge is overcurrent protection. SiC MOSFETs are typically less robust against short circuit and overcurrent events. Due to this, the detection and reaction times, of the short circuit detection part of the gate driver, must be as short as possible. With the integrated short circuit detection mechanism of the ACPL-355JC, this function was easily implemented. The customer wanted to add a few more features in addition to the gate driver circuit, such as DC link voltage measurement, and current measurement interface. Our mission was to fit all these components onto a relatively small printed circuit board while meeting all relevant Isolation Coordination Standards.



The Solution

The evaluation board EB1200M62-355JC features Broadcom’s dual-output isolated gate drive optocouplers ACPL-355JC, which are used to drive the SiC MOSFET module in an industry-standard 62-mm package. It also features precision optically isolated amplifiers ACPL-C87B, which are used for DC bus voltage measurement, and a user interface/buffering circuit for accommodating external output current measurement signals coming from the optically isolated sigma-delta modulator ACPL-736J. EB1200M62-355JC has been developed to support Broadcom customers during their first steps in designing power converter applications with ACPL-355JC drivers.

The EB1200M62-355JC includes the following main features:

  • Two isolated ACPL-355JC gate drive optocouplers with the following features:
    • 10A peak output current
    • 100-kV/μs common-mode rejection
    • VIORM = 2262VPK with CTI > 600V
    • Over-current protection (or DESAT)
    • Soft shutdown during fault
    • Two isolated feedback signals, FAULT (for over-current) and UVLO
  • A single ACPL-C87B optically isolated amplifier for DC bus voltage measurement:
    • 0 to 2V nominal input range
    • 100-kHz bandwidth
    • 3 to 5.5V wide supply range for the output side
    • 15-kV/μs common-mode transient immunity
  • Electrically and mechanically suitable for 62-mm module FF6MR12KM1 and WAB300M12BM3
  • With adjustment of the OC protection and gate resistors, the evaluation board supports the following 62-mm SiC MOSFET modules:
    • FF6MR12KM1
    • FF3MR12KM1
    • FF2MR12KM1
    • WAB300M12BM3
    • WAB400M12BM3
  • DC/DC power supply with current-limit protection and thermal shutdown
  • Isolated SMPS for gate drivers
  • Access to FAULT and UVLO output signals for protection and control development purposes
  • Access to PWM input signals
  • Access to current measurements via the ACPL-736J sigma-delta current sensing module:
  • ±50-mV linear range (±80-mV full scale)
  • 10- to 20-MHz external clock input range
  • 1-bit, the second-order sigma-delta modulator
  • 16-bit resolution, no missing codes
  • 80-dB typical SNR, 78-dB typical SNDR
  • Sensing range of up to 1000A current together with a 0.05-mΩ shunt


Link to the reference manual.