SiC MOSFET Driver with Desaturation Protection and Negative BiasNovember 18, 2019 by Paul Shepard
Inventchip Technology Co., Ltd. (IVCT), today announced the RTM of IVCR1401, the industry's first silicon carbide MOSFET driver with desaturation protection and an integrated negative bias in a SOIC-8 package. Pictured above is the IVCR1401 EVM evaluation module for use with this new SiC MOSFET driver.
SiC MOSFETs are able to switch over ten-times as fast as an IGBT and reduce switching loss significantly. The higher switching speed (dv/dt) requires a driver to have a better noise immunity and be capable of operating at a higher switching frequency. To counteract the Miller effect resulted from high dv/dt, a negative turn-off gate voltage becomes necessary.
Due to the special SiC MOSFET characteristic of NBTI (negative bias temperature instability), the negative turn-off voltage is commonly limited to 5V or below. For the same current rating, a SiC MOSFET has a smaller die size and thermal mass, compared with an IGBT, which requires a SiC driver has a faster desaturation responding time when over-current or short circuit happens.
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The IVCR1401 was specifically designed to solve the design challenges.
The IVCR1401 doubles the desaturation current source from 500uA (commonly used in IGBT drivers) to 1mA, which allows users to use a larger external blanking capacitance and improve circuit's noise immunity. The higher current-source's current shortens desaturation protection responding time as well.
A 3.5V negative bias (VCN) is built up internally within 30uS after power up. It ensures the gate stays at a stable -3.5V at off state. The VCN is also monitored with UVLO protection. The unique negative bias structure makes it simple for a bootstrap circuit to achieve high-site drive with a negative bias.
In addition, the IVCR1401 provides 5V/10mA output to power external circuitry, such as digital isolators, etc. The driver also features a programmable positive gate voltage UVLO threshold. By changing /FAULT pin pull-up resistance, the UVLO threshold can be set to different levels to suit for variable SiC MOSFETs' driving voltage requirement.
Any internal faults can cause the driver to pull the gate output, OUT, and /FAULT pin low for minimum 10uS. The driver recovers to normal operation after the fault conditions are removed.
The IVCR1401 helps engineers solve critical design challenges and reduce driver component counts in many high density and high power applications, such as in the server, telecom, automotive and renewable energy markets.
Summary of features:
- Driver current capacity: 4A sink and source peak drive current
- Wide VCC range up to 35V
- Integrated 3.5V negative bias
- Designed for low side and suitable for bootstrap high-side power
- Programmable UVLO for positive and fixed UVLO for negative gate drive voltage
- Desaturation detection for short circuit protection with internal blanking time
- Fault output when UVLO or OCP detected
- 5V / 10mA reference for external circuit, e.g. digital isolator
- TTL and CMOS compatible input
- SOIC-8 with optional exposed pad for high frequency and power applications
- Low propagation delay 45ns typical with build-in de-glitch filter