Tiny DC/DC converters power IGBT gate drive circuits
Three series of 6W high isolation DC/DC converters from Murata Power Solutions in the form of single devices can provide all gate drive power for half, full and three-phase bridge circuits, saving space and cost while providing optimum performance.
Murata’s MGJ6HB, MGJ6FB, and MGJ63P series DC/DC converters are for simultaneously powering high-side and low-side gate drive circuits for IGBTs, and silicon/silicon carbide MOSFETs in bridge circuits. The devices feature respectively dual, triple, and quad independent outputs that are externally configurable with a simple circuit to provide positive and negative voltages for gate drive power.
By being able to use just one device for powering all gate drives in a bridge application, the space saving achieved is a significant 33 to 50 per cent, according to the company. For example, in a three-phase bridge, the four-output MGJ63P provides isolated power for the three high-side switch drivers and a common rail for the three low-side switch drivers, potentially replacing up to six discrete DC/DC converters.
The converters offer a wide 2:1 input voltage range with nominal inputs of 5.0, 12, and 24V and two, three, or four output channels of 24V are provided with high isolation between outputs. Exhibiting versatility, outputs can also be connected in parallel or series. Providing reliable operation in the fastest of switching systems, the devices suit DC link voltages up to 3kV DC and feature a characterised dV/dt immunity of 80kV/microsecond and a characterised partial discharge performance that provides long service life.
The use of a planar transformer, short circuit and overload protection provide robust operation under system fault conditions, and a low coupling capacitance of typically 15pF that reduces system EMI problems. A frequency synchronisation pin simplifies EMC filter design and an enable pin provides for power saving.
A pending application for UL60950 recognition for reinforced insulation will reduce the overall cost of system approval. Similarly, approvals for ANSI/AAMI ES60601-1, two MOOPs, and two MOPPs at different system voltage levels are pending and when attained will simplify system approval for medical applications.