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46 EE|Times EUROPE — Boards & Solutions Insert

POWER MANAGEMENT
Simplify Your Driver for Power Applications

By Maurizio Di Paolo Emilio

ith the emergence of new fields
of application and markets,
global power requirements have
W skyrocketed in recent years,
making energy savings an essential aspect of
equipment design. This has made high-
efficiency inverter circuits and converters
indispensable, especially for power supplies
and drivers requiring high power conversion.
Along with the need to achieve high
efficiency, the challenges of reducing the
device size have increased. This reduction is
generally achieved by increasing the operat-
ing frequency. That increase, in turn, requires
more complex drivers and optimization of
the drive voltage of the silicon carbide (SiC)
MOSFET or IGBT.
The objective of increasing efficiency
while reducing device size has increased the
demand for high-performance power devices Figure 1: Soft turn-off protection (Image: Tamura)
and gate drivers. The market is therefore
expected to expand for SiC power devices,
which epitomize high efficiency and are the insulation voltage to k , according some freedom in arranging the module
increasingly popular in new-generation to the company. layout to maximize efficiency and minimize
inverters. SiC diodes are already used in the Most of the modules are rated for maxi- noise. Tamura has designed its own planar
power-factor correction (PFC) circuits of mum output power of about 1 0 kW, but a transformer, which is suitable for the 1, 00-
power supplies and high-power inverters, and “ in1” driver unit able to provide up to module series.
SiC MOSFETs are increasingly used in switch- 1 MW is also available. First-generation (up to The company’s GDMs include several
ing applications. SiC MOSFETs can improve 1,200- ) products include the driver module protection modes, such as soft turn-off. As
inverter efficiency by enabling high-speed and driver unit. Second-generation (up to shown in Figure 1, by adding a resistor to the
switching, along with circuit layout of fault 1, 00- ) devices also include three-level soft turn-off pin, it is possible to define the
protection and configuration to reduce the DC DC converters and a in1 driver unit. turn-off time.
noise generated in the gate control circuit. Depending on the specific application, A Miller clamp function in the GDM pre-
designers can decide whether to design a vents malfunction of the SiC power module
TAMURA GATE DRIVER MODULE complete driver around the DC DC converter with a low threshold voltage and high d dt.
With a core competency in magnetic circuits, or use the 2in1 solution (module and driver This protection prevents an increase in gate
Tamura has several years of experience in the units). Tamura says that its all-in-one solu- voltage due to the Miller current of the power
development of SiC IGBT gate driver modules tion saves the time and costs required by a full device connected to the output pin. Finally, an
(GDMs). The company targets the design of design activity, and the company cites other active clamp gate feature protects the power
highly integrated devices, such as modules, benefits of its modules as well. module from surges affecting the collec-
rather than individual components. The For example, suppose there is a problem tor-emitter voltage ( CE) signal.
modules simplify circuit design because they with common-mode noise, and we want to
are essentially plug-and-play Designers need eliminate any malfunction caused by it. A ROHM, TI, MAXIM, AND INFINEON
only define the input and output signals, and typical solution would be to raise the d dt, RO M Semiconductor has created gate
everything else is performed internally by the but that requires low parasitic capacitance. drivers with an integrated isolator that
module, according to Tamura. Tamura modules have very low stray capac- takes full advantage of the performance of
A notable characteristic of the gate driver itance ( pF for the 2DD series and 12 pF for IGBT and MOSFET power. The BM610 F
module is that the gate-driving signal is the 2DMB series) and therefore can suppress integrates short-circuit protection, while
transmitted using magnetic coupling, a the common-mode noise that results from the BM6001 F ’s simple design accelerates
technology with which Tamura has extensive high d dt, preventing equipment malfunc- the product development process, according
experience. Its modules are available both in tion due to noise propagation to the input to RO M. The gate drivers are housed in
a standalone version (“driver module”) and side and the other channels. compact packages that the company says
with a connector board (“driver unit”) able The driver circuit internal impedance are the smallest in the industry to include
to fit on a corresponding power module from is a very low 0 m or less, even at higher the isolator. The products combine the
any manufacturer. Tamura looks to optimize switching frequencies, according to Tamura company’s Bi-CDMOS technology with new
the footprint and profile of its modules and therefore, switching speed is not inhibited on-chip-transformer technology.
recently introduced devices that swap out a by the gate impedance. The small module Late last year, Texas Instruments intro-
larger transformer for a planar equivalent. packages fit within the footprint of most duced isolated gate drivers with integrated
Switching to the planar transformer increased power module types, affording the designer detection for IGBTs and SiC MOSFETs. The

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