High-voltage MOS selection tips
Author: Shenzhen Yuan Zhi Electronics Co., Ltd.Time:2018-03-01 17:15:33Views:2040【SML】
The
high-voltage MOSFET is the research and development and production of
BYD Microelectronics Company. According to the market demand, the main
products are 500V (5A, 9A), 600V (1A, 2A, 4A, 6A, 8A...
label:
The
high-voltage MOSFET is the research and development and production of
BYD Microelectronics Company. According to the market demand, the main
products are 500V (5A, 9A), 600V (1A, 2A, 4A, 6A, 8A, 10A and 12A) 220
/ TO-220F / TO-251 / TO-92 and other plug-in package, there are TO-252
and other D-PAK package. High voltage MOS uses a very wide range of
applications are mainly used in various types of chargers, adapters, PC
power, LCD-TV
power supply, UPS, high-voltage MOS selection of electronic ballasts
and so on, since the product in October 2009 marketing, just six months
with a stable quality, excellent service, good prices at home and abroad
with the same High-voltage MOS in the industry fierce competition shows a place, and the client made a good reputation.
High-voltage
MOSFET components using two basic process technology: one is more
traditional planar processes, such as Fairchild QFET UniFET. The other is a newer charge balance technique. The
planar process is very stable and robust, but the high-voltage MOS
selection technique has a much higher on-resistance, RDS (on), than
charge-balancing techniques such as Fairchild's SuperFET and SupreMOS
MOSFETs for the specified active area and breakdown voltage ) Of RDS (on). For
high-voltage MOS specification specific RDS (on), the significant
difference in the size of the high-voltage MOS selectors active area
affects output characteristics and gate charge to other features such as
thermal resistance and switching speed of the MOSFET components. Figure 1 shows some of the differences between these three process technologies.
With
a typical RDS (on) of 1Ω at a breakdown voltage and size, the new
high-voltage MOS shows that RDS (on) for charge-balanced components such
as Fairchild's SupreMOS MOSFETs is less than 0.25Ω. If
you just focus on RDS (on), you might mistakenly believe that MOSFET
components that are one-fourth the size of traditional components can be
used in existing applications. The idea is wrong because when the die size HV MOS selection technique itself is smaller, it has a higher thermal resistance. Therefore, when you realize that the MOSFET is more than just
an active area characterized by RDS (on), the above is further
validated.
It
also has a high-voltage MOS description called "edge terminations" of
the edge of the ring area, designed to prevent the occurrence of die
edge voltage collapse of the die, leaving the components in the active
area collapse. For
smaller MOSFETs, especially for high-voltage components, the edge
region may be larger than the active region, as shown in FIG. 2. Although
the marginal region does not contribute much to the RDS (on) of the
MOSFET, it contributes to the thermal resistance of the junction to the
package R J JC. Therefore, having a very small active area at higher RDS does not significantly reduce the overall cost of the MOSFET.
The
importance of thermal resistance is manifested in several aspects,
including the rated current of the component, as shown in the following
table. The
three different 600V components listed in the table each have a rated
current of 7A, but the RDS (on) values differ greatly from those of
the RэJC values. Since the MOSFET's current rating is completely determined by
the conduction loss equation, the effect of the reduced thermal
resistance is significant.
Therefore, choosing the right part actually depends on how you intend
to use the part, what switching frequency you are going to use, what
topology and thermal path in the application, and of course the cost you
are prepared to accept.
Some
common guidelines are advanced planar processes that are better
solutions for power factor correction (PFC) and flyback applications
without parasitic diode recovery losses if the RDS (on) required to meet
the efficiency requirements is greater than 1 Ω Such as UniFET (II), QFET or CFET. This is mainly because the lower RэJC helps keep MOSFET components cooler. For
such large RDS (on) requirements, the active area of the charge
reflective component accounts for only a small fraction of the total die
area due to the edge termination. See Figure 1 and Figure 2. For
these applications, planar MOSFETs, even with larger silicon wafers,
are less expensive processes, and they cost about the same package.
2018-03-01
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