650 V SUPERFET) III FRFET)
New Fast Reverse Recovery
Super-Junction MOSFET forHigh Efficiency and Reliable
EV Charging Applications
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AND90126/D

APPLICATION NOTEINTRODUCTION

The fast DC charging pole is rapidly expanding
throughout the world. The fast chargers are required to makeit possible to drive longer distances and overcome range
limitation without spending several hours charging thebattery [1]. The three−phase Vienna PFC and two−level
full−bridge LLC resonant converter using 600~650 V superjunction MOSFETs are typical topologies used fordeveloping power modules for DC EV chargers. These
topologies are popular for EV fast charging poleapplications due to the high efficiency, reduced voltage
stresses on semiconductor switches, and high power density.
Historically, super junction MOSFETs have been used inresonant topologies such as the LLC, but the body diodereverse recovery performance of the super junction
MOSFET is not attractive for many soft−switching
topologies due to its body diode performance. As shown in
Figure 1, the reverse recovery of conventional planar
MOSFET is much softer than that of super−junction
MOSFET. When considering similar circuit situations, asnappy body diode always generates higher voltage spikes
and drain voltage slew rates (dVDS/dt), which often resultsin device failure.

The soft body diode of the Planar MOSFET is suitable forresonant topologies. Furthermore, low reverse recovery
charge (QRR) and robust body diode characteristics arecorrelated to increased reliability. However, low on−state
resistance (RDS(ON)) and stored energy in the output
capacitance (EOSS) of the MOSFET are critical parameters
used to maximize efficiency in resonant converters.
Therefore, the low RDS(ON) and EOSS combined with therobust body diode of the fast recovery super−junction
MOSFETs can effectively minimize resonant energy
required to achieve soft switching without increasing thecirculating energy and improve the system reliability. A fast
recovery body diode Super Junction (SJ) MOSFET called,
SUPERFET® III FRFET®, combines the best−in−classbody diode performance with low dynamic resistance(ROSS) and improved switching transients to optimize
efficiency in resonant converters. In this application note,
power MOSFET parameters of new fast recovery SJ
MOSFETs are analyzed in the two−level full bridge LLC
resonant converter used for EV fast DC charger, along andtheir impact on reliability.
650 V SUPERFET III FRFET
Target Application and Topologies

High voltage Super−Junction MOSFETs were developed
to satisfy specific system requirements such as: improved
system efficiency, reduced voltage spikes, high EMI
performance, increased system reliability and costeffectiveness in several applications, as shown in Figure 2.
SUPERFET III FRFET is optimized for soft switching
topologies such as the Phased Shifted Full Bridge (PSFB) or
LLC resonant topology that requires an improved reverse
recovery body diode, especially for high performance
applications such as Server / Telecom powers and EV
charges.

Figure 1. Reverse Recovery Behavior Comparison
between Planar MOSFET and Super−junction
MOSFET under VDD = 400 V, di/dt = 100 A/ms,
ISD = 20 A

© Semiconductor Components Industries, LLC, 2021

July, 2021 − Rev. 0

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Publication Order Number:AND90126/D

AND90126/D

Figure 2. Target Application for 600 V ~ 800 V Super−Junction MOSFETs
Features and Benefits of 650 V SUPERFET III FRFET

time of the body diode. However, there are some drawbacks
due to the lifetime control processes. More lifetime control
often results in the further increase of MOSFET
on−resistance. This will add more power loss and is criticalto the resonant converters. The SUPERFET III FRFET has
been optimized to combine the lower RDS(ON) while
dramatically improving body diode performance. The
SUPERFET III FRFET reduced the QRR and TRR by about
91% and 71% respectively, compared to those of EASY
DRIVE as shown in Figure 3.

The SUPERFET III FRFET technology can provide low
RDS(ON) and the best−in−class body diode for lower
conduction loss, and increased reliability in many AC−DCSMPS applications, which often require high power density,
high system efficiency and high reliability.
Many optimizations have been achieved on the MOSFET
body diode since more applications require the embedded
body diode to perform as the critical component in thesystem. Lifetime control is a very effective solution used toreduce the reverse recovery charge and reverse recovery

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Figure 3. Body Diode Reverse Recovery Comparison between 650 V SUPERFET III FRFET vs EASY Drive
under VDD = 380 V, ISD = 38 A, di/dt = 200 A/ms, Tj = 255C

for space−constrained applications such as fast EV charging
systems by reducing the number of paralleled devices.
Furthermore, the kelvin source SMD packages such as thePower88 and TOLL are available for space−constrained
applications such as telecom and server power systems. The
new SUPERFET III FRFET provides the best−in−classbody diode performance such as the extremely small QRR,
low voltage spikes, and best−in−class body dioderuggedness, while still providing ultra−low RDS(ON) andexcellent switching performance. SUPERFET III FRFET
achieved 45% lower RDS(ON) compared to previous
generation with faster switching and the best−in class body
diode performance. Table 1 provides other parameter
improvements that truly benefit in resonant converters
applications. As shown in Table 1, Both figures−of−merit(FOM’s) , [RDS(ON) × QG] and [RDS(ON) × QRR] of
SUPERFET III FRFET are dramatically reduced by 46%
and 57% respectively, compared to the previous generation.

Figure 4. Minimum RDS(ON) (Max.) in different
Packages of Power MOSFETs

As shown in Figure 4, the lowest possible maximum
RDS(ON) of the SUPERFET III FRFET is 27 mW for
TO−247 and 82 mW for TO−220 package. It is well suited

Table 1. CRITICAL SPECIFICATION COMPARISON UNDER SAME CONDITION
DUTs

BVDSS

RDS(ON) max.

Qg max.

Trr

Qrr

650 V / 33 mW SUPERFET III FRFET, NTHL033N65SHF

650 V

33 mW

600 V / 41 mW SUPERFET II FRFET, FCH041N60F

600 V

41 mW

182 nC

78 ns

1.4 mC269 nC103 ns

2.6 mC

600 V / 37 mW Fast Recovery SJ, Competitor A

600 V

37 mW

600 V / 38 mW Fast Recovery SJ, Competitor B

600 V

38 mW

128 nC82 ns

1.6 mC

220 nC103 ns

2.5 mCAs shown in Figure 6, SUPERFET III FRFET shows thebest−in−class body diode performance under the same test
condition. The QRR of the SUPERFET III FRFET is reducedby 46%, 22%, and 44% respectively, compared to previous
fast recovery SJ MOSFETs and competitors even though it
has the lowest RDS(ON). Due to the the extremely low QRR,
it shows the lowest voltage spikes during reverse recovery.
The improved body diode of the SUPERFET III FRFET can
effectively prevent device failure by reverse recovery dv/dt
and static breakdown in resonant topologies under abnormal
conditions. The output capacitance determines how much

The Power MOSFET devices used on the primary side of
the LLC resonant converter must have a rugged body diodesince there are a many hard commutation situations that cancreate very high MOSFET stress, especially during output
short−circuit condition or start−up [2].
Figure 5 shows an LLC resonant converter during ashort−circuit condition, where one of the primary side
Power MOSFETs failed.

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AND90126/D
circuit inductance is required to enable ZVS conditions.
SUPERFET III FRFET has approximately 25% less EOSS at
400 V than previous generation. Therefore, lower COSS of
SUPERFET III FRFET requires less resonant energy toachieve soft switching without increasing the circulatingenergy.

Figure 5. Waveforms of Power MOSFETs in LLC
Resonant Converter at Short−Circuit Condition(a) 33 mW SUPERFET III
FRFET(b) 41 mW SUPERFET II
FRFET(c) 37 mW Competitor A(d) 38 mW Competitor B

Figure 6. Comparisons of Reverse Recovery Behavior of Fast Recovery SJ MOSFETs under ISD = 20 A,
di/dt = 800 A/ms, VDS = 400 V
Dynamic ROSS Loss in LLC Resonant Converters

Recently, the power loss from the hysteretic COSS
behavior is analyzed in many papers [3]. Unexpected power
losses associated with the latest SJ MOSFETs in ZVS
topologies generated due to the hysteretic phenomenon of
the output capacitance, COSS. This power losses related to
COSS hysteresis is more critical when operating under highfrequency soft switching conditions, especially in medium
and light loads. Figure 7 describes the COSS charge anddischarge parts, where the electron current (black dashedline) and hole current (red dashed line) and charge pockets(resistance) during charge and discharge of SJ MOSFET.
Current flow of electron and holes originates charges
between the N− epi and P−well pillars and must be removed
through a highly resistive path. The resistance by this charge
pocket (ROSS) can be treated as a equivalent resistor during
charging and discharging. This energy losses can beobserved by the hysteresis loop area large signal COSS
during charge−discharge cycle as shown in Figure 8. Theenergy loss related to the COSS hysteresis of thesuper−junction MOSFET depends on the design.

(a) COSS Charge(b) COSS Discharge

Figure 7. COSS Charge and Discharge of SJ MOSFET,Electron (e−) and hole (h+) Currents and Charge
Pockets (Black and Red)

Figure 9 shows the resulting equivalent circuit of the
MOSFET during COSS charging and discharging in the LLC
resonant converter.

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AND90126/D
ROSS results in a dynamic COSS loss for every switchingcycle and increases the energy dissipated in the device [4].
This additional dynamic COSS of the super junction
MOSFET is much higher than the planar MOSFET due toits epi pillar structure. This dynamic COSS loss is affected bydevice structure, die size, and switching dVDS/dt.

Figure 8. Comparison between Small Signal COSS
(green line) and Large Signal COSS(red and bluelines)

Figure 10. Energy Losses of SJ MOSFET during
ROSS Energy Loss vs Switching dv/dt during
Charging and Discharging [0~400 VDS]

Figure 10 shows energy losses of the super−junction
MOSFET during charging and discharging of the COSS
according to the switching dVDS/dt. The energy loss fromROSS is higher under a high dVDS/dt condition, because of
the higher displacement current generated by the highdVDS/dt (I2 ⋅ ROSS). As a results, the highly resistive paththrough ROSS induces significant Joule heat for electrons
and holes at N−epi and P−well pillars during the higher
dVDS/dt switching. SUPERFET III FRFET is optimized forlower COSS energy dissipation.
Performance Evaluation in 15 kW Fast EV Charging
Module

The temperature and efficiency of the SUPERFET III
FRFET is compared with the best competitor in a two−level
LLC resonant converter of 15 kW fast EV charging module.
Input voltage of the fast EV charging module is operated
from a three−phase 380 VAC input with output voltage andcurrent set to 750 V and 20 A, respectively. Total
8 pcs~16 pcs super junction MOSFETs (Q7~Q14) are usedin the primary side of two−level full−bridge LLC resonant
converter shown in Figure 11.

Figure 9. Equivalent Circuit of MOSFET during
COSS Charging & Discharging in LLC Resonant
Converter

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Q7
D1

D3

Q8

D5

D7

Q1

Q2

Q3

Q4

Q5

Q6

Q9

Q10

Q11

Q 12

250
~ 750 V
D8

D9

D2

D4

D6
Q13

Q14
D10

Figure 11. Power Stage of EV Charging Module : 3 phase Vienna PFC and Two Level Full−bridge LLC
Resonant Converter(a) POUT = 5 kW: 200 V / 25 A / 207 kHz, above resonant
frequency (fs > fr)(b) POUT = 15 kW: 750 V / 20 A / 127 kHz, below resonant
frequency (fs < fr)

Figure 12. Operation Waveforms in 15 kW Two−level FB LLC of EV Charging Module

Output voltage range of the EV charging module is200~750 V and depends on the battery voltage of EV cars.
Figure 12 shows the operation waveforms of the power
MOSFET. At light condition (5 kW, 200 V / 25 A), switchingfrequency (200 kHz) the dVDS/dt during the turn−offtransient is much higher than full load condition (15 kW,
750 V / 20 A, 127 kHz). The MOSFET channel isconducting during period “t1” and the MOSFET COSS ischarged during period “t2” Figure 12 shows the operating
waveforms in the 15 kW two−level FB LLC of the EV
charging module under light and full load. Therefore, ROSS

loss of the primary side MOSFETs is much more critical due
to higher switching frequency and dVDS/dt under light loadcondition.
Especially, power loss of MOSFET is critical because
there are many devices (8~16 pcs) used in the two−level FB
LLC of the EV charging module. It is not only an issue ofefficiency, but also of thermal management and reliability inthis application. Power dissipation in the MOSFETs ishighly dependent on on−resistances, ROSS, gate charge, andbody diode condition period as well as the switchingfrequency and operating temperature.

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AND90126/D
conduction loss and output capacitive loss because of lower
RDS(ON) and ROSS.

Figure 13. Power Loss Distribution under Light
Load and Full Load in Two−level FB LLC of EV
Charging Module

Figure 13 shows the power loss distribution of the
MOSFETs in two−level FB LLC resonant converter of EV
charging module under both light load and full load.
As shown in Figure 13, the ROSS loss is a more critical loss
for light load efficiency. These parasitic−related losses area function of dVDS/dt and the ROSS of output capacitance ofthe MOSFET are proportional to the switching frequency. In
order to increase system efficiency, ROSS loss has to be
reduced while using a low RDS(ON) device. Figure 13 shows
power loss distribution under light load and full load in
two−level FB LLC of EV charging module. Both ROSS loss
and RDS(ON) loss of 33 mW SuperFET III FRFET is reduced
about 16% and 30% compared to 41 mW competitor
respectively in light load and full load condition. Also total
power losses of device in light load is higher than those infull load condition. Therefore case temperature of device ishigher in light load condition in Figure 14. As shown in
Figure 14, efficiency of SUPERFET III FRFET increases
about 0.25%~0.27% and the operating temperature is
reduced by 5.7°C to 9°C compared to the competitor at lightand full load condition, respectively thanks to the reduced

Figure 14. Thermal and Efficiency Comparison in
Two−level FB LLC of 15 kW EV Charging Module
650 V SUPERFET III FRFET HF Series

There are two versions of the SUPERFET III FRFET, theF−version and HF−version. Table 2 shows the performancetrade−off between the SUPERFET III FRFET F−version
and HF−version that can be used as a customer’s design
requirements. The SUPERFET III FRFET HF−version isdesigned with very low ROSS loss since it uses a slightly
different pillar process than the F−version. It is developed tosupport applications that need higher efficiency for both
hard and soft switching topologies. The SUPERFET III
FRFET F−version shows relatively lower turn−off dv/dt for
better EMI, but increases ROSS loss compared to the
HF−version. For better system efficiency, it is recommended
to use the SUPERFET III FRFET HF version since it offers
lower ROSS and switching losses as shown in Figure 15 and16. The trade−off is that the HF−version will switch fasterwith higher dv/dt compared to the F−version.

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Figure 15. Comparisons of Turn−off Switching Characteristics: 82 mW SUPERFET III FRFET F and HF
version under VDD = 380 V, VGS = 10 V, RG = 4.7 W

Figure 16. Power Loss Comparison: SUPERFET III FREFET F vs HF vs Competitor under in Two−level FB
LLC of EV Charging Module

Table 2. PERFORMANCE TRADE−OFF AND BENEFITS BETWEEN SUPERFET III FRFET F VERSION AND HF
VERSION
FRFET F Version
Performance

Benefit

FRFET HF Version

Slow switching @Turn off→ Low peak Vds→ Low dv/dt and Gate Oscillation

Fast switching @Turn off→ lower ROSS loss
→ Lower switching loss

Better EMI

Better system efficiency

Conclusion

minimizing the ROSS loss. The FRFET series can provide
outstanding reliability performance in soft switching
topologies. Due to the very low A·RDS(ON) of theSUPERFET III FRFET, it is highly optimized for thetwo−level FB LLC resonant converter for high power fast
EV charging applications.

The latest SUPERFET III FRFET shows best in classbody diode performance and low dynamic COSS loss. The
SUPERFET III FRFET technology is designed to achieve
better efficiency not only at the full load condition with low
conduction loss, but also at the light load conditions by

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Figure 17. 650 V SUPERFET III FRFET MOSFET Lineup
Reference[3] J.B. Fedison, M. Fornage, M.J. Harrison, and D.R.
Zimmanck, “COSS Related Energy Loss in PowerMOSFETs Used in Zero−Voltage− Switched Applications,”
APEC 2014 Proceedings, pp. 150−156, 16−20 March 2014.
[4] J. Roig, F. Bauwens, “Origin of Anomalous COSS
Hysteresis in Resonant Converters With Superjunction
FETs,” Electron Devices, IEEE Transactions on, vol.62,
no.9, pp.3092−3094, Sept. 2015.

[1] Ministry of Housing and Urban−Rural Development.
(2015, Dec. 7). Notice on Enhancing the Planning andConstruction Work of Electric Vehicle Charging
Infrastructure.
[Online].
SUPERFET
Available:
http://www.mohurd.gov.cn/wjfb/201601/t20160115_
226326.html[2] Wonsuk Choi; Sungmo Young; Dongwook Kim,
“Analysis of MOSFET Failure Modes in LLC Resonant
Converter,” in International Telecommunications Energy
Conference, INTELEC, 2009, pp. 1 − 6Authors

Wonsuk Choi, Sungnam Kim and Jon Gladish,Application Engineer, PSG, ON Semiconductor.

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