Fairchild SupreMOS service manual
www.fairchildsemi.com
AN-9068
Gate Resistor Design Guidelines for SupreMOS® MOSFETs
Summary
The faster switching of power MOSFETs enables higher
power conversion efficiency. However, parasitic
components in the devices and boards are involving
switching characteristics more as the switching speed
increases. This creates unwanted side effects, like voltage
spikes or poor EMI performance. To achieve balance, it is
important to have optimized gate drive circuitry because a
power MOSFET is a gate-controlled device. One of critical
control parameters in gate-drive design is external series
gate resistor (R
maximum values of R
hard-switching applications. As too small R
). This note suggests minimum and
g
for the SupreMOS® MOSFETs in
g
results in
g
excessive dv/dt across drain and source of the MOSFET
during switching-off, low limit is a value that makes
switching dv/dt within the specification in the datasheets.
Silicon Carbide (SiC) Schottky barrier diode, Deuxpeed
rectifier, and STEALTH™2 diodes are used for clamp diode
since the diode characteristics affect the dv/dt. Too large R
causes loss and poor efficiency; therefore, the upper limit is
chosen to have the same switching losses as the SuperFET
MOSFETs or competitors.
Minimum Values According to dv/dt
Table 1 shows low limits of Rg. The unit of Rg in Table 1 is
Ohm (). Since the dv/dt varies by drain current level, it is
tested with two conditions. For example, when using
FCP76N60N with a SiC diode under half of rated current, at
least 13 or larger R
dv/dt under 50V/ns during switching-off transient.
The dv/dt with a SiC diode is lower than dv/dt with other
diodes due to the bigger junction capacitance of SiC SBD.
A gap of the dv/dt values is getting larger at lower drain
current level and smaller R
current, the dv/dt is relatively low and the effect of output
capacitance of the MOSFET and diode junction capacitance
on the dv/dt becomes more significant.
If a specific R
value is needed for other dv/dt not shown in
g
Table 1, it can be selected by referring to Figure 13 through
Figure 18.
is required to keep the switching
g
. This is because, at lower
g
Table 1. Minimum Rg Guidelines Ohms
R
at 1/2 of Id
g
FCP9N60N 0 0 0 0 33 36
FCP11N60N
FCP13N60N 0 0 0 27 36 39
FCP16N60N 0 0 6.8 27 33 36
FCP22N60N 0 13 18 27 36 39
FCP25N60N 0 13 18 22 36 36
FCA36N60N 6.8 13 16 22 33 36
FCA47N60N 6.8 11 13 22 27 27
FCA76N60N 6.8 6.8 6.8 13 16 16
Rg at Rated Id
FCP9N60N 6.8 13 18 27 43 47
FCP11N60N 6.8 13 18 27 36 39
®
g
®
FCP13N60N 10 16 22 30 43 47
FCP16N60N 10 13 18 27 36 39
FCP22N60N 10 16 22 30 43 47
FCP25N60N 13 16 18 27 39 43
FCA36N60N 13 16 18 22 36 39
FCA47N60N 11 13 13 16 27 27
FCA76N60N 6.8 6.8 10 13 18 18
dv/dt<100V/ns dv/dt<50V/ns
SiC Dx S2 SiC Dx S2
0 0 0 0
dv/dt<100V/ns dv/dt<50V/ns
SiC Dx S2 SiC Dx S2
Upper Limits Considering Switching
Losses
When the SuperFET® MOSFET or other previousgeneration power MOSFET is directly replaced with the
SupreMOS MOSFET, switching losses are reduced, but the
dv/dt may be higher. To control the dv/dt of SupreMOS
MOSFETs, increased R
should be a limit line for increasing the R
losses with SupreMOS MOSFET could be larger. Figure 19
through Figure 54 show switching losses acco rd ing to R
each device. R
for similar or less switching loss can be
g
raised. For example, if 10 is used for a FCA35N60
SuperFET MOSFET, 33 achieves similar E
under conditions of half of rated drain current and
STEALTH™2 diode.
is required. In this case, there
g
or switching
g
and E
ON
33 36
for
g
in
OFF
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
Rev. 1.0.3 • 4/6/11
AN-9068 APPLICATION NOTE
Typical Performance Characteristics
140
w/ SiC SBD
1/2 of Id
120
w/ Deuxpeed®rectifier
w/ STEALTHTM 2 diode
100
80
60
dv/dt [V/ns]
40
20
0
0 10203040506070
Rg (Ohm)
Figure 1. FCA76N60N dv/dt at Half I
160
140
120
100
80
60
dv/dt [V/ns]
40
20
0
0 10203040506070
1/2 of Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM 2 diode
Rg (Ohm)
D
180
160
140
120
100
80
dv/dt [V/ns]
60
40
20
0
0 10203040506070
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM 2 diode
Rg (Ohm)
Id
Figure 2. FCA76N60N dv/dt at Rated I
300
250
200
150
100
dv/dt [V/ns]
50
0
0 10203040506070
Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM 2 diode
Rg (Ohm)
D
Figure 3. FCA47N60N dv/dt at Half I
160
140
120
100
80
60
dv/dt [V/ns]
40
20
0
0 10203040506070
1/2 of Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM 2 diode
Rg (Ohm)
D
Figure 5. FCA36N60N dv/dt at Half I
D
Figure 4. FCA47N60N dv/dt at Rated I
330
300
270
240
210
180
150
120
dv/dt [V/ns]
90
60
30
0
0 10203040506070
Figure 6. FCA36N60N dv/dt at Rated I
D
Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM 2 diode
Rg (Ohm)
D
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
Rev. 1.0.3 • 4/6/11 2
AN-9068 APPLICATION NOTE
Typical Performance Characteristics
160
140
120
100
80
60
dv/dt [V/ns]
40
20
0
0 10203040506070
w/ SiC SBD
w/ Deuxpeed® rectifier
w/ STEALTHTM2 diode
Rg (Ohm)
Figure 7. FCP25N60N dv/dt at Half I
1/2 of Id
130
120
110
100
90
80
70
dv/dt [V/ns]
60
50
40
30
20
0 10203040506070
1/2 of Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
350
300
w/ SiC SBD
w/ Deuxpeed® rectifier
w/ STEALTHTM2 diode
Id
250
200
150
dv/dt [V/ns]
100
50
0
0 10203040506070
Rg (Ohm)
D
Figure 8. FCP25N60N dv/dt at Rated I
D
Id
200
180
160
140
120
100
80
dv/dt [V/ns]
60
40
20
0
0 10203040506070
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM diode
Rg [Ohm]
Figure 9. FCP22N60N dv/dt at Half I
120
100
80
60
dv/dt [V/ns]
40
20
0
0 10203040506070
1/2 of Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
Figure 11. FCP16N60N dv/dt at Half I
D
D
Figure 10.FCP22N60N dv/dt at Rated I
200
180
160
140
120
100
80
dv/dt [V/ns]
60
40
20
0
0 10203040506070
Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM diode
Rg [Ohm]
Figure 12.FCP16N60N dv/dt at Rated I
D
D
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
Rev. 1.0.3 • 4/6/11 3
AN-9068 APPLICATION NOTE
Typical Performance Characteristics
100
90
80
70
60
dv/dt [V/ns]
50
40
30
20
0 10203040506070
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
Figure 13. FCP13N60N dv/dt at Half I
1/2 of Id
80
70
60
50
40
dv/dt [V/ns]
30
20
10
0 10203040506070
1/2 of Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
200
180
160
140
120
100
80
dv/dt [V/ns]
60
40
20
0
0 10203040506070
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
Id
D
Figure 14.FCP13N60N dv/dt at Rated I
D
Id
200
180
160
140
120
100
80
dv/dt [V/ns]
60
40
20
0
0 10203040506070
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
Figure 15. FCP11N60N dv/dt at Half I
80
70
60
50
dv/dt [V/ns]
40
30
20
0 10203040506070
Figure 17. FCP9N60N dv/dt at Half I
1/2 of Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
D
D
Figure 16.FCP11N60N dv/dt at Rated I
180
160
140
120
100
dv/dt [V/ns]
80
60
40
20
0 10203040506070
Id
w/ SiC SBD
w/ Deuxpeed®rectifier
w/ STEALTHTM2 diode
Rg [Ohm]
Figure 18.FCP9N60N dv/dt at Rated I
D
D
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
Rev. 1.0.3 • 4/6/11 4
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