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www.fairchildsemi.com
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11
AN-9742 Device Selection Guide for Half-Bridge Welding Machine
(IGBT & Diode)
Summary
Various topologies; including two SW-forward, half-bridge
and full-bridge, have been used for low-voltage / high-
current DC-ARC welding machines for system minimization
and efficiency improvement. Of these topologies, half-
bridge is the most commonly used for small form factor, less
than 230A capacity welding machines. Compared to full-
bridge topology with the same power rating, half-bridge
requires more transformer wiring and higher current
capacity of inverter; but requires fewer power devices.
Taking a Fairchild evaluation board as the example, this
article presents a device selection guide for a half-bridge
welding machine application.
Description of Welding Machine
Generally, based on the type of welding machine, the output
voltage can be calculated as shown in Table 1.
Table 1. Welding Machine Output Voltage
Welding
Machine Output Voltage Example
CO2 0.04•IAC+15 0.04•200A+15=23V
TIG 0.04•IAC+10 0.04•200A+10=18V
DC ARC 0.04•IAC+20 0.04•200A+20=28V
Duty Cycle of a Welding Machine
In the welding industry; duty cycle refers to the minutes out
of a 10-minute period a welder can be operated at maximum
rated output without overheating or burning up the power
source. For instance, a 140A welder with a 60% duty cycle
must be “rested” for at least 4 minutes after 6 minutes of
continuous welding at maximum rated output current 140A.
Allowable Duty Cycle
If actual current in use is smaller than a rated output current,
the welder internal heating decreases. The welder then can
be used at a higher rate than the specified duty cycle. Its
allowable duty cycle can be calculated as:
machine weldingof cycleduty currentoutput using
currentoutput rated2
×
= (1)
For example, since only 80A to 130A current would be
required to weld a 3.2 welding rod, a 140A welder with a
60% duty cycle can operate for a longer time for this
application. Assuming 100A is used to weld a 3.2 welding
rod, actual duty cycle is more than 78.4%.
Besides the actual output current, the temperature also
affects the allowable duty cycle of a welding machine.
Do NOT overheat welder machines.
Table 2. Feasible Welding Materials by Welding Machine
Welding Machine Gas Welding Type Steel
CO2 CO2 Mild, High Tensile
MIG He + Ar Aluminum, SUS, Aluminum Alloy
MAG Sheet Metal, Low Alloy, High Tensile
DC-TIG Stainless, Mild, Copper Alloy, Nickel Alloy, Titanium Alloy, Low Alloy
AC-TIG Aluminum Alloy, Magnesium Alloy, Bass
Mixed TIG Light Alloy, Clad Plate
DC-ARC Steel, Nonferrous Metals
AC-ARC Aluminum
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 2
Fairchild DC-ARC Welding Machine Evaluation Board
Evaluation Board Features
� Input Stage: 50A Bridge Diode (600V, 50A, Square-
Bridge Type)
� Input Filter Stage: Designed Under Consideration of
Conductive Noise and Radiation Noise
� Controller: PIC16F716 (8-Bit ADC and 10-Bit PWM)
� Inverter Stage: FGH40N60SMD (within Co-Pak Diode)
Single or Parallel
� Output Rectifier: FFA60UP30DN * Six Units (Three
Ultra-Fast Diode in Parallel)
� Gate Driver: Opto-Coupler for the Isolation between
Switching Devices and Controller Dual Power Supply
+15V, -5V for IGBT Gate Voltage
� AUX Power Supply: Lower Standby Consumption Green
Integrated PWM IC
� Input Voltage and Frequency: 220VAC 60Hz
� Output Voltage (VOUT) and Output Current (IWEL):
26VDC, 140A
� Efficiency: > 80%
� Idle Power: < 4W
� Switching Frequency: 20KHz
Figure 2 shows the main block diagram of the welding
machine evaluation board. The output current and output
voltage of the DC-ARC welding machine evaluation board
are 26V and 140A, which constitutes a 3kW-class welding
machine. Various Fairchild Semiconductor components are
used to meet the design requirements. The switching
frequency of the machine is 20KHz. Due to their size; the
transformer and inductor are installed beside the board. An
air fan is attached for cooling.
Figure 1. Evaluation Board
Figure 2. Main Block Diagram
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 3
Half-Bridge Inverter Design
The turn ratio of the primary and secondary of the
transformer in a half-bridge topology can be obtained from
the equation:
4
)(1
SWe
MAXMININ
fAB
DVN
∗××
×=
(2)
)(
)(
11
MININMAX
IFO
VD
NVVVN
×
×++= (3)
where VI = VS, IWEL = output current, Id1 & Id2 = diode
current (output high side & output low side).
Output voltage under no load condition is given by:
( )MAX
IFOnolaod
D
VVVV
=+= (4)
where:
VO=output voltage;
VF=diode drop voltage; and
VI=inductor voltage drop.
Transformer’s primary and secondary current can be
obtained by:
( )MAXWELrms DIN
NI ×××= 2
1
21 (5)
( )MAXWELrms DII ×+××= 212
12 (6)
Current running through the IGBT and secondary-side
rectifier diode can be calculated by:
WELIN
IGBT ×=1
2D
NI :Current (7)
Output rectifier diode voltage and current:
22
21)( ,
1
2ddWELMAXINr IIIV
N
NV +=×= (8)
IGBT Selection for Welding Machine
Among various power switching components, Insulated Gate
Bipolar Transistor (IGBT) is the most suitable device for
welding machines thanking for its high current handling
capability and high switching speed. IGBT is a voltage-
controlled power transistor, similar to the power MOSFET
in operation and construction. This device offers superior
performance to the bipolar-transistors. It is the most cost-
effective solution for high power and wide frequency-range
applications. Table 3 shows the characteristics comparison
of IGBT with BJT and MOSFET.
Table 3. Device Characteristics Comparison
Features BJT MOSFETS IGBT
Drive Method Current Voltage Voltage
Drive Circuit Complex Simple Simple
Input Impedance Low High High
Drive Power High Low Low
Switching Speed Slow(µs) Fast(ns) Middle
Operating Frequency
Low Fast
(less than 1MHz) Middle
S.O.A Narrow Wide Wide
Saturation Voltage
Low High Low
Power losses of an IGBT include conduction loss and
switching loss. The conduction loss is determined by
IGBT’s Vce(sat) value and the duty rate. The switching loss is
determined by turn-on and turn-off action during IGBT’s
switching transient. For IGBTs, there are technical trade-off
characteristics between the Vce(sat) and the switching loss. If
Vce(sat) is high, switching loss becomes low and vice versa.
Therefore, the designer should select an IGBT based on the
system configuration and its switching frequency. The total
loss of an IGBT can be expressed as:
Total Loss
=1 Pulse Switching Loss (EON + EOFF)
X Switching Frequency
+ Conduction Loss
(VCS(SAT) X IC X Duty) (9)
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 4
Figure 3 curves show the characteristics comparison
between PT IGBT and field-stop IGBT. PT IGBT has NTC
temperature characteristic: as temperature rises, Vce(sat)
decreases. Field-stop IGBT has PTC temperature
characteristic: as temperature rises, Vce(sat) increases.
Therefore, PT IGBT with NTC characteristic is more
suitable for the application where IGBT is operated solely.
However, if parallel operation of IGBTs is required for
current sharing, field-stop IGBT with PTC characteristic
would be more appropriate.
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0
10
20
30
40
50
60
70
80
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Collector Current, Ic[A]
Collector-Emitter Voltage, Vce(sat)[V]
Tc=25deg.C
Vge=15V
Figure 3. HGTG20N60A4D(PT) vs. FGH40N60UFD/SFD
(Field-Stop Gen1)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0
10
20
30
40
50
60
70
80
Collector Current, Ic[A]
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Tc=125deg.C
Vge=15V
Collector-Emitter Voltage, Vce(sat)[V]
Figure 4. FGH40N60SMD (Field-Stop Gen2)
Reduction of conduction loss and total device cost with
better thermal performance would be the advantage of the
parallel operation of IGBTs. However, for such kind
application, the following must be considered:
� Using high-temperature PTC characteristic IGBT
� Using gate resistor with ≤1% tolerance for each IGBT
� Proper gate PCB layout for symmetrical current paths
� Identical heat sink size and airflow for each IGBT
� Same threshold voltage and saturation voltage
characteristics
The following figures show that the switching loss becomes
the dominant factor over conduction loss in 25kHz and
above switching frequency area.
10 20 30 40
0.0
0.5
1.0
1.5
2.0
Test Condition :
Vcc=400V, Rg=10 ohm, Vge=15V
Tc=25deg.C
Tc=125deg.C
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Total Switching Loss[Eon+Eoff], Ets[m
J]
Collector Current, Ic[A]
Figure 5. Total Switching Loss Ets
vs. Collector Current IC
20.0k 40.0k 60.0k 80.0k 100.0k
0
50
100
150
200
250
Test Condition :
Vcc=400V, Rg=10 ohm,
Vge=15V, Ic=40A, Tc=125deg.C
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Total power loss of IGBT, Pd [W]
Switching Frequency, Fsw[KHz]
Conduction loss
Switchin
g loss[ Eon+ Eo
ff]
Total po
wer lo
ss
Figure 6. Total Power Loss of IGBT Pd
vs. Switching Frequency
The gate resistor is also very critical to the switching loss.
High gate resistance results in high switching loss. On the
other hand, high gate resistance improves EMI performance
as the di/dt is lower during the switching transient. A
properly selected gate resistor should minimize the
switching loss without sacrificing system EMI performance.
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 5
Below are the IGBT turn-off characteristics measurements
with JIG testing. Under the same conditions, FS Planar
Gen2 IGBT FGH40N60SMD shows faster switching
characteristic, lower Vce(sat), and tremendously lower turn-off
loss compared to previous technology devices - PT and FS
Planar Gen1 IGBT.
5 10 15 20 25 30
0.2
0.4
0.6
0.8
1.0
Test Condition :
Vcc=400V, Ic=40A, Vge=15V
FGH40N60SMD
FGH40N60UFD
FGH40N60SFD
HGTG20N60A4D
Tc=25deg.C
Tc=125deg.C
Switching Loss, Eoff[m
J]
Gate Resistance, Rg[ohm]
Figure 7. Turn-Off Loss EO vs. Gate Resistance Rg
1.6 1.8 2.0 2.2 2.4
8
12
16
Tc=25deg.C
FGH40N60SMDFGH40N60SFD
HGTG20N60A4D
FGH40N60UFD
Collector-Emitter Voltage, Vce(sat)[V]
Switching loss, Eoff / A[uJ]
Figure 8. Turn-Off Loss EOFF vs. Collector-Emitter
Vce(sat)
Figure 9 and Figure 10 show the IGBT operation waveforms
of the evaluation board with R-load and welding load. These
waveforms reveal that welding load consumes three times
the current that R-load consumes. Therefore, it is important
to select IGBT with suitable Icm parameter to avoid
saturation at peak-current condition.
Figure 9. R-Load Test at IOUT=14A
Figure 10. Welding-Load Test at 3.2 Pie Welding Rod
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 6
Figure 11 through Figure 16 show turn-off switching loss
EOFF measurement with welding load and R-load. Due to the
leakage inductance and capacitor element, there is huge
difference in EOFF measurement compared with the JIG test
result. The EOFF of FGH40N60SMD shows the lowest loss
from the test.
Figure 11. EOFF Comparison Under
R-Load (FGH40N60SMD)
Figure 12. EOFF Comparison Under
R-Load (FGH40N60UFD)
Figure 13. EOFF Comparison Under
R-Load (FGH40N60SFD)
Figure 14. EOFF Comparison Under
Welding Load (FGH40N60SMD)
Figure 15. EOFF Comparison Under
Welding Load (FGH40N60UFD)
Figure 16. EOFF Comparison Under
Welding Load (FGH40N60SFD)
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 7
Rectifier Diode for Welding Machine
Fairchild Semiconductor provides five kinds of diodes that
cater to different applications. Diodes with lower Vf, Irr, and
Trr characteristics are ideal for welding applications;
however, the common P_N theory dictates that the lower the
Vf, the longer the Trr and vice versa. A designer chooses a
diode with a trade-off point where Vf and Trr benefit the
system efficiency the most. The following figures show
performance comparisons for 600V/8A diodes from each
Fairchild Semiconductor diode technology.
0 20 40 60 80
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
Stealth2 Ulrafast
Hyperfast
Hyperfast2
Stealth
Stealth2
Stealth
Hyperfast2Hyperfast
Ultrafast
Tc=25deg.C
VF [V]
Qrr [nC]
FCS Rectifier Diode Vf vs Qrr, 600V 8A
Figure 17. VF vs. Qrr Trade-Off
-80.0n -40.0n 0.0 40.0n 80.0n 120.0n 160.0n-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
Tc=125deg.C
IF [A]
Time [sec]
Ultrafast
Hyperfast
Hyperfast2
Stealth
Stealth2
FSC Rectifier performance @ 600V, 8A
Figure 18. Reverse Recovery Performance
Figure 19. Test Circuit and Waveforms
rrrrrr tIQ ××=2
1 (10)
Generally, the rectifier diode of welding machine has higher
conduction loss than reverse recovery loss. Therefore, the
diode VF value is more critical for a welding application.
For this reason, ultra-fast diode FFA60UP30DN (30A dual
diode) is used for this evaluation board. Three diodes are
used in parallel for each tap of transformer to lower the VF.
The figures below show the performance of diodes used in
single and parallel configuration. Although the reverse
recovery loss increases, Vf is reduced with parallelized
diodes and better thermal performance can be expected.
Designer caution is required for parallel diode application to
ensure that the air flow does not cause unbalanced current
conditions, as the Vf of diode tends to decrease when the
temperature rises.
0.0 0.6 1.2 1.8
0
20
40
60
80
100
Tc=25deg.C
Tc=125deg.C
VF, Forward Voltage [V]
FFA60UP30DN-Dual
FFA60UP30DN-single
IF, Forward Current [A]
Diode I-V charateristic
Figure 20. Diode I-V Characteristic
100 200 300 400 500
0
60
120
180
240
300
360FFA60UP30DN Qrr charateristic
Tc=25deg.C
Tc=125deg.C
Stored Recovery charge Q
rr [nC]
di/dt [ A/us]
VR = 150V
IF = 30A
Single
Dual
Figure 21. Stored Recovery Charge Qrr vs.
Diode Current Slop di/dt
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 8
Figure 22 shows the diode switching loss when the board is
operating at 20KHz. The conduction loss is about 336µJ,
while the reverse recovery loss is only about 4µJ.
Figure 22. Diode Conduction Loss During Welding
Figure 23. Diode Reverse Recovery Loss
During Welding
Avalanche occurs in a diode with sudden current increase
when the voltage across a diode exceeds the specified Vr
value. Here, the area (Vr(AVL)*Isa) that diode does not fail is
called avalanche energy and the equation is:
])(
[2
1
)(
)(2
DDAVLr
AVLr
saAVL
VV
VILE
−
×××=
)()( )(1 AVLrces VDUTBVIGBTQ >=∴
(11)
Avalanche energy is occurred by the second output inductor,
as shown in the equation. The immunity capability is
proportional to the inductance. The inductance of a welding
machine is generally designed as small value as several µH,
and diode immunity capability value becomes an important
factor for choosing a device.
Avalanche can occur in the secondary-side rectifier of a
welding machine; especially when the welding work is
completed and the reverse pass occurs by inductor.
Immunity capability is measured using a circuit as shown in
Figure 24 with the graph in Figure 25 showing avalanche
energy test result waveform.
Figure 24. UIS Test Circuit
Figure 25. FFA60UP30DN Immunity Capability
Blocking Capacitor
For half-bridge topology; if the two series DC bank
capacitors or the turn-on time of IGBTs are not matched,
DC flux occurs in the transformer. The accumulated DC flux
eventually drives transformer into saturation. The IGBTs
can be destroyed by sharply increased current due to the
saturated transformer. To block the DC flux in the
transformer core, a small DC blocking capacitor is placed in
series with the transformer primary. The value of the DC
blocking capacitor is given by:
swP
D
blocking
FV
IDC
×∆×
=max
(12)
where PV∆ is the permissible droop in primary voltage due
to the DC blocking capacitor.
Below is the waveform of the transformer primary current.
The current abruptly rise due to the saturated transformer
caused by DC bias.
Figure 26. IGBT Saturation Current
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 9
Figure 27. Zoom of IGBT Saturation Current
Power Supply Structure and Design
MOSFET integrated IC FSMG0465R is used for power
supply. Its simple peripheral circuit and 66KHz switching
frequency reduce the PCB and transformer size. In addition,
the efficiency of power has been maximized by the
minimization of idling power that can be achieved from low
power consumption in Standby Mode (<1W at 230VAC input
at 0.5W load). There are transformer type and SMPS type
for the substitute power supply. SMPS type, compared to
linear transformer type, has stable output power over the
influence of input serge, sag, and noise; and minimal design
of size and weight is possible. In addition, transformer type
has a fixed input voltage, whereas SMPS has a wide input
voltage range of 80VAC~264VAC, which can be used for free
voltage welding machine without additional operation.
However, it is necessary to consider counter measures for
noise as the switching noise may affect main inverter. For
further information about Fairchild Power Switches
(FPS™), refer to the application note AN-4150 found at:
http://www.fairchildsemi.com/an/AN/AN-4150.pdf.
Controller Design
The evaluation board uses PIC16f716 for the control
circuits. PIC16f716 controller consists of four ports of 8-bit
AD converter and one port PWM timer with 9-bit, 40KHz
resolution. To generate two PWM pulses from one PWM
signal, a D flip-flop and an AND gate are used to divide the
40KHz PWM into 20KHz PWM pulse (see Figure 28).
Figure 28. PWM Convert 40KHz to 20KHz
Gate Driver Design
A transformer, opto-coupler, or HVIC can be used for a gate
driver. Necessary supply voltages for different gate drivers
are listed as:
� HVIC Driver: +15V, 0V (High and Low Gate),
+ 24V, 0V (Output Detect), +5V, 0V (Controller)
Otpo-Coupler Driver : +15V, 0V, -5V (High-Side Gate),
+15V, 0V, -5V (Low-Side Gate), +24V, 0V (Output Detect),
+5V, 0V (Controller)
Pulse Transformer: +24V, 0V (Output Detect),
+5V, 0V (Controller)
The opto-coupler and transformer provide isolation between
the control circuit and IGBTs. However, a transformer may
cause half bridge cross-conduction due to the offset voltage
of gate-pulse dead-time stage. Through an by integrated
high-voltage MOSFET, the HVIC provides isolations
between the control circuit and the high-side IGBT. This
does not work with negative supply voltage. A negative
supply voltage is necessary for HVIC during a fast
commutation in a half-bridge topology to prevent dv/dt
shoot-through. The shoot-through is linked to a fast voltage
variation across one of the two IGBTs. A current flowing
through collector-emitter capacitor can bring the gate
voltage of an IGBT, when turned off, to rise due to Miller
effect and obtain a cross conduction into the leg.
C11
10uF/10V
C19104
C20104
D1
1N4937
D2
1N4937
D3
1N4937
-15V
C21104
D4
1N4937
C822P
+15V
+15V
C22104
-15V
J2
Output 12
RD2
ERR
Y1
WLD
C3104
J1
Current Limit
123
C23104
R8
10k R91k
VR35k
VR15k
C6
105
G3
PWR
R6
1K
R13 330
R12 330
Temp
+5V
+5V
J3
CT 12
C4104
R11 330
D5
1N4937
U2A
7474
CLK3
CL
R1
D2
PR
E4
Q5
Q6
U1 PIC16C711
GN
D5
VD
D1
4
OSC2/CLKOUT15
MCLR/VPP4
OSC1/CLKIN16
RA0/AN017
RA1/AN118
RA2/AN21
RA3/AN3/VREF2
RA4/TOCKI3
RB0/INT6
RB17
RB28
RB39
RB410
RB511
RB612
RB713
J1
TH 12
R110 ohm/3W
X1
20Mhz
C1
22uF/10V
U5
PS25012
35
8
4
6
U6
PS25012
35
8
4
6
VR25k
R20330
ZD!
1N4099
12
R2
27k
U3A
7409
1
23
R3
1k
U4B
7409
4
56
C2104
R19330
R101K
C7104
+5V
C922P
+5V
+5V
+5V
R16 330
R15 330
R14 330
+5V+5V +5V
C12104
+5VBD1
1
2
Gate2_1
C15104
C16104
gate2_2
+5V
RD1SD
G2
Cont-
G1
Cont+
+5V
gate1_2
Gate1_1
R18 1K
R17 1K
C13470P
C14470P
R71K
LVD
R4
36k
C5104
+5V
+5V
R5
560
Q2
2n3904d/ON
Q1
2n3904d/ON
Temp
C10104
PC1PC817
12
43
Figure 29. Controller Schematic
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 10
dtdVGICG
CG /××××====Q
CGgge IRV ×=
CGCG CdtdvI ×= /
Figure 30. Effect on dv/dt to VGE
Figure 31. Effect on dV/dt to Gate Wave
Based on the above considerations, an opto-coupler is used
for this welding machine evaluation board. Figure 32 and
Figure 33 present the gate waveforms captured with
different types of gate drivers. It is clear the opto-coupler is
the best choice for this welding application.
Figure 32. HVIC Gate Waveform
Figure 33. Transformer Gate Waveform
Figure 34. Opto-Driver Gate Waveform
DC Reactor Design
DC reactor helps stabilize arc current during welding
operation. As DC reactance grows, specter occurs smaller.
On the contrary, if the mobility of arc is lowered and the LDC
value gets too large, it is harder to create an arc. Therefore,
an appropriate reactor choice is necessary. If considering
VOPEN as output no-load voltage, VWEL and IWEL as rated
output voltage or current; the maximum LDC value can be
obtained from the equation:
:
)1( RV
IIn
tRL
open
WEL
R
DC
×−
×−≤
(13)
where R is the equivalent resistance of welding load and Tr
is the rising time of the output current from 0 to the rated
current. Once the maximum LDC value is obtained; the
optimum LDC value can be finalized through testing.
Figure 35. Soft-Start During Welding Operating
Figure 36. Welding Operating
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 11
Conclusion
Better performance is expected for a DC-ARC welding
machine when the inverter devices are selected properly
based on the inverter topology and its switching frequency.
This article presents a power device selection guide for a
half-bridge welding machine application.
When to chose an IGBT, its Vce(sat), Eoff turn-off loss, gate
driver resistor, and Icm characteristics are the critical factors
that require a designer’s careful attention.
For the secondary -side rectifier diodes, it is important to
determine which is the dominant factor, Vf or reverse
recovery loss, based on system switching frequency. The
evaluation board uses three ultra-fast diodes
(FFA60UP30DN) in parallel for each tap of the transformer
to lower the Vf and therefore the conduction loss.
References
[1] Aspandiar, Raiyo, “Voids in Solder Joints,” SMTA Northwest Chapter Meeting, September 21, 2005,
Intel® Corporation.
[2] Bryant, Keith, “Investigating Voids,” Circuits Assembly, June 2004.
[3] Comley, David, et al, “The QFN: Smaller, Faster, and Less Expensive,” Chip Scale Review.com, August /
September 2002.
[4] Englemaier, Werner, “Voids in solder joints-reliability,” Global SMT & Package, December 2005.
[5] IPC Solder Products Value Council, “Round Robin Testing and Analysis of Lead Free Solder Pastes with Alloys of
Tin, Silver, and Copper,” 2005.
[6] IPC-A-610-D, “Acceptance of Electronic Assemblies,” February 2005.
[7] IPC J-STD-001D, “Requirements for Soldered Electrical and Electronic Assemblies.”
[8] IPC-SM-7525A, “Stencil Design Guidelines,” May 2000.
[9] JEDEC, JESD22-B102D, “Solderability,” VA, Sept. 2004.
[10] Syed, Ahmer, et al, “Board-Level Assembly and Reliability Considerations for QFN Type Packages,”
Amkor Technology, Inc., Chandler, AZ.
Related Resources
FGH40N60SMD — 600V, 40A Field Stop IGBT
FFA60UP30DN — 300V Ultrafast Recovery Power Rectifier
FSGM0465R — SMPS Power Switch, 4A, 650V (Green)
Appendix — Circuit Diagrams
C5110uF 630V
2
T1
TRANSFORMER CT
1 5
6
4 8
D3 FGA60UP30DN
D7 FGA60UP30DN
D16 FGA60UP30DN
D17 FGA60UP30DN
D18 FGA60UP30DN
D19 FGA60UP30DN
R6
10
- Output
C23
102
R39
10
C24
102
+ Output
ZD81N4744
ZD91N4733
R54.7k
Gate1
Gate2
C5210nF 630V
ZD71N4733
R44.7k
ZD31N4744
ZD41N4733
Z4
FGA40N60SMD
R9 10/3W
C5310nF 630V
Z2
FGA40N60SMD
R3 10/3W
GND1
ZD61N4744
C541uF M275V
C55472M
C62472M RV1
20D431K
RV220D431K
RV320D431K
P10
1
P11
1
P3
1
L6
L5
LF1RFILTER
L4 52uHC2
400V 560uF
Z3FGA40N60SMD
Z1FGH40N60SMD
R8 10/3W
R74.7k
R1 10/3WZD11N4744
ZD21N4733
R24.7k
-+
BD1
GBP5006
2
1
3
4C1
400V 560uF
- BUS
C61
630V
+ BUS
GND2FAN
1
Gate1
Gate2
C5010uF 630V
CT1
JF3250G
1 3
Figure 37. Main Circuit
AN-9742 APPLICATION NOTE
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 9/9/11 12
L2 10uH
XY
4.7nF/1KV
R204
1K
F201 250V 2A
U201 FGM0465R
FB4
Drain1
GN
D2
Vstr6
Vcc3
R2011M/1W
C214
47nF
R217
1.2k
C216
1000uF 10V
D202
1N4007
D203
MBRF10H100
-+
BD201
2KBP06M3N25
2
1
3
4
R219
8K
R208
1k
C213
102
C224470uF 35V
R2051K
C207
47uF 50V
PC1
12
R215
10
U202TL431
23
1
D201
UF4004
LF201
30mH
D204
MBRF10H100
L1 10uH
R218
18K
C202275Vac 100nF
C215
470uF 10V
C2083.3nF 630V
R202
270K
PC2 817
12
43
C204
47nFD38
1N4744
1
2
D206
MBRF10H100
T101EER3940S
13
7
8
9
10
11
12
14
15
16
3
1
TNR10D471k
C209 102
R216
620
C210
102
L5
4.9uH
C203400V 100uF
R212
10
ZD2011N4745A
1
2
C223
470uF 35V
+15v
gnd
5v
AC220V H
AC220V N
-15V
GND2
C201275Vac 100nF
R20743K/1W
R20675K
C20533nF 100V
C206
100nF
R210
1W 5
R220
8K
R203150K
Q201
2N2222
R211 10
NTC
NTC1
5D-9
R209
100 ohm/0.5W
GND1
L4 10uH
D205
MBRF10H100C220
470uF 35V
D207
MBRF10H100
L3 10uH
C211102
C212102R214 10
C219470uF 35V
15+v
-15V
R21310
C217
470uF 35VC218
470uF 35V
C211470uF 35V
C222470uF 35V
Figure 38. Auxiliary Power Supply
Figure 39. Controller
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