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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
July 2009
FAN7621
PFM Controller for Half-Bridge Resonant Converters
Features
Variable Frequency Control with 50% Duty Cycle for Half-bridge Resonant Converter Topology High Efficiency through Zero Voltage Switching (ZVS) Fixed Dead Time (350ns) Up to 300kHz Operating Frequency Pulse Skipping for Frequency Limit (Programmable) at Light-Load Condition Remote On/Off Control using CON Pin Protection Functions: Over-Voltage Protection (OVP), Overload Protection (OLP), Over-Current Protection (OCP), Abnormal Over-Current Protection (AOCP), Internal Thermal Shutdown (TSD)
Description
The FAN7621 is a pulse frequency modulation controller for high-efficiency half-bridge resonant converters. Offering everything necessary to build a reliable and robust resonant converter, the FAN7621 simplifies designs and improves productivity, while improving performance. The FAN7621 includes a high-side gatedrive circuit, an accurate current controlled oscillator, frequency limit circuit, soft-start, and built-in protection functions. The high-side gate-drive circuit has a common-mode noise cancellation capability, which guarantees stable operation with excellent noise immunity. Using the zero-voltage-switching (ZVS) technique dramatically reduces the switching losses and efficiency is significantly improved. The ZVS also reduces the switching noise noticeably, which allows a small-sized Electromagnetic Interference (EMI) filter. The FAN7621 can be applied to various resonant converter topologies; such as series resonant, parallel resonant, and LLC resonant converters.
Applications
PDP and LCD TVs Desktop PCs and Servers Adapters Telecom Power Supplies Video Game Consoles
Related Resources
AN4151 -- Half-bridge LLC Resonant Converter Design TM using FSFR-series Fairchild Power Switch (FPS )
Ordering Information
Part Number
FAN7621N FAN7621SJ FAN7621SJX -40C ~ 130C RoHS
Operating Junction Temperature
Eco Status
Package
16-DIP 16-SOP 16-SOP
Packaging Method
Tube Tube Tape & Reel
For Fairchild's definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Application Circuit Diagram
Cr L lk VCC
LVcc HV CC
D1
Np
Ns
VO
Lm Ns CF R F
FAN7621
RT
HO CTR
VIN
CDL
CON
D2
KA431
LO CS SG PG
Rsense
Figure 1. Typical Application Circuit (LLC Resonant Half-Bridge Converter)
Block Diagram
LVCC
12
+
VREF I CTC
I CTC
3V
LVCC good Internal Bias
+
-
2ICTC
2V
1V
+
F/F
-
Time Delay
Level-Shift
High-Side Gate Drive
RT CON
8
350ns
Counter (1/4) 2
LVCC I OLP
6
0.4 / 0.6 V +
-
Time Delay
Balancing Delay
Low-Side Gate Drive
350ns Shutdown without delay
+
+
OLP
5V
-
S
Q -Q Q -Q S R
LVCC
23 V
+
LVCC good
R
-1
0.9 V
-
OVP
Auto-restart Protection
50ns Delay
-
VAOCP TSD LVCC < 5V Delay
1.5s
-
Latch Protection
V OCP
0.58 V
+
9
CS
Figure 2. Internal Block Diagram
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
2
+
R
-Q
1
S
Q
11.3 / 14.5V
-
VREF HVCC good
8.7 / 9.2V
HVCC HO CTR LO
+ -
3
14
16
PG SG
10
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Pin Configuration
(1) HVCC (2) CTR (3) HO (4) NC
PG (16) NC (15) LO (14) NC (13)
FAN7621
(5) NC (6) CON (7) NC (8) RT
Figure 3. Package Diagram
LVCC (12) NC (11) SG (10) CS (9)
Pin Definitions
Pin #
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Name
HVCC CTR HO NC NC CON NC RT CS SG NC LVCC NC LO NC PG
Description
This is the supply voltage of the high-side gate-drive circuit IC. This is the drain of the low-side MOSFET. Typically, a transformer is connected to this pin. This is the high-side gate driving signal. No connection. No connection. This pin is for a protection and enabling/disabling the controller. When the voltage of this pin is above 0.6V, the IC operation is enabled. When the voltage of this pin drops below 0.4V, gate drive signals for both MOSFETs are disabled. When the voltage of this pin increases above 5V, protection is triggered. No connection. This pin programs the switching frequency. Typically, an opto-coupler is connected to control the switching frequency for the output voltage regulation. This pin senses the current flowing through the low-side MOSFET. Typically, negative voltage is applied on this pin. This pin is the control ground. No connection. This pin is the supply voltage of the control IC. No connection. This is the low-side gate driving signal. No connection. This pin is the power ground. This pin is connected to the source of the low-side MOSFET.
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(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. TA=25C unless otherwise specified.
Symbol
VHO VLO LVCC VCTR VCON VCS VRT dVCTR/dt PD TJ TSTG
Parameter
High-Side Gate Driving Voltage Low-Side Gate Driving Voltage Low-Side Supply Voltage Center Voltage Control Pin Input Voltage Current Sense (CS) Pin Input Voltage RT Pin Input Voltage Allowable Center Voltage Slew Rate Total Power Dissipation 16-DIP 16-SOP
(1) (1)
Min.
VCTR-0.3 -0.3 -0.3 -0.3 -0.3 -0.3 -5.0 -0.3
Max.
HVCC LVCC 25.0 25.0 600.0 LVCC 1.0 5.0 50 1.56 1.13 +150
Unit
V V V V V V V V/ns W W
C C
HVCC to VCTR High-Side VCC Pin to Center Voltage
Maximum Junction Temperature Storage Temperature Range
Recommended Operating Junction Temperature
-40 -55
+130 +150
Note: 1. The maximum value of the recommended operating junction temperature is limited by thermal shutdown.
Thermal Impedance
Symbol
JA
Parameter
Junction-to-Ambient Thermal Impedance 16-DIP 16-SOP
Value
80 110
Unit
C/W
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Electrical Characteristics
TA=25C and LVCC=17V unless otherwise specified.
Symbol
Supply Section
Parameter
Offset Supply Leakage Current Quiescent HVCC Supply Current Quiescent LVCC Supply Current Operating HVCC Supply Current (RMS Value) Operating LVCC Supply Current (RMS Value)
Test Conditions
HVCC=VCTR (HVCCUV+) - 0.1V (LVCCUV+) - 0.1V fOSC=100kHz, VCON > 0.6V, CLoad=1nF No Switching, VCON < 0.4V fOSC=100kHz, VCON > 0.6V, CLoad=1nF No Switching, VCON < 0.4V
Min.
Typ.
Max.
Unit
A A A mA A mA mA
ILK IQHVCC IQLVCC IOHVCC
50 50 100 5 100 6 2 120 200 8 200 9 4
IOLVCC
UVLO Section
LVCCUV+ LVCCUVLVCCUVH HVCCUV+ HVCCUVHVCCUVH
LVCC Supply Under-Voltage Positive Going Threshold (LVCC Start) LVCC Supply Under-Voltage Negative Going Threshold (LVCC Stop) LVCC Supply Under-Voltage Hysteresis HVCC Supply Under-Voltage Positive Going Threshold (HVCC Start) HVCC Supply Under-Voltage Negative Going Threshold (HVCC Stop) HVCC Supply Under-Voltage Hysteresis
13.0 10.2
14.5 11.3 3.2
16.0 12.4
V V V
8.2 7.8
9.2 8.7 0.5
10.2 9.6
V V V
Oscillator & Feedback Section
VCONDIS VCONEN VRT fOSC DC fSS tSS
Control Pin Disable Threshold Voltage Control Pin Enable Threshold Voltage V-I Converter Threshold Voltage Output Oscillation Frequency Output Duty Cycle Internal Soft-Start Initial Frequency Internal Soft-Start Time fSS=fOSC+40kHz, RT=5.2k RT=5.2k
0.36 0.54 1.5 94 48
0.40 0.60 2.0 100 50 140
0.44 0.66 2.5 106 52
V V V kHz % kHz
2
3
4
ms
Output Section
Isource Isink tr tf VHOH VHOL VLOH VLOL
Peak Sourcing Current Peak Sinking Current Rising Time Falling Time High Level of High-Side Gate Driving Signal (VHVCC-VHO) Low Level of High-Side Gate Driving Signal High Level of High-Side Gate Driving Signal (VLVCC-VLO) Low Level of High-Side Gate Driving Signal
HVCC=17V HVCC=17V CLoad=1nF, HVCC=17V
250 460
360 600 65 35 1.0 0.6
mA mA ns ns V V V V
IO=20mA 1.0 0.6
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Electrical Characteristics (Continued)
TA=25C and LVCC=17V unless otherwise specified.
Symbol Protection Section
IOLP VOLP VOVP VAOCP tBAO VOCP tBO tDA TSD ISU VPRSET
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
OLP Delay Current OLP Protection Voltage LVCC Over-Voltage Protection AOCP Threshold Voltage AOCP Blanking Time OCP Threshold Voltage OCP Blanking Time
(2)
VCON=4V VCON > 3.5V LVCC > 21V
3.8 4.5 21 -1.0
5.0 5.0 23 -0.9 50
6.2 5.5 25 -0.8
A V V V ns
-0.64 1.0
-0.58 1.5 250
-0.52 2.0 400 150 150
V s ns
C
Delay Time (Low-Side) Detecting from (2) VAOCP to Switch Off Thermal Shutdown Temperature
(2)
110 LVCC=7.5V 5
130 100
Protection Latch Sustain LVCC Supply Current Protection Latch Reset LVCC Supply Voltage
A V
Dead-Time Control Section
DT
Dead Time
350
ns
Note: 2. These parameters, although guaranteed, are not tested in production.
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Typical Performance Characteristics
These characteristic graphs are normalized at TA=25C.
1.1
1.1
1.05
1.05
Normalized at 25OC
Normalized at 25OC
1
1
0.95
0.95
0.9 -50 -25 0 25 50
O
0.9
75
100
-50
-25
0
25
50
75
100
Temp ( C)
Temp
(OC)
Figure 4. Low-Side MOSFET Duty Cycle vs. Temperature
1.1
Figure 5. Switching Frequency vs. Temperature
1.1
1.05
1.05
Normalized at 25OC
1
Normalized at 25OC
-50 -25 0 25 50 75 100
1
0.95
0.95
0.9
0.9 -50 -25 0 25 50 75 100
Temp (OC)
Temp (OC)
Figure 6. High-Side VCC (HVCC) Start vs. Temperature
1.1
Figure 7. High-Side VCC (HVCC) Stop vs. Temperature
1.1
1.05
1.05
Normalized at 25OC
1
Normalized at 25OC
-50 -25 0 25 50 75 100
1
0.95
0.95
0.9
0.9 -50 -25 0 25 50 75 100
Temp
(OC)
Temp (OC)
Figure 8. Low-Side VCC (LVCC) Start vs. Temperature
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
Figure 9. Low-Side VCC (LVCC) Stop vs. Temperature
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Typical Performance Characteristics (Continued)
These characteristic graphs are normalized at TA=25C.
1.1
1.1
1.05
1.05
Normalized at 25OC
Normalized at 25OC
1
1
0.95
0.95
0.9 -50 -25 0 25 50 75 100
0.9 -50 -25 0 25 50 75 100
Temp (OC)
Temp (OC)
Figure 10. OLP Delay Current vs. Temperature
1.1
Figure 11. OLP Protection Voltage vs. Temperature
1.1
1.05
1.05
Normalized at 25OC
Normalized at 25OC
1
1
0.95
0.95
0.9 -50 -25 0 25 50 75 100
0.9 -50 -25 0 25 50 75 100
Temp (OC)
Temp
(OC)
Figure 12. LVCC OVP Voltage vs. Temperature
1.1
Figure 13. RT Voltage vs. Temperature
1.1
1.05
1.05
Normalized at 25OC
1
Normalized at 25OC
1
0.95
0.95
0.9 -50 -25 0 25 50 75 100
0.9 -50 -25 0 25 50 75 100
Temp (OC)
Temp (OC)
Figure 14. CON Pin Enable Voltage vs. Temperature
Figure 15. OCP Voltage vs. Temperature
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Functional Description
1. Basic Operation: FAN7621 is designed to drive highside and low-side MOSFETs complementarily with 50% duty cycle. A fixed dead time of 350ns is introduced between consecutive transitions, as shown in Figure 16.
Dead t ime
Gain
1.8
f min
1.6
f normal
f
max
f ISS
High-side MOSFET gate drive
1.4
Low-side MOSFET gate drve
time
1.2
1.0
Figure 16. MOSFETs Gate Drive Signal
0.8
Soft-sta rt
2. Internal Oscillator: FAN7621 employs a currentcontrolled oscillator, as shown in Figure 17. Internally, the voltage of RT pin is regulated at 2V and the charging / discharging current for the oscillator capacitor, CT, is obtained by copying the current flowing out of RT pin (ICTC) using a current mirror. Therefore, the switching frequency increases as ICTC increases.
VREF I CTC I CTC
3V
0.6
60 70 80 90 100 110 120 130 140 150 Frequency (kHz)
Figure 18. Resonant Converter Typical Gain Curve
VCC
+
LVCC HV CC
S
-
Q -Q
Rmax Rmin RSS CON CSS
CT
F/F
-
FAN7621
SG
2I CTC
1V
R
+
RT
HO CTR LO
RT
3
Figure 17. Current Controlled Oscillator
3. Frequency Setting: Figure 18 shows the typical voltage gain curve of a resonant converter, where the gain is inversely proportional to the switching frequency in the ZVS region. The output voltage can be regulated by modulating the switching frequency. Figure 19 shows the typical circuit configuration for RT pin, where the opto-coupler transistor is connected to the RT pin to modulate the switching frequency.
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
+
2V
Counter (1/4)
-
Gate drive
CS PG
R sense
Figure 19. Frequency Control Circuit
The minimum switching frequency is determined as:
f min =
5.2k x 100(kHz ) Rmin
(1)
Assuming the saturation voltage of opto-coupler transistor is 0.2V, the maximum switching frequency is determined as:
f max = (
5.2k 4.68k + ) x 100(kHz ) Rmin Rmax
(2)
To prevent excessive inrush current and overshoot of output voltage during startup, increase the voltage gain of the resonant converter progressively. Since the voltage gain of the resonant converter is inversely proportional to the switching frequency, the soft-start is
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Rmax
R min
RSS CON CSS
FAN7621
SG
implemented by sweeping down the switching frequency ISS from an initial high frequency (f ) until the output voltage is established. The soft-start circuit is made by connecting R-C series network on the RT pin, as shown in Figure 19. FAN7621 also has an internal soft-start for 3ms to reduce the current overshoot during the initial cycles, which adds 40kHz to the initial frequency of the external soft-start circuit, as shown in Figure 20. The initial frequency of the soft-start is given as:
VCC
LV CC HV CC RT
HO
f ISS = (
5.2k 5.2k ) x 100 + 40 (kHz ) + Rmin RSS
(3)
CTR
It is typical to set the initial (soft-start) frequency of two ~ three times the resonant frequency (fO) of the resonant network. The soft-start time is three to four times the RC time constant. The RC time constant is as follows:
LO CS
PG
TSS = RSS CSS
fs f
ISS
(4)
Figure 22. Control Pin Configuration for Pulse Skipping
40kHz
Control loop take over
Remote On / Off: When an auxiliary power supply is used for standby, the main power stage using FAN7621 can be shut down by pulling down the control pin voltage, as shown in Figure 23. R1 and C1 are used to ensure soft-start when switching resumes.
OP1
time
Main Output
Figure 20. Frequency Sweeping of Soft-Start 4. Control Pin: The FAN7621 has a control pin for protection, cycle skipping, and remote on/off. Figure 21 shows the internal block diagram for control pin.
FAN7621
R1
C1
Main Off
LVCC
CON
IOLP
6 0.4 / 0.6V + -
RT
Rmin
Aux Output
+
Stop Switching S R Q -Q
OLP
5V
-
CON
LVCC
23V
+
-
LVCC good
Auto-restart protection
OVP
OP1
Figure 21. Internal Block of Control Pin Protection: When the control pin voltage exceeds 5V, protection is triggered. Detailed applications are described in the protection section. Pulse Skipping: FAN7621 stops switching when the control pin voltage drops below 0.4V and resumes switching when the control pin voltage rises above 0.6V. To use pulse-skipping, the control pin should be connected to the opto-coupler collector pin. The frequency that causes pulse skipping is given as:
SKIP
Figure 23. Remote On / Off Circuit 5. Protection Circuits: The FAN7621 has several selfprotective functions, such as Overload Protection (OLP), Over-Current Protection (OCP), Abnormal Over-Current Protection (AOCP), Over-Voltage Protection (OVP), and Thermal Shutdown (TSD). OLP, OCP, and OVP are auto-restart mode protections; while AOCP and TSD are latch-mode protections, as shown in Figure 24. Auto-Restart Mode Protection: Once a fault condition is detected, switching is terminated and the MOSFETs remain off. When LVCC falls to the LVCC stop voltage of 11.3V, the protection is reset. FAN7621 resumes normal operation when LVCC reaches the start voltage of 14.5V.
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=
5.2 k 4.16 k + R min R max
x100 (kHz)
(5)
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Latch-Mode Protection: Once this protection is triggered, switching is terminated and the gate output signals remain off. The latch is reset only when LVCC is discharged below 5V.
LV CC
7
+
resistor may not be available due to the severe power dissipation in the resistor. In that case, indirect current sensing using the resonant capacitor voltage can be a good alternative because the amplitude of the resonant p-p capacitor voltage (Vcr ) is proportional to the resonant p-p current in the primary side (Ip ) as:
LV CC good
11 / 14 V
V REF
-
Internal Bias
VCr p - p =
Shutdown
I p p- p 2 f sCr
(6)
OCP OLP OVP LV CC good CON 20k
Auto-restart protection
S R Q -Q
Latch protection
Q -Q S R
To minimize power dissipation, a capacitive voltage divider is generally used for capacitor voltage sensing, as shown in Figure 27.
LVCC HV CC
AOCP
F/F
F/F
TSD LV CC < 5V
CDL
RT
FAN7621
HO CTR
Ip
Figure 24. Protection Blocks Current Sensing Using Resistor: FAN7621 senses drain current as a negative voltage, as shown in Figure 25 and Figure 26. Half-wave sensing allows low power dissipation in the sensing resistor, while full-wave sensing has less switching noise in the sensing signal.
CON
LO CS SG PG
Csense
CB 100 Cr
Vsense
LV CC HV CC
Ip
FAN7621
RT
HO CTR
C DL V CS
CON
LO CS SG PG
I ds
VCr VCrp-p
R sense
V CS I ds
Vsense
Vsensepk CB = VCr p- p Csense+ C B
Vsensepk = VCON 2
pk Vsense
Figure 25. Half-Wave Sensing
I ds
VCON
pk Vsense
tDelay =R dCd
LVCC HV CC
V CS
Figure 27. Current Sensing Using Resonant Capacitor Voltage 5.1 Over-Current Protection (OCP): When the sensing pin voltage drops below -0.6V, OCP is triggered and the MOSFETs remain off. This protection has a shutdown time delay of 1.5s to prevent premature shutdown during startup. 5.2 Abnormal Over-Current Protection: (AOCP): If the secondary rectifier diodes are shorted, large current with extremely high di/dt can flow through the MOSFET before OCP or OLP is triggered. AOCP is triggered without shutdown delay when the sensing pin voltage drops below -0.9V. This protection is latch mode and reset when LVCC is pulled down below 5V.
FAN7621
SG
RT
HO CTR
C DL V CS
CON
LO CS PG
I ds
R sense
Figure 26. Full-Wave Sensing Current Sensing Using Resonant Capacitor Voltage: For high-power applications, current sensing using a
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1 11
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
5.3 Overload Protection (OLP): Overload is defined as the load current exceeding its normal level due to an unexpected abnormal event. In this situation, the protection circuit should trigger to protect the power supply. However, even when the power supply is in the normal condition, the overload situation can occur during the load transition. To avoid premature triggering of protection, the overload protection circuit should be designed to trigger only after a specified time to determine whether it is a transient situation or a true overload situation. Figure 27 shows a typical overload protection circuit. By sensing the resonant capacitor voltage on the control pin, the overload protection can be implemented. Using RC time constant, shutdown delay can be also introduced. The voltage obtained on the control pin is given as:
PCB layout. Figure 28 shows an example for the dutybalanced case. The yellow and blue lines show the primary current flows when the lower-side and higherside MOSFETs turns on, respectively. The primary current does not enclose any component of controller. In addition, it is helpful to reduce the duty imbalance to make the loop configured between CON pin and optocoupler as small as possible, as shown in the red line in Figure 28.
VCON =
CB VCr p - p 2(CB + Csense )
p-p
(7)
where VCr voltage.
is the amplitude of the resonant capacitor
5.4 Over-Voltage Protection: (OVP): When the LVCC reaches 23V, OVP is triggered. This protection is used when auxiliary winding of the transformer to supply VCC to the controller is utilized. 5.5 Thermal Shutdown (TSD): If the temperature of the junction exceeds approximately 130C, the thermal shutdown triggers. 6. PCB Layout Guideline: Duty imbalance problems may occur due to the radiated noise from main transformer, the inequality of the secondary-side leakage inductances of main transformer, and so on. Among them, it is one of the dominant reasons that the control components in the vicinity of RT pin are enclosed by the primary current flow pattern on PCB layout. The direction of the magnetic field on the components caused by the primary current flow is changed when the high-and-low side MOSFET turns on by turns. The magnetic fields with opposite direction from each other induce a current through, into, or out of the RT pin, which makes the turnon duration of each MOSFET different. It is strongly recommended to separate the control components in the vicinity of RT pin from the primary current flow pattern on
Figure 28. Example for Duty Balancing
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Typical Application Circuit (Half-Bridge LLC Resonant Converter)
Application
LCD TV
Device
FAN7621
Input Voltage Range
390VDC (340~400VDC)
Rated Output Power
192W
Output Voltage (Rated Current)
24V-8A
Features
High efficiency ( >94% at 400VDC input) Reduced EMI noise through zero-voltage-switching (ZVS) Enhanced system reliability with various protection functions
C110 ope n
R 103 400k V CC =16~ 20V DC U5 R 109 1M R 108 10k R 112 10k U4 ZD 101 6.8V C105 0.33 F JP 5 0
D 101 1N 4937
C102 22 nF
EE R 3542
D 202 F Y P F 2010 D N
C 201 C 202 2000 F / 2000 F / 35V 35V
VO
R 110 1M F101
LVCC HVCC
D102 1N4148 Q1 F C PF11N60F C 106 150 nF R113 3.3 R 115 10k R 202 D 201 F Y P F 2010 D N 1k
3.15A/250V
R 111 45k
FAN7621
RT
R 104 5.1k R 105 7.5k R 107 7.7k C 107 10F C 104 o pe n C 111 680 pF
R 201 10k U2 R 204 62k
HO CTR LO
C 204 12 nF R 205 2k
CON
C 101 220 F / 450V
JP 1, 0 JP 2, 0 JP 3, 0 JP 4, 0
V IN =340 ~400 V DC
D102 1N4148
U2
C 108 12 nF R 102 1k
CS
C 103 100 pF
R114 3.3
R 116 10k
Q2 F C PF11N60F C 301
C 203 47nF
R 203 33k
SG
PG
R205 7k
R101 0.2
Figure 29. Typical Application Circuit
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Typical Application Circuit (Continued)
Usually, LLC resonant converters require large leakage inductance value. To obtain a large leakage inductance, sectional winding method is used. Core: EER3542 (Ae=107 mm ) Bobbin: EER3542 (Horizontal)
2
Figure 30. Transformer Construction
Pin (S F) Np Ns1 Ns2 81 12 9 16 13
Wire 0.12x30 (Litz Wire) 0.1x100 (Litz Wire) 0.1x100 (Litz Wire) Pin Specification 630H 5% 135H 5%.
Turns 36 4 4
Winding Method Section Winding Section Winding Section Winding Remark
Primary-Side Inductance (Lp) Primary-Side Effective Leakage (Lr)
1 8 1 8
100kHz, 1V Short one of the secondary windings
For more detailed information regarding the transformer, visit http://www.santronics-usa.com/documents.html or contact sales@santronics-usa.com or +1-408-734-1878 (Sunnyvale, California USA).
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
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FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Physical Dimensions
16
19.68 18.66
A
9
6.60 6.09
1
8
(0.40)
TOP VIEW
0.38 MIN 5.33 MAX 3.42 3.17 3.81 2.92 2.54 0.58 A 0.35 1.78 1.14 17.78
SIDE VIEW NOTES: UNLESS OTHERWISE SPECIFIED A THIS PACKAGE CONFORMS TO JEDEC MS-001 VARIATION BB B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS ARE EXCLUSIVE OF BURRS, MOLD FLASH, AND TIE BAR PROTRUSIONS D) CONFORMS TO ASME Y14.5M-1994 E) DRAWING FILE NAME: N16EREV1
Figure 31. 16-Lead Dual Inline Package (DIP)
8.13 7.62
0.35 0.20 8.69
15 0
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/.
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
www.fairchildsemi.com 15
FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
Physical Dimensions
Figure 32. 16-Lead Small Outline Package (SOP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/.
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
www.fairchildsemi.com 16
FAN7621 -- PFM Controller for Half-Bridge Resonant Converters
(c) 2009 Fairchild Semiconductor Corporation FAN7621 * Rev. 1.0.1
www.fairchildsemi.com 17

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