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PDF FAN7621S Data sheet ( Hoja de datos )
| Número de pieza | FAN7621S | |
| Descripción | PFM Controller | |
| Fabricantes | Fairchild Semiconductor | |
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Hay una vista previa y un enlace de descarga de FAN7621S (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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July 2010
FAN7621S
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
Auto-Restart Operation for All Protections with
an External LVCC
Protection Functions: Over-Voltage Protection
(OVP), Over-Current Protection (OCP), Abnormal
Over-Current Protection (AOCP), Internal Thermal
Shutdown (TSD)
Applications
PDP and LCD TVs
Desktop PCs and Servers
Adapters
Telecom Power Supplies
Video Game Consoles
Description
The FAN7621S 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 FAN7621S
simplifies designs and improves productivity, while
improving performance. The FAN7621S includes a high-
side gate-drive 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
significantly improves efficiency. The ZVS also reduces
the switching noise noticeably, which allows a small-
sized Electromagnetic Interference (EMI) filter.
The FAN7621S can be applied to various resonant
converter topologies; such as series resonant, parallel
resonant, and LLC resonant converters.
Related Resources
AN4151 — Half-Bridge LLC Resonant Converter Design
Using FSFR-Series Fairchild Power Switch (FPSTM)
Ordering Information
Part Number
FAN7621SSJ
FAN7621SSJX
Operating Junction
Temperature
-40°C to +130°C
Package
16-Lead, Small Outline Package (SOP)
Packaging
Method
Tube
Tape & Reel
www.DataSheet4U.com
© 2009 Fairchild Semiconductor Corporation
FAN7621S • Rev. 1.0.1
www.fairchildsemi.com
1 page  
Electrical Characteristics
TA=25°C and LVCC=17V unless otherwise specified.
Symbol
Parameter
Test Conditions
Supply Section
ILK Offset Supply Leakage Current
IQHVCC
IQLVCC
Quiescent HVCC Supply Current
Quiescent LVCC Supply Current
IOHVCC
Operating HVCC Supply Current
(RMS Value)
IOLVCC
Operating LVCC Supply Current
(RMS Value)
HVCC=VCTR
(HVCCUV+) - 0.1V
(LVCCUV+) - 0.1V
fOSC=100kHz, CLoad=1nF
No Switching
fOSC=100kHz, CLoad=1nF
No Switching
UVLO Section
LVCCUV+ LVCC Supply Under-Voltage Positive-Going Threshold (LVCC Start)
LVCCUV- LVCC Supply Under-Voltage Negative-Going Threshold (LVCC Stop)
LVCCUVH LVCC Supply Under-Voltage Hysteresis
HVCCUV+ HVCC Supply Under-Voltage Positive-Going Threshold (HVCC Start)
HVCCUV- HVCC Supply Under-Voltage Negative-Going Threshold (HVCC Stop)
HVCCUVH HVCC Supply Under-Voltage Hysteresis
Oscillator & Feedback Section
VRT V-I Converter Threshold Voltage
fOSC Output Oscillation Frequency
DC Output Duty Cycle
RT=5.2kΩ
fSS
Internal Soft-Start Initial Frequency
fSS=fOSC+40kHz, RT=5.2kΩ
tSS Internal Soft-Start Time
Output Section
Isource
Peak Sourcing Current
Isink
tr
tf
VHOH
VHOL
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
VLOH
High Level of High-Side Gate Driving
Signal (VLVCC-VLO)
www.DataSheeVt4LOUL.com
Low Level
Signal
of
High-Side
Gate
Driving
HVCC=17V
HVCC=17V
CLoad=1nF, HVCC=17V
IO=20mA
Min.
11.2
8.9
8.2
7.8
1.5
94
48
2
250
460
Typ.
50
100
5
100
6
2
12.5
10.0
2.5
9.2
8.7
0.5
2.0
100
50
140
3
360
600
65
35
Max. Unit
50 μA
120 μA
200 μA
8 mA
200 μA
9 mA
4 mA
13.8 V
11.1 V
V
10.2 V
9.6 V
V
2.5 V
106 kHz
52 %
kHz
4 ms
mA
mA
ns
ns
1.0 V
0.6 V
1.0 V
0.6 V
© 2009 Fairchild Semiconductor Corporation
FAN7621S • Rev. 1.0.1
5
www.fairchildsemi.com
5 Page 
6. Current Sensing Using Resistor: FAN7621S senses
drain current as a negative voltage, as shown in Figure
23 and Figure 24. Half-wave sensing allows low power
dissipation in the sensing resistor, while full-wave
sensing has less switching noise in the sensing signal.
7. PCB Layout Guidelines: Duty imbalance problems
may occur due to the radiated noise from the main
transformer, the inequality of the secondary-side leakage
inductances of main transformer, and so on. 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 turn-on 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 PCB layout. Error!
Reference source not found. shows an example for the
duty-balanced case. The yellow and blue lines show the
primary current flows when the lower-side and higher-
side MOSFETs turn on, respectively. The primary current
does not enclose any component of controller.
Figure 23. Half-Wave Sensing
Figure 24. Full-Wave Sensing
www.DataSheet4U.com
Figure 25. Example for Duty Balancing
© 2009 Fairchild Semiconductor Corporation
FAN7621S • Rev. 1.0.1
11
www.fairchildsemi.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet FAN7621S.PDF ] | |
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