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PDF FAN7621B Data sheet ( Hoja de datos )
| Número de pieza | FAN7621B | |
| Descripción | PFM Controller | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
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July 2010
FAN7621B
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)
Applications
PDP and LCD TVs
Desktop PCs and Servers
Adapters
Telecom Power Supplies
Video Game Consoles
Description
The FAN7621B 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 FAN7621B
simplifies designs and improves productivity, while
improving performance. The FAN7621B 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
efficiency is significantly improved. The ZVS also
reduces the switching noise noticeably, which allows a
small-sized Electromagnetic Interference (EMI) filter.
The FAN7621B 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
FAN7621BSJ
FAN7621BSJX
Operating Junction
Temperature
Package
-40°C ~ 130°C
16-Lead Small Outline Package (SOP)
Packaging
Method
Tube
Tape & Reel
www.DataSheet4U.com
© 2009 Fairchild Semiconductor Corporation
FAN7621B • 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
IQHVCC
IQLVCC
IOHVCC
Offset Supply Leakage Current
Quiescent HVCC Supply Current
Quiescent LVCC Supply Current
Operating HVCC Supply Current
(RMS Value)
IOLVCC
Operating LVCC Supply Current
(RMS Value)
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
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
VCONDIS Control Pin Disable Threshold Voltage
VCONEN Control Pin Enable Threshold Voltage
VRT V-I Converter Threshold Voltage
fOSC Output Oscillation Frequency
DC Output Duty Cycle
RT=5.2kΩ
fSS Internal Soft-Start Initial Frequency
tSS Internal Soft-Start Time
Output Section
fSS=fOSC+40kHz, RT=5.2kΩ
Isource
Peak Sourcing Current
Isink Peak Sinking Current
tr Rising Time
tf Falling Time
VHOH
High Level of High-Side Gate Driving
Signal (VHVCC-VHO)
www.DataSheeVt4HUOL.com
Low Level
Signal
of
High-Side Gate Driving
VLOH
High Level of High-Side Gate Driving
Signal (VLVCC-VLO)
VLOL
Low Level of High-Side Gate Driving
Signal
HVCC=17V
HVCC=17V
CLoad=1nF, HVCC=17V
IO=20mA
Min. Typ. Max. Unit
50 μA
50 120 μA
100 200 μA
5 8 mA
100 200 μA
6 9 mA
2 4 mA
11.2 12.5 13.8
8.90 10.00 11.10
2.5
8.2 9.2 10.2
7.8 8.7 9.6
0.5
V
V
V
V
V
V
0.36 0.40 0.44 V
0.54 0.60 0.66 V
1.5 2.0 2.5
V
94 100 106 kHz
48 50 52 %
140 kHz
2 3 4 ms
250 360
460 600
65
35
mA
mA
ns
ns
1.0 V
0.6 V
1.0 V
0.6 V
© 2009 Fairchild Semiconductor Corporation
FAN7621B • Rev. 1.0.1
5
www.fairchildsemi.com
5 Page 
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
10.0V, the protection is reset. FAN7621B resumes
normal operation when LVCC reaches the start voltage of
12.5V.
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.
LVCC
12
1 0 /12.5V
+ L VCC good V REF
-
Internal
Bias
OCP
OLP
OV P
L VCC good
CON
20k
A u t o- re st a rt
protec tion
SQ
R -Q
F /F
Latch
protec tion
QS
-Q R
F /F
Shutdo wn
AOCP
TSD
LVCC < 5V
Figure 24. Protection Blocks
Current Sensing Using Resistor: FAN7621B 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.
Ids
CDL
L VCC
HVCC
RT
HO
CON
CTR
VCS
CS
LO
SG PG
VCS
Rsense
Ids
Figure 26. Full-Wave Sensing
Current Sensing Using Resonant Capacitor Voltage:
For high-power applications, current sensing using a
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
capacitor
current in
tvhoeltapgriema(Vrycrps-ipd)eis(Ipppr-po)paosrt:ional
to
the
resonant
V p−p
Cr
=
I p−p
p
2π fsCr
(6)
CDL
LVCC
HVCC
RT
HO
CON
CTR
VCS
CS
LO
SG PG
Rsense
Ids
Ids
V
CS
Figure 25. Half-Wave Sensing
www.DataSheet4U.com
© 2009 Fairchild Semiconductor Corporation
FAN7621B • Rev. 1.0.1
11
www.fairchildsemi.com
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet FAN7621B.PDF ] | |
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