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PDF FAN6208 Data sheet ( Hoja de datos )
| Número de pieza | FAN6208 | |
| Descripción | Secondary-Side Synchronous Rectifier Controller | |
| Fabricantes | Fairchild Semiconductor | |
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Hay una vista previa y un enlace de descarga de FAN6208 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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November 2010
FAN6208
Secondary-Side Synchronous Rectifier Controller for
LLC Topology
Features
Specialized SR Controller for LLC or LC Resonant
Converters
Secondary-Side Timing Detection with Timing
Estimator
Gate-Shrink Function to Prevent Shoot-Through
During Load and Line Transient
Green-Mode Function for Higher Efficiency at Light-
Load Condition
Programmable Dead Time between Primary-Side
Gate Drive Signal and SR Drive Signal
Advanced Output-Short / Overload Protection
Based on the Feedback Information
Internal Over-Temperature Protection (OTP)
VDD Pin Over-Voltage Protection (OVP)
Description
FAN6208 is a synchronous rectification (SR) controller
for isolated LLC or LC resonant converters that can
drive two individual SR MOSFETs emulating the
behavior of rectifier diodes. FAN6208 measures the SR
conduction time of each switching cycle by monitoring
the drain-to-source voltage of each SR and determines
the optimal timing of the SR gate drive. FAN6208 uses
the change of opto-coupler diode current to adaptively
shrink the duration of SR gate drive signals during load
transients to prevent shoot-through. To improve light-
load efficiency, Green-Mode operation is employed,
which disables the SR drive signals, minimizing gate
drive power consumption at light-load condition.
Optimal timing circuits and protection functions are
integrated in an 8-pin SOP package, which allows high-
efficiency power supply design with fewer components.
Applications
LCD TV
PC Power
Open-Frame SMPS
Ordering Information
Part Number Operating Temperature Range
Package
Packing Method
FAN6208MY
-40°C to +105°C
8-Pin Small Outline Package (SOP)
Tape & Reel
www.DataSheet4U.com
© 2010 Fairchild Semiconductor Corporation
FAN6208 • Rev. 1.0.1
www.fairchildsemi.com
1 page  
Electrical Characteristics
VDD=20V, TA=25°C, unless otherwise specified. All voltages are with respect to GND unless otherwise noted.
Symbol
Parameter
Conditions
VDD Section
VDD DC Supply Voltage
IDD-OP1
Operating Current
IDD-OP2
Operating Current
IDD-ST
Startup Current
VTH-ON1 VTH-ON2 On Threshold Voltage
VTH-OFF1
VTH-OFF2
Off Threshold Voltage
VDD-OVP1
VDD-OVP2
VCC Over-Voltage
Protection
VDD-OVP-HYS1
VDD-OVP-HYS2
VCC Over-Voltage
Protection Hysteresis
tOVP1,tOVP2
VCC Over-Voltage-
Protection Debounce
VDD=12V, DETL=50KHz,
CL=6nF, RRP=24K
VDD=12V, DETL=100KHz
VDD=8V
DETL Section
VDETL1
VDETL2
Threshold Voltage for LOW VDD=12V, DETL=50KHz,
Detection of DETL
CL=6nF, RRP=24KΩ
tSR-ON-DETL1
tSR-ON-DETL2
Delay from DETL LOW to
SR Gate Turn-On
tDB+ tPD+ tR
VDETL-FLOATING1
VDETL-FLOATING2
DETL Floating Voltage
VDD=12V, DETL Pin
Floating
IDETL-SOURCE1
IDETL-SOURCE2
DETL Source Current
VDETL1=0V
tDETL_Green_LF1
tDETL_Green_LF2
DETL LOW Time
Threshold for Green Mode
at Low-Frequency
Operation
VRP < 1.5V
tDET(L)_Green_HF1
tDET(L)_Green_HF2
DETL LOW Time
Threshold for Green Mode
at High-Frequency
Operation
VRP > 1.5V
Thermal Shutdown
TSHUTDOWN
www.DataSheTeSt4TUAR.TcUoPm
Shutdown Temperature
Hysteresis
Startup Temperature
Temperature Rising,
VDD=15V
Before Startup
Min.
VTH-OFF
7.0
2.4
180
9.3
8.3
26
1.3
30
1.7
300
4.5
40
3.50
1.75
Typ.
8.5
3.2
300
9.7
8.8
27
1.8
60
2.0
350
50
3.75
1.90
140
20
120
Max.
28
10.0
4.0
500
10.1
9.3
28
2.3
100
2.3
400
60
4.00
2.05
Units
V
mA
mA
μA
V
V
V
V
μs
V
ns
V
μA
μs
μs
°C
Continued on the following page…
© 2010 Fairchild Semiconductor Corporation
FAN6208 • Rev. 1.0.1
5
www.fairchildsemi.com
5 Page 
Green Mode
Switching frequency increases in LLC topology at light-
load condition, which increases the power consumption
for the SR gate drive. Green mode reduces power loss
at light load. FAN6208 has two ways to enable green
mode. Green mode is triggered when DETL voltage is
pulled LOW for less than 3.75µs (LF mode) or 1.90µs
(HF mode) for seven switching cycles. FAN6208
resumes normal SR gate driving when DETL voltage is
pulled LOW for longer than 3.75µs (LF mode) or 1.90µs
(HF mode) for seven switching cycles.
When DETL voltage is pulled HIGH for longer than
24µs. This occurs when the LLC resonant converter
operates in burst mode (skipping mode).
VDD Pin Over-Voltage Protection
Over-voltage conditions are usually caused by an open
feedback loop. VDD over-voltage protection prevents
damage of SR MOSFET. When the voltage on the VDD
pin exceeds 27V, FAN6208 disables gate output.
Internal Over-Temperature Protection
Internal over-temperature protection prevents the SR
gate from fault triggering in high temperatures. If the
temperature is over 140°C, the SR gate is disabled until
the temperature drops below 120°C.
Short-Circuit Protection
As depicted in Figure 13, FAN6208 monitors the current
through the opto-coupler diode by measuring the
voltage across the resistor in series with the opto-
coupler diode. When the output of the power supply is
short circuited, the output voltage drops and the cathode
of the shunt regulator (KA431) is saturated to HIGH. No
current flows through the opto coupler diode. The output
short protection is triggered when the voltage between
VDD and FD is smaller than 0.3V, as shown in Figure 19.
Figure 19. Output Short Protection by Feedback
Detection
www.DataSheet4U.com
© 2010 Fairchild Semiconductor Corporation
FAN6208 • Rev. 1.0.1
11
www.fairchildsemi.com
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet FAN6208.PDF ] | |
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