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PDF FS8S0965RCB Data sheet ( Hoja de datos )
| Número de pieza | FS8S0965RCB | |
| Descripción | Power Switch | |
| Fabricantes | Fairchild Semiconductor | |
| Logotipo |  |
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FS8S0965RCB
Fairchild Power Switch(FPS)
www.fairchildsemi.com
Features
• Burst Mode Operation to Reduce the Power Consumption
in the Standby Mode
• External pin for Synchronization and Soft Start
• Wide Operating Frequency Range up to 150kHz
• Low Start-up Current (Max:80uA)
• Low Operating Current (Max:15mA)
• Pulse by Pulse Current Limiting
• Over Voltage Protection (Auto Restart Mode)
• Over Load Protection (Auto Restart Mode)
• Abnormal Over Current Protection (Auto Restart Mode)
• Internal Thermal Shutdown (Auto Restart Mode)
• Under Voltage Lockout
• Internal High Voltage SenseFET
Application
• Monitor SMPS
Description
FS8S0965RCB is a Fairchild Power Switch (FPS) that is
specially designed for off-line SMPS of CRT monitor with
minimal external components. This device is a current mode
PWM controller combined with a high voltage power
SenseFET in a single package. The PWM controller features
integrated oscillator to be synchronized with the external
sync signal, under voltage lockout, optimized gate driver and
temperature compensated precise current sources for the
loop compensation. This device also includes various fault
protection circuits such as over voltage protection, over load
protection, abnormal over current protection and over tem-
perature protection. Compared with discrete MOSFET and
PWM controller solution, FPS can reduce total cost, compo-
nent count, size and weight simultaneously increasing effi-
ciency, productivity and system reliability. This device is well
suited for the cost effective monitor power supply.
TO-220-5L
Internal Block Diagram
1
1. Drain 2. GND 3. VCC 4. Feedback 5. Sync
Vcc
Vref
3
Soft start 5
& Sync
Burst Mode Detector
Vfb<=1V
Vss>3V
No sync
Burst Mode
Controller
Sync
Detector
Vref
9V/15V
OSC
Vcc good
Vref
Drain
1
Internal
Bias
FB 4
Vcc
Idelay
VSD
Vcc
Vovp
TSD
Vref
IFB
2.5R
R
PWM
SQ
RQ
LEB
Gate
driver
UVLO Reset
(Vcc<9V)
SQ
RQ
AOCP
Vocl
2 GND
©2003 Fairchild Semiconductor Corporation
Rev.1.0.1
1 page  
wEwlwe.DcattarSicheaetl4UC.chomaracteristics (Continued)
(Ta=25°C unless otherwise specified)
FS8S0965RCB
Parameter
UVLO SECTION
Start Threshold Voltage
Stop Threshold Voltage
OSCILLATOR SECTION
Initial Frequency
Voltage Stability
Temperature Stability (1)
Maximum Duty Cycle
Minimum Duty Cycle
FEEDBACK SECTION
Feedback Source Current
Feedback Sink Current
Shutdown Feedback Voltage
Shutdown Delay Current
PROTECTION SECTION
Over Voltage Protection
Over Current Latch Voltage (2)
Thermal Shutdown Temp.(1)
SYNC & SOFTSTART SECTION
Softstart Vortage
Softstart Current
Sync High Threshold Voltage
Sync Low Threshold Voltage
Symbol
Condition
VSTART
VSTOP
VFB=GND
VFB=GND
FOSC
FSTABLE
∆FOSC
DMAX
DMIN
-
12V ≤ Vcc ≤ 23V
-25°C ≤ Ta ≤ 85°C
-
-
IFBSO
IFBSI
VSD
Idelay
VFB=GND
VFB=4V,VCC=19V
Vfb ≥ 6.9V
VFB=5V
VOVP
VOCL
TSD
Vcc ≥ 27V
-
-
VSS Vfb=2
ISS Vss=0V
VSH Vcc=16V,Vfb=5V
VSL Vcc=16V,Vfb=5V
Min. Typ. Max. Unit
14 15 16 V
8 9 10 V
18 20 22 kHz
0 1 3%
0 ±5 ±10 %
92 95 98 %
- - 0%
0.7 0.9 1.1 mA
2.4 3.0 3.6 mA
6.9 7.5 8.1 V
1.6 2.0 2.4 µA
34 37
-
0.95 1.0 1.05
140 160 -
V
V
°C
4.7 5.0 5.3 V
0.8 1.0 1.2 mA
6.7 7.2 7.9 V
5.4 5.8 6.2 V
Note:
1. These parameters, although guaranteed at the design, are not tested in mass production.
2. These parameters, although guaranteed, are tested in EDS(wafer test) process.
5
5 Page 
FS8S0965RCB
wFwuw.nDactatSiohenet4aUl.cDomescription
1. Start up : To guarantee stable operation of the
control IC, FS8S0965RCB has UVLO circuit with 6V
hysteresis band. Figure 1 shows the relation between the sup-
ply current (Icc) and the supply voltage (Vcc). Before Vcc
reaches 15V, the FPS consumes only startup current of
80µA, which is usually provided by the DC link through
start-up resistor. When Vcc reaches 15V, the FPS begins
operation and the operating current increases to 15mA as
shown. Once the control IC starts operation, it continues its
normal operation until Vcc goes below the stop voltage of
9V
Icc
3. Protection function : FS8S0965RCB has 4 self
protective functions such as abnormal over current protec-
tion (AOCP), over load protection (OLP), over voltage pro-
tection (OVP) and thermal shutdown (TSD). Because these
protection circuits are fully integrated into the IC without
external components, the reliability can be improved without
cost increase. In the event of these fault conditions, the FPS
enters into auto-restart operation. Once the fault condition
occurs, switching operation is terminated and MOSFET
remains off, which forces Vcc to be reduced. When Vcc
reaches 9V, the protection is reset and the supply current
reduces to 80 uA. Then, Vcc begin to increase with the cur-
rent provided through the start-up resistor. When Vcc
reaches 15V, the FPS resumes its normal operation if the
fault condition is removed. In this manner, the auto-restart
alternately enables and disables the switching of the power
MOSFET until the fault condition is eliminated as illustrated
in figure 3.
15mA
80uA
Vstop=9V
Vstart=15V
Vcc
OVP
Figure 1. Strat up with hysteresis
2. Feedback Control : FS8S0965RCB employs primary side
regulation, which permits elimination of feedback circuit
components in the secondary side such as opto coupler and
TL431. Figure 2 shows the primary side control circuit. The
primary side regulation voltage (Vpsr) is controlled to the
breakdown voltage of zener diode (Dz). Because current
mode control is employed, the drain current of the power
MOSFET is limited by the inverting input of PWM compara-
tor (Vfb*). When MOSFET turns on, usually there exists
high current spike in the MOSFET current caused by pri-
mary-side capacitance and secondary-side rectifier reverse
recovery. In order to prevent premature termination of the
switching pulse due to the current spike, the FPS employs
leading edge blanking (LEB). The leading edge blanking cir-
cuit inhibits the PWM comparator for a short time after the
MOSFET is turned on.
V
Vds
Prote c tion is a c tiva te d
(O CP,O LP,O VP or TSD)
V
Vcc
15V
9V
Vcc
tim e
Au to re sta rt
tim e
Figure 3. Auto restart operation after protection
3.1 Abnormal Over Current Protection (AOCP) : When
the secondary rectifying diodes or the transformer pins are
shorted, a steep current with extremely high di/dt can flow
during the LEB time. Therefore, the abnormal over current
protection (AOCP) block is added to ensure the reliability as
shown in figure 4. It turns off the SenseFET within 300ns
after the abnormal over current condition is sensed.
V psr
Vcc Vref
2uA 0.9mA
Vfb FB
4
DZ Cfb
D1 D2
Vfb*
OSC
2.5R
R
RZ
Gate
driver
VSD OLP
Figure 2. Primary side control circuit
11
OVP
OLP
TSD
S Q'
R
UVLO
GATE
DRIVER
PWM Comp
AOCP COMP.
Vsense : 1V
Figure 4. AOCP block
SenseFET
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet FS8S0965RCB.PDF ] | |
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