2004 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev.1.0.1
Features
Current Mode PWM Control With a Fixed Operating
Frequency (300kHz)
Pulse by Pulse Current Limit
Over Load Protection
Over Voltage Protection
Thermal Shutdown
Built-in Auto-Restart Circuit
Line Under Voltage Detection and Sleep on/off Function
Internal High Voltage SenseFET (QFET)
Supports Forward or Flyback Topology
Application
DC-DC Converter
Description
The FS6X1220R is specially designed for an off-line DC-
DC converters 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 includes integrated fixed frequency oscillator, line
under voltage lockout, sleep on/off function, thermal
shutdown protection, over voltage protection, pulse-by-pulse
current limit and temperature compensated precise current
sources for a loop compensation. Compared with discrete
MOSFET and PWM controller solution, the FS6X1220R can
reduce total cost, component count, size and weight simulta-
neously increasing efficiency, productivity, and system
reliability. This device is well suited for DC to DC converter
applications up to 40W of output power.
TO-220F-5L
1
1. Drain 2. GND 3. V
CC
4. Feedback 5. Line Sense
D2-PAK-5L
Internal Block Diagram
V
SL
V
LU
9V/15V
3
1
2
4
5
Vref
Line UVLO
Enable
Internal
Bias
S
Q
Q
R
OSC
Vcc
Vref
I
delay
I
FB
V
SD
TSD
Vovp
Vcc
Line UVLO
S
Q
Q
R
R
28R
Vcc good
Vcc good
Vcc
Drain
Line
Sense
FB
GND
Gate driver
FS6X1220R
Fairchild Power Switch (FPS
TM
)
FS6X1220R
2
Pin Description
Pin Number
Pin Name
Pin Function Description
1
Drain
High voltage power SenseFET drain connection.
2
GND
This pin is the control ground and the SenseFET source.
3
Vcc
This pin is the positive supply input. This pin provides internal operating current
for both start-up and steady-state operation.
4
Feedback
(FB)
This pin is internally connected to the inverting input of the PWM comparator.
The collector of an opto-coupler is typically tied to this pin. For stable
operation, a capacitor should be placed between this pin and GND. If the
voltage of this pin reaches 7.5V, the over load protection is activated resulting
in shutdown of the IC.
5
Line Sense
(LS)
According to the voltage of this pin, three operation modes are defined; Normal
operation mode, Line under voltage lock out mode and Sleep mode. If the
voltage of this pin is smaller than 2.55V, the IC goes into line under voltage
lock out stopping switching operation. If the voltage of this pin is smaller than
1.8V, the IC enters into sleep mode. During sleep mode, reference voltage
generation circuit including shunt regulator is disabled and only 300uA
operation current is required.
FS6X1220R
3
Absolute Maximum Ratings
(Ta=25
C, unless otherwise specified)
Notes:
1. Tj=25
C to 150C
2. Repetitive rating: Pulse width limited by maximum junction temperature
3. L=4.7 mH, starting Tj=25
C
Parameter
Symbol
Value
Unit
Drain-Gate Voltage (R
GS
=1M
)
V
DGR
200
V
Gate-Source (GND) Voltage
V
GS
30
V
Drain Current Pulsed
(2)
I
DM
32.8
A
DC
Single Pulsed Avalanche Energy
(3)
E
AS
210
mJ
Continuous Drain Current (Tc = 25C)
I
D
8.2
A
DC
Continuous Drain Current (T
C
=100
C)
I
D
5.2
A
DC
Supply Voltage
V
CC
35
V
Input Voltage Range
V
FB
-0.3 to Vcc
V
V
LS
-0.3 to Vcc
V
Total Power Dissipation
P
D
(Watt H/S)
45
W
Derating
0.36
W/
C
Operating Junction Temperature
T
j
+150
C
Operating Ambient Temperature
T
A
-25 to +85
C
Storage Temperature Range
T
STG
-55 to +150
C
FS6X1220R
4
Electrical Characteristics (SenseFET part)
(Ta=25
C unless otherwise specified)
Note:
1. Pulse test : Pulse width
300S, duty 2%
Parameter
Symbol
Condition
Min.
Typ.
Max.
Unit
Drain Source Breakdown Voltage
BV
DSS
V
GS
=0V, I
D
=250
A
200
-
-
V
Zero Gate Voltage Drain Current
I
DSS
V
DS
=200V, V
GS
=0V
-
-
1
A
V
DS
=160V
V
GS
=0V, T
C
=125
C
-
-
10
A
Static Drain Source On Resistance
(1)
R
DS(ON)
V
GS
=10V, I
D
=4.1A
-
0.24
0.30
Forward Transconductance
gfs
V
DS
=40V, I
D
=4.1A
-
7.1
-
mho
Input Capacitance
Ciss
V
GS
=0V, V
DS
=25V,
f = 1MHz
-
700
910
pF
Output Capacitance
Coss
-
125
160
Reverse Transfer Capacitance
Crss
-
18
25
Turn On Delay Time
td(on)
V
DD
=100V, I
D
=11.6A
(MOSFET switching
time is essentially
independent of
operating temperature)
-
13
35
ns
Rise Time
tr
-
120
250
Turn Off Delay Time
td(off)
-
30
70
Fall Time
tf
-
55
120
Total Gate Charge
(Gate-Source+Gate-Drain)
Qg
V
GS
=10V, I
D
=11.6A,
V
DS
=160V (MOSFET
switching time is essentially
independent of
operating temperature)
-
18
23
nC
Gate-Source Charge
Qgs
-
5
-
Gate-Drain (Miller) Charge
Qgd
-
8
-
FS6X1220R
5
Electrical Characteristics
(Continued)
(Ta=25
C unless otherwise specified)
Note:
1. These parameters, although guaranteed at the design, are not tested in mass production.
2. These parameter indicates inductor current.
Parameter
Symbol
Condition
Min.
Typ.
Max.
Unit
UVLO SECTION
Start Threshold Voltage
V
START
V
FB
= GND
14
15
16
V
Stop Threshold Voltage
V
STOP
V
FB
= GND
8
9
10
V
OSCILLATOR SECTION
Initial Frequency
F
OSC
-
270
300
330
kHz
Voltage Stability
F
STABLE
12V
V
CC
23V
0
1
3
%
Temperature Stability (1)
F
OSC
-25
C Ta 85C
0
5
10
%
Maximum Duty Cycle
D
MAX
-
72
80
88
%
Minimum Duty Cycle
D
MIN
-
-
-
0
%
FEEDBACK SECTION
Feedback Source Current
I
FB
V
FB
= GND
0.7
0.9
1.1
mA
Shutdown Feedback Voltage
V
SD
V
FB
6.9V
6.9
7.5
8.1
V
Shutdown Delay Current
I
DELAY
V
FB
= 5V
4.0
5.0
6.0
A
LINE SENSE SECTION
Line UVLO Threshold Voltage
V
LU
-
2.4
2.55
2.7
V
Sleep On/Off Threshold Voltage
V
SL
-
1.5
1.8
2.1
V
CURRENT LIMIT(SELF-PROTECTION)SECTION
Peak Current Limit (2)
I
OVER
-
2.82
3.2
3.58
A
PROTECTION SECTION
Thermal Shutdown Temp (1)
TSD
-
140
160
-
C
Over Voltage Protection
V
OVP
Vcc
6.9V
23
25
27
V
TOTAL DEVICE SECTION
Start Up Current
I
START
V
FB
= GND, V
CC
= 14V
-
60
120
uA
Sleep Mode Current
I
SLEEP
V
UVLO
= 1V, V
CC
= 16V
-
300
500
uA
Operating Supply Current
I
OP
V
FB
= GND, V
CC
= 16V
-
10
15
mA
I
OP(MIN)
V
FB
= GND, V
CC
= 12V
I
OP(MAX)
V
FB
= GND, V
CC
= 20V
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