2002 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.2
Features
Current Mode Control
Pulse by Pulse Current Limiting
Low External Components
Under Voltage Lockout(UVLO): 9V/15V
Stand-by Current: Typ. 100uA
Power Saving Mode Current: Typ. 200uA
Operating Current: Typ. 7mA
Soft Start
On/Off Control
Over Load Protection(OLP)
Over Voltage Protection(OVP)
Over Current Protection(OCP)
Over Current Limit(OCL)
Operating Frequency up to 500kHz
1A Totem-Pole Output Current
Applications
Off-Line & DC-DC Converter
Description
The FAN7554 is a fixed frequency current mode PWM
controller. It is specially designed for off-line and DC to DC
converter applications with minimal external components.
These integrated circuits feature a trimmed oscillator for
precise duty cycle control, a temperature compensated
reference, an ON/OFF control, a high gain error amplifier, a
current sensing comparator, and a high current totem-pole
output. The FAN7554 has various protection functions such
as an over load protection, an over current protection, and
the over voltage protection, which include built-in auto
restart circuit. The FAN7554 is available in the 8-DIP
package as well as the 8-SOP package.
FAN7554
Versatile PWM Controller
8-DIP
8-SOP
1
1
FAN7554
2
Internal Block Diagram
Absolute Maximum Ratings
( Ta = 25
C, unless otherwise specified )
Note:
1. Junction -to -air thermal resistance test environments.
-. Pneumatic heat sink fixture.
-. Clamping pressure 60psi through 12mm diameter cylinder.
-. Thermal grease applied between PKG and heat sink fixture
Parameter
Symbol
Value
Unit
Supply Voltage
Vcc
30
V
Output Current
I
O
1
A
Input Voltage to FB Pin
V
FB
-0.3 to V
SD
V
Input Voltage to IS Pin
V
IS
-0.3 to V
OC
V
Power Dissipation at T
A
25
C
8-DIP
8-SOP
P
D
0.85
0.42
W
Operating Temperature
T
OPR
-25 to +85
C
Storage Temperature
T
STG
-55 to +150
C
Thermal Resistance, Junction-to-Air (Note1)
8-DIP
8-SOP
R
ja
147.8
291.4
C/W
OSC
6
7
1
5
4
3
8
FB
Rt/Ct
Vcc
OUT
GND
I S
2
S/S
1.5V
+
3.5V
0.3V
14V
15V/9V
UVLO
2V
OLP
6V
5uA
Vcc
Offset(0.1V)
PWM
R
MAX. 1V
2R
UVLO-out
S
Q
R
CLK
PWR
/
SAVE
on
off
Vref
S
Q
R
1k
Vref
100uA
Vref
1mA
Vref
S
R
Q
OVP
34V
OVP-out
OCL-out
OCL
_
+
_
+
_
+
_
+
_
+
_
+
_
+
_
OSC
6
6
7
7
1
1
5
5
4
4
3
3
8
8
FB
Rt/Ct
Vcc
OUT
GND
I S
2
2
S/S
1.5V
+
3.5V
0.3V
14V
15V/9V
UVLO
2V
OLP
6V
5uA
Vcc
5uA
Vcc
Offset(0.1V)
PWM
R
MAX. 1V
2R
UVLO-out
S
Q
R
CLK
PWR
/
SAVE
on
off
Vref
S
Q
R
1k
1k
Vref
100uA
Vref
1mA
Vref
S
R
Q
OVP
34V
OVP-out
OCL-out
OCL
_
+
_
+
_
+
_
+
_
+
_
+
_
+
_
FAN7554
3
Temperature Characteristics
( -25
C
Ta
85
C )
PIN Array
PIN Definitions
Parameter
Symbol
Value
Unit
Vref Temperature Stability
V
REF
3
0.5
%
Fosc Temperature Stability
F
OSC
2
5
%
Pin Number
Pin Name
Pin Function Description
1
FB
Inverting(-) Input of PWM Comparator, ON/OFF Control & OLP Sensing
Terminal.
2
S/S
Soft Start
3
IS
Non-Inverting(+) Input of PWM Comparator, OCL Sensing Terminal
4
Rt/Ct
Oscillator Time Constant(Rt/Ct)
5
GND
Ground
6
OUT
Output of Gate Driver
7
Vcc
Power Supply
8
Vref
Output of 5V Reference
Vref
Vcc
OUT
GND
7
7
7
7
6
6
6
6
5
5
5
5
8
8
8
8
2
2
2
2
3
3
3
3
4
4
4
4
1
1
1
1
Y
Y
Y
Y W
W
W
W W
W
W
W
A
A
A
A N
N
N
N 7
7
7
7 5
5
5
5 5
5
5
5 4
4
4
4
F
F
F
F
Rt/Ct
IS
S/S
FB
FAN7554
4
Electrical Characteristics
(Ta = 25
C, Vcc=16V, Rt=10k
, Ct=3.3nF unless otherwise specified)
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
< REFERENCE SECTION >
Reference Output Voltage
V
REF
T
j
=25
C , Iref =1mA
4.90
5.00
5.10
V
Line Regulation
V
REF1
Vcc =12V ~ 25V
-
6
20
mV
Load Regulation
V
REF2
Iref =1mA ~ 20mA
-
6
25
mV
Short Circuit Output Current
I
SC
T
j
= 25
C
-
0.1
0.18
A
< OSCILLATOR SECTION >
Oscillation Frequency
F
OSC
T
j
= 25
C
45
50
55
kHz
Frequency Change with Vcc
F
OSC1
Vcc = 12V ~ 25V
-
0.05
1.0
%
Ramp High Voltage
V
RH
-
-
2.8
-
V
Ramp Low Voltage
V
RL
-
-
1.2
-
V
Discharge Current
Idisch
V
RT/CT
= 3.3V
6.1
-
9.4
mA
< PWM SECTION >
Sense Threshold Voltage
V
TH(IS)
V
FB
= 5V
0.8
1.0
1.2
V
Feedback Threshold Voltage
V
TH(FB)
V
IS
= 0V
0.2
0.3
0.4
V
Feedback Source Current
I
FB
V
FB
= 0V, V
S/S
= 5V
-
1.0
-
mA
Max. Duty Cycle
D
(MAX)
-
92
95
98
%
Min. Duty Cycle
D
(MIN)
-
-
-
0
%
< PROTECTION SECTION >
Shutdown Delay Current
I
SD
4V
V
FB
V
SD
3.5
5
6.5
uA
Shutdown Feedback Voltage
V
SD
V
FB
> 5V
5.4
6
6.6
V
Over Current Protection
V
OC
V
IS
> 1.5V,
t
on
> 500nS
1.6
2
2.4
V
Over Voltage Protection
V
OVP
-
30
34
38
V
< ON/OFF CONTROL SECTION >
Off Mode Sink Current
I
SINK
V
FB
< V
TH(FB)
, V
S/S
= 5V
-
4
-
mA
Off Threshold Voltage
V
OFF
V
FB
< V
TH(FB)
1.2
1.5
1.8
V
< SOFT-START SECTION >
Soft Start Current
I
S/S
V
FB
= 5V, V
S/S
= 0V
-
1.1
-
mA
Soft Start Limit Voltage
V
LIM(S/S)
Vcc = 16V
-
5.2
-
V
<OUTPUT SECTION>
Low Output Voltage1
V
OL1
V
CC
= 18V, I
O
= 50mA
-
0.15
0.4
V
High Output Voltage1
V
OH1
V
CC
= 18V, I
O
= -50mA
13
15
17
V
Low Output Voltage2
V
OL2
V
CC
= 18V, I
O
= 200mA
-
1.5
2.5
V
High Output Voltage2
V
OH2
Vcc = 18V, Io = -200mA
12
14
16
V
Rising Time (Note1)
t
R
T
j
= 25
C, C
L
= 1nF
-
80
-
ns
Falling Time (Note1)
t
F
T
j
= 25
C, C
L
= 1nF
-
40
-
ns
<UVLO SECTION>
Start Threshold Voltage
V
TH(ST)
-
13.2
15
16.2
V
Min. Operating Voltage
V
OPR(M)
-
8.2
9
10.2
V
FAN7554
5
Electrical Characteristics
(Continued)
(Ta = 25
C, Vcc=16V, Rt =10k
,
Ct = 3.3nF unless otherwise specified)
Note:
1. These parameters, although guaranteed, are not 100% tested in production.
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
<TOTAL STAND-BY CURRENT SECTION>
Start-up Current
I
ST
-
-
0.1
0.2
mA
Operating Supply Current
I
OP
-
-
7
10
mA
Off State Current
I
OFF
V
FB
<V
TH(FB)
,V
S/S
<V
OFF
-
0.2
0.4
mA
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