www.fairchildsemi.com
FAN7554
Versatile PWM Controller
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
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.
8-DIP
Applications
• Off-Line & DC-DC converter
8-SOP
1
1
Rev. 1.0.3
©2003 Fairchild Semiconductor Corporation
FAN7554
Internal Block Diagram
Rt/Ct
4
3.5V
+
_
_
S
Q
R
off
PWR
/
SAVE
Vref
8
+
34V
+
+
_
_
+
_
_
_
OVP
Vcc
7
Vref
100uA
+
+
_
UVLO
Vref
S/S
2
1k
+
0.3V
1.5V
on
15V/9V
OSC
CLK
PWM
+
_
_
S
Q
R
14V
FB
1
1mA
Absolute Maximum Ratings
( Ta = 25°C, unless otherwise specified )
Parameter
Supply voltage
Output current
Input voltage to FB pin
Input voltage to IS pin
Power dissipation at T
A
≤
25°C
8-DIP
8-SOP
Operating temperature
Storage temperature
Thermal resistance, junction-to-air (Note1)
8-DIP
8-SOP
Symbol
Vcc
I
O
V
FB
V
IS
P
D
T
OPR
T
STG
Rθja
Value
30
±1
-0.3 to V
SD
-0.3 to V
OC
0.85
0.42
-25 to +85
-55 to +150
147.8
291.4
Unit
V
A
V
V
W
°C
°C
°C/W
Note:
1.
Junction -to -air thermal resistance test environments.
- JESD51-2 : Integrated circuits thermal test method environmental conditions-natural convection (still air).
- JESD51-3 : Low effective thermal conductivity test board for leaded surface mount packages.
- JESD51-10 : Test boards for through-hole perimeter leaded package thermal measurements.
2
_
_
6V
+
+
_
MAX. 1V
2R
R
6
OUT
Vref
Vcc
5uA
OLP
OVP-out
OCL-out
Offset(0.1V)
3
OCL
S
R
UVLO-out
Q
2V
IS
5 GND
FAN7554
Temperature Characteristics
( -25°C
≤
Ta
≤
85°C )
Parameter
Vref temperature stability
Fosc temperature stability
Symbol
∆V
REF
3
∆F
OSC
2
Value
±0.5
±5
Unit
%
%
PIN Array
Vref
Vcc
OUT
GND
8
7
6
5
YWW
FA N7554
1
FB
2
S/S
3
IS
4
Rt/Ct
PIN Definitions
Pin Number
1
2
3
4
5
6
7
8
Pin Name
FB
S/S
IS
Rt/Ct
GND
OUT
Vcc
Vref
Soft start
Non-inverting(+) input of PWM comparator, OCL sensing terminal
Oscillator time constant(Rt/Ct)
Ground
Output of gate driver
Power supply
Output of 5V reference
Pin Function Description
Inverting(-) input of pwm comparator, on/off control & OLP sensing terminal.
3
FAN7554
Electrical Characteristics
(Ta = 25°C, Vcc=16V, Rt=10kΩ, Ct=3.3nF unless otherwise specified)
Parameter
< REFERENCE SECTION >
Reference output voltage
Line regulation
Load regulation
Short circuit output current
< OSCILLATOR SECTION >
Oscillation frequency
Frequency change with Vcc
Ramp high voltage
Ramp low voltage
Discharge current
< PWM SECTION >
Sense threshold voltage
Feedback threshold voltage
Feedback source current
Max. duty cycle
Min. duty cycle
< PROTECTION SECTION >
Shutdown delay current
Shutdown feedback voltage
Over current protection
Over voltage protection
< ON/OFF CONTROL SECTION >
Off mode sink current
Off threshold voltage
< SOFT-START SECTION >
Soft start current
Soft start limit voltage
<OUTPUT SECTION>
Low output voltage1
High output voltage1
Low output voltage2
High output voltage2
Rising time (Note1)
Falling time (Note1)
<UVLO SECTION>
Start threshold voltage
Min. operating voltage
V
TH(ST)
V
OPR(M)
-
-
13.2
8.2
15
9
16.2
10.2
V
V
V
OL1
V
OH1
V
OL2
V
OH2
t
R
t
F
V
CC
= 18V, I
O
= 50mA
V
CC
= 18V, I
O
= -50mA
V
CC
= 18V, I
O
= 200mA
Vcc = 18V, Io = -200mA
T
j
= 25°C, C
L
= 1nF
T
j
= 25°C, C
L
= 1nF
-
13
-
12
-
-
0.15
15
1.5
14
80
40
0.4
17
2.5
16
-
-
V
V
V
V
ns
ns
I
S/S
V
LIM(S/S)
V
FB
= 5V, V
S/S
= 0V
Vcc = 16V
-
-
1.1
5.2
-
-
mA
V
I
SINK
V
OFF
V
FB
< V
TH(FB)
, V
S/S
= 5V
V
FB
< V
TH(FB)
-
1.2
4
1.5
-
1.8
mA
V
I
SD
V
SD
V
OC
V
OVP
4V
≤
V
FB
≤
V
SD
V
FB
> 5V
V
IS
> 1.5V,
t
on
> 500nS
-
3.5
5.4
1.6
30
5
6
2
34
6.5
6.6
2.4
38
uA
V
V
V
V
TH(IS)
V
TH(FB)
I
FB
D
(MAX)
D
(MIN)
V
FB
= 5V
V
IS
= 0V
V
FB
= 0V, V
S/S
= 5V
-
-
0.8
0.2
-
92
-
1.0
0.3
1.0
95
-
1.2
0.4
-
98
0
V
V
mA
%
%
F
OSC
∆F
OSC1
V
RH
V
RL
Idisch
T
j
= 25°C
Vcc = 12V ~ 25V
-
-
V
RT/CT
= 3.3V
45
-
-
-
6.1
50
0.05
2.8
1.2
-
55
1.0
-
-
9.4
kHz
%
V
V
mA
V
REF
∆V
REF1
∆V
REF2
I
SC
T
j
=25°C , Iref =1mA
Vcc =12V ~ 25V
Iref =1mA ~ 20mA
T
j
= 25°C
4.90
-
-
-
5.00
6
6
0.1
5.10
20
25
0.18
V
mV
mV
A
Symbol
Conditions
Min.
Typ.
Max.
Unit
4
FAN7554
Electrical Characteristics
(Continued)
(Ta = 25°C, Vcc=16V, Rt =10kΩ, Ct = 3.3nF unless otherwise specified)
Parameter
Start-up current
Operating supply current
Off State current
Symbol
I
ST
I
OP
I
OFF
Conditions
-
-
V
FB
<V
TH(FB)
,V
S/S
<V
OFF
Min.
-
-
-
Typ.
0.1
7
0.2
Max.
0.2
10
0.4
Unit
mA
mA
mA
<TOTAL STAND-BY CURRENT SECTION>
Note:
1. These parameters, although guaranteed, are not 100% tested in production.
5
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