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RS2201
Switching Power Supply Controller
Description
RS2201, produced by advanced integrated circuit process, is a switch power supply controller, which could offer over-load and
saturation protection, and achieve green economize on energy and environmental protection standard. RS2201 could achieve
AC/DC conversion and can be widely applied to economical switching power supply equipment. For instance, Charger、DVD,
Induction cooker, STB, Printer, LCD and so on.
Features
Over-load and saturation protection could protect over-load, switch transformer saturation and output short circuit or the
relative failures.
It is economical that triode is used for switch device, which could start up the circuit with its amplification function and
reduce ten times of power consumption of the start-up resistance.
Built-in Synchronized Slope Compensation circuit, thermal protection circuit, slope current drive circuit.
Zero-load output power consumption could be less than 0.3W, is less than 0.2W while 220V AC input.
Pin to Pin THX201
Pb-Free DIP-8 and SOP-8 Package.
Applications
Switching AC/DC Adaptor
Battery Charger
Open Frame Switching Power Supply
Standby Power Supplies
Set-Top Box Power Supplies
384X Replacement
Pin Configurations
Name
CT
VR
FB
GND
IS
OE
OB
VCC
Description
By connecting a cap to ground to set the switching frequency
2.5V reference voltage output
Feedback pin
GND
Current sense.
Power Transistor Emitter drive output and start-up current input.
Power Transistor Base drive output and start-up current control.
Power Supply.
DS-RS2201-01
Nov, 2007
www.Orister.com
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Typical Application Circuit
Operation description
Initially, after power up, no output of VR. FB pull-up current source is turn off. OE inputs start-up current from power
transistor to VCC. OB controls the base current of power transistor and limits the collector current (start-up accept current
of RS2201) of power transistor so to safeguard the power transistor. When the VCC voltage rises to 7.8V, the start-up
phase completes and goes to the normal operation.
In normal operation, VCC voltage must keep 4.75~9.8V, VR outputs 2.5V reference voltage. FB pull-up current source
turns on. Oscillator outputs OSC1 to decide the maximum duty cycle and OSC2 to trigger power supply entering the open
cycle and cover spike value of power transistor start-up current. If FB is less than 1.8V(about 1.2-1.8V), the less the FB is,
the wider the oscillation cycle is.（This characteristics reduces the standby consumption of the switching power supply）.
If external feedback intends to get VCC greater than 9.8V, the internal feedback circuit regular VCC on 9.8V.（Making use
of this characteristics to stable output voltage no using external feedback circuit, but the regulating is not precise）.
In open cycle, OB provides the base current for power transistor, OE pulls down the emitter of power transistor to IS and
OB adopts slop current drive (OB open current is IS function, when IS=0V,OB open current is about 40mA, and OB open
current is increasing with IS linear increasing. When IS increases 0.6V, OB open current is about 120mA. This
characteristics makes use of output current of OB effectively and reduces power consumption of RS2201). If IS detects the
FB designated current, it enters closed cycle. In closed cycle, OB pulls down, the power transistor is not be turn off
immediately but OE clamps 1.5V (after power transistor is turn off, the base is reverse bias, the breakdown voltage of
power transistor is improved). In the open or closed cycle, if power transistor is detected to exceed upper limit current, the
upper limit current trigger will set firstly and forces FB to pull down, duty cycle reduced, so to protect power transistor and
transformer. In the next closed cycle start-up time, or when FB is less than 1.8V, upper current trigger resets. In addition,
RS2201 is built in thermal protection, when the internal temperature is above 140
℃
, it will widen the cycle of oscillator, so
that the temperature of RS2201 will not exceed 150
℃
. Slop compensation is built in to stabilization open/closed cycle
during the maximum duty cycle or the continual current mode of RS2201.
If VCC reduces to 4.4V, oscillator is turn off, OSC1 OSC2 low level, power supply keeps closed cycle. when VCC
continually reduces to about 4.0 V , RS2201 enters start-up phase again.
DS-RS2201-01
Nov, 2007
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Page No. : 3/3
Fig.1 OPEN/CLOSED CYCLE WAVES IN NORMAL OPERATION
Electrical parameter definition
Start-up accept current: OE node current when OB has a 0.1mA pull-down current in start-up phase.
Start-up static current: VCC connects to filter capacitor and adjustable current source, CT connects to 680PF，other pins
are floating. It is the minimum current that could oscillate the VCC.
Start-up voltage: The max. value of VCC oscillation above.
Restart voltage: The min. value of VCC oscillation above.
Voltage of Oscillator is turn off: VCC value, which stops the oscillator in falling time of VCC oscillation above.
Static current: In normal operation, FB connects to the grand through 1.8K resistor. VCC power supply current.
The pull-up/ pull-down current of oscillator: In normal operation, FB=2.5V,CT=1.25V, pull-up /pull-down current on CT.
Fig.2 RS2201 ALL SIGNAL WAVES
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Nov, 2007
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Page No. : 4/4
FB pull-up current: In normal operation, when FB=2.5V,IS=0V, pull up current on FB.
FB protecting upper limit current: In normal operation, FB=2.5V,IS=0.8V，pull down current on FB.
Internal feedback power supply voltage: In normal operation, VCC value of RS2201 power supply without external standby
feedback circuit.
IS upper limit current: FB=2.5V，external adjustable power supply to IS, there is minimal IS voltage of pull-down current on
FB.
Slope current drive: OB open current is IS function, when IS=0V,OB open current is about 40mA, and OB open current is
increasing with IS linear increasing. When IS increases 0.6V, OB open current is about 120mA.
OSC Frequency
: C function of CT pin external capacitor, is about C*24000 seconds.
Electrical Characteristics
Symbol
Ics
Parameter
Start-up accept current
Start-up static current
Start-up voltage
Oscillator cut off voltage
Restart voltage
Inner oscillator voltage
Operating Current
VR reference voltage
Oscillator Frequency
Oscillator pull-up current
Oscillator pull-down current
Maximum Duty Cycle
FB Feedback Voltage
FB pull-up current
FB prevent upper limit current
IS upper limit current
OE Clamp Voltage
OB open current
OB open current
OB closed current
OB closed current
OE output current
Conditions
Min.
1.6
7.6
4.25
9.6
VCC=8V
2.4
CT*24000
CT=1.25V
CT=1.25V
CT=680PF
IS=0.5V,CT=0.6V
FB=2.5V,IS=0V
FB=2.5V,IS=0.8V
R IS-GND =0.75Ω
OE=0.001~1.2A
IS=0.5V
IS=0.0V
OB-IS=1V
OB-IS=0.25V
OE-IS=0.6V
Typ.
2.0
55
7.8
4.50
4.0
10.0
3.5
2.5
64
100
1.9
55
4.8
590
310
0.60
1.6
120
44
-210
-4.5
-1.2
Max.
2.4
80
8.0
4.75
10.4
2.6
Unit
mA
uA
V
V
V
V
mA
V
KHz
uA
mA
%
V
uA
uA
V
V
mA
mA
mA
mA
A
Icc
VR
Fosc
53
61
0.54
102
32
-145
0.62
140
60
-230
-6
-1
DS-RS2201-01
Nov, 2007
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Page No. : 5/5
RS2201 - 12W（12V/1A）Demo Board Circuit Diagram
BOM List
Part Location
R1
R2
R3
R4, R5
R6
R7, R10
R8
R9
R11
R12
C1, C2
C3
C4
C5
C6
C7
C8
C9,C10
CX1
CY1
B1
D1;D2
D3
D4
F1
L1
LF1
Q1
T1
LED1
U1
U2
U3
Description
RES;SMD;1206;+/-5%
RES;SMD;1206;+/-5%
RES;SMD;0805;+/-5%
RES;SMD;1206;+/-5%
RES;SMD;0805;+/-5%
RES;SMD;0805;+/-5%
RES;SMD;0805;+/-5%
RES;SMD;0805;+/-3%
RES;SMD;0805;+/-3%
RES;MOF;+/-5%,1W
C/E;Ф10*15;105
℃
;+/-20%;KMG
C/C;DIP;+/-10%;Pintch=200mil
C/E;Ф5*11;105
℃
;+/-20%
C/C;DIP;+/-10%;Pintch=200mil
C/C;SMD;+/-10%;0805
C/C;SMD;+/-10%;0805
C/C;SMD;+/-10%;0805
C/E;Ф8*12;105
℃
;+/-20%;Pintch=150mil
C/X1;+/-20%;275V;Pintch=400mil;DAIN
C/Y1;+/-20%;Pintch=400mil;
BRIGE; SMD;1A
DIODE; 3A;100V;
DO-201AD
DIODE; 1A;1000V;Fast Recovery;SMA-214
DIODE;1A;100V;DO-35
FUSE,T2AL/250V;4.5*14.5L;Glass
Ф7*10;
1 A
FILTER;UU9.8
1.5A;TRANSISTOR;Vcev≥700V HFE=20;+/-10%;TO225A
TRANSFORMER;
GREEN;Ф3
DIP8
DIP
SOT23-3
Value
2.2M
100K
4.7Ω
47Ω
1K
3.3K
10K
10K
39K
1Ω
10uF/400V
222/1KV
47uF/25V
102/100V
681/25V
104/25V
103/25V
470uF/16V
104/275Vac
222M/400V
1A/600V
SR3100
FR107
1N4148
FUSE
10uH
20mH
MJE13003
EI-22
GREEN
RS2201
PC817
TL431
QTÝ
1
1
1
1
1
2
1
1
1
1
2
1
1
1
1
1
1
2
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
UNIT
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
PCS
DS-RS2201-01
Nov, 2007
www.Orister.com
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