Datasheet
Power Supply Pwm Supervisor
SDC4818
General Description
Features
The SDC4818 controller is designed for switching mode

power supply for desktop PCs. Utilizing minimum number
Over-voltage/Under-voltage protection for
3.3V/±5V/±12V
T
N
E
of external components, the SDC4818 includes all of the

Over-power protection
functions for push-pull and/or half-bridge topology,

Short-circuit protection
decreasing the production cost and PCB space, and

AC input under voltage protection
increasing the MTBF for power supply.

Power good circuitry

PSON for remote controller

Delay time for PSON and PG signal

Two internal TL431 shunt regulators provide stable
Two internal TL431 shunt regulators provide stable
reference voltage for 3.3V and 5V standby regulator.
M
U
C
reference voltage for 3.3V and 5V standby regulator
D
Applications
L
A


I
T

O
Soft-start and maximum 93% duty cycle

ATX power supply
SFX(MICRO-ATX) power supply
NLX power supply
N
E
D
I
F
N
O
C
D
S
C
DIP-20
Figure 1. Package Type
December, 2013 Rev. 1.1
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Pin Configuration
Package:DIP-20
T
PSON
1
20
VCC
V33
2
19
RI
V5
3
18
SS
OPP
4
17
IN
UVAC
5
16 COMP
NVP
6
15
GND
V12
7
14
FB1
OP2
8
13
VREF1
OP1
9
12
VREF2
PG
10
11
FB2
Figure 2. Pin Configuration
Pin Number
Pin Name
1
PSON
2
V33
3
V5
4
OPP
5
UVAC
6
NVP
7
V12
8
OP2
9
OP1
10
PG
O
M
U
C
O
L
A
I
T
N
E
D
I
F
N
11
N
E
D
Function
Remote on/off input
OVP/UVP sense input for 3.3V
OVP/UVP sense input for 5V
Over-power sense input
Power good detection input
UVP sense input for negative voltage
OVP/UVP sense input for 12V
PWM totem-pole output 2
PWM totem-pole output 1
Power good signal
FB2
Output for second opamp loop
VREF2
Input for second opamp loop
VREF1
Input for first opamp loop
FB1
Output for first opamp loop
GND
Ground
COMP
Error amplifier output
17
IN
Input of error amplifier
18
SS
The soft-start function set through an external capacitor
19
RI
Reference setting by an external resistor
20
VCC
Supply voltage
12
13
C
14
15
D
S
16
C
Table 1. Pin Description
December, 2013 Rev. 1.1
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Functional Block Diagram
RI
VCC
1
19
20
14
13
Control
PSON
2
V33
LOGIC & DELAY
3
OVP
V5
7
UVP
V12
4
M
+
-
PWM
5
UVAC
0.7V
2.1V
6
NVP
OUT
PUT
C
U
FB2
9
OP1
8
OP2
O
D
OPP
OPP
VREF2
11
VCC
UVS
T
N
E
12
431
VREF
FB1
VREF1
L
A
+
10
18
17
IN
SS
PG
GND
N
E
15
COMP
I
T
+
-
16
Figure 3. Functional Block Diagram
D
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Ordering Information
T
SDC4818 X X X - X
Circuit Type
DIP-20
-40°C~85°C
U
Package
DIP-20: Z
C
O
Part Number
Temperature
M
Blank: Tube
Reference
A: 2.45V-2.50V
B: 2.50V-2.55V
Package
N
E
E1: Pb-free
G1: Halogen-free
L
A
D
Marking ID
Packing Type
Pb-free
Halogen-free
Pb-free
Halogen-free
SDC4818AZ -E1
SDC4818AZ -G1
SDC4818G
Tube
SDC4818BZ -E1
I
T
SDC4818
SDC4818BZ -G1
SDC4818
SDC4818G
Tube
N
E
D
I
F
N
O
C
C
D
S
December, 2013 Rev. 1.1
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Absolute Maximum Ratings (NOTE: Stresses greater than those listed under Absolute Maximum Ratings may cause
permanent damage to the device.)
Parameter
Symbol
Value
Unit
Supply voltage
V CC
12
V
FB1, FB2 Output
V FB
16
PG Output
I OUT1
30
FB1, FB2 Output
I OUT2
30
Power dissipation(Ta=25°C)
P D1
1.5
Power dissipation(Ta=90°C)
P D2
0.5
Storage temperature
T STG
Latch-up test per JEDEC 78
-
C
ESD, HBM model per Mil-Std-883, Method 3015
HBM
ESD, MM model per JEDEC EIA/JESD22-A115
MM
Thermal Resistance（Junction to Ambient）
θ JA
L
A
mA
mA
M
W
U
O
D
T
N
E
V
W
-55~155
°C
200
mA
2000
V
200
V
82.5
℃/W
Table 2. Absolute Maximum Ratings
I
T
Recommended Operating Conditions
Parameter
Symbol
Supply voltage
V CC
Oscillation frequency
f OSC
Operating temperature
T OPR
D
I
F
N
E
Min
Max
Unit
4.5
5.5
V
60
70
kHz
-40
85
°C
Table 3. Recommended Operating Conditions
N
O
C
C
D
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Electrical Characteristics (Ta=25°C, V CC =5.0V, unless otherwise specified)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Supply voltage
V CC
-
4.5
5.0
7.0
V
Standby supply current
I CC
PG=High
-
5
10
mA
3.3V OVP
V OVP1
-
3.9
4.1
4.3
V
5V OVP
V OVP2
-
5.8
6.1
6.5
V
12V OVP
V OVP3
-
13.9
14.5
14.9
3.3V UVP
V UVP1
-
2.0
2.6
2.8
V
5V UVP
V UVP2
-
3.0
3.6
M
V
3.9
V
12V UVP
V UVP3
-
6.0
7.2
8.0
V
3.3V UVS
V UVS1
-
2.5
2.8
3.0
V
5V UVS
V UVS2
-
12V UVS
V UVS3
-
V OPPS
V UVAC =1.5V
Negative voltage protection
V NVP
NVP source current
I NVP
OVP debounce Time
t OVP
UVP debounce Time
t UVP
UVS debounce Time
t UVS
OPP debounce Time
t OPP
Over power protection with delay
time
t NVP
Reference voltage
4.3
4.5
V
9.4
10.1
10.4
V
2.02
2.40
2.66
V
-
1.9
2.05
2.2
V
RI=75k
50
61
72
uA
RI=75k
0.5
0.7
1.3
ms
RI=75k
35
60
80
ms
RI=75k
0.5
0.7
1.3
ms
RI=75k
4.0
7.0
10.0
ms
RI=75k
4.0
7.0
10.0
ms
I
T
D
I
F
NVP debounce Time
O
L
A
N
E
N
E
U
C
T
D
4.0
Reference
V REF
I FB =0.5mA, Ta=25°C
2.475
2.5
2.525
V
R EGLI-FB
4V<V FB <16V
-
1
-
mV/V
I OUT-FB
V FB >2V
10
-
-
mA
t PG
RI=75k
200
300
400
ms
UVAC sense voltage
V UVAC
-
0.65
0.7
0.75
V
PG output rise time
D
S
tR
C L =100pF,V PULLUP =5V,
-
1
-
us
PG output fall time
tF
R PULLUP =1k
-
300
-
ns
Output low voltage
V OL2
I PG =5mA
-
-
0.5
V
Sink current of PG
I ON2
V PG =5V
-
-
1
uA
PSON input voltage
V PSON
-
1
1.4
2.0
V
PSON drive current
I PSON
-
-
-
0.5
mA
PSON to on debounce time
t PSON (ON)
RI=75k
20
40
50
ms
PSON to off debounce time
t PSON (OFF)
RI=75k
10
20
30
ms
PSON to off delay time
t PSOFF
RI=75k
2
4.8
6.5
ms
N
Regulation
Output pull current
PG delay time
C
O
C
PG
Remote On/Off Section
December, 2013 Rev. 1.1
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Datasheet
Power Supply Pwm Supervisor
Parameter
SDC4818
Symbol
Conditions
Min
Typ
Max
Unit
Error Amp Section
T
Reference voltage(SDC4818A)
V2.5
-
2.45
-
2.50
V
Reference voltage(SDC4818B)
V2.5
-
2.50
-
2.55
V
Bias current
I IB
-
-
-
0.1
uA
Open loop voltage gain
V AOL
-
50
60
-
dB
Unit gain bandwidth
BW
-
0.3
1
Power supply rejection ratio
PSRR
-
50
-
M
MHz
Oscillation Section
Oscillation frequency
f OSC
Charge current
U
-
dB
65
70
kHz
C
-
N
E
RI=75k
60
Soft Start Section
O
5.7
7.0
uA
-
0.25
0.5
V
4
-
-
V
I SS
RI=75k
Pwm Output Section
D
4.0
Output voltage low
V OL
I O =5mA
Output voltage high
V OH
V 12 =12V
Output restance
RO
-
2.0
3.9
4.2
kΩ
Max duty
D MAX
-
85
-
93
%
L
A
I
T
Table 4. Electrical Characteristics
N
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D
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Function Description
The SDC4818 is a power management IC for computers. It
L0
N
E
C0
such as AC fail detection, over power protection, negative
voltage protection, over/under voltage protection and
UVAC
provides power down signal for PG. Built-in high precision
M
R1
oscillator provides accurate protection and delay time for
0.7V
R2
U
monitoring. And internal regulators TL431 are used for
stable output 3.3V and 5V standby, with few peripheral
T
+5V
integrates various monitoring functions and protections,
+
-
C1
C
components. Built-in soft-start decreases stress of
Figure 4. AC Fails Detection
O
transformer against saturation. SD4818 used for pull-push
Over Power Protection (OPP)
or half-bridge power system with high efficiency and
stability.
D
The over power protection is designed to detect over
Remote Switch Control (PSON)
L
A
power and short circuit. When the voltage of OPP is
is connected to PSON. When the control signal is low, PC
power is on. And when the control signal is high, PC
higher than 2.4V and maintain this situation over 7msec,
I
T
The PC generates the remote switch control signal which
PG will be pulled low and the power outputs will be
locked.
N
E
power is off.
AC Fails Detection (UVAC)
ID
The AC line voltage is coupled from the primary side to
the secondary side through the main transformer, and
OP1
VDD
F
UVAC is connected to the secondary side by a resistor.
N
OP2
When UVAC voltage drops below 0.7V and maintains this
situation over 200us, the PG signal will be pulled low , and
O
it indicates that the AC line is power-down. The voltage
C
R1
R2
C1
R3
amplitude of the PWM switching signal from the
secondary side is proportional to the AC line voltage.
C
Adjusting the ratio of the voltage divider can set the
D
S
threshold for the power-down.
December, 2013 Rev. 1.1
©2013 Shaoxing Devechip Microelectronics Co., Ltd.
Figure 5. Over Power Protection
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Negative Voltage Protection (NVP)
V NVP =I NVP ×R 1 +V -5V -0.7V
The negative voltage protection is designed to provide
T
VCC
under voltage protection for negative voltage output.
N
E
Overload and short circuit can cause under voltage of
negative voltage output. When the voltage of NVP is
higher than 2.1V and this situation exists for longer than
-12V
7msec, the power outputs will be off and be locked.
R2
R1
-5V
Adjusting the resistor will set the threshold for locking the
M
2.1V
+
-
U
power outputs off. The threshold is determined by:
C
V NVP =I NVP × (R 1 +R 2 )+V -12V
Figure 6. Negative Voltage Protection
O
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A
D
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D
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O
C
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Timing Diagram
T
VCC
N
E
PSON
M
3.3V
tPSON(ON)
U
5V,12V
C
O
tOVP
tPSON(OFF)
NVP
L
A
PG
N
E
tPG
D
I
F
C
Figure 6
N
VCC
PSON
C
O
Voltage<VUVAC
D
S
UVAC
tNVP
I
T
SS(ON/OFF)
tPSOFF
D
tUVP
tOPP
OPP
SS(ON/OFF)
PG
Figure 7
December, 2013 Rev. 1.1
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10/13
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December, 2013 Rev. 1.1
©2013 Shaoxing Devechip Microelectronics Co., Ltd.
R8
3K3
XC1 104/250V
R13
1K
OP1
OP2
+12V
R42
75K
OPP
IN
FB2
VREF2
VREF1
FB1
GND
COMP
11
12
13
14
15
16
FB1
PG
FB2
Vref2
R47
4K6
R49
330K
C27 0.47uF R41 3K9
C23
R44
30K 103/50V
Vref1
R48 13R
C26 0.1uF R46 2K7
+5V
+3.3V
C35
47u/16V
Q2
13009
C34
103
4
3
2
1
U3B
PC817C
R64
4R7
R24
22R
C28
102/1KV
R63
0R8,1/2W
5
6
7
8
D23
1N4007
R53
100K/1W
SDC606P
D21
FR104
R52 560K
R51 560K
R27
2K7
R26
1R
C14
222M/1KV
D17
FR157
D16
FR157
E
D
D
T3A
C
B
D25
SB540
R54
10R
C30
681
C19
47u/50V
D24
FR103
VCC
R31
47R
D18
STPS2045CT
D20
FR104
R6
10R
FB1
R65
47R
U3A
PC817C
R56
10K
C31
1500u/16V
C32
470u/16V
R55
10K
D22
FR104
L5
DR6*8
L3
T80-52
C15
472/100V
UVAC
C6
102
L1C
C24
104/50V
R57
10K
R28
2K7
R66
10K5
TH2A
10K
R61
470R
+5VSB
D26
1N4148
Q7
C945
C3
104
R58
10K
Vref1
M
R45
1K
C36
100u/16V
R67
220R
+5V
D27
1N4148
1
2
FAN1
CON2
Vref2
+3.3VS
+3.3V
+12V
R37 R39
4K7 1K
R7
10R
R38
68R/2W
-12V
+12V
C11
1u/50V
R60 22K
VCCD
R62
2K7
FB2
R34
100R
C19
1000u/10V
R33
100R/2W
Q8
C945
R59
3K3
R23
22R
D11
1N4148
Q5
A928
R11
2K
L4
R6*10
C17
2200u/10V
C18
2200u/10V
R32
4R7/4W
C16
2200u/10V
C9
680u/16V
R10
330R/1W
Power Supply Pwm Supervisor
R36
100R
PG
OP1
OP2
VS12
NVP
UVAC
SS
18 C21
104/50V
17
C25
104
HV
R21
22R
DAC
C12
4u7/50V
R29
2K7
Q1
13009
C5
102
L1B
C8
3300u/16V
U
10
9
8
7
6
5
V5
RI
19 R43
75K
20
+12V
+5VSB
D15
1N4148
C14
4u7/50V
R25
1R
D19
STPS2045CT
R5
10R
C4
102
L1A
C
+5V
-12V
R40
30K
4
V33
VCC
R50 33K
R9 10R
R22
22R
C
D6
FR204
O
C20
102
+5V
3
2
PSON
C22
103
D10
1N4148
R20
560R
D14
1N4148
R30
100R/3W
T1A
ERL-35
R3
10R
B
D5
STPS20H100CT
C7
102/100V
D
UVAC
+3.3V
1
SDC4818
R35 30K
R12
3K
R17
30K
R18
330K
R19
1K2
OP2
T2
EEL-16
ZNR3
TVR05241
C3
105/250V
ZNR2
TVR05241
N
E
R68
1K
R16
68K
D9
1N4148
C10
1u/50V
Q4
C945
D4
DIODE
C2
470u/200V
R2
910K
R1
910K
R4
10R
L
A
I
T
PSON
VCCD
D7
1N4148
D13
FR102
Dac
D3
DIODE
D2
DIODE
C1
470u/200V
D1
DIODE
N
D
I
F
D8
1N4148
Q3
C945
D12
FR102
CY4
102/250V
CX1
474/250V
LF2
EF25
PFC Inductor
C
R14
1K2
LF1
T16*8
CY3
102/250V
O
OP1
VCCD
R15
1K2
ZNR1
TVR10471
RX1
1M/2W
5A/250V
C
N
CY2
222/250V
CY1
222/250V
D
S
GND
L
Datasheet
SDC4818
Typical Application
T
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Datasheet
Power Supply Pwm Supervisor
SDC4818
Package Dimension
DIP-20
T
N
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M
U
C
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L
A
I
T
Min
D
I
F
A
3.710
A1
0.510
A2
3.200
N
B
0.380
B1
C
D
E
C
E1
C
O
Dimensions In Inches
Max
Min
Max
4.310
0.146
0.170
0.020
3.600
0.126
0.142
0.570
0.015
0.022
1.524(BSC)
0.060(BSC)
0.204
0.360
0.008
0.014
25.950
26.550
1.022
1.045
6.200
6.600
0.244
0.260
7.320
7.920
0.288
0.312
e
D
S
N
E
Dimensions In Millimeters
Symbol
D
2.540(BSC)
0.100(BSC)
L
3.000
3.600
0.118
0.142
E2
8.400
9.000
0.331
0.354
December, 2013 Rev. 1.1
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Datasheet
Power Supply Pwm Supervisor
SDC4818
T
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Shaoxing Devechip Microelectronics Co., Ltd.
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http://www.sdc-semi.com/
N
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D
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F
N
IMPORTANT NOTICE
Information in this document is provided solely in connection with Shaoxing Devechip Microelectronics Co., Ltd. (abbr. SDC) products.
O
SDC reserves the right to make changes, corrections, modifications or improvements, to this document, and the products and services
C
described herein at anytime, without notice. SDC does not assume any responsibility for use of any its products for any particular
purpose, nor does SDC assume any liability arising out of the application or use of any its products or circuits. SDC does not convey
C
any license under its patent rights or other rights nor the rights of others.
D
S
© 2013 Devechip Microelectronics - All rights reserved
Contact us:
Headquarters of Shaoxing
Shenzhen Branch
Address: Tian Mu Road, No13,
Address: 22A, Shangbu building, Nan Yuan Road, No.68,
Shaoxing city, Zhejiang province, China
Futian District, Shenzhen city, Guangdong province, China
Zip code: 312000
Zip code: 518031
Tel: (86) 0575-8861 6750
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