Parameter
DC Input Voltage
Power Dissipation*
Junction Temperature
Storage Temperature
Thermal Resistance (Junction to Case)
Thermal Resistance (Junction to Ambient Air)
Symbol
VIN
PD
Tj
Tstg
Rth(j-c)
Rth(j-a)
Surface Mount, Separate Excitation Switching Type
●SI-8000SD Series
Symbol
VIN1
IO
Tjop
Top
■Absolute Maximum Ratings
■ Recommended Operating Conditions
Unit
V
W
°C
°C
°C/W
°C/W
Part Number SI-8033SD SI-8050SD
VO (V) 3.3 5.0
IO (A) 3
Ratings
43
3
+125
–40 to +125
3
33.3
Ratings
SI-8033SD SI-8050SD
5.5 to 28 7 to 40
0 to 3.0
–30 to +125
–30 to +125
■Features
• Surface-mount package (TO263-5)
• Output current: 3.0 A
• High efficiency: 79% typ. (SI-8033SD), 84% typ. (SI-8050SD)
• Requires 4 external components
• Phase correction and output voltage adjustment performed internally
• Built-in reference oscillator (60 kHz)
• Built-in overcurrent protection, thermal protection circuit
• Output ON/OFF capable
• Soft start possible via ON/OFF pin
■Applications
• Power supplies for telecommunication equipment
• Onboard local power supplies
■Lineup
Conditions
Glass epoxy board mounting in a 40 x 40 mm (copper area: 100%)
Glass epoxy board mounting in a 40 x 40 mm (copper area: 100%)
Unit
V
A
°C
°C
Parameter
DC Input Voltage Range
Output Current Range*
Operating Junction Temperature Range
Operating Temperature Range*
*: Limited by Ta-PD characteristics.
*: Limited by thermal protection circuit.
SI-8000SD Series
●SI-8000SD Series
■External Dimensions (Unit : mm)
Pin Arrangement
qVIN
wSWOUT
eGND
rVOS
tON/OFF
Plastic Mold Package
Type
Flammability: 94V-0
Weight: Approx. 1.48g
Parameter
Output V oltage
Efficiency
Switching Frequency
Line Regulation
Load Regulation
Temperature Coefficient of Output Voltage
Overcurrent Protection
Starting Current
Soft
Low-Le v el Voltage
Start Pin
*
Low-State Output Current
■Electrical Characteristics (Ta=25°C)
Unit
V
%
kHZ
mV
mV
mV/°C
A
V
µ
A
Symbol
VO
Conditions
η
Conditions
f
Conditions
∆VOLINE
Conditions
∆VOLOAD
Conditions
∆VO/∆Ta
IS1
Conditions
VSSL
ISSL
Conditions
* Pin 5 is a soft star t pin. Connecting a capacitor to this pin enables a soft
start at power-on. By using this pin, the output can also be turned on or off .
By setting the voltage of this pin to VSSL or lower, the output is stopped.
Driving a transistor with an open collector can perf orm switching of the po-
tential of the soft start pin.
When using both the soft-star t and ON/OFF functions together, the dis-
charge current from C3 flows to the ON/OFF control transistor, so ensure
that this current is limited for protection. The soft start pin is pulled up to the
power supply in the IC, so no external voltage can be applied. If this pin is
not used, leave it open.
SI-8000SD SI-8000SD
ON/OFF5 ON/OFF5 ON/OFF
C3C3
5
VOUT. ON/OFF Soft start Soft start
+VOUT. ON/OFF
SI-8000SD
(0.40)
15.30±0.3
(6.8)
9.2±0.2
4.9±0.2
2.54±0.3
(4.6)
9.2±±0.2 1.2±0.2
4.9±0.2
(0.75) 2.0±0.1
(1.75)
15.3±0.3
9.90±0.2
Case temperature
measurement point
(15°)
(0.5)
2-R0.3
10.0±0.02
3-R0.3
(2×R0.45)
(R0.3)
(R0.3)
0.88±0.10
1.5 Dp:±0.2
φ
(1.7±0.25)
12345
(1.7±0.25)(1.7±0.25)(1.7±0.25)
0.8±0.1 0.8±0.1
4.5±0.2
1.3
0.10±0.15
2.4±0.2
+0.10
–0.05
10.0±0.2
(4.4)
(8.0)
(3°)(3°)
(3°)
(3°)(3°)
0~6°
Ratings
SI-8033SD SI-8050SD
min. typ. max. min. typ. max.
3.17 3.3 3.43 4.8 5.0 5.2
VIN=15V, IO=1A VIN=20V, IO=1A
79 84
VIN=15V, IO=1A VIN=20V, IO=1A
60 60
VIN=15V, IO=1A VIN=20V, IO=1A
25 80 40 100
VIN=8 to 28V, IO=1A VIN=10 to 30V, IO=1A
10 30 10 40
VIN=15V, IO=0.5 to 1.5A VIN=20V, IO=0.5 to 1.5A
±0.5 ±0.5
3.1 3.1
VIN=15V VIN=20V
0.2 0.2
20 30 40 20 30 40
VSSL=0.2V
■Example of Pattern on PC Board
* For the optimum operating conditions, use one-point GND wiring centering on pin 3, and place each component as closely as
possible.
●SI-8000SD Series
■Block Diagram ■Standard Connection Circuit Diagram
Area of copper on glass epoxy board vs.
thermal resistance (junction to ambient air) (typical value)
4
35
GNDS.S
2
VIN SWOUT
VOS
1
Reset Latch & driver
Thermal
protection
Oscillator
Comparator
Error
amplifier
Internal power
supply Overcurrent
protection
Reference voltage
V
IN
C
1
C
3
D1
L1
C
2
V
IN
GNDS.S
GND
SI-8000SD
SW
OUT
V
OS
12
4
35
+ +
V
OUT
GND
Diode D1
•Be sure to use Schottky-barrier diode as D1.
If you use a f ast recovery diode or any other diode, supplying a reverse voltage generated from the reco very or
ON voltage of the diode may damage the IC.
Choke coil L1
•If the winding resistance of the choke coil is too high, the efficiency may drop below the rated value.
•Because the overcurrent protection start current is about 3.5 A, take care concerning heat radiation from the
choke coil due to magnetic saturation in the case of overloading or short-circuiting of the load.
Capacitors C1, C2, and C3
•Use high-frequency, low-impedance capacitors for switching power supplies as C1 and C2 because a large
ripple current flows through them. If the impedance of C2 is high, the switching waveform may be abnormal at
low temperatures . Do not use a capacitor with an extremely low equivalent series resistance (ESR), such as an
OS capacitor or tantalum capacitor, as C2, because such a capacitor may cause abnormal oscillation.
•C3 is a capacitor f or soft start. Leave pin 5 open if the soft start function is not used. This pin is pulled up inside
the IC.
To create the optimum operating conditions, place each component as closely as possible.
SPB-G56S
KA
N.C
C
1
C
2
C
3
SI-8000SD
GNDGND
5
S1
Vins
Vos Vout
L1
Vin SW
SI-8000SD
6.8±0.1
9±0.23.7±0.054±0.1
11±0.2
9±0.1
1.7±0.1 1±0.05
Unit : mm
Recommended pattern Recommended land pattern
C1: 50V/1000
µ
F
C2: 50V/1000
µ
F
C3: 0.01
µ
F
(only when soft start function is used)
L1: 150
µ
H
D1: SPB-G56 (Sanken)
55
50
45
40
35
300 200 400 600 800 1000
Copper area (mm2)
Thermal resistance (junction to ambient air)
j-a (°C/W)
1200 1400 1600 1800
With glass epoxy board measuring 40 × 40 mm
θ
■SI-8033SD
●SI-8000SD Series
Applications
Varying output voltage
The output voltage can be varied in the same manner as SI-8000S. Refer of the catalog.
■PD-Ta Characteristics
Find the efficiency from the efficiency cur ve and substi-
tute in the percentage, because the efficiency varies de-
pending on the input voltage and output current.
VO: Output voltage
VIN: Input voltage
IO: Output current
ηχ
: Efficiency
VF: Forward voltage of D1
0.4V (IO=2A) ··· SPB-G56S (Sanken)
Thermal design for D1 must be performed separately.
3.5
3
2.5
2
1.5
1
0.5
0
–25 0 25 50 75 100 125
Power dissipation PD (W)
Ambient temperature Ta (°C)
Copper laminate aera:
40×40 mm
( j-a : 33.3°C/W)
20×40 mm
( j-a : 37°C/W)
20×20 mm
( j-a : 44°C/W)
10×10 mm
( j-a : 53°C/W)
θ
θ
θ
θ
When mounted on glass epo xy board
measuring 40 × 40 mm
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Input voltage V
IN
[V]
Output current I
O
(A)
3.5
3
2.5
2
1.5
1
0.5
00 0.5 1 1.5 2 2.5 3 3.5
Output current I
O
(A)
V
IN
5.5V 8V
28V
20V
Power dissipation Pd (W)
Operable range
With glass epoxy board
measuring 40 × 40 mm
15V
Power dissipation vs. Output current (typical value) Output current vs. Input voltage (typical value)
■SI-8050SD
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Input voltage V
IN
[V]
Output current I
O
(A)
3.5
3
2.5
2
1.5
1
0.5
00 0.5 1 1.5 2 2.5 3 3.5
Output current I
O
(A)
V
IN
7V 10V
20V
30V, 40V
Power dissipation Pd (W)
Operable range
With glass epoxy board
measuring 40 × 40 mm
Power dissipation vs. Output current (typical value) Output current vs. Input voltage (typical value)
PD=VO • IO 100 –1 – VF • IO 1–VO
ηχ
VIN
■Typical Characteristics Examples (SI-8033SD)
Efficiency Output voltage rise Load regulation
Overcurrent protection characteristics Thermal protection Temperature characteristics
0 0.5 1.0 1.5 2.0 2.5 3.0
Output current I
O
(A)
6V 8V
15V
V
IN
=28V
100
90
80
70
60
50
40
30
Efficiency η
(%)
T
a
=25°C
6012345
5
4
3
2
1
0
Output current I
O
(A)
Output voltage V
O
(V)
V
IN
=6V 15V 28V
T
a
=25°C
024681012
5
4
3
2
1
0
Input voltage VIN (V)
Output voltage VO (V)
1A
3A
I
O
=0A
*Load=C.C T
a
=25°C
50 75 100 125 150 175 200
5
4
3
2
1
0
Output voltage V
O
(V)
Ambient temperature T
a
(°C)
TSD OFF TSD ON
V
IN
=15V, I
O
=0A
0 0.5 1.0 1.5 2.0 2.5 3.0
3.40
3.35
3.30
3.25
3.20
3.15
Output current I
O
(A)
Output voltage V
O
(V)
V
IN
=28V
15V
8V
6V
T
a
=25°C
–50 –25 0 25 50 75 100
90
80
70
60
50
40
3.40
3.35
3.30
3.25
3.20
3.15
Ambient temperature T
a
(°C)
Efficiency η (%) Frequency F
req
(kHz)
Output voltage V
O
(V)
V
O
η
Freq
V
IN
=15V, I
O
=1A
●SI-8000SD Series
Efficiency Output voltage rise Load regulation
Overcurrent protection characteristics Thermal protection Temperature characteristics
0 0.5 1.0 1.5 2.0 2.5 3.0
Output current I
O
(A)
100
90
80
70
60
50
40
30
Efficiency η
(%)
7V 10V
20V
V
IN
=40V
T
a
=25°C
6012345
10
8
6
4
2
0
Output current I
O
(A)
Output voltage V
O
(V)
V
IN
=7V 20V 40V
T
a
=25°C
024681012
10
8
6
4
2
0
Input voltage VIN (V)
Output voltage VO (V)
1A
3A
I
O
=0A
*Load=C.C T
a
=25°C
0 0.5 1.0 1.5 2.0 2.5 3.0
5.15
5.10
5.05
5.00
4.95
4.90
Output current IO (A)
Output voltage VO (V)
VIN=40V
20V
10V
7V
Ta=25°C
50 75 100 125 150 175 200
10
8
6
4
2
0
Output voltage V
O
(V)
Ambient temperature T
a
(°C)
TSD OFF TSD ON
V
IN
=20V, I
O
=0A
–50 –25 0 25 50 75 100
100
90
80
70
60
50
5.15
5.10
5.05
5.00
4.95
4.90
Ambient temperature T
a
(°C)
Efficiency η (%) Frequency F
req
(kHz)
Output voltage V
O
(V)
V
O
η
Freq
V
IN
=20V, I
O
=1A
●SI-8000SD Series
■Typical Characteristics Example (SI-8050SD)
