SI-8001FFE
Description
The SI-8001FFE DC voltage regulator is a DC-to-DC buck
convertor that attains an oscillation frequency of 300 kHz,
and has an integrated miniaturized choke coil, allowing it to
serve as a small, high efficiency power supply in a compact
TO220F package.
The internal switching regulator function provides high
efficiency switching regulation without any need for adjustment.
The device requires only six external support components. The
optional soft start function requires an additional capacitor.
Optional on/off control can be performed using a transistor.
The SI-8001FFE includes overcurrent and overtemperature
protection circuits.
Applications include:
▪ DVD recorder
▪ FPD TV
▪ Telecommunications equipment
▪ Office automation equipment, such as printers
▪ On-board local power supply
▪ Output voltage regulator for second stage of SMPS
(switched mode power supply)
Features and Benefits
▪ 3.5 A output current supplied in a small, through-hole
mount power package
▪ High efficiency: 83% at VIN
= 15 V, IO
= 2.0 A,VO
= 5 V
▪ Requires only six external components (optional soft
start requires an additional capacitor)
▪ Oscillation circuit built-in (frequency 300 kHz typical)
▪ Constant-current mode overcurrent protection circuit and
overtemperature protection circuit built-in
▪ Soft start function built-in (can be implemented as an
on/off function; output-off state at low level)
▪ Low current consumption during output-off state
DC-to-DC Step-Down Converter
Package: TO220F-5
Not to scale
Functional Block Diagram
Latch and
Driver
Overcurrent
Protection
Overtemperature
Protection
Reference
Voltage
Osc
Reset
Comparator
Error
Amplifier
VIN 1
3
4
2VOUT
Di C2
C1
GND
ADJ
SW
IN
R1
R2
L1
PReg
On/Off
Soft Start
5
C3
SS
Di
RK-46
(Sanken)
27469.057
DC-to-DC Step-Down Converter
SI-8001FFE
2
All performance characteristics given are typical values for circuit or
system baseline design only and are at the nominal operating voltage and
an ambient temperature, TA, of 25°C, unless oth er wise stated.
Selection Guide
Part Number Output Voltage
Adjustable Range
(V)
Efficiency,
Typ.
(%)
Input Voltage,
Max.
(V)
Output Current,
Max.
(A) Packing
SI-8001FFE 0.8 to 24 83 40 3.5 50 pieces per tube
Absolute Maximum Ratings
Characteristic Symbol Remarks Rating Units
DC Input Voltage VIN 43 V
Power Dissipation
PD1-1
Connected to infinite heatsink; TJ(max) = 150°C, limited by internal
overtemperature protection. 22.7 W
PD1-2 Connected to infinite heatsink; TJ = 125°C. 18.2 W
PD2-1
No heatsink; TJ(max) = 150°C, limited by internal overtemperature
protection. 2.15 W
PD2-2 No heatsink; TJ = 125°C. 1.72 W
Junction Temperature TJ
Internal overtemperature protection circuit may enable when TJ ≥
130°C. During product operation, recommended TJ ≤ 125°C. –40 to 150 °C
Storage Temperature Tstg –40 to 150 °C
Thermal Resistance (junction-to-case) RθJC 5.5 °C/W
Thermal Resistance (junction-to-ambient air) RθJA 58 °C/W
Recommended Operating Conditions*
Characteristic Symbol Remarks Min. Max. Units
DC Input Voltage Range VIN VIN (min) is the greater of 4.5 V or VO+3 V. See
remarks 40 V
DC Output Voltage Range VO0.8 24 V
DC Output Current Range IO
VIN ≥ VO + 3 V; to be used within the allowable package
power dissipation characteristics (refer to Power Dissipation
chart).
0 3.5 A
Operating Junction Temperature Range TJOP –30 125 °C
Operating Temperature Range TOP
To be used within the allowable package power dissipation
characteristics (refer to Power Dissipation chart). –30 85 °C
*Required for normal device functioning according to Electrical Characteristics table.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
3
SI-8000FFE
(a)
V
O
on/off
control only
(c)
V
O
on/off and
soft start control
(b)
Soft start
only
C3
SS
5
SI-8000FFE
SS
5
SI-8000FFE
SS
5
System
TTL
C3
System
TTL
Terminal List Table
Name Number Function
IN 1 Supply voltage
SW 2 Regulated supply output
GND 3 Ground terminal
ADJ 4 Terminal for resistor bridge feedback
SS 5
The SS terminal is used to enable soft start and to control on/off operation of the IC output,
VO (see figure 2). If neither soft start nor on/off control is used, leave pin open.
To enable soft start, connect a capacitor between SS and ground. To control on/off
operation, connect an NPN bipolar transistor, in a TTL open collector output configuration,
between the SS terminal and GND. Turn off is done by decreasing VSSL below its rated
level.
When both soft start and VO on/off are used, a protection measure such as current limiting
is required because, if the capacitance of C3 large, the discharge current of C3 flows
across the transistor for on/off operation. Because a pull-up type resistor is provided inside
the IC, no external voltage can be applied.
Pin-out Diagram
Figure 2. Alternative configurations for SS pin. If neither soft start nor VO on/off is required, the SS pin is left open.
ELECTRICAL CHARACTERISTICS1, valid at TA = 25°C, VO = 5 V (adjusted), R1 = 4.2 kΩ, R1 = 0.8 kΩ
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Reference Voltage VADJ VIN = 15 V, IO = 0.2 A 0.784 0.800 0.816 V
Reference Voltage Temperature Coefficient ∆VADJ
/∆TV
IN = 15 V, IO = 0.2 A, TC = 0 to 100 °C – ±0.1 – mV/°C
Efficiency2ηVIN = 15 V, IO = 2 A – 83 – %
Operating Frequency fOVIN = 15 V, IO = 2 A 270 300 330 kHz
Line Regulation VLine VIN = 10 to 30 V, IO = 2 A – – 80 mV
Load Regulation VLoad VIN = 15 V, IO = 0.2 to 3.5 A – – 50 mV
Overcurrent Protection Threshold Current ISVIN = 15 V 3.6 – – A
SS Terminal On/Off Operation Threshold Voltage VSSL – – 0.5 V
SS Terminal On/Off Operation Outflow Current ISSL VSSL = 0 V – 6 30 μA
Quiescent Current 1 IqVIN = 15 V, IO = 0 A – 6 – mA
Quiescent Current 2 Iq(off) VIN = 15 V, VSS = 0 V – 200 600 μA
1Using circuit shown in Typical Application Circuit diagram.
2Efficiency is calculated as: η(%) = ([VO × IO] × [VIN × IIN]) × 100.
123 45
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
4
90
85
80
75
70
65
60
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
I
O
(A)
η(%)
6.00
5.00
4.00
3.00
2.00
1.00
0
5.10
5.08
5.06
5.04
5.02
5.00
4.98
4.96
4.94
4.92
4.90
012345678
V
O
(V)
Efficiency versus
Output Current
V
O
= 3.3 V
Efficiency versus
Output Current
V
O
= 5.0 V
Efficiency versus
Output Current
V
O
= 12.0 V
Low Voltage
Behavior:
Output Voltage
versus
Supply Voltage
8V
15 V
40 V
30 V
20 V
01 23
Load Regulation:
Output Voltage
versus
Output Current
V
O
(V)
I
O
(A)
0
2
4
8
6
10
0 10203040
Quiescent Current
versus
Supply Voltage
I
O
= 0 A
SS pin open
I
q
(mA)
V
IN
(V)
V
IN
(V)
V
IN
100
95
90
85
80
75
70
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
I
O
(A)
η(%)
8V 15 V
40 V
30 V
20 V
V
IN
I
O
V
IN
0A
0.5 A
1A
40 V
30 V
15 V
10 V
8V
2A
3.5 A
90
85
80
75
70
65
60
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
I
O
(A)
η(%)
15V
40 V
30 V
20 V
V
IN
V
IN
15 V
8V
30 V
40 V
Behavior at
Turn-Off:
Quiescent Current
versus
Input Voltage
I
O
= 0 A
V
SS
= 0 V
0
2
1
3
5
4
6
0123 54
Overcurrent
Protection:
Output Voltage
versus
Output Current
V
O
(V)
I
O
(A)
400
300
200
100
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
V
IN
(V)
I
Q
(μA)
Performance Characteristics
At TA = 25°C, VO = 5 V Adjusted, R1 = 4.2 kΩ, R2 = 0.8 kΩ
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
5
Thermal Performance Characteristics
24
22
20
18
16
14
12
10
8
6
4
2
0
–40 –20 0 20 40 60 80
Power Dissipation versus Ambient Temperature
Shin Etsu G746 silicon grease
P
D
(W)
T
A
(°C)
No heat sink
T
J
(max) = 125°C
No heat sink
T
J
(max) = 150°C
Al heat sink
75 mm × 75 mm × 2 mm
R
θJA
= 7.6°C/W
T
J
(max) = 125°C
Al heat sink
100 mm × 200 mm × 2 mm
R
θJA
= 5.2°C/W
T
J
(max) = 125°C
Al heat sink
200 mm × 200 mm × 2 mm
R
θJA
= 2.3°C/W
T
J
(max) = 125°C
Infinite heat sink
T
J
(max) = 150°C
Infinite heat sink
T
J
(max) = 125°C
6
5
4
3
2
1
0
0 20 40 60 80 100 120 140 180160
T
J
(°C)
V
O
(V)
Overtemperature
Protection:
Output Voltage versus
Junction Temperature
V
IN = 15 V, IO = 10 mA
OTP On
OTP Off
The application must be designed to ensure that the TJ(max)
of the device is not exceeded during operation. To do so, it is
necessary to determine values for maximum power dissipation,
PD(max), and ambient temperature, TA(max).
PD can be calculated from input values:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−⋅−
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−⋅=
IN
O
OF
x
OOD
V
V
IVIVP 11
100
H
where:
VO is output voltage in V,
VIN is input supply voltage in V,
IO is output current in A,
ηx is IC efficiency in percent (varies with VIN and IO; refer to
efficiency performance curves for value), and
VF is forward voltage for the input diode, Di. In these tests, the
Sanken RK46 was used, at 0.5 V and IO = 3.5 A. For application
design, obtain thermal data from the datasheet for the diode.
PD is substantially affected by the heat conductance properties of
the application, in particular any heatsink connected to the device
radiation fin. The relationships of PD, TA, and heatsink type is
represented in the Power Dissipation chart.
Because the heat dissipation capacity of the heatsink depends
substantively on how it is used in the actual application, thermal
characteristics of the application must be confirmed by testing.
The internal overtemperature protection circuit may enable when
TJ ≥ 130°C.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
6
Component Selection
VIN 1
GND GND
2
4
3
GNDSS
IN SW
ADJ
C1 C2
L1
Di
VO
R1
R2
IADJ
5
C3
Soft Start Only
SI-8001FFE
Component Rating
C1 470 μF
C2 680 μF
C3 0.1 μF (For soft start function)
Di RK-46 (Sanken)
L1 47 μH
Diode Di A Schottky-barrier diode must be used for Di. If other
diode types are used, such as fast recovery diodes, the IC may be
destroyed because of the reverse voltage applied by the recovery
voltage or ON voltage.
Choke Coil L1 If the winding resistance of the choke coil is too
high, the efficiency may be reduced below rating. Because the
overcurrent protection start current is approximately 4.2 A, atten-
tion must be paid to the heating of the choke coil by magnetic
saturation due to overload or short-circuited load.
Capacitors C1, C2, and C3 Because for SMPS, large ripple
currents flow across C1 and C2, capacitors with high frequency
and low impedance must be used. If the impedance of C2 is too
high, the switching waveform may not be normal at low tempera-
tures. Do not use either OS or tantalum types of capacitors for
C2, because those cause an abnormal oscillation.
C3 is required only if the soft start function is used. If not using
soft-start, leave the SS terminal open. A pull-up resistor is pro-
vided inside the IC.
Resistor Bridge R1 and R2 comprise the resistor bridge for the
output voltage, VO, and are calculated as follows:
()()
) , and
(()
Ω
×
===Ω
×
−
=
−
=
−−
k
I
V
R2
V
IVV
R1
ADJ
ADJO
ADJ
ADJO
8.0
1018.0
1018.0
33
IADJ should always be set to 1 mA. Note that R2 should always be
present to ensure stable operation, even if VO, is set to 0.8 V (that
is, even if there is no R1). VO should be at least VIN + 8%.
R1
R2
GND
L1
C1 C2
U1 C3 S1
D1
Vin
Vsw
Vout
Vadj/Vos
R1
R2
L1
GNDGND
C3 S1
Vadj/Vos
Vout
Vsw
D1
Vin
C1 C2
U1
GND
All external components should be mounted as close as possible
to the SI-8001FFE. The ground of all components should be
connected at one point.
Recommended PCB Layout
Typical Application Diagram
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
7
2.54 ±0.2
0.7
15. 87 ±0.2
5. 4
3. 3 ± 0. 1
6. 68 ± 0. 2
2.76 ±0.2
7
10.16 ± 0.2
4.7±0.2
Φ
3.2±0.2
0.6 +0.1
-0.05
0.8
(2)
4.3 ±0.7
8.2 ±0.7
4 x 1.7±0.6 = (6.8) 0.5 +0.2
-0.1
(4-R1)
R-end
(17.9)
4. 3 ± 0. 6
Branding
XXXXXXXX
XXXXXXXX
XXXXXXXX
XXXXXXXX
Leadform: 1113A
Weight: 2.3 g typical
Dimensions in millimeters
Branding codes (exact appearance at manufacturer discretion):
1st line, type: 8001FFE
2nd line, lot: SK YMW
Where: Y is the last digit of the year of manufacture
M is the month (1 to 9, O, N, D)
W is the week of the month (1 to 5)
3rd line, tracking number: nnnn
PACKAGE OUTLINE DRAWING
RoHS directive compliant
Device pins lead (Pb) free
Leadframe: 1113A
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
8
PACKING SPECIFICATION
ANTISTATIC
528
7
8
12.6
570
50
155
L
W
H
Dimensions in mm
Carton Type
Outer Carton A
Outer Carton B
L
580
580
W
180
335
H
140
140
Quantity
2 inner cartons, 1200 pieces per outer carton
4 inner cartons, 2400 pieces per outer carton
14.4
5.05.53.9
1.5
1.2
0.7
1.8
34.0
14.012.0
10.6
5.2
Inner Carton
12 tubes per carton
600 pieces per inner carton
Tube
50 pieces per tube
Outer Carton
(See table)
A
AView A-A
View A-A Enlargement
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
9
WARNING — These devices are designed to be operated at lethal voltages and energy levels. Circuit designs
that embody these components must conform with applicable safety requirements. Pre cau tions must be
taken to prevent accidental contact with power-line potentials. Do not connect ground ed test equipment.
The use of an isolation transformer is recommended during circuit development and breadboarding.
Cautions for Use
• Operation of the product in parallel to increase current is not
permitted.
• Although the product has an internal overtemperature protection
circuit, that is intended only to protect the product from temporary
excess heating due to overloads. Long-term reliability cannot
be guaranteed when the product is operated under continuous
overload conditions.
Because reliability can be affected adversely by improper storage
environments and handling methods, please observe the following
cautions.
Cautions for Storage
• Ensure that storage conditions comply with the standard
temperature (5°C to 35°C) and the standard relative humidity
(around 40 to 75%); avoid storage locations that experience
extreme changes in temperature or humidity.
• Avoid locations where dust or harmful gases are present and
avoid direct sunlight.
• Reinspect for rust on leads and solderability of products that have
been stored for a long time.
Cautions for Testing and Handling
When tests are carried out during inspection testing and other
standard test periods, protect the products from power surges
from the testing device, shorts between adjacent products, and
shorts to the heatsink.
Remarks About Using Silicone Grease with a Heatsink
• When silicone grease is used in mounting this product on a
heatsink, it shall be applied evenly and thinly. If more silicone
grease than required is applied, it may produce stress.
• Volatile-type silicone greases may permeate the product and
produce cracks after long periods of time, resulting in reduced
heat radiation effect, and possibly shortening the lifetime of the
product.
• Our recommended silicone greases for heat radiation purposes,
which will not cause any adverse effect on the product life, are
indicated below:
Type Suppliers
G746 Shin-Etsu Chemical Co., Ltd.
YG6260 GE Toshiba Silicone Co., Ltd.
SC102 Dow Corning Toray Silicone Co., Ltd.
Heatsink Mounting Method
Torque When Tightening Mounting Screws. The recommended tightening
torque for this product package type is: 58.8 to 68.6 N•cm (6.0 to
7.0 kgf•cm).
Soldering
• When soldering the products, please be sure to minimize the
working time, within the following limits:
260±5°C 10 s
350±5°C 3 s
• Soldering iron should be at a distance of at least 1.5 mm from the
body of the products
Electrostatic Discharge
• When handling the products, operator must be grounded.
Grounded wrist straps worn should have at least 1 MΩ of
resistance to ground to prevent shock hazard.
• Workbenches where the products are handled should be
grounded and be provided with conductive table and floor mats.
• When using measuring equipment such as a curve tracer, the
equipment should be grounded.
• When soldering the products, the head of soldering irons or the
solder bath must be grounded in other to prevent leak voltages
generated by them from being applied to the products.
• The products should always be stored and transported in our
shipping containers or conductive containers, or be wrapped in
aluminum foil.
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
DC-to-DC Step-Down Converter
SI-8001FFE
10
The products described herein are manufactured in Ja pan by Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc.
Sanken and Allegro reserve the right to make, from time to time, such de par tures from the detail spec i fi ca tions as may be re quired to per mit im-
prove ments in the per for mance, reliability, or manufacturability of its prod ucts. Therefore, the user is cau tioned to verify that the in for ma tion in this
publication is current before placing any order.
The information in clud ed herein is believed to be accurate and reliable. Application and operation examples described in this document are given
for reference only and Sanken assumes no responsibility for any infringement of industrial property right, intellectual property rights or any other
rights of Sanken or any third party which may result from its use.
When using the products herein, the applicability and suitability of such products for the intended purpose shall be the users responsibility to
determine.
Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and defect of semiconductor products
at a certain rate is inevitable.
Users of Sanken products are requested to take, at their own risk, preventative measures including safety design of the equipment or systems
against any possible injury, death, fires or damages to society due to device failure or malfunction.
Sanken products listed in this document are designed and intended for the use as components in general purpose electronic equipment or appara-
tus (home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). When considering the use of Sanken products in
the applications where higher reliability is required (transportation equipment and its control systems, traffic signal control systems or equipment,
fire/crime alarm systems, various safety devices, etc.), please contact your nearest Sanken sales representative to discuss and obtain written confir-
mation of your specifications.
The use of Sanken products without the written consent of Sanken in the applications where extremely high reliability is required (aerospace equip-
ment, nuclear power control systems, life support systems, etc.) is strictly prohibited. Anti-radioactive ray design is not considered for the products
listed herein.
Copyright © 2007 Allegro MicroSystems, Inc.
This datasheet is based on Sanken datasheet SSJ-03144
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com