Designed to meet high-current requirements at high efficiency in
industrial and consumer applications; embedded core, memory, or logic
supplies; TVs, VCRs, and office or telecommunications equipment, the
SI-8033JF dc/dc step-down (buck) converter offers a constant 125 kHz
switching frequency essential for low EMI noise. The npn switch is
included on the die along with the oscillator, control, and logic circuitry
requiring only four external components for a regulated 3.3 V output at
up to 1.5 A.
A wide input voltage range and integrated thermal and overcurrent
protection enhance overall system reliability. Reference accuracy and
excellent temperature characteristics are provided. An output-enable
input gives the designer complete control over power up, standby, or
power down.
This device is supplied in a fully molded TO-220-style 5-lead
flange-mounted , high power, isolated plastic package. A similar device
in a lower-power surface-mount plastic package is the SI-8033JD.
FEATURES
■5.3 V to 40 V Input Range
■1.5 A Output Current at 3.3 V
■2% Output Voltage Tolerance
■Foldback Current Limiting
■Constant 125 kHz Switching Frequency
■200 µA Maximum Standby Current
■Soft Start Prevents Supply Voltage Dip
■Remote Voltage Sensing
■Thermal Protection
APPLICATIONS
■TVs, VCRs, Electronic Games
■Embedded Core, Memory, or Logic Supplies
■Printers and Other Office Equipment
■Industrial Machinery
■Telecommunications Equipment
Step-Down to 3.3 V, 1.5 A, DC/DC Converter
Data Sheet
27469.22*
Always order by complete part number, e.g., SI-8033JF .
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VI. . . . . . . . . . . . . 43 V
Output Current, IO. . . . . . . . . . . 1.5 A*
Enable Input Voltage, VOE . . . . . . . . . . . 6 V
Junction Temperature, TJ. . . . +125°C
Storage Temperature Range,
TS. . . . . . . . . . . . -40°C to +125°C
* Output current rating is limited by input
voltage, duty cycle, and ambient tempera-
ture. Under any set of conditions, do not
exceed a junction temperature of +125°C.
SI-8033
JF
Sanken Power Devices
from Allegro MicroSystems
Switching
Regulators
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Switching
Regulators
2
FUNCTIONAL BLOCK DIAGRAM
Copyright © 2004, 2005 Allegro MicroSystems, Inc.
Recommended Operating Conditions
Min Max Units
DC Input Voltage (IO ≤ 1 A) 5.3 6.3 V
(IO ≤ 1.5 A) 6.3 40 V
DC Output Current (VI ≥ 6.3 V) 0 1.5 A
Operating Junction Temp. -30 +125 °C
For the availability of parts meeting -40°C require-
ments, contact Allegro’s Sales Representative.
Allowable Package Power Dissipation
This data sheet is based on Sanken data sheet SSJ-02163
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
www.allegromicro.com
Switching
Regulators
3
ELECTRICAL CHARACTERISTICS at TA = +25°C, VI = 15 V, IO = 0.5 A (unless otherwise noted).
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Output Voltage VO3.234 3.30 3.366 V
Ref. Volt. Temp. Coeff. aVref — ±0.5 — mV/°C
Output Short-Circuit Current IOM See note 1.6 — — A
Efficiency η—77— %
Operating Frequency f — 125 — kHz
Line Regulation ∆VO(∆VI) VI = 8 V ~ 30 V, IO = 0.5 A — 25 80 m V
Load Regulation ∆VO(∆IO) VI = 15 V, IO = 0.2 A ~ 0.8 A — 10 30 m V
Quiescent Current IIQ IO = 0 A — 7.0 — m A
VCE = 0.3 V — — 200 µA
Chip Enable Voltage VCE Converter turn-off voltage — — 0.5 V
Soft-Start Current ISS VSS = 0 V — — -100 µ A
Typical values are given for circuit design information only.
Note: Output short-circuit current is at point where output voltage has decreased 5% below VO(nom).
SI-8033JF Test Circuit
C1 = 220 µF/50 V
C2 = 470 µF/25 V
C3 = 0.47 µF/10 V
L1 = 100 µH
D1 = Sanken RK-16
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Switching
Regulators
4
TYPICAL CHARACTERISTICS
(TA = 25°C)
Efficiency Overcurrent Protection
Low-Voltage Behavior Load Regulation
Temperature Stability
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
www.allegromicro.com
Switching
Regulators
5
APPLICATIONS INFORMATION
Input Capacitor (C1). Capacitors with low impedance
for high-frequency ripple current must be used.
Output Capacitor (C2). Capacitors with low impedance
for high-frequency ripple current must be used. Especially
when the C2 impedance is high, the switching waveform
may not be normal at low temperatures. Film or tantalum
capacitor for C2 may cause abnormal oscillations.
Catch Diode (D1). Diode D1 must be a Schottky diode.
Other diode types will result in increased forward voltage
spikes, reverse current flow, increased IC power dissipa-
tion during the off period, and possible destruction of the
IC.
Choke Coil (L1). If the winding resistance of the choke
coil is too high, the circuit efficiency will decrease. As the
overcurrent protection start current is approximately 2.5 A,
attention must be paid to the heating of the coil by magnetic
saturation due to overload. To reduce the output ripple, the
inductor may be increased at the expense of excessive
board area and cost.
Typical ApplicationSI-8033JF
Soft-Start Capacitor (C3). Soft start for the converter
is enabled by connecting a capacitor between terminal 5
and ground. The converter may be turned off by decreasing
the terminal 5 voltage below 0.5 V with either an npn
small-signal transistor or the output of open-collector TTL.
If both a large soft-start capacitor and on/off control are
desired, collector current limiting must be used to prevent
transistor damage. No external voltage can be applied to
terminal 5.
Parallel Operation. Parallel operation to increase load
current is not permitted.
Overcurrent Protection. The SI-8000JF series has a
built-in fold-back type overcurrent protection circuit, which
limits the output current at a start-up mode. It thus cannot
be used in applications that require current at the start-up
mode such as:
(1) constant-current load,
(2) power supply with positive and negative outputs to
common load (a center-tap type power supply), or
(3) raising the output voltage by putting a diode or a
resistor between the device ground and system ground.
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Switching
Regulators
6
Layout Guideline
APPLICATIONS INFORMATION (cont.)
Thermal Protection. Circuitry turns off the switching
transistor when the junction temperature rises above 150°C.
It is intended only to protect the device from failures due to
excessive junction temperatures and should not imply that
output short circuits or continuous overloads are permitted.
Heat Radiation and Reliability. The reliability of the
IC is directly related to the junction temperature (TJ) in its
operation. Accordingly, careful consideration should be
given to heat dissipation. The graph on page 2 illustrates
the effect of thermal resistance on the allowable package
power dissipation.
When mounting to a heat sink, apply silicone grease (Shin-
Etsu Chemical G746, Dow Corning Toray Silicone SC102,
or Toshiba Silicone SY6260). Recommended mounting
hardware torque: 0.588 ~ 0.686 Nm or 6.0 ~ 7.0 kgf•cm
(4.34 ~ 5.06 lbf•ft).
The junction temperature (TJ) can be determined from
either of the following equations:
TJ = (PDRθJA) + TA
or TJ = (PDRθJC) + TC
where PD = VIII – VOIO – VFIO(1 – [VO/VI])
or the adjacent graph,
VF = the Schottky diode forward voltage, and
RθJC = 6°C/W.
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
www.allegromicro.com
Switching
Regulators
7
Dimensions in Millimeters
Terminal Finish: Sn–3Ag–0.5Cu, 2nd level interconnect category (e1)
Product Weight: Approx. 2.3 g
Terminal spacing is measured at lead tips.
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Switching
Regulators
8
Primary Packing: 50 pieces per stick
Product Thickness: 0.7 mm ±0.3 mm
Material: Hard polyvinylchloride (transparent)
Warp: Within 2 mm against L-shape dimension
Secondary Packing: Ten sticks, four layers (2000 pieces
per box). Cardboard box.
Inner Cover
Stick
Shock-Absorbing
Material (50-100 mm)
Stick
Underlay
Shipping Container Dimensions in Millimeters
SI-8033JF
Step-Down
to 3.3 V, 1.5 A,
DC/DC Converter
www.allegromicro.com
Switching
Regulators
9
The products described herein are manufactured in Japan by Sanken
Electric Co., Ltd. for sale by Allegro MicroSystems, Inc.
Sanken and Allegro reserve the right to make, from time to time, such
departures from the detail specifications as may be required to permit
improvements in the performance, reliability, or manufacturability of its
products. Therefore, the user is cautioned to verify that the information
in this publication is current before placing any order.
When using the pr oducts described her ein, the applicability and
suitability of such pr oducts for the intended purpose shall be r eviewed at
the users responsibility .
Although Sanken undertakes to enhance the quality and r eliability of
its pr oducts, the occurr ence of failur e and defect of semiconductor
pr oducts at a certain rate is inevitable.
Users of Sanken pr oducts ar e r equested to take, at their own risk,
pr eventative measur es including safety design of the equipment or
systems against any possible injury , death, fir es or damages to society
due to device failure or malfunction.
Sanken pr oducts listed in this publication are designed and intended
for use as components in general-purpose electr onic equipment or
apparatus (home appliances, office equipment, telecommunication
equipment, measuring equipment, etc.). Their use in any application
r equiring radiation har dness assurance (e.g., aerospace equipment) is
not supported.
When considering the use of Sanken pr oducts in applications wher e
higher r eliability is r equired (transportation equipment and its contr ol
systems or equipment, fir e- or burglar-alarm systems, various safety
devices, etc.), contact a company sales r epresentative to discuss and
obtain written confirmation of your specifications.
The use of Sanken pr oducts without the written consent of Sanken in
applications wher e extremely high r eliability is requir ed (aer ospace
equipment, nuclear power-contr ol stations, life-support systems, etc.) is
strictly pr ohibited.
The information included herein is believed to be accurate and
reliable. Application and operation examples described in this publica-
tion are given for reference only and Sanken and Allegro assume no
responsibility for any infringement of industrial property rights,
intellectual property rights, or any other rights of Sanken or Allegro or
any third party that may result from its use.
EI16EI
