April 30, 2008
LM3678 High-Performance, Miniature 1.5A Step-Down DCDC Converter for Handheld Applications
LM3678 High-Performance, Miniature 1.5A Step-Down DC-DC Converter for Handheld
Applications
General Description
The LM3678 step-down DC-DC converter is optimized for
powering low voltage circuits from a single Li-Ion cell battery
and input voltage rails from 2.5V to 5.5V. It provides up to 1.5A
load current, over the entire input voltage range. LM3678 offers a 0.8V/1.2V option. One of the pair of voltages is set
through the VSELECT pin.
LM3678 operates in PWM mode with a fixed frequency of
3.3MHz. Internal synchronous rectification provides high efficiency during PWM mode operation. In shutdown mode, the
device turns off and reduces battery consumption to 0.01µA
(typ).
The LM3678 is available in a 3mm x 3mm LLP-10 package.
A high switching frequency of 3.3MHz (typ.) allows use of tiny
surface-mount components. Only three external surfacemount components, an inductor and two ceramic capacitors,
are required (solution size less than 33 mm2). For voltages
other than the voltage shown, please refer to ordering information section or contact National Semiconductor.
Typical Application Circuit
Features
V
■
■
■
■
■
■
■
■
■
= 0.8V/1.2V
OUT
VIN = 2.5V to 5.5V
1.5A maximum load capability
3.3MHz PWM fixed switching frequency (typ.) allows the
use of 1µH inductor
+/- 3% DC output voltage precision
0.01µA typical shutdown current
Internal synchronous rectification for high efficiency
Internal soft start
Current overload and thermal shutdown protection
Applications
PDAs and Smart Phones
■
Personal Media Players
■
W-LAN
■
USB Modem Applications
■
Digital still cameras
■
Portable Hard disk drives
■
Efficiency vs. Output Current
( V
OUT
= 1.2V)
Note: V
© 2008 National Semiconductor Corporation 202045 www.national.com
H = 1.2V, V
SEL
L = 0.8V
SEL
FIGURE 1.
20204501
20204504
Functional Block Diagram
LM3678
FIGURE 2. LM3678 Block Diagram
www.national.com 2
20204505
Connection Diagram and Package Mark Information
LM3678
Top View
20204502
Bottom View
20204503
Pin Descriptions
Pin # Name Description
1 GND Power Ground pin.
2 GND Analog Ground Pin
3 SW Switching node connection to the internal PFET switch and NFET synchronous rectifier
4 VDD Analog supply input. Connect to the input filter capacitor (Figure 1).
5 VDD Power supply Input. Connect to the input filter capacitor (Figure 1).
6 VSELECT Output voltage select ( For example)
VSELECT = LOW, V
VSELECT = HIGH , V
7 PGOOD Power Good Flag. This commom drain logic output is pulled to ground when the output
voltage is not within +/-7.5% of regulation.
8 PWM Connect PWM pin to VIN.
9 EN Enable pin. The device is in shutdown mode when voltage to this pin is <0.4V and enabled
when >1.0V. Do not leave this pin floating.
10 FB Feedback analog input. Connect directly to the output filter capacitor for fixed voltage
versions.
DAP DAP Die Attach Pad, connect the DAP to GND on PCB layout to enhance thermal
performance. It should not be used as a primary ground connection.
OUT
OUT
= 0.8V
= 1.2V
Ordering Information
Voltage Option Order Number Package Marking Supplied As
LM3678SDE-1.2 S021B 250 units, Tape-and-Reel
0.8V/1.2V
LM3678SD-1.2 S021B 1000 units, Tape-and-Reel
LM3678SDX-1.2 S021B 4500 units, Tape-and-Reel
3 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
LM3678
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
VIN Pin: Voltage to GND −0.2V to 6.0V
EN Pin: −0.2V to 6.0V
FB, SW Pin: (GND−0.2V) to
Continuous Power Dissipation
(Note 3)
Junction Temperature (T
J-MAX
) +150°C
Internally Limited
(VIN + 0.2V)
Storage Temperature Range −65°C to +150°C
Maximum Lead Temperature
260°C
(Soldering, 10 sec.)
Operating Ratings (Notes 1, 2)
Input Voltage Range 2.5V to 5.5V
Recommended Load Current 0mA to 1.5A
Junction Temperature (TJ) Range −30°C to +125°C
Ambient Temperature (TA) Range (Note4)−30°C to +85°C
Thermal Properties
Junction-to-Ambient Thermal
Resistance (θJA) (LLP-10) for
4 layer board (Note 5)
49.8°C/W
Electrical Characteristics (Notes 2, 6, 8) Limits in standard typeface are for T
= 25°C. Limits in boldface type
J
apply over the full operating ambient temperature range (−30°C ≤ TA ≤ +85°C). Unless otherwise noted, specifications apply to
the LM3678 Typical Application Circuit (pg. 1) with VIN = EN = 3.6V
Symbol Parameter Condition Min Typ Max Units
V
FB
V
REF
R
DSON (P)
R
DSON (N)
I
LIM
I
SHDN
EN
IH
EN
IL
I
EN
F
OSC
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of
the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see
the Electrical Characteristics tables.
Note 2: All voltages are with respect to the potential at the GND pin.
Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ= 150°C (typ.) and disengages at
TJ= 130°C (typ.).
Note 4: In Applications where high power dissipation and/or poor package resistance is present, the maximum ambient temperature may have to be derated.
Maximum ambient temperature (T
the application (P
− (θJAx P
Note 5: Junction to ambient thermal resistance is highly application and board layout dependent. In applications where high power dissipation exists, special care
must be given to thermal dissipation issues in board design.
Note 6: Refer to datasheet curves for closed loop data and its variation with regards to supply voltage and temperature. Electrical Characteristic table reflects
open loop data (FB=0V and current drawn from SW pin ramped up until cycle by cycle current limit is activated). Closed loop current limit is the peak inductor
current measured in the application circuit by increasing output current until output voltage drops by 10%.
Note 7: Min and Max limits are guaranteed by design, test or statistical analysis. Typical numbers are not guaranteed, but do represent the most likely norm.
Note 8: The parameters in the electrical characteristic table are tested at VIN= 3.6V unless otherwise specified. For performance over the input voltage range
refer to datasheet curves.
Feedback Voltage VSELECT = Low & High -3 +3 %
Internal Reference Voltage (Note 7) 0.5 V
Pin-Pin Resistance for PFET VIN= VGS= 3.6V 150 200
Pin-Pin Resistance for NFET VIN= VGS= 3.6V 110 150
Switch Peak Current Limit Open loop 1.9 2.15 2.4 A
Shutdown Supply Current EN = 0V 1 µA
Logic High Input VIN = 3.6V 1.2 V
Logic Low Input VIN = 3.6V 0.4 V
Enable (EN) Input Current 0.01 1 µA
Internal Oscillator Frequency PWM Mode 2.7 3.3 3.6 MHz
D-MAX
) is dependent on the maximum operating junction temperature (T
) and the junction to ambient thermal resistance of the package (θJA) in the application, as given by the following equation: T
D-MAX
).
A-MAX
), the maximum power dissipation of the device in
J-MAX
A-MAX
= T
mΩ
mΩ
J-MAX
www.national.com 4
Typical Performance Characteristics
LM3678SD, Circuit of Figure 1, VIN= 3.6V, V
= 1.2V, CIN = 10µF, C
OUT
= 22µF, and TA= 25°C, unless otherwise noted.
OUT
LM3678
Quiescent Supply Current vs. Temperature
20204533
NFET_ R
vs. Temperature
DSON
Switching Frequency vs. Temperature
20204535
PFET_R
vs. Temperature
DSON
20204536
ILIMIT vs. Temperature (Open Loop)
20204538
20204537
Efficiency PWM Mode vs. ILOAD (0.8V)
20204522
5 www.national.com
LM3678
Efficiency PWM Mode vs. ILOAD (1.2V)
20204523
Line Transient Response
(V
= 0.8V, LOAD = 500mA)
OUT
20204552
Line Transient Response
(V
OUT
Load Transient Response
(VIN = 3.6V, V
= 1.2V, LOAD = 500mA)
= 0.8V, Load Step 0 ↔ 500mA)
OUT
20204553
(VIN = 3.6V, V
(VIN = 3.6V, V
Load Transient Response
= 1.2V, Load Step 0 ↔ 500mA)
OUT
Load Transient Response
= 0.8V, Load Step 500mA ↔ 1A)
OUT
20204513
20204514
www.national.com 6
20204515
LM3678
(VIN = 3.6V, V
VSELECT Transient Response
Load Transient Response
= 1.2V, Load Step 500mA ↔ 1A)
OUT
(VIN = 3.6V, No LOAD)
VSELECT Transient Response
(VIN = 3.6V, LOAD = 500mA)
20204541
20204520
VSELECT Transient Response
(VIN = 3.6V, LOAD = 1A)
(VIN = 3.6V, V
Start Up
= 1.2V, LOAD = 1A)
OUT
20204542
20204550
(VIN = 3.6V, V
Start Up
= 1.2V, LOAD = 500mA)
OUT
20204547
20204551
7 www.national.com
LM3678
Switching Waveform
(V
= 1.2V, LOAD = 1A)
OUT
20204556
www.national.com 8
LM3678
Operation Description
DEVICE INFORMATION
The LM3678, a high efficiency step down DC-DC switching
buck converter, delivers a constant voltage from a single LiIon battery and input voltage rails from 2.5V to 5.5V to
portable devices such as cell phones and PDAs. Using a voltage mode architecture with synchronous rectification, the
LM3678 has the ability to deliver up to 1.5A depending on the
input voltage, output voltage, ambient temperature and the
inductor chosen.
Additional features include soft-start, under voltage protection, current overload protection, and thermal shutdown protection. As shown in Figure 1, only three external power
components are required for implementation.
The part uses an internal reference voltage of 0.5V. It is recommended to keep the part in shutdown until the input voltage
is 2.5V or higher.
CIRCUIT OPERATION
During the first portion of each switching cycle, the control
block in the LM3678 turns on the internal PFET switch. This
allows current to flow from the input through the inductor to
the output filter capacitor and load. The inductor limits the
current to a ramp with a slope of (VIN–V
ergy in a magnetic field.
During the second portion of each cycle, the controller turns
the PFET switch off, blocking current flow from the input, and
then turns the NFET synchronous rectifier on. The inductor
draws current from ground through the NFET to the output
filter capacitor and load, which ramps the inductor current
down with a slope of - V
OUT
/L.
The output filter stores charge when the inductor current is
high, and releases it when inductor current is low, smoothing
the voltage across the load.
The output voltage is regulated by modulating the PFET
switch on time to control the average current sent to the load.
The effect is identical to sending a duty-cycle modulated rectangular wave formed by the switch and synchronous rectifier
at the SW pin to a low-pass filter formed by the inductor and
output filter capacitor. The output voltage is equal to the average voltage at the SW pin.
PWM OPERATION
During device operation the converter operates as a voltagemode controller with input voltage feed forward. This allows
the converter to achieve good load and line regulation. The
DC gain of the power stage is proportional to the input voltage.
To eliminate this dependence, feed forward inversely proportional to the input voltage is introduced.
The output voltage is regulated by switching at a constant
frequency and then modulating the energy per cycle to control
power to the load. At the beginning of each clock cycle the
PFET switch is turned on and the inductor current ramps up
until the comparator trips and the control logic turns off the
switch. The current limit comparator can also turn off the
switch in case the current limit of the PFET is exceeded. Then
)/L, by storing en-
OUT
the NFET switch is turned on and the inductor current ramps
down. The next cycle is initiated by the clock turning off the
NFET and turning on the PFET.
20204555
FIGURE 3. Typical PWM Operation
INTERNAL SYNCHRONOUS RECTIFICATION
The LM3678 uses an internal NFET as a synchronous rectifier
to reduce rectifier forward voltage drop and associated power
loss. Synchronous rectification provides a significant improvement in efficiency whenever the output voltage is relatively low compared to the voltage drop across an ordinary
rectifier diode.
CURRENT LIMITING
A current limit feature allows the LM3678 to protect itself and
external components during overload conditions by implementing current limiting with an internal comparator that trips
at 2.15A (typ). If the output is shorted to ground the device
enters a timed current limit mode where the NFET is turned
on for a longer duration until the inductor current falls below
a low threshold. This allows the inductor current more time to
decay, thereby preventing runaway.
SHUTDOWN MODE
Setting the EN input pin low (<0.4V) places the LM3678 in
shutdown mode. During shutdown the PFET switch, NFET
switch, reference, control and bias circuitry of the LM3678 are
turned off. Setting EN high (>1.0V) enables normal operation.
It is recommended to set EN pin low to turn off the LM3678
during system power up and undervoltage conditions when
the supply is less than 2.5V. Do not leave the EN pin floating.
SOFT START
The LM3678 has a soft-start circuit that limits in-rush current
during start-up. During start-up the switch current limit is increased in steps. Soft start is activated only if EN goes from
logic low to logic high after VIN reaches 2.5V. Soft start is implemented by increasing switch current limit in steps of
250mA, 500mA, 1A and 2A (typical switch current limit). The
start-up time thereby depends on the output capacitor and
load current demanded at start-up.
9 www.national.com
Inductor Selection
There are two main considerations when choosing an induc-
LM3678
tor; the inductor should not saturate, and the inductor current
ripple should be small enough to achieve the desired output
voltage ripple. Different saturation current rating specifications are followed by different manufacturers so attention
must be given to details. Saturation current ratings are typically specified at 25°C. However, ratings at the maximum
ambient temperature of application should be requested from
the manufacturer. Shielded inductors radiate less noise and
should be preferred.
There are two methods to choose the inductor saturation current rating.
Method 1:
The saturation current should be greater than the sum of the
maximum load current and the worst case average to peak
inductor current. This can be written as
•
I
: average to peak inductor current
RIPPLE
•
I
: maximum load current (1.5A)
OUTMAX
•
VIN: maximum input voltage in application
•
L : minimum inductor value including worst case
tolerances (30% drop can be considered for method 1)
•
f : minimum switching frequency (2.7Mhz)
•
V
: output voltage
OUT
For a more conservative approach, a 1µH inductor with a saturation current rating of at least 2.5A is recommended for
most applications.
Input Capacitor Selection
A ceramic input capacitor of 10uF, 6.3V is sufficient for most
applications. Place the input capacitor as close as possible to
the VIN pin of the device. A larger value may be used for improved input voltage filtering. Use X7R or X5R types; do not
use Y5V. DC bias characteristics of ceramic capacitors must
be considered when selecting case sizes like 0805 and 0603.
The input filter capacitor supplies current to the PFET switch
of the LM3678 in the first half of each cycle and reduces voltage ripple imposed on the input power source. A ceramic
capacitor’s low ESR provides the best noise filtering of the
input voltage spikes due to this rapidly changing current. Select a capacitor with sufficient ripple current rating. The input
current ripple can be calculated as:
TABLE 1. Suggest Inductors and Their Suppliers
Model Vendor Dimensions
NR4012T1R0N Taiyo Yuden 4 x 4 x 1.2
LPS4012-102L Coilcraft 3.9 x 3.9 x 1.2
LPS4012-102L Coilcraft 3.9 x 3.9 x 1.8
Output Capacitor Selection
A ceramic output capacitor of 22µF, 6.3V is sufficient for most
applications. Use X7R or X5R types; do not use Y5V. DC bias
characteristics of ceramic capacitors must be considered
when selecting case sizes like 0805 and 0603. DC bias characteristics vary from manufacturer to manufacturer and dc
bias curves should be requested from them as part of the capacitor selection process.
The output filter capacitor smooths out current flow from the
inductor to the load, helps maintain a steady output voltage
during transient load changes and reduces output voltage
ripple. These capacitors must be selected with sufficient capacitance and sufficiently low ESR to perform these functions.
The output voltage ripple is caused by the charging and discharging of the output capacitor and by the R
calculated as:
Voltage peak-to-peak ripple due to capacitance can be expressed as follow:
and can be
ESR
LxWxH (mm)
Voltage peak-to-peak ripple due to ESR can be expressed as
follow:
V
PP-ESR
Because these two components are out of phase the rms (root
mean squared) value can be used to get an approximate value of peak-to-peak ripple.
The peak-to-peak ripple voltage rms value can be expressed
as follow:
Note that the output voltage ripple is dependent on the inductor current ripple and the equivalent series resistance of the
output capacitor (R
The R
dependent); make sure the value used for calculations is at
the switching frequency of the part.
D.C.R (max) I
60mΩ
100mΩ
40mΩ
= (2 * I
is frequency dependent (as well as temperature
ESR
RIPPLE
ESR
) * R
).
ESR
SAT
2.5A
2.5A
3.4A
www.national.com 10
TABLE 2. Suggested Capacitors and Their Suppliers
LM3678
Model Type Vendor Voltage Rating
10µF for C
22µF for C
Board Layout Considerations
PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a DCDC converter and surrounding circuitry by contributing to EMI,
ground bounce, and resistive voltage loss in the traces. These
can send erroneous signals to the DC-DC converter IC, resulting in poor regulation or instability.
Good layout for the LM3678 can be implemented by following
a few simple design rules below.
1.
2.
3.
IN
GRM21BR60J106K Ceramic, X5R Murata 6.3V 0805 (2012)
JMK212BJ106K Ceramic, X5R Taiyo-Yuden 6.3V 0805 (2012)
C2012X5R0J106K Ceramic, X5R TDK 6.3V 0805 (2012)
OUT
JMK212BJ226MG Ceramic, X5R Taiyo-Yuden 6.3V 0805 (2012)
reduces ground bounce at the LM3678 by giving it a lowimpedance ground connection.
4.
Use wide traces between the power components and for
power connections to the DC-DC converter circuit. This
reduces voltage errors caused by resistive losses across
the traces.
5.
Route noise sensitive traces, such as the voltage
feedback path, away from noisy traces between the
power components. The voltage feedback trace must
remain close to the LM3678 circuit and should be direct
Place the LM3678, inductor and filter capacitors close
together and make the traces short. The traces between
these components carry relatively high switching
currents and act as antennas. Following this rule reduces
radiated noise. Special care must be given to place the
input filter capacitor very close to the VIN and GND pin.
Arrange the components so that the switching current
loops curl in the same direction. During the first half of
each cycle, current flows from the input filter capacitor
through the LM3678 and inductor to the output filter
capacitor and back through ground, forming a current
loop. In the second half of each cycle, current is pulled
up from ground through the LM3678 by the inductor to
the output filter capacitor and then back through ground
forming a second current loop. Routing these loops so
the current curls in the same direction prevents magnetic
field reversal between the two half-cycles and reduces
radiated noise.
Connect the ground pins of the LM3678 and filter
capacitors together using generous component-side
copper fill as a pseudo-ground plane. Then, connect this
to the ground-plane (if one is used) with several vias. This
reduces ground-plane noise by preventing the switching
currents from circulating through the ground plane. It also
but should be routed opposite to noisy components. This
reduces EMI radiated onto the DC-DC converter’s own
voltage feedback trace. A good approach is to route the
feedback trace on another layer and to have a ground
plane between the top layer and layer on which the
feedback trace is routed. In the same manner for the
adjustable part it is desired to have the feedback dividers
on the bottom layer.
6.
Place noise sensitive circuitry, such as radio IF blocks,
away from the DC-DC converter, CMOS digital blocks
and other noisy circuitry. Interference with noise-
sensitive circuitry in the system can be reduced through
distance.
For detailed layout information, refer to Application Note 1722
LM3678 Evaluation Board.
In mobile phones, for example, a common practice is to place
the DC-DC converter on one corner of the board, arrange the
CMOS digital circuitry around it (since this also generates
noise), and then place sensitive preamplifiers and IF stages
on the diagonally opposing corner. Often, the sensitive circuitry is shielded with a metal pan and power to it is postregulated to reduce conducted noise, using low-dropout
linear regulators.
Case Size
Inch (mm)
11 www.national.com
Physical Dimensions inches (millimeters) unless otherwise noted
LM3678
Non Pullback LLP-10, 0.5mm Pitch
The dimensions for X1, X2, and X3 are as given:
NS Package Number SDA10A
X1 = 3mm +/- 0.030mm
X2 = 3mm +/- 0.030mm
X3 = 0.800mm +/- 0.075mm
www.national.com 12
Notes
LM3678
13 www.national.com
Notes
For more National Semiconductor product information and proven design tools, visit the following Web sites at:
Applications
Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench
Audio www.national.com/audio Analog University www.national.com/AU
Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes
Data Converters www.national.com/adc Distributors www.national.com/contacts
Displays www.national.com/displays Green Compliance www.national.com/quality/green
Ethernet www.national.com/ethernet Packaging www.national.com/packaging
Interface www.national.com/interface Quality and Reliability www.national.com/quality
LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns
Power Management www.national.com/power Feedback www.national.com/feedback
Switching Regulators www.national.com/switchers
LDOs www.national.com/ldo
LED Lighting www.national.com/led
PowerWise www.national.com/powerwise
Serial Digital Interface (SDI) www.national.com/sdi
Temperature Sensors www.national.com/tempsensors
Wireless (PLL/VCO) www.national.com/wireless
Products Design Support
THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION
(“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY
OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO
SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS,
IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS
DOCUMENT.
TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT
NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL
PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR
APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND
APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE
NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS.
EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO
LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE
AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR
PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY
RIGHT.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR
SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and
whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected
to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform
can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness.
National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other
LM3678 High-Performance, Miniature 1.5A Step-Down DC-DC Converter for Handheld
brand or product names may be trademarks or registered trademarks of their respective holders.
Copyright© 2008 National Semiconductor Corporation
For the most current product information visit us at www.national.com
www.national.com
National Semiconductor
Americas Technical
Support Center
Email: support@nsc.com
Tel: 1-800-272-9959
National Semiconductor Europe
Technical Support Center
Email: europe.support@nsc.com
German Tel: +49 (0) 180 5010 771
English Tel: +44 (0) 870 850 4288
National Semiconductor Asia
Pacific Technical Support Center
Email: ap.support@nsc.com
National Semiconductor Japan
Technical Support Center
Email: jpn.feedback@nsc.com
Loading...