NSC LM3508TL Synchronous magnetic constant current white led driver Datasheet

LM3508
Synchronous Magnetic Constant Current White LED Driver
General Description
Features
The LM3508 is a synchronous boost converter (no external
Schottky diode required) that provides a constant current output. It is designed to drive up to 4 series white LEDs at 30mA
from a single-cell Li-Ion battery. A single low power external
resistor is used to set the maximum LED current. The LED
current can be adjusted by applying a PWM signal of up to
100kHz to the DIM pin. Internal soft-start circuitry is designed
to eliminate high in-rush current at start-up. For maximum
safety, the device features an advanced short-circuit protection when the output is shorted to ground. Additionally, overvoltage protection and an 850kHz switching frequency allow
for the use of small, low-cost output capacitors with lower
voltage ratings. During shutdown, the output is disconnected
from the input preventing a leakage current path through the
LEDs to ground. The LM3508 is available in a tiny 9-bump
chip-scale micro-SMD package.
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Drives 4 Series White LEDs with up to 30mA
>80% Peak Efficiency
Up to 100kHz PWM Brightness Control
Accurate ±5% LED Current Regulation across VIN range
Internal Synchronous PFET (No Schottky Diode
Required)
True Shutdown Isolation
Output Short-Circuit Protection
17.5V Over-Voltage Protection
Internal Soft-Start Eliminates Inrush Current
Wide Input Voltage Range: 2.7V to 5.5V
850kHz Fixed Frequency Operation
Low Profile 9-Bump Micro-SMD Package (1.514mm x
1.514mm x 0.6mm)
Applications
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White LED Backlighting
Handheld Devices
Digital Cameras
Portable Applications
Typical Application Circuit
30004201
© 2007 National Semiconductor Corporation
300042
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LM3508 Synchronous Magnetic Constant Current White LED Driver
April 2007
LM3508
Connection Diagram
Top View
30004202
9-Bump (Large) µ-SMD (1.514mm x 1.514mm x 0.6mm) NS Package Number TLA09
Ordering Information
Part Number
Package Type
LM3508TL
9-Bump micro SMD
NSC Package Drawing Top Mark
TL09SDA
D31
250 Units, Tape and Reel
Supplied As
LM3508TLX
9-Bump micro SMD
TL09SDA
D31
3000 Units, Tape and Reel
Pin Descriptions/Functions
Pin
Name
A1
PGND
Function
Power Ground Connection.
A2
SW
Inductor connection and drain connection for both NMOS and PMOS power devices.
A3
OUT
Output capacitor connection, PMOS source connection for synchronous rectifier, and OVP
sensing node.
B1
ILED
Regulated current source input.
B2
DIM
Current source modulation input. A logic low at DIM turns off the internal current source. A logic
high turns the LEDs fully on (VSET=200mV). Apply a PWM signal at DIM for LED brightness control.
B3
IN
C1
SET
Current sense connection and current source output. Connect a 1% resistor (RSET) from SET to
PGND to set the maximum LED current (ILED = 200mV/RSET) .
C2
EN
Enable input. A logic low at EN turns off the LM3508. A logic high turns the device on.
C3
AGND
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Input voltage connection.
Analog ground. Connect AGND to PGND through a low impedance connection.
2
Operating Conditions
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
VIN
VOUT
VSW
VILED, VSET, VDIM, VEN
Continuous Power Dissipation
(Note )
Junction Temperature
Lead Temperature
(Note 4)
Storage Temperature Range
ESD Rating(Note 9)
Human Body Model
Input Voltage Range
Ambient Temperature Range
(Note 5)
Junction Temperature Range
−0.3V to 6V
−0.3V to 22V
−0.3V to 22V
(Notes 1, 2)
2.7V to 5.5V
−30°C to +85°C
−30°C to +105°C
Thermal Properties
−0.3V to 6V
Internally Limited
Junction to Ambient Thermal
Resistance (θJA)(Note 6)
64.7°C/W
ESD Caution Notice
+150°C
National Semiconductor recommends that all integrated circuits be handled with appropriate ESD precautions. Failure to
observe proper ESD handling techniques can result in damage to the device.
+300°C
-65°C to +150°C
2kV
Electrical Characteristics
Specifications in standard type face are for TA = 25°C and those in boldface type apply over the Operating Temperature Range
of TA = −30°C to +85°C. Unless otherwise specified VIN =3.6V.(Note 7)
Symbol
Parameter
Conditions
Min
Typ
LED Current
Regulation
RSET = 10Ω
20
RSET = 6.67Ω
30
VSET
Voltage at SET Pin
3.0V < VIN < 5.5V
VILED
Voltage at ILED Pin
VHR
Current Sink
Headroom Voltage
Where ILED = 95% of
NMOS Switch On
Resistance
ISW = 100mA
0.5
PMOS Switch On
Resistance
VOUT = 10V, ISW = 65mA
2.2
ID
RDSON
190
nominal, RSET = 20Ω
200
Max
Units
mA
210
mV
500
mV
400
mV
Ω
ICL
NMOS Switch
Current Limit
ILSW
SW Leakage Current VSW = VIN = 5.5V, OUT
Floating, VEN = PGND
0.01
µA
IOUT_SHUTDOWN
Outout Pull-Down
Resistance in
Shutdown
630
Ω
VOVP
370
500
VEN = 0V
Output Over-Voltage ON Threshold (VOUT rising)
Protection
OFF Threshold (VOUT
falling)
17.5
fSW
Switching Frequency 3.0V < VIN < 5.5V
715
DMAX
Maximum Duty Cycle
VSC
Output Voltage
Threshold for Short
Circuit Detection
VOUT Falling
0.93×VIN
VOUT Rising
0.95×VIN
EN Threshold
Voltage
On Threshold
DIM Threshold
Voltage
On Threshold
DIM Bias Current
(Note 8)
VDIM = 1.8V
VEN_TH
VDIM_TH
IDIM
620
19.8
21.8
V
18.6
850
nA
1150
91
MHz
%
V
1.1
Off Threshold
0.5
1.1
Off Threshold
0.5
4.7
3
V
V
µA
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LM3508
Absolute Maximum Ratings (Notes 1, 2)
LM3508
Symbol
Parameter
Conditions
IEN
EN Bias Current
(Note 8)
VEN = 1.8V
IOUT
OUT Bias Current
VOUT = 16V, device not
switching
ROUT_SHUTDOWN
Output Pull-Down
Resistance in
Shutdown
VEN = 0V, VOUT < VIN
Min
Typ
Max
Units
4.7
µA
420
µA
630
Ω
IQ
Quiescent Current
VILED > 0.5V, 3.0V < VIN <
Device Not Switching 5.5V, SW Floating
IQ_SW
Switching Supply
Current
825
µA
tSTART_UP
From EN Low to High VOUT = 17V, ILED = 20mA
to Inductor Current
Steady State
470
µs
VEN = 0V, 3.0V < VIN < 5.5V
0.18
0.3
0.01
0.5
mA
Note 1: Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended
to be functional, but device parameter specifications may not be guaranteed. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: All voltages are with respect to PGND.
Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown enagaes at TJ = +150°C (typ.) and disengages at
TJ = +140°C (typ.).
Note 4: For more detailed soldering information and specifications, please refer to National Semiconductor Application Note 1112: Micro SMD Wafer Level Chip
Scale Package (AN-1112), available at www.national.com.
Note 5: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be
derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = +125ºC), the maximum power
dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the
following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX).
Note 6: Junction-to-ambient thermal resistance (θJA) is taken from thermal modeling performed under the conditions and guidelines set forth in the JEDEC
standard JESD51-7. The test board is a 4-layer FR-4 board mesuring (102mm × 76mm × 1.6mm) with a 2 × 1 array of thermal vias. The ground plane on the
board is (50mm × 50mm). Thickness of copper layers are (36µm/18µm/18µm/36µm) (1.5oz/1oz/1oz/1.5oz copper). Ambient temperature in simulation is +22°C,
still air. Power dissipation is 1W.
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.
Unless otherwise specified, conditions for typical specifications are VIN = 3.6V, TA = +25°C.
Note 8: There is a typical 383kΩ pull-down on this pin.
Note 9: The human body model is a 100pF capacitor discharged through 1.5kΩ resistor into each pin. (MIL-STD-883 3015.7).
Typical Performance Characteristics VIN = 3.6V, RSET = 10Ω, L = TDK VLF3012AT-220MR33 (22µH),
LEDs are OSRAM (LW M67C), COUT = CIN = 1µF, TA = +25°C, unless otherwise noted.
4 LED Efficiency vs ILED
(L = TDK VLF3012AT-220MR33, RL = 0.66Ω)
3 LED Efficiency vs ILED
(L = TDK VLF3012AT-220MR33, RL = 0.66Ω)
30004242
30004241
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Converter Output Voltage vs LED Current
30004243
30004258
Efficiency vs VIN (ILED = 20mA)
Efficiency vs VIN (ILED = 30mA)
30004260
30004261
Peak Current Limit vs VIN
Switching Frequency vs VIN
30004214
30004213
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LM3508
2 LED Efficiency vs ILED
(L = TDK VLF3012AT-220MR33, RL = 0.66Ω)
LM3508
Maximum Duty Cycle vs VIN
Quiescent Current vs VIN
(EN = GND)
30004215
30004217
Quiescent Current vs VIN
(Device Not Switching, VIN = VSW)
Quiescent Current vs VIN
(Device Switching)
30004216
30004218
SET Voltage vs VIN
SET Voltage vs DIM Frequency
(50% Duty Cycle at DIM)
30004259
30004219
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LM3508
SET Voltage vs DIM Duty Cycle
NFET On-Resistance vs VIN
(ISW = 250mA)
30004262
30004224
PFET On-Resistance vs Temperature
(VSW = 10.4V, VOUT = 10V)
Over Voltage Limit vs VIN
(VOUT Rising)
30004227
30004225
Over Voltage Limit vs VIN (VOUT Falling)
Start-Up Waveform
30004257
4 LEDs, ILED = 30mA, VIN = 3.6V
Channel 1: VOUT (10V/div)
Channel 2: EN (2V/div)
Channel 4: IIN (200mA/div)
Time Base: 100µs/div
30004228
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LM3508
Over-Voltage Protection Function
Line-Step Response
30004237
VIN = 3.6V, VOUT = 18.86V
Channel 1: VOUT (1V/div)
Channel 4: IIN (500mA/div)
Time Base: 400µs/div
30004255
VIN = 3.6V, 4 LEDs
Channel 1: VOUT (AC Copupled, 1V/div)
Channel 3: VIN (AC Coupled, 500mV/div)
Channel 4: ILED (DC Coupled, 5mA/div)
Time Base: 200µs/div
Output Short-Circuit Response
Typical Operating Waveforms (DIM High)
30004256
VIN = 3.6V, ILED = 30mA
Channel 1: VOUT (10V/div)
Channel 2: IIN (100mA/div)
Time Base: 200µs/div
30004229
VIN = 3.6V, 4 LEDs, ILED = 30mA, VOUT = 15.8V
Channel 1: VOUT (AC Coupled, 100mV/div)
Channel 2: VSW (DC Coupled, 10V/div)
Channel 4: IL (DC Coupled, 100mA/div)
Time Base: 400ns/div
Typical Operating Waveforms (DIM With 20kHz Square
Wave)
DIM Operation (ILED changing from 30mA to 15mA)
30004238
30004230
VIN = 3.6V, 4 LEDs, ILED = 15mA
Channel 1: VOUT (AC Coupled, 200mV/div)
Channel 3: VIN (AC Coupled, 100mV/div)
Channel 2: IL (DC Coupled, 100mA/div)
Channel 4: DIM (DC Coupled, 2V/div)
Time Base: 10µs/div
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VIN = 3.6V
Channel 4: ILED (DC Coupled, 10mA/div)
Channel 2: VOUT (AC Coupled, 2V/div)
Channel 1: DIM (DC Coupled, 2V/div, 20kHz, 50% duty cycle)
Channel 3: IIN (DC Coupled, 200mA/div)
Time Base: 400µs/div
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LM3508
Operation
30004203
FIGURE 1. LM3508 Block Diagram
The LM3508 utilizes a synchronous step-up current mode
PWM controller and a regulated current sink to provide a
highly efficient and accurate LED current for white LED bias.
The internal synchronous rectifier increases efficiency and
eliminates the need for an external diode. Additionally, internal compensation eliminates the need for external compensation components resulting in a compact overall solution.
Figure 1 shows the detailed block diagram of the LM3508.
The output of the boost converter (OUT) provides power to
the series string of white LED’s connected between OUT and
ILED. The boost converter regulates the voltage at ILED to
500mV. This voltage is then used to power the internal current
source whose output is at SET.
The first stage of the LM3508 consists of the synchronous
boost converter. Operation is as follows: At the start of each
switching cycle the oscillator sets the PWM controller. The
controller turns the low side (NMOS) switch on and the synchronous rectifier (PMOS) switch off. During this time current
ramps up in the inductor while the output capacitor supplies
the current to the LED’s. The error signal at the output of the
error amplifier is compared against the sensed inductor current. When the sensed inductor current equals the error signal, or when the maximum duty cycle is reached, the NMOS
switch turns off and the PMOS switch turns on. When the
PMOS turns on, the inductor current ramps down, restoring
energy to the output capacitor and supplying current to the
LED’s. At the end of the clock period the PWM controller is
again set and the process repeats itself. This action regulates
ILED to 500mV.
The second stage of the LM3508 consists of an internal current source powered by the ILED voltage and providing a
regulated current at SET. The regulated LED current is set by
connecting an external resistor from SET to PGND. VSET is
adjusted from 0 to 200mV by applying a PWM signal of up to
typically 100kHz at DIM (see Typical Performance Characteristic of SET voltage vs DIM frequency). The PWM signal at
DIM modulates the internal 200mV reference and applies it to
an internal RC filter resulting in an adjustable SET voltage and
thus an adjustable LED current.
Start-Up
The LM3508 features a soft-start to prevent large inrush currents during start-up that can cause excessive voltage ripple
on VIN. During start-up the average input current is ramped
up at a controlled rate. For the typical application circuit, driving 4LED’s from a 3.6V lithium battery at 30mA, when EN is
driven high the average input current ramps from zero to 160mA in 470µs. See plot of Soft Start functionality in the Typical
Performance Characteristics.
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LM3508
figure 1) will be fully on, appearing as a 5Ω resistor between
ILED and SET.
DIM Operation
DIM is the input to the gate of an internal switch that accepts
a logic level PWM waveform and modulates the internal
200mV reference through an internal RC filter. This forces the
current source regulation point (VSET) to vary by the duty cycle
(D) of the DIM waveform making ILED = D × 200mV / RSET.
The cutoff frequency for the filter is approximately 500Hz. DIM
frequencies higher than 100kHz cause the LED current to
drastically deviate from their nominal set points. The graphs
of SET voltage vs DIM frequency, SET voltage vs VIN and SET
voltage vs DIM duty cycle (see Typical Performance Characteristics) show the typical variation of the current source set
point voltage.
Output Short Circuit Protection
The LM3508 provides a short circuit protection that limits the
output current if OUT is shorted to PGND. During a short at
OUT when VOUT falls to below VIN × 0.93, switching will stop.
The PMOS will turn into a current source and limit the output
current to 35mA. The LM3508 can survive with a continuous
short at the output. The threshold for OUT recovering from a
short circuit condition is typically VIN × 0.95.
Output Over-Voltage Protection
When the load at the output of the LM3508 goes high
impedance the boost converter will raise VOUT to try and
maintain the programmed LED current. To prevent over-voltage conditions that can damage output capacitors and/or the
device, the LM3508 will clamp the output at a maximum of
21.8V. This allows for the use of 25V output capacitors available in a tiny 1.6mm × 0.8mm case size.
During output open circuit conditions when the output voltage
rises to the over voltage protection threshold (VOVP = 19.8V
typical) the OVP circuitry will shut off both the NMOS and
PMOS switches. When the output voltage drops below 18.6V
(typically) the converter will begin switching again. If the device remains in an over voltage condition the cycle will be
repeated resulting in a pulsed condition at the output. See
waveform for OVP condition in the Typical Performance Characteristics.
Enable Input and Output Isolation
Driving EN high turns the device on while driving EN low
places the LM3508 in shutdown. In shutdown the supply current reduces to less than 1µA, the internal synchronous PFET
turns off as well as the current source (N2 in figure 1). This
completely isolates the output from the input and prevents
leakage current from flowing through the LED’s. In shutdown
the leakage current into SW and IN is typically 400nA. EN has
an internal 383kΩ pull-down to PGND.
Peak Current Limit/Maximum
Output Current
The LM3508 boost converter provides a peak current limit.
When the peak inductor current reaches the peak current limit
the duty cycle is terminated. This results in a limit on the maximum output power and thus the maximum output current the
LM3508 can deliver. Calculate the maximum LED current as
a function of VIN, VOUT, L and IPEAK as:
Light Load Operation
During light load conditions when the inductor current reaches
zero before the end of the switching period, the PFET will turn
off, disconnecting OUT from SW and forcing the converter
into discontinuous conduction. At the beginning of the next
switching cycle, switching will resume. (see plot of discontinuous conduction mode in the Typical Performance Characteristics graphs).
Boost converters that operate in the discontinuous conduction mode with fixed input to output conversion ratios (VOUT/
VIN) have load dependent duty cycles, resulting in shorter
switch on-times as the load decreases. As the load is decreased the duty cycle will fall until the converter hits its
minimum duty cycle (typically 15%). To prevent further decreases in the load current altering the VOUT/VIN ratio, the
LM3508 will enter a pulsed skip mode. In pulse skip mode the
device will only switch as necessary to keep the LED current
in regulation.
and fSW = 850kHz. Efficiency and IPEAK can be found in the
efficiency and IPEAK curves in the Typical Performance Characteristics.
Output Current Accuracy
The LM3508 provides highly accurate output current regulation of ±5% over the 3V to 5.5V input voltage range. Accuracy
depends on various key factors. Among these are; the tolerance of RSET, the frequency at DIM (ƒDIM), and the errors
internal to the LM3508 controller and current sink. For best
accuracy, use a 1% resistor for RSET and keep ƒDIM between
1kHz and 100kHz. Refer to the Typical Performance Characteristics for VSET vs VIN, VSET vs ƒDIM, and VSET vs DIM duty
cycle.
Thermal Shutdown
The LM3508 provides a thermal shutdown feature. When the
die temperature exceeds +150°C the part will shutdown, turning off both the NMOS and PMOS FET’s. The part will startup again with a soft-start sequence when the die temperature
falls below +115°C.
Applications Information
Voltage Head Room at ILED
BRIGHTNESS ADJUSTMENT
A logic high at DIM forces SET to regulate to 200mV. Adjust
the maximum LED current by picking RSET (the resistor from
SET to GND) such that:
If the LED current is increased to a point where the peak inductor current is reached, the boost converter's on-time is
terminated until the next switching cycle. If the LED current is
further increased the 500mV regulated voltage at ILED begins
to drop. When VILED drops below the current sink headroom
voltage (VHR = 400mV typ.) the current sink FET (see N2 in
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Once ILED_MAX is set, the LED current can be adjusted from
ILED_MAX down to ILED_MIN by applying a logic level PWM signal
to DIM. This results in:
The output voltage ripple component due to the output capacitors ESR is found by:
where D is the duty cycle of the PWM pulse applied to DIM.
The LM3508 can be brought out of shutdown while a signal
is applied to DIM, allowing the device to turn on into a low LED
current mode. A logic low at DIM will shut off the current
source making ILED high impedance however, the boost converter continues to operate. Due to an offset voltage at SET
(approximately +/-2mV) the LED’s can faintly illuminate even
with DIM pulled to GND. If zero LED current is required then
pulling EN low will shutdown the current source causing the
LED current to drop to zero. DIM has an internal 383kΩ pull
down to PGND.
Table 1. Recommended Output Capacitor Manufacturers
INPUT CAPACITOR SELECTION
Choosing the correct size and type of input capacitor helps
minimize the input voltage ripple caused by the switching action of the LM3508’s boost converter. For continuous inductor
current operation the input voltage ripple is composed of 2
primary components, the capacitor discharge (delta VQ) and
the capacitor’s equivalent series resistance (delta VESR). The
ripple due to strictly to the capacitor discharge is:
Manufact
urer
Part
Number
Value
Case Size
Voltage
Rating
GRM39X5
R105K25
D539
1µF
0603
25V
Murata
C1608X5
R1E105M
1µF
0603
25V
TDK
INDUCTOR SELECTION
The LM3508 is designed to operate with 10µH to 22µH
inductor’s. When choosing the inductor ensure that the inductors saturation current rating is greater than
The ripple due to strictly to the capacitors ESR is:
Additionally, the inductor’s value should be large enough such
that at the maximum LED current, the peak inductor current
is less than the LM3508’s peak switch current limit. This is
done by choosing L such that
In the typical application circuit, a 1µF ceramic input capacitor
works well. Since the ESR in ceramic capacitors is typically
less than 5mΩ and the capacitance value is usually small, the
input voltage ripple is primarily due to the capacitive discharge. With larger value capacitors such as tantalum or
aluminum electrolytic the ESR can be greater than 0.5Ω. In
this case the input ripple will primarily be due to the ESR.
Output Capacitor Selection
In a boost converter such as the LM3508, during the on time,
the inductor is disconnected from OUT forcing the output capacitor to supply the LED current. When the PMOS switch
(synchronous rectifier) turns on the inductor energy supplies
the LED current and restores charge to the output capacitor.
This action causes a sag in the output voltage during the on
time and a rise in the output voltage during the off time.
The LM3508’s output capacitor is chosen to limit the output
ripple to an acceptable level and to ensure the boost converter
is stable. For proper operation use a 1µF ceramic output capacitor. Values of 2.2µF or 4.7µF can be used although startup current and start-up time will be increased. As with the
Values for IPEAK and efficiency can be found in the plot of peak
current limit vs. VIN in the Typical Performance Characteristics graphs.
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LM3508
input capacitor, the output voltage ripple is composed of two
parts, the ripple due to capacitor discharge (delta VQ) and the
ripple due to the capacitors ESR (delta VESR). Most of the time
the LM3508 will operate in continuous conduction mode. In
this mode the ripple due to capacitor discharge is given by:
LM3508
1, Use a separate ground plane for power ground (PGND)
and analog ground (AGND).
2, Keep high current paths such as SW and PGND connections short.
3, Connect the return terminals for the input capacitor and the
output capacitor together at a single point as close as possible
to PGND.
4, Connect PGND and AGND together as close as possible
to the IC. Do not connect them together anywhere else.
5, Connect the input capacitor (CIN) as close as possible to
IN.
6, Connect the output capacitor (COUT) as close as possible
to OUT.
7, Connect the positive terminal of RSET as close as possible
to ILED and the negative terminal as close as possible to
PGND. This ensures accurate current programming.
Table 2. Recommended Inductor Manufacturers
MANUFACT
URER
L
Part
Number
Size
Saturation
Current
TDK
22µ VLF3010
H AT-220M
R33
2.6mm×2.
8mm×1m
m
330mA
TDK
22µ VLF3012
H AT-220M
R33
2.6mm×2.
8mm×1.2
mm
330mA
Toko
22u D3313FB 3.3mm×3.
H (1036FB- 3mm×1.3
220M)
mm
350mA
LAYOUT CONSIDERATIONS
Proper layout is essential for stable, jitter free operation, and
good efficiency. Follow these steps to ensure a good layout.
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LM3508
Physical Dimensions inches (millimeters) unless otherwise noted
9-Bump Micro SMD Package (TL09AAA)
For Ordering, Refer to Ordering Information Table
NS Package Number TLA09AAA
X1 = 1.514mm (±0.03mm), X2 = 1.514mm (±0.03mm), X3 = 0.6mm (±0.075mm)
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LM3508 Synchronous Magnetic Constant Current White LED Driver
Notes
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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.
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brand or product names may be trademarks or registered trademarks of their respective holders.
Copyright© 2007 National Semiconductor Corporation
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