Analog Devices Inc. 的 LTC3490 規格書

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LTC3490
3490fa
■
Portable Lighting
■
Rechargeable Flashlights
Single Cell Minimum Component LED Driver
Single Cell 350mA
LED Driver
■
350mA Constant Current Output
■
2.8V to 4V Output Compliance
■
1- or 2-Cell NiMH or Alkaline Input
■
Synchronous Rectification: Up to 90% Efficiency
■
Fixed Frequency Operation: 1.3MHz
■
Low Quiescent Current: <1mA
■
Very Low Shutdown Current: <50µA
■
Open LED Output Limited to 4.7V
■
V
IN
Range: 1V to 3.2V
■
Dimming Control
■
Undervoltage Lockout to Protect Batteries
■
Low Profile (0.75mm) 3mm × 3mm Thermally
Enhanced 8-Lead DD and S8 Packages
Efficiency vs VIN at VLED = 3.5V
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
The LTC
®
3490 provides a constant current drive for 1W
LED applications. It is a high efficiency boost converter
that operates from 1 or 2 NiMH or alkaline cells and
generates 350mA of constant current with up to 4V of
compliance. It contains a 100mΩ NFET switch and a
130mΩ PFET synchronous rectifier. The fixed switching
frequency is internally set to 1.3MHz.
The LTC3490 limits the output voltage to 4.7V if the output
load is disconnected. It also features an analog dimming
capability that reduces the drive current proportional to
the CTRL/SHDN pin voltage. A low-battery logic output
signals when the battery has dropped below 1V/cell. An
undervoltage lockout circuit shuts down the LTC3490
when the battery voltage drops below 0.85V/cell. The
feedback loop is internally compensated to minimize com-
ponent count.
+
SW
CAP
ON/OFF
LED
1 NiMH OR
ALKALINE
CELL 4.7µF
LOBAT
3490 TA01
V
IN
CTRL/SHDN
CELLS
1M
HIGH
CURRENT
LED
GND
LTC3490
3.3µH
350mA
V
IN
(V)
1
0
EFFICIENCY (%)
10
30
40
50
100
70
1.5 2
3490 TA02
20
80
90
60
2.5 3
I
OUT
= 350mA
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
, / iiiiiii t t / :1 L L T E 3 VW 3: L 9 1 L em I: :I 7 sw J 1 L CAP GND 3 L 1 LED L: :I L 7777777 J I: :I an PACKAGE 5 HEAD (3mm xamm) PLAsnc DEN EVLE rmxazm mtqaverwmmm ”Wrist-,0 gmzfiu;c,w[ EXPOSED PAD rent 9) ts GND MUST BESDLDERED m PCB (more 5) LTC3490EDD LBRO LTC349UESS ELECTRICHL CHflflflCI'EBISTICS The c denntes specitinatinns which apply ever the temperature range, ntherwise specitinatinns are TA = 25301”, = 2.5V unless otherwise specified. SYMBOL PARAMETER CONDITIONS MIN VW tnput Sugpty Range 1 VtNtSTART) Mlntrnurn StartrUp Voltage tNote 3) LLEmMAX) LED Drtve Current VCTRUSHDN : VIN‘ DD Package 25°C to 85°C 330 74040 to <25°c 310="" vctrushdn="WM" 53="" package="" 25°c="" to="" 85°c="" 337="" 74040="" to=""><25°c 325="" llemshdm="" led="" drtve="" current="" tn="" shutdown="" vctrushdn="" :="" 0v="" vled="" output="" compttance="" voltage="" 0="" 2.8="" vledtoth="" output="" vottage="" dvervottage="" llrnlt="" open="" led="" 0="" 4.2="" mmshdm="" tnput="" current,="" shutdown="" vctrushdn="" :="" 0v="" exctudtng="" swttcn="" leakage="" mwwve)="" tnput="" current,="" active="" exctudtng="" load="" power="" w="" swttcntng="" frequency="" 0="" 1.0="" ‘lwmost="" leakage="" current="" nmos="" swttch="" romnmos)="" unrreslstance,="" nmus="" swttch="" 2="" l7jcheqr="">
2
LTC3490
3490fa
Supply Voltage (V
IN
) ................................... –0.3V to 6V
Input Voltages (CTRL/SHDN, CELLS) ......... – 0.3V to 6V
Output Voltages (CAP, LED, SW)................ –0.3V to 6V
ABSOLUTE AXI U RATI GS
WWWU
(Note 1)
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................. –65°C to 125°C
Lead Temperature (Soldering, 10 sec, S8) .......... 300°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Input Supply Range 1 3.2 V
V
IN(START)
Minimum Start-Up Voltage (Note 3) 0.9 1 V
I
LED(MAX)
LED Drive Current V
CTRL/SHDN
= V
IN
, DD Package
25°C to 85°C 330 350 370 mA
–40°C to <25°C 310 350 385 mA
V
CTRL/SHDN
= V
IN
, S8 Package
25°C to 85°C 337 350 363 mA
–40°C to <25°C 325 345 365 mA
I
LED(SHDN)
LED Drive Current in Shutdown V
CTRL/SHDN
= 0V 0.1 1 µA
V
LED
Output Compliance Voltage ●2.8 4 V
V
LED(OVL)
Output Voltage Overvoltage Limit Open LED ●4.2 4.7 V
I
IN(SHDN)
Input Current, Shutdown V
CTRL/SHDN
= 0V, Excluding Switch Leakage 20 50 µA
I
IN(ACTIVE)
Input Current, Active Excluding Load Power 20 30 mA
f
SW
Switching Frequency ●1.0 1.3 1.6 MHz
I
L(NMOS)
Leakage Current, NMOS Switch 0.1 µA
R
ON(NMOS)
On-Resistance, NMOS Switch 0.1 Ω
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are TA = 25°C. VIN = 2.5V unless otherwise specified.
ELECTRICAL CHARACTERISTICS
LTC3490EDD LBRQ
T
JMAX
= 125°C, θ
JA
= 43°C/ W (NOTE 4)
EXPOSED PAD (PIN 9) IS GND
MUST BE SOLDERED TO PCB (NOTE 5)
LTC3490ES8 3490
T
JMAX
= 125°C, θ
JA
= 150°C/ W (NOTE 4)
TOP VIEW
9
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
5
6
7
8
4
3
2
1CELLS
VIN
SW
GND
CTRL/SHDN
LOBAT
CAP
LED
1
2
3
4
8
7
6
5
TOP VIEW
CTRL/SHDN
LOBAT
CAP
LED
CELLS
V
IN
SW
GND
S8 PACKAGE
8-LEAD PLASTIC SO
WU
U
PACKAGE/ORDER I FOR ATIO
ORDER PART NUMBER
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DD PART MARKING ORDER PART NUMBER S8 PART MARKING
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
L7LJCUW 02 04 us VCTRWW (V) DE 25a \ ‘5 2 25 Vw (V) 349mm 3
3
LTC3490
3490fa
I
L(PMOS)
Leakage Current, PMOS Switch 0.1 µA
R
ON(PMOS)
On-Resistance, PMOS Switch 0.13 Ω
V
IH
Input High (CELLS) V
IN
– 0.4 V
Input High (SHDN) V
IN
• 0.9 V
V
IL
Input Low (CELLS) 0.4 V
Input Low (SHDN) V
IN
• 0.2 V
I
IN
Input Current (CTRL/SHDN, CELLS) 0.01 µA
K
CTRL
Control Gain, I
LED
/V
CTRL
Scales Linearity with V
IN
, V
IN
= 1V 500 mA/V
R
ON(LOBAT)
On-Resistance, LOBAT Output V
IN
< V
IN(LOBAT)
●300 Ω
V
IN(LOBAT1)
Input Voltage, Low Battery, 1 Cell V
CELLS
= 0V ●0.8 1.12 V
V
IN(LOBAT2)
Input Voltage, Low Battery, 2 Cells V
CELLS
= V
IN
●1.8 2.24 V
V
IN(UVLO2)
Input Voltage, Undervoltage Lockout, V
CELLS
= V
IN
●1.4 1.8 V
2 Cells
V
IN(UVLO1)
Input Voltage, Undervoltage Lockout, V
CELLS
= 0 V ●0.7 0.9 V
1 Cell
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are TA = 25°C. VIN = 2.5V unless otherwise specified.
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3490 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C range are
assured by design, characterization and correlation with statistical process
controls.
Note 3: The LTC3490 input voltage may drop below the minimum start-up
voltage once the LED voltage has risen above 2.3V.
Note 4: This device includes overtemperature protection intended to
protect the device during momentary overload conditions. The maximum
junction temperature may be exceeded when overtemperature protection
is active. Continuous operation above the specified maximum operating
junction temperature may result in device degradation or failure.
Note 5: The Exposed Pad of the DFN package must be soldered to a
PCB pad for optimum thermal conductivity. This pad must be connected
to ground.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Oscillator Frequency
vs Temperature ILED vs VCTRL
VCTRL/VIN (V)
0
ILED (mA)
150
200
250
0.6 1
3490 G02
100
50
00.2 0.4 0.8
300
350
400
MAXIMUM
MINIMUM
ILED vs VIN
VIN (V)
ILED (mA)
325
350
375
2.5
3490 G03
300
275
250 11.5 23
VLED = 3.5V
TEMPERATURE (°C)
–50
FREQUENCY (MHz)
1.280
1.320
3490 G01
1.240
1.200 050 100
1.400
1.360
360 355 355 354 E 352 E 350 3 343 345 3“ 342 340 233323435354 VLEDLV) EFFICIENCV (0).) mo 90 an 70 so 50 an 30 20 )0 too zuu ‘lED W‘) 300 40 Pln FUI'IC'I'IOI'IS CELLS (Pin 1): A logic input to set the low»bat undervoltage shutdown thresholds. A logic low GND)will setthethresholdstort cell.Alogic hig VIN) will set the thresholds for 2 cells. VIN (Pin 2): Supply Voltage. SW (Pin 3): Swrtch Input. Connect this pin to an inductor from ViN. GND (Pin 4): CirCUit Ground. LED (Pin 5): Output Drive Current to LED. CAP (Pin 6): Filter Capacitor. A 4.7uF low ESR 0 should be tied to this pin. LDBAT (Pin 7): Low active, open-drain logic out eating a low-battery condition. L7LJHE/AR
4
LTC3490
3490fa
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U
PI FU CTIO S
CELLS (Pin 1): A logic input to set the low-battery and
undervoltage shutdown thresholds. A logic low (tied to
GND) will set the thresholds for 1 cell. A logic high (tied to
V
IN
) will set the thresholds for 2 cells.
V
IN
(Pin 2): Supply Voltage.
SW (Pin 3): Switch Input. Connect this pin to an external
inductor from V
IN
.
GND (Pin 4): Circuit Ground.
LED (Pin 5): Output Drive Current to LED.
CAP (Pin 6): Filter Capacitor. A 4.7µF low ESR capacitor
should be tied to this pin.
LOBAT (Pin 7): Low active, open-drain logic output indi-
cating a low-battery condition.
CTRL/SHDN (Pin 8): Analog Control Voltage and Shut-
down. When V
IN
• 0.2 < V
CTRL
< V
IN
• 0.9, the LED drive
current varies according to the formula:
IV
VmA
LED CTRL
IN
=⎛
⎝
⎜⎞
⎠
⎟
500 0 2•–.
When V
CTRL
> V
IN
• 0.9, the LED drive current is clamped
at 350mA. When V
CTRL
< V
IN
• 0.2, then the part is in low
power shutdown.
Exposed Pad (Pin 9, DD Package): Ground. This pin must
be soldered to the PCB to provide both electrical contact
to ground and good thermal contact to the PCB.
ILED vs VLED
VLED (V)
2.8
340
ILED (mA)
342
346
348
350
360
354
3 3.2 3.4 3.6 3.8
3490 G04
344
356
358
352
4
VIN = 2.4V
TYPICAL PERFOR A CE CHARACTERISTICS
UW
ILED (mA)
0
0
EFFICIENCY (%)
10
30
40
50
100
70
100 200
3490 G05
20
80
90
60
300 400
VIN = 2.4V
VIN = 1.2V
Efficiency vs ILED
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5
LTC3490
3490fa
FU CTIO AL DIAGRA
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W
–
+
2
3
6
SW
CAP
GATE
CONTROL
AND
DRIVERS
BATTERY
MONITOR
PWM
LOGIC
LIMIT
V
IN
8
CTRL/
SHDN
START-UP
OSCILLATOR
I
REF
SENSE
AMP
OVERVOLTAGE
DETECT
DIMMING
AMP
19.2Ω0.1Ω
250k
40k
V
REF
/2
–
+
–
+
–
+
P BODY
CONTROL
5
LED
LOBAT
3490 FD
1CELLS
GND
SHUTDOWN
7
4
L7LJUEAR
6
LTC3490
3490fa
OPERATIO
U
The LTC3490 is a high efficiency, constant current source
for 1W high intensity white LEDs. These high intensity
LEDs require a fixed current of 350mA with a voltage
compliance of 2.8V to 4V.
The LTC3490 operates with 1 or 2 NiMH or alkaline cells.
It functions as a boost converter with a current sense re-
sistor providing the control feedback. If the battery voltage
is greater than the required LED compliance, it will cycle
off periodically to maintain the correct average current. It
features a low voltage start-up circuit that will start with an
input voltage of only 1V. Once the drive voltage exceeds
2.3V, the circuit operates from the drive voltage.
All of the loop compensation is internal; only the main filter
capacitor is needed for stable operation.
Dimming Function
During normal operation with the CTRL/SHDN pin con-
nected to V
IN
, the LED drive current is controlled at
350mA. The drive current can be reduced by changing the
voltage on the CTRL/SHDN pin.
For V
IN
• 0.2 < V
CTRL
< V
IN
• 0.9, the LED current is
proportional to V
CTRL
/V
IN
. This allows a simple potenti-
ometer from V
IN
to control the current without sensitivity
to the battery voltage. The LED drive current is given by the
formula:
IV
VmA
LED CTRL
IN
=⎛
⎝
⎜⎞
⎠
⎟
500 0 2•–.
When V
CTRL
> V
IN
• 0.9, the LED drive current is clamped
at 350mA.
Open-Circuit Protection
Since this is a boost converter attempting to drive a cur-
rent into the load, an open or high impedance load will cause
the regulator loop to increase the output voltage in an ef-
fort to achieve regulation. To protect the device, maximum
output voltage is limited to 4.7V under all conditions.
Undervoltage Sense and Protection
The undervoltage lockout prevents excessive inductor
peak current and protects the batteries from deep dis-
charging which can damage them. The low-battery indica-
tor allows the end user to be made aware that the batteries
are nearing the end of their useful life.
L7LJCUW
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LTC3490
3490fa
APPLICATIO S I FOR ATIO
WUUU
The LTC3490 requires only four external components to
operate: an inductor, an output capacitor, a switch and a
pull-down resistor. The inductor is nominally set at 3.3µH
and the capacitor at 4.7µF. Optional components include
an input capacitor and dimming resistors.
COMPONENT SELECTION
Inductor Selection
The high frequency operation of the LTC3490 allows the
use of small surface mount inductors. The minimum
inductance value is proportional to the operating fre-
quency and is limited by the following constraints:
LfH
and
LVV V
f Ripple V H
IN MIN OUT MAX IN MIN
OUT MAX
≥
≥
()
3
() ( ) ()
()
•–
••
where:
f = Operating Frequency (Hz)
Ripple = Inductor Current Ripple (A)
V
IN(MIN)
= Minimum Input Voltage (V)
V
OUT(MAX)
= Maximum Output Voltage (V)
The inductor current ripple is typically set to 20% to 40%
of the inductor current.
The peak inductor current is given by:
II
VIRRI
VRI
VV V
LfV
LPK OUT OUT OUT P N IN
IN N IN
IN OUT IN
OUT
=+
()
+
()
•–•
–•
–
•••2
where:
V
IN
= Input Voltage (V)
V
OUT
= Output Voltage (V)
I
OUT
= LED Drive Current (A)
I
IN
= Input Current = V
OUT
/V
IN
• I
OUT
(A)
R
P
= R
DSON
of the PFET Switch (Ω)
R
N
= R
DSON
of the NFET Switch (Ω)
For high efficiency, choose an inductor with a high fre-
quency core material, such as ferrite, to reduce core
losses. The inductor should have low ESR (equivalent
series resistance) to reduce the I
2
R losses and must be
able to handle the peak inductor current at full load without
saturating. In single cell applications, the inductor ESR
must be below 25mΩ to keep the efficiency up and
maintain output current regulation. Dual cell applications
can tolerate significantly higher ESR (up to 75mΩ) with
minimal efficiency degradation. Molded chokes or chip
inductors usually do not have enough core to support the
peak inductor currents in the 1A to 2A region. If radiated
noise is an issue, use a toroid, pot core or shielded bobbin
inductor to minimize radiated noise. See Table 1 for a list
of suggested inductors. Look closely at the manufacturers
data sheets; they specify saturation current differently.
Table 1. Inductor Information
INDUCTOR PART NUMBER ESR (mΩ) SATURATION CURRENT (A)
TOKO A918CY-3R3M 47 1.97
TYCO DN4835-3R3M 58 2.15
TDK SLF7045T-3R3M2R5 20 2.5
Output Capacitor Selection
The output capacitor value and equivalent series resis-
tance (ESR) are the primary factors in the output ripple.
The output ripple is not a direct concern for LED drive as
the LED will operate at the average current value. However
the peak pulsed forward current rating of the LED must not
be exceeded to avoid damaging the LED.
L7LJUEAR
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LTC3490
3490fa
The output ripple voltage has two primary components.
The first is due to the value of the capacitor and is given by:
VR IV
CV f
CAP LPK IN
OUT
=•
••
The second is due to the capacitor ESR:
VR
ESR
= I
LPK
• R
ESR
The LED current ripple and peak pulsed current are calcu-
lated by:
IR VR VR
RR
II
IR
LED CAP ESR
SENSE LED
PPFC OUT LE
=+
=+
•
DD
2
where:
R
SENSE
= Internal Sense Resistor = 0.1Ω
R
LED
= Dynamic Impedance of the LED
Low ESR capacitors should be used to minimize output
ripple. Ceramic X5R or X7R type capacitors are recom-
mended. See Table 2 for a list of component suppliers.
Table 2. Capacitor Information
CAPACITOR PART NUMBER DESCRIPTION
TDK C2012X5R0J475K 4.7µF, 6.3V, X5R in 0805
AVX 1210ZC475MAT 4.7µF, 10V, X7R in 1210
Taiyo Yuden CELMK316BJ475ML 4.7µF, 10V, X7R in 1206
Input Capacitor Selection
Most battery-powered applications do not need an input
capacitor. In supply-powered applications or battery ap-
plications with long leads to the battery, a low ESR 3.3µF
capacitor reduces switching noise and peak currents.
Design Example
The example will use a Lumileds DS25 white LED. The key
specifications are:
V
F
(at I
F
= 350mA) = 3.4 ±0.6V
R
LED
= 1Ω
Peak Pulsed Forward Current = 0.5A
Component values will be calculated for 1 or 2 NiMH cells
and assumes the end-of-charge voltage to be 0.9V per cell.
The operating frequency is assumed to be 1MHz, the
worst-case low frequency. The allowed inductor ripple
current is 0.31A. Table 3 shows a summary of the key
parameters.
Table 3. Summary of Key Parameters
PARAMETER 1-CELL 2-CELL UNITS
L
MIN
2.2 3.2 µH
Choose L 3.3 3.3 µH
I
IN
1.56 0.78 A
I
LPK
1.93 0.96 A
Choose C 4.7 4.7 µF
Cap ESR 5 5 mΩ
VR
CAP
0.09 0.09 V
VR
ESR
0.01 0.005 V
IR
LED
0.10 0.09 A
I
PPFC
0.40 0.39 A
where:
I
LPK
is the peak inductor current
VR
CAP
is the ripple voltage due to the output capacitor
value
VR
ESR
is the ripple voltage due to the output capacitor
ESR
IR
LED
is the LED current ripple
I
PPFC
is the LED peak pulsed forward current
PC Board Layout Checklist
Keep the inductor and output capacitor as close to the IC
as possible. Make traces as short and wide as is feasible.
Parasitic resistance and inductance reduce efficiency and
increase ripple.
Keep resistance in the battery connections as low as
possible. In single cell applications, only 0.1Ω in the
battery connections will have a dramatic effect in effi-
ciency and battery life. I
2
R losses can exceed 100mW and
the converter operates lower on the efficiency curve.
APPLICATIO S I FOR ATIO
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LTC3490
3490fa
TYPICAL APPLICATIO S
U
2-Cell Adjustable Amplitude LED Driver
+
+
SW
CAP
LED
2 NiMH OR
ALKALINE
CELLS 4.7µF
LOBAT
3490 TA03
V
IN
CTRL/SHDN
CELLS
1M
LUMILEDS
LUXEON
LXHL-BW02
GND
LTC3490
3.3µH
ON/OFF
Soft Turn-Off LED Driver
+
SW
CAP
LED
1 NiMH OR
ALKALINE
CELL 4.7µF
LOBAT
3490 TA04
VIN
CTRL/SHDN
CELLS
1M
ON/OFF
1µF
LUMILEDS
LUXEON
LXHL-BW02
GND
LTC3490
3.3µH
350mA
APPLICATIO S I FOR ATIO
WUUU
Red Luxeon LEDs
The red, red-orange and amber Luxeon LEDs have a lower
forward voltage than the white, blue and green LEDs. Since
the LTC3490 internal circuitry is powered from the output,
it requires a minimum LED voltage of 2.5V for reliable
operation. The minimum forward voltage on the red LEDs
is only 2.31V. The LTC3490 requires an additional 190mV
for proper operation. In non-dimming applications, this can
be accomplished with a 0.6Ω resistor in series with the
LED. The resistor voltage drops too low in dimming appli-
cations, so a Schottky diode is recommended to keep
sufficient voltage at the output at lower currents.
\0—1 I |_ I+ .||-. RES‘STOR Vw (V) 1 O L7LJDEAR
10
LTC3490
3490fa
TYPICAL APPLICATIO S
U
Luxeon Red LED Driver Without Dimming
+
SW
CAP
ON/OFF
LED
1 NiMH OR
ALKALINE
CELL 4.7µF
3490 TA06
LOBAT
V
IN
CTRL/SHDN
CELLS
1M LUMILEDS
LUXEON
LXHL-BD03
GND
LTC3490
0.6Ω
3.3µH
Luxeon Red LED Driver with Dimming
+
SW
CAP
ON/OFF
LED
1 NiMH OR
ALKALINE
CELL 4.7µF
MBRM120E
3490 TA07
LOBAT
V
IN
CTRL/SHDN
CELLS
1M
LUMILEDS
LUXEON
LXHL-BD03
GND
LTC3490
3.3µH
VIN (V)
1
EFFICIENCY (%)
50
60
70
RESISTOR
3
3490 G06
40
30
01.5 22.5
20
10
90
80
SCHOTTKY
Efficiency vs VIN with Red LED
11
LTC3490
3490fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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PACKAGE DESCRIPTIO
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
3.00 ±0.10
(4 SIDES)
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
0.38 ± 0.10
BOTTOM VIEW—EXPOSED PAD
1.65 ± 0.10
(2 SIDES)
0.75 ±0.05
R = 0.115
TYP
2.38 ±0.10
(2 SIDES)
14
85
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
0.00 – 0.05
(DD8) DFN 1203
0.25 ± 0.05
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
1.65 ±0.05
(2 SIDES)2.15 ±0.05
0.50
BSC
0.675 ±0.05
3.5 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160
±
.005
RECOMMENDED SOLDER PAD LAYOUT
.045
±
.005
.050 BSC
.030
±
.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
.||-: L7LJUEAR
12
LTC3490
3490fa
© LINEAR TECHNOLOGY CORPORATION 2005
LT 0606 REV A • PRINTED IN THE USA
PART NUMBER DESCRIPTION COMMENTS
LT®1618 Constant Current, Constant Voltage 1.4MHz, V
IN
: 1.6V to 18V, V
OUT(MAX)
= 34V, I
Q
= 1.8mA, I
SD
< 1µA, MS/EDD
High Efficiency Boost Regulator Packages
LT1932 Constant Current, 1.2MHz, High Efficiency White V
IN
: 1V to 10V, V
OUT(MAX)
= 34V, I
Q
= 1.2mA, I
SD
< 1µA, ThinSOT Packages
LED Boost Regulator
LT1937 Constant Current, 1.2MHz, High Efficiency White V
IN
: 2.5V to 10V, V
OUT(MAX)
= 34V, I
Q
= 1.9mA, I
SD
< 1µA, ThinSOTTM/SC70
LED Boost Regulator Packages
LTC3205 High Efficiency, Multi-Display LED Controller V
IN
: 2.8V to 4.5V, V
OUT(MAX)
= 6V, I
Q
= 50µA, I
SD
< 1µA, QFN24 Package
LTC3216 1A Low Noise, High Current LED Charge Pump with V
IN
: 2.9V to 4.4V, V
OUT(MAX)
= 5.5V, I
Q
= 300µA, I
SD
< 2.5µA, DFN Package
Independent Flash/Torch Current Control
LTC3402 2A, 3MHz Micropower Synchronous Boost Converter V
IN
: 0.85V to 5V, V
OUT(MAX)
= 5V, I
Q
= < 38µA, I
SD
< 1µA,
MS/EDD Packages
LTC3453 500mA Synchronous Buck-Boost High Current LED V
IN
: 2.7V to 5.5V, V
OUT(MAX)
= 5.5V, I
Q
= 0.6mA, I
SD
< 6µA, QFN Package
Driver in QFN
LT3465/LT3465A Constant Current, 1.2MHz/2.7MHz, High Efficiency V
IN
: 2.7V to 16V, V
OUT(MAX)
= 34V, I
Q
= 1.9mA, I
SD
< 1µA, ThinSOT Package
White LED Boost Regulator with Integrated Schottky
Diode
LT3466 Dual Constant Current, 2MHz, High Efficiency V
IN
: 2.7V to 24V, V
OUT(MAX)
= 40V, I
Q
= 5mA, I
SD
< 16µA, DFN Package
White LED Boost Regulator with Integrated Schottky
Diode
LT3479 3A, Full-Featured DC/DC Converter with Soft-Start V
IN
: 2.5V to 24V, V
OUT(MAX)
= 40V, I
Q
= 6.5mA, I
SD
< 1µA, DFN/TSSOP
and Inrush Current Protection Packages
ThinSOT is a trademark of Linear Technology Corporation.
RELATED PARTS
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
LED Driver Drops to 20% Amplitude on Low-Battery Detect
+
SW
CAP
LED
1 NiMH OR
ALKALINE
CELL 4.7µF
LOBAT
3490 TA05
V
IN
CTRL/SHDN
CELLS
1M
LUMILEDS
LUXEON
LXHL-BWO2
GND
LTC3490
432k
1M
ON/OFF
3.3µH
350mA/70mA
TYPICAL APPLICATIO
U