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PDF LTC3490 Data sheet ( Hoja de datos )
| Número de pieza | LTC3490 | |
| Descripción | Single Cell 350mA LED Driver | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC3490
Single Cell 350mA
LED Driver
FEATURES
■ 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
■ VIN 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
U
APPLICATIO S
■ Portable Lighting
■ Rechargeable Flashlights
DESCRIPTIO
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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
Single Cell Minimum Component LED Driver
3.3µH
1 NiMH OR +
ALKALINE
CELL
VIN SW
ON/OFF
CAP
LTC3490
350mA
CTRL/SHDN LED
CELLS LOBAT
1M
GND
4.7µF
HIGH
CURRENT
LED
3490 TA01
Efficiency vs VIN at VLED = 3.5V
100
IOUT = 350mA
90
80
70
60
50
40
30
20
10
0
1 1.5
2
VIN (V)
2.5 3
3490 TA02
3490fa
1
1 page  
W
FU CTIO AL DIAGRA
2 VIN
–
+
3
SW
P BODY
CONTROL
LTC3490
CAP
6
CTRL/
SHDN
8
CELLS
1
GATE
CONTROL
AND
DRIVERS
LIMIT
SENSE
AMP
+
19.2Ω 0.1Ω
PWM
LOGIC
START-UP
–
DIMMING
AMP
+
–
OVERVOLTAGE
DETECT
OSCILLATOR
VREF/2
LED
5
250k
40k
IREF
LOBAT
7
BATTERY
MONITOR
SHUTDOWN
GND
4
3490 FD
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5
5 Page 
LTC3490
PACKAGE DESCRIPTIO
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698)
0.675 ±0.05
R = 0.115
TYP
5
0.38 ± 0.10
8
3.5 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
3.00 ±0.10
(4 SIDES)
1.65 ± 0.10
(2 SIDES)
0.75 ±0.05
0.00 – 0.05
4
0.25 ± 0.05
(DD8) DFN 1203
1
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
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
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.050 BSC
.045 ±.005
.189 – .197
(4.801 – 5.004)
NOTE 3
8 765
.245
MIN .160 ±.005
.228 – .244
(5.791 – 6.197)
.150 – .157
(3.810 – 3.988)
NOTE 3
.030 ±.005
TYP
RECOMMENDED SOLDER PAD LAYOUT
.010
(0.254
–
–
.020
0.508)
×
45°
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
1
.053 – .069
(1.346 – 1.752)
2
.016 – .050
(0.406 – 1.270)
NOTE:
1. DIMENSIONS
IN
INCHES
(MILLIMETERS)
.014 – .019
(0.355 – 0.483)
TYP
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)
34
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 0303
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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11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC3490.PDF ] | |
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