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PDF LM3842 Data sheet ( Hoja de datos )
| Número de pieza | LM3842 | |
| Descripción | step-down constant current LED driver | |
| Fabricantes | ETC | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LM3842 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
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LM3842
Features
n Efficiency up to 93%
n 180 μA(TYP.) Quiescent Current
n Output Current: Up to 1A
n Internal Synchronous Rectifier
n 1.5MHz Switching Frequency
n Soft Start
n Under-Voltage Lockout
n Short LED Protection
n Open LED Protection
n Thermal Shutdown
n 5-pin Small SOT23-5 Packages
n Pb-Free Package
Applications
n 3AA or 4AA Batteries Powered Flashlight
n 1 Cell Li-Ion Battery Powered Flashlight
General Description
The LM3842 is a step-down constant current
LED driver. When the input voltage down to lower
than LED forward voltage, then LM3842 run into
LDO mode.
The LM3842 supports a range of input voltages
from 2.5V to 6.0V, allowing the use of a single
Li+/Li-polymer cell, 3AA or 4AA cell, USB, and
other standard power sources.
The FB voltage is only 0.1V to achieve high
efficiency.
LM3842 employ
internal power switch and
synchronous rectifier to minimize external part
count and realize high efficiency.
During shutdown, the input is disconnected from
the output and the shutdown current is less than
1μA. Other key features include under-voltage
lockout to prevent deep battery discharge of the
Li+ battery.
.
Typical Application
http://www.DataSheet4U.net/
1 Cell Li-Ion Battery
3AA or 4AA Batteries
VIN
C IN
10µF
VIN SW
GND
FB
EN
L
4.7µH
1~5W
WLED
Co
10µF
Rs
ILED =0.1/Rs
1
10/2010
datasheet pdf - http://www.DataSheet4U.net/
1 page  
LM3842
Typical Performance Characteristics
TA =25°C, CIN =10μF, CO =10μF, L=4.7μH, unless otherwise noted.
Eifficiency VS Input Voltage
96%
94%
92%
90%
88%
86%
84%
82%
3
330m A
750m A
1A
3.5 4 4. 5 5
Input Volt age (V)
5 .5
Output Current VS Input Voltage
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1 Rcs=0.135ohm
0
3 3.5 4
4.5
5
Input Voltage (V)
Rdson VS Input Voltage
0.4
5.5
0.35
0.3
0.25
0.2
0.15
0.1
2
34 5
Input Voltage
Output Current VS Input Voltage
350
300
250
200
150
100
50
0 Rcs=0.3ohm
2.5 3 3.5 4 4.5 5 5.5 6
6 Vin(V)
Output Current VS Input Voltage
1200
1000
http://www.DataSheet4U.net/
800
600
400
200
0 Rcs=0.1ohm
2.5 3 3.5 4 4.5 5 5.5 6
6 Vin(V)
0.6 Rdson VS Temperature
0.5 Vin=3.6V
0.4
0.3
0.2
0.1 Vin=4.2V
Vin =3.6V
Vin =2.7V
0
6
20
70
Temper ature(℃)
120
5
10/2010
datasheet pdf - http://www.DataSheet4U.net/
5 Page 
Outline Dimensions
SOT23-5
D
e1
LM3842
L REF.
θ
L1 (REF.)
eb
RE F.
A
A1
A2
c
D
E
E1
L
L1
θ
b
e
e1
Millimeter
http://www.DataSheet4U.net/
Min
Max
1.10 MAX
0 0.10
0.70
1
0.12 REF.
2.70
3.10
2.60
3.00
1.40
1.80
0.45 REF.
0.60 REF.
0º 10º
0.30
0.50
0.95 REF.
1.90 REF.
11
10/2010
datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet LM3842.PDF ] | |
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