LT1946A Ver la hoja de datos (PDF) - Linear Technology
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LT1946A Datasheet PDF : 12 Pages
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LT1946A
2.7MHz Boost DC/DC
Converter with 1.5A Switch
and Soft-Start
FEATURES
s 1.5A, 36V Internal Switch
s 2.7MHz Switching Frequency
s Integrated Soft-Start Function
s Adjustable Output from VIN to 35V
s Low VCESAT Switch: 300mV at 1.5A (Typical)
s 12V at 430mA from a 5V Input
s Small Thermally Enhanced 8-Lead MSOP Package
U
APPLICATIO S
s TFT-LCD Bias Supplies
s GPS Receivers
s DSL Modems
s Local Power Supply
DESCRIPTIO
The LT®1946A is a fixed frequency step-up DC/DC con-
verter containing an internal 1.5A, 36V switch. Capable of
generating 12V at 430mA from a 5V input, the LT1946A is
ideal for powering large TFT-LCD panels. The LT1946A
switches at 2.7MHz, allowing the use of tiny, low profile
inductors and low value ceramic capacitors. Loop com-
pensation can be either internal or external, giving the user
flexibility in setting loop compensation and allowing opti-
mized transient response with low ESR ceramic output
capacitors. Soft-start is controlled with an external capaci-
tor which determines the input current ramp rate during
start up. The 8-lead MSOP package and high switching
frequency ensure a low profile overall solution less than
1.1mm high.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
VIN
L1
2.2µH
D1
5V
6
5
VIN
SW
3
R1
182k
OFF ON
SHDN
C1
2
LT1946A FB
2.2µF
1
VC
7
COMP
RC
27.4k
SS
GND*
R2
CC
CSS 8
4
21k
270pF
100nF
VOUT
12V
430mA
C2
2.2µF
C1: 2.2µF, X5R or X7R, 6.3V
C2: 2.2µF, X5R or X7R, 16V
D1: MICROSEMI UPS120 OR EQUIVALENT
L1: SUMIDA CR43-2R2
* EXPOSED PAD MUST ALSO BE GROUNDED
1946A TA01
Figure 1. 5V to 12V, 430mA Step-Up DC/DC Converter
Efficiency
90
85
80
75
70
65
60
55
50
0
100 200 300 400 500
LOAD CURRENT (mA)
1946A TA01
sn1946a 1946afs
1
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