LT1946A_15 Datasheet, PDF (1/12 Pages) Linear Technology – 2.7MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start

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
V_IN
L1
2.2µH
D1
5V
6
5
V_IN
SW
3
R1
182k
OFF ON
SHDN
C1
2
LT1946A FB
2.2µF
1
V_C
7
COMP
R_C
27.4k
SS
GND*
R2
C_C
C_SS ⁸
4
21k
270pF
100nF
V_OUT
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