LT1949-1_15 Datasheet, PDF (1/8 Pages) Linear Technology – 1.1MHz, 1A Switch PWM DC/DC Converter

FEATURES
s _{1A, 0.5Ω, 30V Internal Switch}
s _{1.1MHz Fixed Frequency Operation}
s _{Operates with VIN as Low as 1.5V}
s _{Low-Battery Detector Stays Active in Shutdown}
s _{Low VCESAT Switch: 410mV at 800mA}
s _{Pin-for-Pin Compatible with the LT1317B}
s _{Uses Ceramic Capacitors}
s _{Small 8-Lead MSOP Package}
U
APPLICATIO S
s _{LCD Bias Supplies}
s _{GPS Receivers}
s _{Battery Backup}
s _{Portable Electronic Equipment}
s _{Diagnostic Medical Instrumentation}
Final Electrical Specifications
LT1949-1
1.1MHz, 1A Switch
PWM DC/DC Converter
June 2000
DESCRIPTIO
The LT^®1949-1 is a fixed frequency step-up DC/DC con-
verter with a 1A, 0.5Ω internal switch. Capable of gener-
ating 10V at 175mA from a 3.3V input, the LT1949-1 is
ideal for generating bias voltages for large screen LCD
panels. Constant frequency 1.1MHz operation results in a
low noise output that is easy to filter and the 30V switch
rating allows output voltage up to 28V using a single
inductor. The high switching frequency allows the use of
ceramic output capacitors. An external compensation pin
gives the user flexibility in optimizing loop compensation,
allowing small, low ESR ceramic capacitors to be used at
the output. The 8-lead MSOP package ensures a low
profile overall solution.
The LT1949-1 includes a low-battery detector that stays
alive when the device goes into shutdown. Quiescent
current in shutdown is 50µA, while operating current is
8mA.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
3.3V
C1
3.3µF
CERAMIC
L1
4.7µH
V_IN
SW
LT1949-1
SHUTDOWN SHDN
FB
V_C
GND
84.5k
50pF
C1, C2: TAIYO YUDEN LMK325BJ335MD
D1: MBRM120LT3
L1: SUMIDA CLQ4D10-4R7
D1
R1
196k
1%
3pF
V_OUT
10V
175mA
R2
28k
1%
C2
3.3µF
CERAMIC
1949-1 F01
Figure 1. 3.3V to 10V/175mA DC/DC Converter
90
V_OUT = 10V
80
70
3.6V_{IN 4.2VIN} 3V_IN
60
50
40
30
20
5
10
50 100
LOAD CURRENT (mA)
300
1949-1 F02
Figure 2. 3.3V to 10V Converter Efficiency
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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