LT1949 Datasheet, PDF (1/8 Pages) Linear Technology – 600kHz, 1A Switch PWM DC/DC Converter

FEATURES
s _{1A, 0.5Ω, 30V Internal Switch}
s _{Operates with VIN as Low as 1.5V}
s _{600kHz Fixed Frequency Operation}
s _{Low-Battery Detector Stays Active in Shutdown}
s _{Low VCESAT Switch: 410mV at 800mA}
s _{Pin-for-Pin Compatible with the LT1317B}
s _{Small 8-Lead MSOP and SO Packages}
U
APPLICATIO S
s _{LCD Bias Supplies}
s _{GPS Receivers}
s _{Battery Backup}
s _{Portable Electronic Equipment}
s _{Diagnostic Medical Instrumentation}
LT1949
600kHz, 1A Switch
PWM DC/DC Converter
DESCRIPTIO
The LT^®1949 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 is ideal
for generating bias voltages for large screen LCD panels.
Constant frequency 600kHz 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. 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 and SO packages ensure a low profile overall
solution.
The LT1949 includes a low-battery detector that stays
alive when the device goes into shutdown. Quiescent
current in shutdown is 25µA, while operating current is
4.5mA.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
3.3V
+
C1
22µF
SHUTDOWN
L1
10µH
V_IN
SW
LT1949
SHDN
FB
V_C
GND
68k
330pF
D1
R1
1M
R2
140k
V_OUT
10V
175mA
C2
10µF
CERAMIC
C1: AVX TAJA226M006R
C2: TAIYO YUDEN LMK325BJ106MN
D1: MBRM120LT3
L1: SUMIDA CDRH62B-100
1949 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 F02
Figure 2. 3.3V to 10V Converter Efficiency
1