LT1612_1 Datasheet, PDF (1/12 Pages) Linear Technology – Synchronous, Step-Down 800kHz PWM DC/DC Converter

LT1612
Synchronous, Step-Down
800kHz PWM
DC/DC Converter
FEATURES
s _{Operates from Input Voltage As Low As 2V}
s _{Internal 0.7A Synchronous Switches}
s _{Uses Ceramic Input and Output Capacitors}
s _{620mV Reference Voltage}
s _{800kHz Fixed Frequency Switching}
s _{Programmable Burst Mode Operation}
s _{Low Quiescent Current: 160µA}
s _{8-Lead MSOP or SO Package}
U
APPLICATIO S
s _{Portable Devices}
s _{Lithium-Ion Step-Down Converters}
s _{5V to 3.3V Conversion}
s _{2-Cell Alkaline Step-Down Converters}
DESCRIPTIO
The LT^®1612 is an 800kHz, synchronous step-down DC/
DC converter that operates from an input voltage as low
as 2V. Internal 0.45Ω switches deliver output currents up
to 500mA, and the 800kHz switching frequency allows the
use of small, low value ceramic input and output capaci-
tors. Input voltage ranges from 5.5V down to 2V and
output voltage can be set as low as the 620mV reference.
The device features Burst Mode^TM operation, keeping
efficiency high at light loads. Burst Mode operation can be
defeated by pulling the MODE pin high, enabling constant
switching throughout the load range for low noise.
No-load quiescent current is 160µA and shutdown current
is less than 1µA. The device is available in 8-lead SO and
MSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
V_IN
2V
C1
10µF
0.1µF
V_IN BOOST
SHDN
SW
LT1612
MODE
FB
V_C
GND
33.2k
R2
232k
330pF
1%
L1
10µH
100pF
R1
215k
1%
V_OUT
1.2V
500mA
C2
68µF
3.15V
C1: TAIYO-YUDEN JMK325BJ106MN
C2: PANASONIC EEFCDOF680R
L1: SUMIDA CD43-100
Figure 1. 2V to 1.2V Converter
1612 F01a
Efficiency for LT1612 vs Linear Regulator
V_OUT = 1.2V
90
80
V_IN = 2V
70
V_IN = 3V
60
V_IN = 2V (LINEAR)
50
40
30
10
V_IN = 3V (LINEAR)
100
LOAD CURRENT (mA)
500
1612 • F01b
sn1612 1612fs
1