LTC1872
1
1872fa
For more information
www.linear.com/LTC1872
Typical applicaTion
FeaTures
DescripTion
Constant Frequency
Current Mode Step-Up
DC/DC Controller in SOT-23
The
LTC
®
1872
is a constant frequency current mode step-
up DC/DC controller providing excellent AC and DC load
and line regulation. The device incorporates an accurate
undervoltage lockout feature that shuts down the LTC1872
when the input voltage falls below 2.0V.
The LTC1872 boasts a ±2.5% output voltage accuracy
and consumes only 270µA of quiescent current. For ap-
plications where efficiency is a prime consideration, the
LTC1872 is configured for Burst Mode operation, which
enhances efficiency at low output current.
In shutdown, the device draws a mere 8µA. The high
550kHz constant operating frequency allows the use of a
small external inductor.
The LTC1872 is available in a small footprint 6-lead
SOT-23.
applicaTions
n
High Efficiency: Over 90%
n
High Output Currents Easily Achieved
n
Wide V
IN
Range: 2.5V to 9.8V
n
V
OUT
Limited Only by External Components
n
Constant Frequency 550kHz Operation
n
Burst Mode™ Operation at Light Load
n
Current Mode Operation for Excellent Line and Load
Transient Response
n
Low Quiescent Current: 270µA
n
Shutdown Mode Draws Only 8µA Supply Current
n
±2.5% Reference Accuracy
n
Tiny 6-Lead SOT-23 Package
n
Lithium-Ion-Powered Applications
n
Cellular Telephones
n
Wireless Modems
n
Portable Computers
n
Scanners
L
, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Figure 1. LTC1872 High Output Current 3.3V to 5V Boost Converter
Efficiency vs Load Current
I
TH
/RUN
LTC1872
147k
422k
80.6k
R1
0.03Ω
L1
4.7µH
220pF
C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT
C2: MURATA GRM42-2X5R226K6.3
D1: IR10BQ015
L1: MURATA LQN6C4R7M04
M1: IRLMS2002
R1: DALE 0.25W
GND
V
FB
5
4
6
1872 TA01
1
2
3
NGATE
V
IN
SENSE
–
C1
10µF
10V
V
IN
3.3V
V
OUT
5V
1A
C2
2
×
22F
6.3V
+
M1 D1
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
95
90
85
80
75
70
65
10
100
1000
1872 TA01b
V
IN
= 3.3V
V
OUT
= 5V
