LTC1872 Datasheet, PDF (1/12 Pages) Linear Technology – Constant Frequency Current Mode Step-Up DC/DC Controller in SOT-23

LTC1872
Constant Frequency
Current Mode Step-Up
DC/DC Controller in SOT-23
FEATURES
s _{High Efficiency: Over 90%}
s _{High Output Currents Easily Achieved}
s _{Wide VIN Range: 2.5V to 9.8V}
s _{VOUT Limited Only by External Components}
s _{Constant Frequency 550kHz Operation}
s _{Burst Mode}^TM _{Operation at Light Load}
s _{Current Mode Operation for Excellent Line and Load}
Transient Response
s _{Low Quiescent Current: 270µA}
s _{Shutdown Mode Draws Only 8µA Supply Current}
s _{±2.5% Reference Accuracy}
s _{Tiny 6-Lead SOT-23 Package}
U
APPLICATIO S
s _{Lithium-Ion-Powered Applications}
s _{Cellular Telephones}
s _{Wireless Modems}
s _{Portable Computers}
s _Scanners
DESCRIPTIO
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 applica-
tions 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
147k
220pF
80.6k
1
I_TH/RUN
5
V_IN
LTC1872
2
GND
SENSE^{– 4}
3
V_FB
6
NGATE
422k
R1
0.03Ω
L1
4.7µH
C1
10µF
10V
+ C2
M1 ^D1
2× 22µF
6.3V
V_IN
3.3V
V_OUT
5V
1A
C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT
C2: MURATA GRM42-2X5R226K6.3
D1: IR10BQ015
L1: MURATA LQN6C4R7M04
M1: IRLMS2002
R1: DALE 0.25W
1872 TA01
Figure 1. LTC1872 High Output Current 3.3V to 5V Boost Converter
Efficiency vs Load Current
100
V_IN = 3.3V
95 ^{VOUT = 5V}
90
85
80
75
70
65
1
10
100
LOAD CURRENT (mA)
1000
1872 TA01b
1