LTC3872-1_15 Datasheet, PDF (1/20 Pages) Linear Technology – No RSENSE Current Mode Boost DC/DC Controller

LTC3872-1
No R_SENSE
Current Mode Boost
DC/DC Controller
Features
n _{No Current Sense Resistor Required}
n _{VOUT up to 60V}
n _{Constant Frequency 550kHz Operation}
n _{Internal Soft-Start and Optional External Soft-Start}
n _{Adjustable Current Limit}
n _{Pulse Skipping at Light Load}
n _{VIN Range: 2.75V to 9.8V}
n _{±1.5% Voltage Reference Accuracy}
n _{Current Mode Operation for Excellent Line and Load}
Transient Response
n _{Low Profile (1mm) SOT-23 and 2mm × 3mm DFN}
Packages
Applications
n _{Telecom Power Supplies}
n _{42V Automotive Systems}
n _{24V Industrial Controls}
n _{IP Phone Power Supplies}
Description
The LTC^®3872-1 is a constant frequency current mode
boost DC/DC controller that drives an N-channel power
MOSFET and requires very few external components. The
No R_SENSE^TM architecture eliminates the need for a sense
resistor, improves efficiency and saves board space.
The LTC3872-1 provides excellent AC and DC load and
line regulation with ±1.5% output voltage accuracy. It
incorporates an undervoltage lockout feature that shuts
down the device when the input voltage falls below 2.3V.
LTC3872-1 has the same functionality as the standard
LTC3872 except that it has no frequency foldback in cur-
rent limit.
High switching frequency of 550kHz allows the use of a
small inductor. The LTC3872-1 is available in an 8-lead
low profile (1mm) ThinSOT^TM package and 8-pin 2mm ×
3mm DFN package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No R_SENSE and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
Typical Application
High Efficiency 3.3V Input, 5V Output Boost Converter
1.8nF _17.4k
I_TH
V_IN
47pF V_IN
IPRG
LTC3872-1
GND
SW
V_FB RUN/SS NGATE
11k
1%
1nF
34.8k
1%
1µH
D1
M1 _100µF
×2
V_IN
3.3V
10µF
V_OUT
5V
2A
38721 TA01
Efficiency and Power Loss vs Load Current
100
90
80
70
60
50
40
30
20
10
0
1
10
1
0.1
0.01
10
100
1000
LOAD CURRENT (mA)
0.001
10000
38721 TA01b
For more information www.linear.com/LTC3872-1
38721f
1