LT1961_15 Datasheet, PDF (1/16 Pages) Linear Technology – 1.5A, 1.25MHz Step-Up Switching Regulator

LT1961
1.5A, 1.25MHz Step-Up
Switching Regulator
FEATURES
■ _{1.5A Switch in a Small MSOP Package}
■ _{Constant 1.25MHz Switching Frequency}
■ _{Wide Operating Voltage Range: 3V to 25V}
■ _{High Efficiency 0.2Ω Switch}
■ _{1.2V Feedback Reference Voltage}
■ _{±2% Overall Output Voltage Tolerance}
■ _{Uses Low Profile Surface Mount External}
Components
■ _{Low Shutdown Current: 6μA}
■ _{Synchronizable from 1.5MHz to 2MHz}
■ _{Current-Mode Loop Control}
■ _{Constant Maximum Switch Current Rating at All Duty}
Cycles*
■ _{Thermally Enhanced Exposed Pad 8-Lead Plastic}
MSOP Package
U
APPLICATIO S
■ _{DSL Modems}
■ _{Portable Computers}
■ _{Battery-Powered Systems}
■ _{Distributed Power}
DESCRIPTIO
The LT^®1961 is a 1.25MHz monolithic boost switching
regulator. A high efficiency 1.5A, 0.2Ω switch is included
on the die together with all the control circuitry required to
complete a high frequency, current-mode switching regu-
lator. Current-mode control provides fast transient re-
sponse and excellent loop stability.
New design techniques achieve high efficiency at high
switching frequencies over a wide operating voltage range.
A low dropout internal regulator maintains consistent
performance over a wide range of inputs from 24V sys-
tems to Li-Ion batteries. An operating supply current of
1mA maintains high efficiency, especially at lower output
currents. Shutdown reduces quiescent current to 6μA.
Maximum switch current remains constant at all duty
cycles. Synchronization allows an external logic level
signal to increase the internal oscillator from 1.5MHz to
2MHz.
The LT1961 is available in an exposed pad, 8-pin MSOP
package. Full cycle-by-cycle switch current limit protec-
tion and thermal shutdown are provided. High frequency
operation allows the reduction of input and output filtering
components and permits the use of chip inductors.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. *Patent Pending
TYPICAL APPLICATIO
5V to 12V Boost Converter
6.8μH
V_IN
5V
2.2μF
CERAMIC
1
V_IN
2
V_SW
OPEN
OR
HIGH
= ON
5 _SHDN
SYNC
8
LT1961
GND ^VC
3,4 7
FB ⁶
6800pF
6.8k
UPS120
100pF
90.9k
10k
1%
*MAXIMUM OUTPUT CURRENT IS SUBJECT TO THERMAL DERATING.
V_OUT
12V
0.5A*
10μF
CERAMIC
1961 TA01
Efficiency vs Load Current
90
85
80
75
70
65
60
0
V_IN = 5V
V_OUT = 12V
100 200 300 400 500
LOAD CURRENT (mA)
1961 TA01a
1961fa
1