LT1072
1.25A High Efficiency
Switching Regulator
FEATURES
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DESCRIPTIO
Available in MiniDiP, TO-220, and TO-3 Packages
Wide Input Voltage Range 3V to 60V
Low Quiescent Current—6mA
Internal 1.25A Switch
Very Few External Parts Required
Self-Protected Against Overloads
Operates in Nearly All Switching Topologies
Shutdown Mode Draws Only 50µA Supply Current
Flyback-Regulated Mode has Fully Floating Outputs
Can be Externally Synchronized
The LT
®
1072 is a monolithic high power switching
regulator. It can be operated in all standard switching
configurations including buck, boost, flyback, forward,
inverting and “Cuk”. A high current, high efficiency switch
is included on the die along with all oscillator, control, and
protection circuitry. Integration of all functions allows the
LT1072 to be built in a standard 5-pin TO-3 or TO-220
power package as well as the 8-pin miniDlP. This makes it
extremely easy to use and provides “bust proof” operation
similar to that obtained with 3-pin linear regulators.
The LT1072 operates with supply voltages from 3V to 60V,
and draws only 6mA quiescent current. It can deliver load
power up to 20 watts with no external power devices. By
utilizing current-mode switching techniques, it provides
excellent AC and DC load and line regulation.
The LT1072 has many unique features not found even on
the vastly more difficult to use low power control chips
presently available. It uses an adaptive anti-sat switch
drive to allow very wide ranging load currents with no loss
in efficiency. An externally activated shutdown mode
reduces total supply current to 50µA typical for standby
operation. Totally isolated and regulated outputs can be
generated by using the optional “flyback regulation mode”
built into the LT1072, without the need for optocouplers or
extra transformer windings.
APPLICATIO S
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Logic Supply 5V at 2.5A
5V Logic to
±15V
Op Amp Supply
Offline Converter up to 50W
Battery Upconverter
Power lnverter (+ to –) or (– to +)
Fully Floating Multiple Outputs
Driver for High Current Supplies
USER NOTE:
This data sheet is only intended to provide specifications, graphs, and a general functional
description of the LT1072. Application circuits are included to show the capability of the LT1072.
A complete design manual (AN-19) should be obtained to assist in developing new designs. This
manual contains a comprehensive discussion of both the LT1070 and the external components used
with it, as well as complete formulas for calculating the values of these components. The manual
can also be used for the LT1072 by factoring in the lower switch current rating.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
5V
220µH**
Boost Converter (5V to 12V)
25
Maximum Output Power*
V
IN
V
SW
POWER (W)
20
BUCK-BOOST
V
O
= 30V
BOOST
10
FLYBACK
ISOLATED
C3
25µF*
+
–
LT1072
10.7k
GND
V
C
1k
FB
12V, 0.25A
15
+
1µF
–
*REQUIRED IF INPUT LEADS
≥
2”
**PULSE ENGINEERING 52626
1.24k
+
470µF
–
5
BUCK-BOOST
V
O
= 5V
0
0
10
30
20
INPUT VOLTAGE (V)
40
50
LT1072 • TA01
*ROUGH GUIDE ONLY. BUCK MODE P
OUT
= 1A x V
OUT
.
MINIDIP OUTPUT POWER MAY BE LIMITED BY PACKAGE TEMPERATURE
RISE AT HIGH INPUT VOLTAGES OR HIGH DUTY CYCLES
LT1072 • TA02
U
1072fc
U
U
1
LINER [ LINEAR TECHNOLOGY ]
