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LT1070/LT1071
5A and 2.5A High Efficiency
Switching Regulators
■
Wide Input Voltage Range: 3V to 60V
■
Low Quiescent Current: 6mA
■
Internal 5A Switch (2.5A for LT1071)
■
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
■
Comes in Standard 5-Pin Packages
■
Can be Externally Synchronized (Consult Factory)
FEATURES
The LT
®
1070/LT1071 are monolithic high power switch-
ing regulators. They can be operated in all standard switch-
ing configurations including buck, boost, flyback, for-
ward, 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 func-
tions allows the LT1070/LT1071 to be built in a standard
5-pin TO-3 or T0-220 power package. This makes it ex-
tremely easy to use and provides “bust proof” operation
similar to that obtained with 3-pin linear regulators.
The LT1070/LT1071 operate with supply voltages from 3V
to 60V, and draw only 6mA quiescent current. They can
deliver load power up to 100W with no external power
devices. By utilizing current mode switching techniques,
they provide excellent AC and DC load and line regulation.
The LT1070/LT1071 have many unique features not found
even on the vastly more difficult to use low power control
chips presently available. They use adaptive antisat 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 LT1070/LT1071, without the need for
optocouplers or extra transformer windings.
DESCRIPTION
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USER NOTE:
This data sheet is only intended to provide specifications, graphs and a general functional
description of the LT1070/LT1071. Application circuits are included to show the capability of the
LT1070/LT1071. A complete design manual (AN19) 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 LT1071 by factoring in the lower switch current
rating. A second Application Note, AN25, which details off-line applications is available.
TYPICAL APPLICATION
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+
R1
10.7k
1%
R2
1.24k
1%
1070/71 TA01
12V
1A
R3
1k
C1
1µF
C2
1000µF
+
C3*
100µF
L1**
150µH
D1
5V
V
SW
V
C
V
IN
LT1070
GND
FB
C3
100µF
L2
10µH
OUTPUT
FILTER
*
**
REQUIRED IF INPUT LEADS ≥ 2"
PULSE ENGINEERING 92113
INPUT VOLTAGE (V)
0
POWER (W)**
60
80
100
40
1070/71 TA02
40
20
0
10
20
30
50
BOOST
BUCK/BOOST
V
O
= 30V
FLYBACK
ISOLATED
BUCK/BOOST
V
O
= 5V
ROUGH GUIDE ONLY. BUCK MODE P
OUT
= 5A • V
OUT
.
SPECIAL TOPOLOGIES DELIVER MORE POWER
DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071
*
**
Maximum Output Power*
Boost Converter (5V to 12V)
APPLICATIONS
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■
Logic Supply 5V at 10A
■
5V Logic to ±15V Op Amp Supply
■
Off-Line Converter Up to 200W
■
Battery Upconverter
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Power Inverter (+ to –) or (– to +)
■
Fully Floating Multiple Outputs
■
For Lower Current Applications, See the LT1072
, LTC and LT are registered trademarks of Linear Technology Corporation.
