LT1070/LT1071
5A and 2.5A High Efficiency
Switching Regulators
DESCRIPTIO
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FEATURES
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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 TO-220 Package
Can be Externally Synchronized (Consult Factory)
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APPLICATIO S
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Logic Supply 5V at 10A
5V Logic to ±15V Op Amp Supply
Off-Line Converter Up to 200W
Battery Upconverter
Power Inverter (+ to –) or (– to +)
Fully Floating Multiple Outputs
For Lower Current Applications, See the LT1072
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.
The LT ®1070/LT1071 are monolithic high power switching regulators. They 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 LT1070/LT1071 to be built in a standard
5-pin T0-220 power package. This makes it extremely
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
Maximum Output Power*
Boost Converter (5V to 12V)
100
L2
10µH
80
L1**
150µH
OUTPUT
FILTER
C3
100µF
D1
VIN
C3*
100µF
+
+
LT1070
GND
VC
12V
1A
VSW
C2
1000µF
R1
10.7k
1%
POWER (W)**
BOOST
5V
BUCK/BOOST
VO = 30V
60
FLYBACK
40
ISOLATED
20
BUCK/BOOST
VO = 5V
FB
R3
1k
C1
1µF
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
R2
1.24k
1%
0
0
10
30
20
INPUT VOLTAGE (V)
40
50
1070/71 TA02
1070/71 TA01
*ROUGH GUIDE ONLY. BUCK MODE POUT = 5A • VOUT.
SPECIAL TOPOLOGIES DELIVER MORE POWER
**DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071
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