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LT1071CT

Part # LT1071CT
Description IC REG MULT CONFIG INV ADJ TO220
Category IC
Availability In Stock
Qty 2
Qty Price
1 + $2.55601
Manufacturer Available Qty
Linear Technology
Date Code: 8815
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Technical Document


DISCLAIMER: The information provided herein is solely for informational purposes. Customers must be aware of the suitability of this product for their application, and consider that variable factors such as Manufacturer, Product Category, Date Codes, Pictures and Descriptions may differ from available inventory.

1
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
U
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
U
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
, LTC and LT are registered trademarks of Linear Technology Corporation.
2
LT1070/LT1071
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
Reference Voltage Measured at Feedback Pin, V
C
= 0.8V 1.224 1.244 1.264 V
1.214 1.244 1.274 V
I
B
Feedback Input Current V
FB
= V
REF
350 750 nA
1100 nA
g
m
Error Amplifier Transconductance I
C
= ±25µA 3000 4400 6000 µmho
2400 7000 µmho
Error Amplifier Source or Sink Current V
C
= 1.5V 150 200 350 µA
120 400 µA
Error Amplifier Clamp Voltage Hi Clamp, V
FB
= 1V 1.80 2.30 V
Lo Clamp, V
FB
= 1.5V 0.25 0.38 0.52 V
Reference Voltage Line Regulation 3V V
IN
V
MAX
, V
C
= 0.8V 0.03 %/V
A
V
Error Amplifier Voltage Gain 0.9V V
C
1.4V 500 800 V/V
Minimum Input Voltage 2.6 3.0 V
I
Q
Supply Current 3V V
IN
V
MAX
, V
C
= 0.6V 6 9 mA
Control Pin Threshold Duty Cycle = 0 0.8 0.9 1.08 V
0.6 1.25 V
Normal/Flyback Threshold on Feedback Pin 0.4 0.45 0.54 V
ABSOLUTE MAXIMUM RATINGS
W
WW
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Supply Voltage
LT1070/LT1071 (Note 2) .................................... 40V
LT1070HV/LT1071HV (Note 2)........................... 60V
Switch Output Voltage
LT1070/LT1071 .................................................. 65V
LT1070HV/LT1071HV......................................... 75V
Feedback Pin Voltage (Transient, 1ms) ................ ±15V
Operating Junction Temperature Range
Commercial (Operating) ....................... 0°C to 100°C
Commercial (Short Circuit)................... 0°C to 125°C
Industrial ......................................... 40°C to 125°C
Military ............................................ 55°C to 150°C
Storage Temperature Range ................ 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
PACKAGE/ORDER INFORMATION
W
U
U
ORDER PART
NUMBER
LT1070CK
LT1070HVCK
LT1070HVMK
LT1070IK
LT1070MK
LT1071CK
LT1071HVCK
LT1071HVMK
LT1071MK
ORDER PART
NUMBER
LT1070CT
LT1070HVCT
LT1070HVIT
LT1070IT
LT1071CT
LT1071HVCT
LT1071HVIT
LT1071IT
T
JMAX
= 100°C, θ
JA
= 35°C/ W, Q
JC
= 2°C (LT1070C, I)
T
JMAX
= 150°C, θ
JA
= 35°C/ W, Q
JC
= 2°C (LT1070M)
T
JMAX
= 100°C, θ
JA
= 35°C/ W, Q
JC
= 4°C (LT1071C, I)
T
JMAX
= 150°C, θ
JA
= 35°C/ W, Q
JC
= 4°C (LT1071M)
2
4
1
3
V
SW
V
C
FB
CASE 
IS GND
V
IN
K PACKAGE
4-LEAD TO-3 METAL CAN
BOTTOM VIEW
T
JMAX
= 100°C, θ
JA
= 75°C/ W, Q
JC
= 2°C (LT1070C, I)
T
JMAX
= 100°C, θ
JA
= 75°C/W, Q
JC
= 4°C (LT1071C)
T PACKAGE
5-LEAD PLASTIC TO-220
V
IN
V
SW
GND
FB
V
C
FRONT VIEW
5
4
3
2
1
ELECTRICAL CHARACTERISTICS
V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF
, output pin open unless otherwise specified.
(Note 1)
3
LT1070/LT1071
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
FB
Flyback Reference Voltage I
FB
= 50µA 15 16.3 17.6 V
14 18.0 V
Change in Flyback Reference Voltage 0.05 I
FB
1mA 4.5 6.8 8.5 V
Flyback Reference Voltage Line Regulation I
FB
= 50µA, 3V V
IN
V
MAX
(Note 3) 0.01 0.03 %/V
Flyback Amplifier Transconductance (g
m
) I
C
= ±10µA 150 300 650 µmho
Flyback Amplifier Source and Sink Current V
C
= 0.6V, I
FB
= 50µA (Source) 15 32 70 µA
V
C
= 0.6V, I
FB
= 50µA (Sink) 25 40 70 µA
B
V
Output Switch Breakdown Voltage 3V V
IN
V
MAX
,
I
SW
= 1.5mA
(LT1070/LT1071)
65 90 V
(LT1070HV/LT1071HV)
75 90 V
V
SAT
Output Switch “On” Resistance (Note 4) LT1070 0.15 0.24
LT1071
0.30 0.50
Control Voltage to Switch Current LT1070 8 A/V
Transconductance LT1071 4 A/V
I
LIM
Switch Current Limit (LT1070) Duty Cycle 50%, T
J
25°C 510A
Duty Cycle 50%, T
J
< 25°C 511A
Duty Cycle = 80% (Note 5)
410A
Switch Current Limit (LT1071) Duty Cycle 50%, T
J
25°C 2.5 5.0 A
Duty Cycle 50%, T
J
< 25°C 2.5 5.5 A
Duty Cycle = 80% (Note 5)
2.0 5.0 A
I
IN
Supply Current Increase During 25 35 mA/A
I
SW
Switch “On” Time
f Switching Frequency 35 40 45 kHz
33 47 kHz
DC (Max) Maximum Switch Duty Cycle 90 92 97 %
Flyback Sense Delay Time 1.5 µs
Shutdown Mode Supply Current 3V V
IN
V
MAX
, V
C
= 0.05V 100 250 µA
Shutdown Mode Threshold Voltage 3V V
IN
V
MAX
100 150 250 mV
50 300 mV
V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF
, output pin open unless otherwise specified.
The denotes the specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
Note 2: Minimum switch “on” time for the LT1070/LT1071 in current limit is
1µs. This limits the maximum input voltage during short-circuit conditions,
in the buck and inverting modes only
, to 35V. Normal (unshorted) conditions
are not affected. Mask changes are being implemented which will reduce
minimum “on” time to 1µs, increasing maximum short-circuit input voltage
above 40V. If the present LT1070/LT1071 (contact factory for package date
code) is being operated in the buck or inverting mode at high input voltages
and short-circuit conditions are expected, a resistor must be placed in series
with the inductor, as follows:
The value of the resistor is given by:
R = – R
L
t • f • V
IN
– V
F
I
LIMIT
t = Minimum “on” time of LT1070/LT1071 in current limit, 1µs
f = Operating frequency (40kHz)
V
F
= Forward voltage of external catch diode at I
LIMIT
I
LIMIT
= Current limit of LT1070 (8A), LT1071 (4A)
R
L
= Internal series resistance of inductor
Note 3: V
MAX
= 55V for LT1070HV and LT1071HV to avoid switch
breakdown.
Note 4: Measured with V
C
in hi clamp, V
FB
= 0.8V. I
SW
= 4A for LT1070
and 2A for LT1071.
Note 5: For duty cycles (DC) between 50% and 80%, minimum
guaranteed switch current is given by I
LIM
= 3.33 (2 – DC) for the
LT1070 and I
LIM
= 1.67 (2 – DC) for the LT1071.
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