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PDF LT1072 Data sheet ( Hoja de datos )
| Número de pieza | LT1072 | |
| Descripción | 1.25A High Efficiency Switching Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LT1072
1.25A High Efficiency
Switching Regulator
FEATURES
■ 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
U
APPLICATIO S
■ 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.
DESCRIPTIO
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.
TYPICAL APPLICATIO
Boost Converter (5V to 12V)
5V 220µH**
VIN VSW
C3
25µF*
+
–
LT1072
GND VC FB
1k
+
1µF –
*REQUIRED IF INPUT LEADS ≥ 2”
**PULSE ENGINEERING 52626
10.7k
12V, 0.25A
1.24k
+
– 470µF
LT1072 • TA01
Maximum Output Power*
25
20
15
BOOST
10
BUCK-BOOST
VO = 30V
FLYBACK
ISOLATED
5
BUCK-BOOST
VO = 5V
0
0 10 20 30 40 50
INPUT VOLTAGE (V)
*ROUGH GUIDE ONLY. BUCK MODE POUT = 1A x VOUT.
MINIDIP OUTPUT POWER MAY BE LIMITED BY PACKAGE TEMPERATURE
RISE AT HIGH INPUT VOLTAGES OR HIGH DUTY CYCLES
LT1072 • TA02
1072fc
1
1 page  
LT1072
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Current* vs Switch Current
80
70
60
50
40
30
20
10
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
SWITCH CURRENT (A)
*AVERAGE LT1072 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT
LT1072 • TPC10
Normal/Flyback Mode Threshold
on Feedback Pin
500 –24
490 –22
480 –20
470
460 FEEDBACK PIN VOLTAGE
(AT THRESHOLD)
450
–18
–16
–14
440 –12
430 –10
420
FEEDBACK PIN CURRENT
(AT THRESHOLD)
–8
410 –6
400 –4
–50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
LT1072 • TPC13
Shutdown Thresholds
400
–400
350 CURRENT (OUT OF VC PIN)
300
–350
–300
250 –250
200
VOLTAGE
150
–200
–150
100 –100
VC VOLTAGE IS REDUCED UNTIL
50 REGULATOR CURRENT DROPS
–50
BELOW 300µA
00
–75 –50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
LT1072 • TPC16
Supply Current vs Input Voltage*
15
TJ = 25°C
14
NOTE THAT THIS CURRENT DOES NOT
13 INCLUDE DRIVER CURRENT, WHICH IS
12
A FUNCTION OF LOAD CURRENT AND
DUTY CYCLE.
90% DUTY CYCLE
11
10
9 50% DUTY CYCLE
8
10% DUTY CYCLE
7
6
0% DUTY CYCLE
5
0 10 20 30 40 50 60
INPUT VOLTAGE (V)
*UNDER VERY LOW OUTPUT CURRENT CONDITIONS,
DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH
10% OR LESS
LT1072 • TPC11
Supply Current vs Supply Voltage
(Shutdown Mode)
160
TJ = 25°C
140
120
100
VC = 50mV
80
60
40
20 VC = 0V
0
0 10 20 30 40 50 60
SUPPLY VOLTAGE (V)
LT1072 • TPC12
Shutdown Mode Supply Current
200
180
160
140
120 TJ = 150°C
100
80
60 – 55°C ≤ TJ ≤ 125°C
40
20
0
0 10 20 30 40 50 60 70 80 90 100
VC PIN VOLTAGE (mV)
LT1072 • TPC14
Idle Supply Current vs
Temperature
11
10 VC = 0.6V
9
8
7 VSUPPLY = 60V
6
VSUPPLY = 3V
5
4
3
2
1
–75 –50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
LT1072 • TPC17
Error Amplifier Transconductance
5000
4500
4000
Gm =
∆I
∆V
(VC PIN)
(FB PIN)
3500
3000
2500
2000
1500
1000
500
0
–75 –50 –25 0 25 50 75 100 125 150
TEMPERATURE (C°)
LT1072 • TPC15
Feedback Pin Clamp Voltage
500
450
400
–55°C
350
300 25°C
250
150°C
200
150
100
50
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
FEEDBACK CURRENT (mA)
LT1072 • TPC18
1072fc
5
5 Page 
TYPICAL APPLICATIO S
D3†
1N4001
C4 +
5µF
Positive to Negative Buck-Boost Converter
R5†
470Ω, 1W
VIN VSW
LT1072
GND VC FB
R3
5k
C2
0.1µF
C5
100µF*
R1
10.7k
VIN
10 TO 30V
D2 R4
1N914 47Ω
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
†TO AVOID START-UP PROBLEMS
FOR INPUT VOLTAGES BELOW 10V,
CONNECT ANODE OF D3 TO VIN,
AND REMOVE R5. C1 MAY BE
REDUCED FOR LOWER OUTPUT
CURRENTS. C1 ≈ (500µF)(IOUT).
FOR 5V OUTPUTS, REDUCE R3
TO 1.5k, INCREASE C2 TO 0.3µF,
AND REDUCE R6 TO 100Ω
+
R2
1.24k
C3
2µF
D1
L1**
200µH
+ C1†
1000µF
R6
470Ω
VOUT
–12V AT 2A
LT1072 • TA07
LT1072
External Current Limit
VX
R2
R1
500Ω
≈ 2V
D1
LT1072
GND VC
LT1072 • TA08
Voltage Boosted Boost Converter
VIN +
15V
R4
1.5k
1/2W
C3
0.68
VIN VSW
LT1072
GND VC FB
C2
0.047µF
R3
10k
D2 1 TOTAL INDUCTANCE = 8mH
L1 INTERLEAVE PRIMARY AND
N = 5 SECONDARY FOR LOW LEAKAGE
INDUCTANCE
R1 D1
98k VOUT
100V AT 75mA
R2 +
1.24k
C1
200µF
LT1072 • TA09
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11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LT1072.PDF ] | |
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