LT1071IT [Linear]
5A and 2.5A High Efficiency Switching Regulators; 5A和2.5A高效率开关稳压器型号: | LT1071IT |
厂家: | Linear |
描述: | 5A and 2.5A High Efficiency Switching Regulators |
文件: | 总12页 (文件大小:317K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1070/LT1071
5A and 2.5A High Efficiency
Switching Regulators
U
FEATURES
DESCRIPTION
The LT®1070/LT1071 are monolithic high power switch-
ingregulators.Theycanbeoperatedinallstandardswitch-
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.
■
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)
TheLT1070/LT1071operatewithsupplyvoltagesfrom3V
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.
U
APPLICATIONS
■
Logic Supply 5V at 10A
■
5V Logic to ±15V Op Amp Supply
■
Off-Line Converter Up to 200W
TheLT1070/LT1071havemanyuniquefeaturesnotfound
even on the vastly more difficult to use low power control
chipspresentlyavailable. Theyuseadaptiveantisatswitch
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
generatedbyusingtheoptional“flybackregulationmode”
built into the LT1070/LT1071, without the need for
optocouplers or extra transformer windings.
■
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
U
TYPICAL APPLICATION
Maximum Output Power*
Boost Converter (5V to 12V)
100
L2
10µH
80
BOOST
BUCK/BOOST
O
5V
L1**
OUTPUT
FILTER
C3
V
= 30V
150µH
60
40
20
0
100µF
FLYBACK
D1
V
12V
1A
IN
V
SW
FB
ISOLATED
+
R1
C2
1000µF
+
LT1070
10.7k
C3*
1%
100µF
BUCK/BOOST
= 5V
V
GND
V
C
O
R2
1.24k
1%
0
10
20
30
40
50
R3
1k
C1
1µF
INPUT VOLTAGE (V)
1070/71 TA02
*ROUGH GUIDE ONLY. BUCK MODE P
= 5A • V
.
OUT
OUT
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
SPECIAL TOPOLOGIES DELIVER MORE POWER
1070/71 TA01
**DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071
1
LT1070/LT1071
W W U W
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage
Operating Junction Temperature Range
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
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
U
W U
PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
ORDER PART
NUMBER
BOTTOM VIEW
V
V
C
SW
FRONT VIEW
5
4
3
2
1
V
V
1
4
IN
LT1070CT
LT1070CK
2
CASE
IS GND
SW
LT1070HVCT
LT1070HVIT
LT1070IT
LT1070HVCK
LT1070HVMK
LT1070IK
3
GND
FB
V
V
C
FB
IN
LT1071CT
LT1070MK
LT1071CK
LT1071HVCK
LT1071HVMK
LT1071MK
T PACKAGE
5-LEAD PLASTIC TO-220
K PACKAGE
4-LEAD TO-3 METAL CAN
LT1071HVCT
LT1071HVIT
LT1071IT
TJMAX = 100°C, θJA = 75°C/ W, QJC = 2°C (LT1070C, I)
TJMAX = 100°C, θJA = 75°C/ W, QJC = 4°C (LT1071C)
TJMAX = 100°C, θJA = 35°C/ W, QJC = 2°C (LT1070C, I)
JMAX = 150°C, θJA = 35°C/ W, QJC = 2°C (LT1070M)
TJMAX = 100°C, θJA = 35°C/ W, QJC = 4°C (LT1071C, I)
TJMAX = 150°C, θJA = 35°C/ W, QJC = 4°C (LT1071M)
T
ELECTRICAL CHARACTERISTICS VIN = 15V, VC = 0.5V, VFB = VREF, output pin open unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Reference Voltage
Measured at Feedback Pin, V = 0.8V
1.224
1.214
1.244
1.244
1.264
1.274
V
V
REF
C
●
●
●
●
I
Feedback Input Current
V
FB
= V
REF
350
4400
200
750
1100
nA
nA
B
g
m
Error Amplifier Transconductance
Error Amplifier Source or Sink Current
Error Amplifier Clamp Voltage
∆I = ±25µA
C
3000
2400
6000
7000
µmho
µmho
V = 1.5V
C
150
120
350
400
µA
µA
Hi Clamp, V = 1V
1.80
0.25
2.30
0.52
V
V
FB
Lo Clamp, V = 1.5V
0.38
FB
Reference Voltage Line Regulation
Error Amplifier Voltage Gain
Minimum Input Voltage
Supply Current
3V ≤ V ≤ V
, V = 0.8V
●
●
0.03
%/V
V/V
V
IN
MAX
C
A
0.9V ≤ V ≤ 1.4V
500
800
2.6
6
V
C
3.0
9
I
3V ≤ V ≤ V
, V = 0.6V
MAX
mA
Q
IN
C
Control Pin Threshold
Duty Cycle = 0
0.8
0.6
0.9
1.08
1.25
V
V
●
Normal/Flyback Threshold on Feedback Pin
0.4
0.45
0.54
V
2
LT1070/LT1071
ELECTRICAL CHARACTERISTICS VIN = 15V, VC = 0.5V, VFB = VREF, output pin open unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Flyback Reference Voltage
I
= 50µA
15
14
16.3
17.6
18.0
V
V
FB
FB
●
Change in Flyback Reference Voltage
0.05 ≤ I ≤ 1mA
4.5
6.8
0.01
300
8.5
0.03
650
V
%/V
FB
Flyback Reference Voltage Line Regulation
I
= 50µA, 3V ≤ V ≤ V
(Note 3)
FB
IN
MAX
Flyback Amplifier Transconductance (g )
∆I = ±10µA
C
150
µmho
m
Flyback Amplifier Source and Sink Current
V = 0.6V, I = 50µA (Source)
●
●
15
25
32
40
70
70
µA
µA
C
FB
V = 0.6V, I = 50µA (Sink)
C
FB
B
V
Output Switch Breakdown Voltage
3V ≤ V ≤ V
(LT1070/LT1071)
(LT1070HV/LT1071HV)
, I = 1.5mA
V
IN
MAX SW
●
●
65
75
90
90
V
V
Output Switch “On” Resistance (Note 4)
LT1070
LT1071
●
●
0.15
0.30
0.24
0.50
Ω
Ω
SAT
Control Voltage to Switch Current
Transconductance
LT1070
LT1071
8
4
A/V
A/V
I
Switch Current Limit (LT1070)
Duty Cycle ≤ 50%, T ≥ 25°C
●
●
●
5
5
4
10
11
10
A
A
A
LIM
J
Duty Cycle ≤ 50%, T < 25°C
J
Duty Cycle = 80% (Note 5)
Switch Current Limit (LT1071)
Duty Cycle ≤ 50%, T ≥ 25°C
●
●
●
2.5
2.5
2.0
5.0
5.5
5.0
A
A
A
J
Duty Cycle ≤ 50%, T < 25°C
J
Duty Cycle = 80% (Note 5)
∆I
Supply Current Increase During
Switch “On” Time
25
40
35
mA/A
IN
∆I
SW
f
Switching Frequency
35
33
45
47
kHz
kHz
●
●
DC (Max)
Maximum Switch Duty Cycle
Flyback Sense Delay Time
90
92
97
%
µs
µA
1.5
100
150
Shutdown Mode Supply Current
Shutdown Mode Threshold Voltage
3V ≤ V ≤ V
, V = 0.05V
C
250
IN
MAX
MAX
3V ≤ V ≤ V
100
50
250
300
mV
mV
IN
The
●
denotes the specifications which apply over the full operating
t = Minimum “on” time of LT1070/LT1071 in current limit, ≈1µs
f = Operating frequency (40kHz)
temperature range.
V = Forward voltage of external catch diode at I
Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.
F
LIMIT
I
= Current limit of LT1070 (≈8A), LT1071 (≈4A)
LIMIT
R = Internal series resistance of inductor
L
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,
inthebuckandinvertingmodesonly,to≈35V.Normal(unshorted)conditions
are not affected. Mask changes are being implemented which will reduce
minimum“on”timeto≤1µs, increasingmaximumshort-circuitinputvoltage
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:
Note 3: V
= 55V for LT1070HV and LT1071HV to avoid switch
MAX
breakdown.
Note 4: Measured with V in hi clamp, V = 0.8V. I = 4A for LT1070
C
FB
SW
and 2A for LT1071.
Note 5: For duty cycles (DC) between 50% and 80%, minimum
guaranteed switch current is given by I = 3.33 (2 – DC) for the
LIM
LT1070 and I = 1.67 (2 – DC) for the LT1071.
LIM
The value of the resistor is given by:
t • f • V – V
IN
F
R =
– R
L
I
LIMIT
3
LT1070/LT1071
TYPICAL PERFORMANCE CHARACTERISTICS
U W
Switch Current Limit vs Duty Cycle
Maximum Duty Cycle
Flyback Blanking Time
16
14
12
10
8
96
95
2.2
2.0
FOR LT1071, DIVIDE
VERTICAL SCALE BY 2
94
1.8
–55°C
125°C
25°C
93
92
1.6
1.4
6
4
91
90
1.2
1.0
2
0
0
10 20 30 40 50 60 70 80 90 100
–75 –50 –25
0
25 50 75 100 125 150
–75 –50 –25
0
25 50 75 100 125 150
DUTY CYCLE (%)
JUNCTION TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
1070/71 G01
1070/71 G02
1070/71 G03
Isolated Mode Flyback
Reference Voltage
Minimum Input Voltage
Switch Saturation Voltage
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
23
22
21
20
19
18
17
16
15
2.9
2.8
FOR LT1071, DIVIDE
CURRENT BY 2
SWITCH CURRENT = 5A
150°C
R
= 500Ω
FEEDBACK
R
100°C
2.7
25°C
–55°C
= 1k
2.6
2.5
FEEDBACK
SWITCH CURRENT = 0A
R
= 10k
FEEDBACK
2.4
2.3
4
5
0
1
2
3
6
7
8
–75 –50 –25
0
25 50 75 100 125 150
–75 –50 –25
0
25 50 75 100 125 150
SWITCH CURRENT (A)
TEMPERATURE (°C)
TEMPERATURE (°C)
1070/71 G05
1070/71 G06
1070/71 G04
Feedback Bias Current
vs Temperature
Reference Voltage
vs Temperature
Line Regulation
1.250
1.248
1.246
1.244
1.242
1.240
1.238
1.236
1.234
42
41
40
39
38
37
36
35
34
800
700
600
500
400
300
200
100
0
5
4
SWITCHING
FREQUENCY
T
= 150°C
3
2
1
0
J
T
= 25°C
J
REFERENCE
V0LTAGE
T
= –55°C
J
–1
–2
–3
–4
–5
–75 –50 –25
0
25 50 75 100 125 150
–75 –50 –25
0
25 50 75 100 125 150
0
10
30
40
50
60
20
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
1070/71 G08
1070/71 G09
1070/71 G07
4
LT1070/LT1071
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
(Shutdown Mode)
Driver Current* vs Switch Current
Supply Current vs Input Voltage*
160
140
120
100
80
160
140
120
100
16
15
14
13
12
11
10
9
T
J
= 25°C
T
= 25°C
J
90% DUTY CYCLE
I
≤ 10mA
SWITCH
V
C
= 50mV
80
60
T = –55°C
J
50% DUTY CYCLE
60
T ≥ 25°C
J
40
40
20
0
10% DUTY CYCLE
0% DUTY CYCLE
8
20
V
C
= 0V
30
7
0
6
0
1
2
3
4
5
0
10
20
40
50
60
0
10
30
40
50
60
20
SWITCH CURRENT (A)
SUPPLY VOLTAGE (V)
INPUT VOLTAGE (V)
1070/71 G10
1070/71 G11
1070/71 G12
*UNDER VERY LOW OUTPUT CURRENT
CONDITIONS, DUTY CYCLE FOR MOST
CIRCUITS WILL APPROACH 10% OR LESS
*AVERAGE LT1070 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT
Normal/Flyback Mode Threshold
on Feedback Pin
Shutdown Mode Supply Current
Error Amplifier Transconductance
500
–24
–22
–20
–18
–16
–14
–12
–10
–8
200
180
160
140
120
100
80
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
∆I (V PIN)
C
g
=
m
490
480
470
460
450
440
430
420
410
400
∆V (FB PIN)
FEEDBACK PIN VOLTAGE
(AT THRESHOLD)
T = 150°C
J
60
–55°C ≤ T ≤ 125°C
FEEDBACK PIN CURRENT
(AT THRESHOLD)
J
40
–6
20
–4
150
0
0
–50
50
100 125
0
10 20 30
60 70 80 90 100
–75 –50 –25
0
25 50 75 100 125 150
–25
0
25
75
40 50
TEMPERATURE (°C)
V
C
PIN VOLTAGE (mV)
TEMPERATURE (°C)
1070/71 G13
1070/71 G14
1070/71 G14
Idle Supply Current
vs Temperature
Shutdown Thresholds
Feedback Pin Clamp Voltage
500
450
400
350
300
250
200
150
100
50
11
400
350
300
250
200
150
100
50
–400
–350
–300
–250
–200
–150
–100
–50
V
= 0.6V
C
10
9
8
7
6
5
4
3
2
1
CURRENT
(OUT OF V PIN)
C
–55°C
25°C
V
= 60V
= 3V
SUPPLY
150°C
V
VOLTAGE
SUPPLY
V
VOLTAGE IS REDUCED UNTIL
C
REGULATOR CURRENT DROPS
BELOW 300µA
0
0
0
–75 –50 –25
0
25 50 75 100 125 150
–75 –50 –25
0
25 50 75 100 125 150
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7
0.8
0.9 1.0
TEMPERATURE (°C)
TEMPERATURE (°C)
FEEDBACK CURRENT (mA)
1070/71 G16
1070/71 G14
1070/71 G18
5
LT1070/LT1071
TYPICAL PERFORMANCE CHARACTERISTICS
U W
Transconductance of Error
Amplifier
Switch “Off” Characteristics
VC Pin Characteristics
300
200
7000
6000
5000
4000
3000
2000
1000
0
–30
0
1000
900
800
700
600
500
400
300
200
100
0
T = 25°C
J
θ
30
V
= 1.5V
FB
100
(CURRENT INTO
g
m
60
V
PIN)
C
0
90
V
=
SUPPLY
–100
–200
–300
–400
V
= 0.8V
FB
120
150
180
210
(CURRENT OUT OF V PIN)
C
3V 15V
40V 55V
–1000
0
0.5
1.0
1.5
2.0
2.5
1k
10k
100k
1M
10M
0
10 20 30 40 50 60 70 80 90 100
SWITCH VOLTAGE (V)
FREQUENCY (Hz)
V
PIN VOLTAGE (V)
C
1070/71 G21
1070/71 G19
1070/71 G20
W
BLOCK DIAGRAM
16V
SWITCH
OUT
V
IN
2.3V
REG
FLYBACK
ERROR
AMP
40kHz
OSC
5A, 75V
SWITCH
LOGIC
COMP
DRIVER
MODE
SELECT
ANTISAT
–
FB
ERROR
AMP
V
C
+
+
CURRENT
AMP
0.02Ω
(0.04Ω LT1071)
SHUTDOWN
CIRCUIT
–
1.24V
REF
GAIN ≈ 6
0.15V
1070/71 BD
U
OPERATION
voltage is obtained by using the output of a voltage
sensing error amplifier to set current trip level. This
techniquehasseveraladvantages. First, ithasimmediate
response to input voltage variations, unlike ordinary
switchers which have notoriously poor line transient
response. Second, it reduces the 90° phase shift at
The LT1070/LT1071 is a current mode switcher. This
means that switch duty cycle is directly controlled by
switchcurrentratherthanbyoutputvoltage.Referringto
the Block Diagram, the switch is turned “on” at the start
of each oscillator cycle. It is turned “off” when switch
current reaches a predetermined level. Control of output
6
LT1070/LT1071
U
OPERATION
midfrequencies in the energy storage inductor. This
greatly simplifies closed-loop frequency compensation
under widely varying input voltage or output load condi-
tions. Finally, it allows simple pulse-by-pulse current
limiting to provide maximum switch protection under
output overload or short-circuit conditions. A low drop-
out internal regulator provides a 2.3V supply for all
internal circuitry of the LT1070/LT1071. This low drop-
out design allows input voltage to vary from 3V to 60V
with virtually no change in device performance. A 40kHz
oscillator is the basic clock for all internal timing. It turns
“on” the output switch via the logic and driver circuitry.
Special adaptive antisat circuitry detects onset of satura-
tion in the power switch and adjusts driver current
instantaneously to limit switch saturation. This mini-
mizes driver dissipation and provides very rapid turn-off
of the switch.
transformercoupledflybacktopologyregulator.Byregu-
lating the amplitude of the flyback pulse, the output
voltage can be regulated with no direct connection be-
tween input and output. The output is fully floating up to
the breakdown voltage of the transformer windings.
Multiple floating outputs are easily obtained with addi-
tionalwindings.AspecialdelaynetworkinsidetheLT1070/
LT1071 ignores the leakage inductance spike at the
leading edge of the flyback pulse to improve output
regulation.
The error signal developed at the comparator input is
brought out externally. This pin (VC) has four different
functions. Itisusedforfrequencycompensation, current
limit adjustment, soft starting and total regulator shut-
down. During normal regulator operation this pin sits at
a voltage between 0.9V (low output current) and 2.0V
(high output current). The error amplifiers are current
output (gm) types, so this voltage can be externally
clamped for adjusting current limit. Likewise, a capacitor
coupled external clamp will provide soft start. Switch
duty cycle goes to zero if the VC pin is pulled to ground
through a diode, placing the LT1070/LT1071 in an idle
mode. Pulling the VC pin below 0.15V causes total
regulator shutdown, with only 50µA supply current for
shutdown circuitry biasing. See AN19 for full application
details.
A 1.2V bandgap reference biases the positive input of the
error amplifier. The negative input is brought out for
output voltage sensing. This feedback pin has a second
function; when pulled low with an external resistor, it
programs the LT1070/LT1071 to disconnect the main
error amplifier output and connects the output of the
flyback amplifier to the comparator input. The LT1070/
LT1071 will then regulate the value of the flyback pulse
with respect to the supply voltage. This flyback pulse is
directly proportional to output voltage in the traditional
U
TYPICAL APPLICATIONS (Note that maximum output currents are divided by 2 for the LT1071)
Driving High Voltage NPN
C1
Driving High Voltage FET (for Off-Line
D2
Applications, See AN25)
R2**
D
S
G
R1*
Q1
Q1
D1
D1
V
IN
V
V
IN
SW
V
SW
LT1070/LT1071
GND
*SETS I
B(ON)
LT1070/LT1071
GND
+
10V
TO
20V
**SETS I
B(OFF)
1070/71 TA03
1070/71 TA16
7
LT1070/LT1071
TYPICAL APPLICATIONS
U
(Note that maximum output currents are divided by 2 for the LT1071)
Negative Buck Converter
+
C2
1000µF
D1
LOAD
L1**
200µH
R1
4.64k
V
–5.2V
4.5A
IN
V
SW
+
Q1
2N3906
C3
100µF
LT1070
OPTIONAL INPUT
FILTER
FB
C1
GND
V
C
L3
OPTIONAL
OUTPUT
FILTER
+
C4
200µF
R2
1.24k
R3
L2
4µH
V
IN
–20V
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
1070/71 TA12
Positive Buck Converter
V
IN
D3
L2
4µH
V
IN
OPTIONAL
OUTPUT
FILTER
C5
V
SW
FB
200µF
+
C3
LT1070
2.2µF
D2
R1
+
1N914
C5*
3.74k
100µF
GND
V
C
+
R2
C2
1µF
R3
470Ω
R4
10Ω
1.24k
L1**
100µH
C1
1µF
r
5V
4.5A
+
100mA
C4
1000µF
D1
MINIMUM
1070/71 TA14
*REQUIRED IF INPUT LEADS ≥2"
**PULSE ENGINEERING 92112
Negative Current Boosted Buck Converter
+
MINIMUM
LOAD = 10mA
R1
C1
–V
5V
OUT
T1
1:N
10A
R5
C3
•
R4
12k
D1
V
– 0.6V
OUT
1mA
Q1
2N3906
R1 =
V
•
IN
V
SW
+
LT1070
FB
GND
V
C
R2
R3
C2
1.24k
1070/71 TA13
–V
IN
8
LT1070/LT1071
U
(Note that maximum output currents are divided by 2 for the LT1071)
TYPICAL APPLICATIONS
Positive Current Boosted Buck Converter
V
IN
28V
470Ω
2W
R6
470Ω
C3
0.47µF
•
C6
0.002µF
D2
•
V
1:N
IN
V
SW
FB
N ≈ 0.25
LT1070
R2
1k
R7
1.24k
D1
GND
V
C
V
IN
7
–
2
3
R3
680Ω
+
V
6
R5
5k
–
LM308
COMP +
V
+
C5*
100µF
4
C1
0.33µF
8
R4
1.24k
200pF
V
OUT
5V
R1
5k
10A
+
C2
5000µF
*REQUIRED IF INPUT LEADS ≥ 2"
1070/71 TA19
Positive to Negative Buck/Boost Converter
Negative to Positive Buck/Boost Converter
†
†
R5
TO AVOID START-UP
†
L2
D3
470Ω
1W
PROBLEMS FOR INPUT
VOLTAGES BELOW 10V,
CONNECT ANODE OF D3
1N4001
V
OPTIONAL
IN
10V TO 30V
C3
L1**
OUTPUT
150µH
TO V AND REMOVE R5.
IN
C5*
100µF
FILTER
C1 MAY BE REDUCED FOR
V
IN
V
SW
LOWER OUTPUT CURRENTS.
D1
V
12V
2A
OUT
C1 ≈ (500µF)(I ) FOR 5V
OUT
V
IN
+
V
SW
FB
C4
5µF
OUTPUTS, REDUCE R3 TO
1.5k, INCREASE C2 TO 0.3µF
AND REDUCE R6 TO 100Ω.
+
LT1070
R1
11.3k
C2
1000µF
D2
1N914
+
R1
R4
47Ω
C4*
100µF
10.7k
LT1070
FB
Q1
GND
V
C
+
+
L3
†
R3
5k
C1
0.1µF
R2
C3
C1
R6
470Ω
GND
V
C
1.24k
2µF 1000µF
OPTIONAL
INPUT
FILTER
R3
2.2k
R2
1.24k
D1
V
–12V
2A
OUT
C1
0.22µF
1070/71 TA09
V
IN
–12V
L1**
200µH
1070/71 TA05
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
*REQUIRED IF INPUT LEADS ≥ 2"
**PULSE ENGINEERING 92113
9
LT1070/LT1071
TYPICAL APPLICATIONS (Note that maximum output currents are divided by 2 for the LT1071)
U
Current Boosted Boost Converter
Voltage Boosted Boost Converter
R4
C3
680Ω
R4
C3
0.68µF
D1
I
V
28V
4A
OUT
1W
TOTAL
INDUCTANCE = 4mH
N
D2
D2
1
L1
N = 5
V
V
IN
INTERLEAVE PRIMARY
AND SECONDARY FOR
LOW LEAKAGE
IN
V
V
SW
SW
FB
R1
27k
+
+
V
V
IN
15V
IN
16V TO 24V
INDUCTANCE
LT1070
LT1070
D1
+
R1
98k
C1
V
OUT
100V
FB
GND
V
GND
V
C
C
300mA
+
R3
R2
1.24k
R2
1.24k
C1
200µF
R3
C2
10k
C2
0.047µF
1070/71 TA10
1070/71 TA11
Negative Input/Negative Output Flyback Converter
Negative Boost Regulator
•
D2
C3
R6
R2
5k
R3
1k
V
IN
•
V
SW
+
T1
1:N
V
IN
Q1
2N3906
V
SW
C1
R
+
O
R1
27k
R1*
C1
1000µF
LT1070
(MINIMUM
LOAD)
+
+
LT1070/LT1071
C4*
470µF
+
–V
C3
OUT
FB
R3
3.3k
C2
GND
V
C
10µF
FB
V
– 1.6V
OUT
200µA
GND
V
C
*R1 =
R2
1.24k
R4
R5
C2
L1
200µH
1.24k
D1
V
–28V
1A
0.22µF
OUT
V
IN
1070/71 TA17
–15V
–V
IN
*REQUIRED IF INPUT LEADS ≥ 2"
1070/71 TA15
External Current Limit
External Current Limit
V
IN
V
SW
V
X
LT1070/LT1071
LT1070/LT1071
R2
R1
+
= 2V
D1
V
IN
FB
GND
V
C
GND
V
C
500Ω
R1
1k
R2
C2
Q1
C1
1000pF
1070/71 TA04
R
S
NOTE THAT THE LT1070/LT1071
GND PIN IS NO LONGER COMMON
–
TO V
1070/71 TA06
IN
10
LT1070/LT1071
U
TYPICAL APPLICATIONS (Note that maximum output currents are divided by 2 for the LT1071)
Flyback Converter
CLAMP TURN-ON
SPIKE
V
SNUB
L2
10µH
V
+ V
OUT
N
F
a
PRIMARY FLYBACK VOLTAGE =
V
IN
b
LT1070/LT1071 SWITCH VOLTAGE
AREA “a” = AREA “b” TO MAINTAIN
ZERO DC VOLTS ACROSS PRIMARY
C4
OPTIONAL
FILTER
0V
200µF
V
+ V
F
OUT
D1
V
OUT
V
IN
SECONDARY VOLTAGE
)
c
5V
6A
(N)(V
IN
20V TO 30V
1 N
AREA “c” = AREA “d” TO MAINTAIN
ZERO DC VOLTS ACROSS SECONDARY
0V
C3
0.47µF
R4
•
d
+
C1
2000µF
∆I
D2
I
PRI
•
V
IN
V
SW
FB
PRIMARY CURRENT
N = 1/3
0
0
0
R1
+
C4*
100µF
I
N
3.74k
LT1070
PRI
SECONDARY CURRENT
LT1070 SWITCH CURRENT
I
PRI
GND
V
C
R2
1.24k
R3
1.5k
C2
I
PRI
0.15µF
SNUBBER DIODE CURRENT
1070/71 TA08
*REQUIRED IF INPUT LEADS ≥ 2"
(I )(L )
PRI
L
t =
V
SNUB
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
T Package
5-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1421)
K Package
4-Lead TO-3 Metal Can
(LTC DWG # 05-08-1311)
0.165 – 0.180
0.147 – 0.155
(3.734 – 3.937)
0.760 – 0.775
(19.30 – 19.69)
0.320 – 0.350
(8.13 – 8.89)
0.390 – 0.415
(9.906 – 10.541)
(4.191 – 4.572)
0.045 – 0.055
(1.143 – 1.397)
DIA
0.060 – 0.135
(1.524 – 3.429)
0.230 – 0.270
(5.842 – 6.858)
0.570 – 0.620
0.420 – 0.480
(10.67 – 12.19)
0.620
(14.478 – 15.748)
0.460 – 0.500
(11.684 – 12.700)
(15.75)
TYP
0.330 – 0.370
(8.382 – 9.398)
0.700 – 0.728
(17.78 – 18.491)
0.038 – 0.043
(0.965 – 1.09)
1.177 – 1.197
(29.90 – 30.40)
0.095 – 0.115
(2.413 – 2.921)
0.655 – 0.675
(16.64 – 19.05)
0.152 – 0.202
(3.861 – 5.131)
0.470 TP
P.C.D.
0.260 – 0.320
(6.60 – 8.13)
0.151 – 0.161
(3.84 – 4.09)
DIA 2 PLC
0.013 – 0.023
(0.330 – 0.584)
0.057 – 0.077
(1.448 – 1.956)
0.135 – 0.165
(3.429 – 4.191)
0.155 – 0.195
(3.937 – 4.953)
0.028 – 0.038
(0.711 – 0.965)
0.167 – 0.177
(4.24 – 4.49)
R
T5 (TO-220) 0398
0.495 – 0.525
(12.57 – 13.34)
R
72°
18°
K4(TO-3) 0695
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LT1070/LT1071
TYPICAL APPLICATIONS
U
(Note that maximum output currents are divided by 2 for the LT1071)
Totally Isolated Converter
OPTIONAL
OUTPUT FILTER
L1
D1
10µF
15V
COM
–15V
1:N
+
+
+
+
R4
1.5k
C3
0.47µF
C1
C5
N
•
500µF
200µF
L2
10µF
N
C4
500µF
C6
200µF
V
IN
•
V
SW
+
N = 0.875 = 7:8
FOR V = 15V
+
V
IN
5V
C5*
100µF
OUT
LT1070/LT1071
≈16V
SWITCH VOLTAGE
FB
V
GND
V
C
IN
t
t
ON
OFF
500Ω
0V
V
F
R2
C2
0.01µF
V
(DIODE FORWARD VOLTAGE)
SECONDARY VOLTAGE
1070/71 TA07
5k
OUT
0V
*REQUIRED IF INPUT LEADS ≥ 2"
(N)(V
)
IN
Forward Converter
L1
70µH
D1
V
OUT
5V
6A
T1
I
M
N
•
•
R4
C2
+
C1
2000µF
D2
D3
•
V
IN
V
SW
V
R1
3.74k
IN
LT1070
D4
20V TO 30V
FB
GND
V
C
Q1
R2
1.24k
R6
330Ω
R3
C3
R5
1Ω
C4
1070/71 TA18
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1074/LT1076
High Voltage Switching Regulators
40V Input (60V for HV Versions), 100kHz, 5A and 2A
LT1170/LT1171/
LT1172
100kHz High Efficiency Switching Regulators
40V Input (65V for HV Versions), 5A/2.5A/1.25A Internal Switch
LT1370/LT1371
LT1374/LT1376
500kHz High Efficiency Switching Regulators
100kHz High Efficiency Switching Regulators
35V, 6A/3A Internal Switch
25V Input, 4.5A/1.5A Internal Switch
10701fd LT/TP 1098 2K REV D • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1989
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
相关型号:
LT1072CIT
IC 1.25 A SWITCHING REGULATOR, 40 kHz SWITCHING FREQ-MAX, PSFM5, TO-220, 5 PIN, Switching Regulator or Controller
Linear
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