LT1170/LT1171/LT1172
POWER (W) **
100
100kHz, 5A, 2.5A and 1.25A
High Efficiency Switching Regulators
FeaTures DescripTion
n
Wide Input Voltage Range: 3V to 60V
n
Low Quiescent Current: 6mA
n
Internal 5A Switch
(2.5A for LT1171, 1.25A for LT1172)
n
Shutdown Mode Draws Only 50µA Supply Current
n
Very Few External Parts Required
n
Self-Protected Against Overloads
n
Operates in Nearly All Switching Topologies
n
Flyback-Regulated Mode Has Fully Floating Outputs
n
Comes in Standard 5-Pin Packages
n
LT1172 Available in 8-Pin MiniDIP and
Surface Mount Packages
n
Can Be Externally Synchronized
applicaTions
n
Logic Supply 5V at 10A
n
5V Logic to ±15V Op Amp Supply
n
Battery Upconverter
n
Power Inverter (+ to –) or (– to +)
n
Fully Floating Multiple Outputs
USER NOTE:
This data sheet is only intended to provide specifications, graphs, and a general functional
description of the LT1170/LT1171/LT1172. Application circuits are included to show the capability
of the LT1170/LT1171/LT1172. 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 LT1170/LT1171/LT1172 by factoring in
the higher frequency. A CAD design program called SwitcherCAD is also available.
The LT®1170/LT1171/LT1172 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 LT1170/LT1171/LT1172 to be built in a standard
5-pin TO-3 or TO-220 power package as well as the 8-pin
packages (LT1172). This makes them extremely easy to
use and provides “bust proof” operation similar to that
obtained with 3-pin linear regulators.
The LT1170/LT1171/LT1172 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 LT1170/LT1171/LT1172 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 typically for
standby operation.
L, LT, LTC, LTM, Linear Technology, the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion
Boost Converter (5V to 12V)
L1**
5V
µH
50
D1
V
IN
V
+
C3*
100µF
*REQUIRED IF INPUT LEADS ≥ 2"
GND
LT1170
V
C
R3
1k
MBR330
SW
FB
C1
1µF
** COILTRONICS 50-2-52
PULSE ENGINEERING 92114
L2
OUTPUT
10µH
FILTER
C3
100µF
12V
+
C2
1000µF
For more information www.linear.com/LT1170
R1
10.7k
1%
R2
1.24k
1%
1170/1/2 TA01
1A
Maximum Output Power*
LT1170
80
60
BOOST
40
20
0
10
0
FLYBACK
BUCK-BOOST
V
20
INPUT VOLTAGE (V)
BUCK-BOOST
= 30V
V
O
= 5V
O
30
* ROUGH GUIDE ONLY. BUCK MODE
= (5A)(V
P
OUT
SPECIAL TOPOLOGIES DELIVER
MORE POWER.
** DIVIDE VERTICAL POWER SCALE
BY TWO FOR LT1171, BY FOUR
FOR LT1172.
40
50
OUT
)
LT1170/1/2 TA02
117012fi
1
LT1170/LT1171/LT1172
1
2
3
4
8
7
6
5
TOP VIEW
GND
V
C
FB
NC*
E2
V
SW
E1
V
IN
J8 PACKAGE
8-LEAD CERDIP
absoluTe MaxiMuM raTings
Supply Voltage
LT1170/LT1171/LT1172HV (Note 2) ....................... 60V
LT1170/LT1171/LT1172 (Note 2) ............................40V
Switch Output Voltage
LT1170/LT1171/LT1172HV .....................................75V
LT1170/LT1171/LT1172 .........................................65V
LT1172S8 ..............................................................60V
Feedback Pin Voltage (Transient, 1ms) ................... ±15V
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec .................... 300°C
pin conFiguraTion
BOTTOM VIEW
V
SW
1
4
V
IN
K PACKAGE
4-LEAD TO-3 METAL CAN
= 150°C, θJC = 2°C/W, θJA = 35°C/W
JMAX
= 100°C, θJC = 2°C/W, θJA = 35°C/W
JMAX
= 150°C, θJC = 4°C/W, θJA = 35°C/W
JMAX
= 100°C, θJC = 4°C/W, θJA = 35°C/W
JMAX
= 150°C, θJC = 8°C/W, θJA = 35°C/W
JMAX
= 100°C, θJC = 8°C/W, θJA = 35°C/W
JMAX
Based on continuous operation.
= 125°C for intermittent fault conditions.
OBSOLETE
T
= 125°C, θJA = 100°C/W
JMAX
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
OBSOLETE
LT1170MK: T
LT1170CK: T
LT1171MK: T
LT1171CK: T
LT1172MK: T
LT1172CK: T
T
JMAX
(Note 1)
Operating Junction Temperature Range
LT1170M/LT1171M (OBSOLETE) ....... –55°C to 150°C
LT1172M (OBSOLETE) ....................... –55°C to 125°C
LT1170/LT1171/LT1172HVC,
LT1170/LT1171/LT1172C (Oper.) ............. 0°C to 100°C
LT1170/LT1171/LT1172HVC
LT1170/LT1171/LT1172C (Sh. Ckt.) ........ 0°C to 125°C
LT1170/LT1171/LT1172HVI,
LT1170/LT1171/LT1172I (Oper.) .......... –40°C to 100°C
LT1170/LT1171/LT1172HVI,
LT1170/LT1171/LT1172I (Sh. Ckt.) ...... –40°C to 125°C
V
C
2
3
CASE
IS GND
FB
GND
V
FB
NC*
N8 PACKAGE
8-LEAD PDIP
T
JMAX
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
TOP VIEW
1
2
C
3
4
8-LEAD PLASTIC SO
T
= 100°C, θJA = 100°C/W (N)
JMAX
= 100°C, θJA = 120°C/W to 150°C/W
depending on board layout (S)
E2
8
V
7
SW
E1
6
V
5
IN
S8 PACKAGE
FRONT VIEW
5
TAB IS
GND
T
= 100°C, θJA = *°C/W
JMAX
* θ will vary from approximately 25°C/W with 2.8 sq.
in. of 1oz. copper to 45°C/W with 0.20 sq. in. of 1oz.
copper. Somewhat lower values can be obtained with
additional copper layers in multilayer boards.
4
3
2
1
Q PACKAGE
5-LEAD DD
2
V
IN
V
SW
GND
FB
V
C
TOP VIEW
1
NC
2
NC
3
GND
4
V
C
5
FB
6
NC
7
NC
8
NC
SW PACKAGE
16-LEAD PLASTIC SO WIDE
= 100°C, θJA = 150°C/W
T
JMAX
Based on continuous operation.
= 125°C for intermittent fault conditions.
T
JMAX
16
NC
15
NC
14
E2
13
V
SW
12
E1
11
V
IN
10
NC
9
NC
For more information www.linear.com/LT1170
TAB IS
GND
5-LEAD PLASTIC TO-220
LT1170CT/LT1170HVCT: T
LT1171CT/LT1171HVCT: T
LT1172CT/LT1172HVCT: T
Based on continuous operation.
= 125°C for intermittent fault conditions.
T
JMAX
FRONT VIEW
5
4
3
2
1
T PACKAGE
=100°C, θJC = 2°C/W, θJA = 75°C/W
JMAX
=100°C, θJC = 4°C/W, θJA = 75°C/W
JMAX
=100°C, θJC = 8°C/W, θJA = 75°C/W
JMAX
V
IN
V
SW
GND
FB
V
C
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LT1170/LT1171/LT1172
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1172MJ8 (OBSOLETE) LT1172MJ8#TR LT1172 8-Lead CERDIP –55°C to 125°C
LT1172CJ8#PBF (OBSOLETE) LT1172CJ8#TRPBF 8-Lead CERDIP 0°C to 100°C
LT1170MK#PBF (OBSOLETE) LT1170MK#TRPBF 4-Lead TO-3 Metal Can –55°C to 125°C
LT1170CK#PBF (OBSOLETE) LT1170CK#TRPBF 4-Lead TO-3 Metal Can 0°C to 100°C
LT1171MK#PBF (OBSOLETE) LT1171MK#TRPBF 4-Lead TO-3 Metal Can –55°C to 125°C
LT1171CK#PBF (OBSOLETE) LT1171CK#TRPBF 4-Lead TO-3 Metal Can 0°C to 100°C
LT1172MK#PBF (OBSOLETE) LT1172MK#TRPBF 4-Lead TO-3 Metal Can –55°C to 125°C
LT1172CK#PBF (OBSOLETE) LT1172CK#TRPBF 4-Lead TO-3 Metal Can 0°C to 100°C
LT1172CN8#PBF LT1172CN8#TRPBF LT1172 8-Lead PDIP or 8-Lead Plastic SO 0°C to 100°C
LT1172IN8#PBF LT1172IN8#TRPBF LT1172 8-Lead PDIP or 8-Lead Plastic SO –40°C to 100°C
LT1172CS8#PBF LT1172CS8#TRPBF 1172 8-Lead PDIP or 8-Lead Plastic SO 0°C to 100°C
LT1172IS8#PBF LT1172IS8#TRPBF 1172I 8-Lead PDIP or 8-Lead Plastic SO –40°C to 100°C
LT1170CQ#PBF LT1170CQ#TRPBF LT1170 5-Lead DD 0°C to 100°C
LT1170IQ#PBF LT1170IQ#TRPBF LT1170 5-Lead DD –40°C to 100°C
LT1170HVCQ#PBF LT1170HVCQ#TRPBF LT1170HV 5-Lead DD 0°C to 100°C
LT1171CQ#PBF LT1171CQ#TRPBF LT1171 5-Lead DD 0°C to 100°C
LT1171IQ#PBF LT1171IQ#TRPBF LT1171 5-Lead DD –40°C to 100°C
LT1171HVCQ#PBF LT1171HVCQ#TRPBF LT1171HV 5-Lead DD 0°C to 100°C
LT1171HVIQ#PBF LT1171HVIQ#TRPBF LT1171HV 5-Lead DD –40°C to 100°C
LT1172CQ#PBF LT1172CQ#TRPBF LT1172 5-Lead DD 0°C to 100°C
LT1172HVCQ#PBF LT1172HVCQ#TRPBF LT1172HV 5-Lead DD 0°C to 100°C
LT1172HVIQ#PBF LT1172HVIQ#TRPBF LT1172HV 5-Lead DD –40°C to 100°C
LT1172CSW#PBF LT1172CSW#TRPBF LT1172CSW 16-Lead Plastic SO Wide 0°C to 100°C
LT1170CT#PBF LT1170CQ#TRPBF LT1170 5-Lead Plastic TO-220 0°C to 100°C
LT1170IT#PBF LT1170IT#TRPBF LT1170 5-Lead Plastic TO-220 –40°C to 100°C
LT1170HVCT#PBF LT1170HVCT#TRPBF LT1170HV 5-Lead Plastic TO-220 0°C to 100°C
LT1170HVIT#PBF LT1170HVIT#TRPBF LT1170 5-Lead Plastic TO-220 –40°C to 100°C
LT1171CT#PBF LT1171CT#TRPBF LT1171 5-Lead Plastic TO-220 0°C to 100°C
LT1171IT#PBF LT1171IT#TRPBF LT1171 5-Lead Plastic TO-220 –40°C to 100°C
LT1171HVCT#PBF LT1171HVCT#TRPBF LT1171HV 5-Lead Plastic TO-220 0°C to 100°C
LT1171HVIT#PBF LT1171HVIT#TRPBF LT1171HV 5-Lead Plastic TO-220 –40°C to 100°C
LT1172CT#PBF LT1172CT#TRPBF LT1172 5-Lead Plastic TO-220 0°C to 100°C
LT1172HVCT#PBF LT1172HVCT#TRPBF LT1172HV 5-Lead Plastic TO-220 0°C to 100°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
http://www.linear.com/product/LT1170#orderinfo
For more information www.linear.com/LT1170
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3
LT1170/LT1171/LT1172
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
I
B
g
m
A
V
I
Q
V
FB
BV Output Switch Breakdown Voltage
V
SAT
I
LIM
∆I
∆I
f Switching Frequency
Reference Voltage Measured at Feedback Pin
V
= 0.8V
C
Feedback Input Current VFB = V
REF
Error Amplifier Transconductance ∆IC = ±25µA l3000
Error Amplifier Source or Sink Current
= 1.5V l150
V
C
Error Amplifier Clamp Voltage Hi Clamp, VFB = 1V
Lo Clamp, V
Reference Voltage Line Regulation 3V ≤ V
V
= 0.8V
C
= 1.5V
FB
≤ V
MAX
IN
Error Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V 500 800 V/V
Minimum Input Voltage (Note 5)
Supply Current 3V ≤ VIN ≤ V
, VC = 0.6V 6 9 mA
MAX
Control Pin Threshold Duty Cycle = 0
Normal/Flyback Threshold on Feedback Pin 0.4 0.45 0.54 V
Flyback Reference Voltage (Note 5) IFB = 50µA l15.0
Change in Flyback Reference Voltage
Flyback Reference Voltage Line Regulation
(Note 5)
Flyback Amplifier Transconductance (g
) ∆IC = ±10µA 150 300 650 µmho
m
Flyback Amplifier Source and Sink Current V
0.05 ≤ I
I
FB
7V ≤ V
I
FB
3V ≤ V
I
SW
≤ 1mA 4.5 6.8 9 V
FB
= 50µA
≤ V
IN
MAX
= 0.6V Source
C
= 50µA Sink
≤ V
IN
, LT1170/LT1171/LT1172
MAX
= 1.5mA LT1170HV/LT1171HV/LT1172HV
LT1172S8
Output Switch “On” Resistance (Note 3) LT1170
LT1171
LT1172
Control Voltage to Switch Current
T
ransconductance
LT1170
LT1171
LT1172
Switch Current Limit (LT1170) Duty Cycle = 50% TJ ≥ 25°C
Duty Cycle = 50%
TJ < 25°C
Duty Cycle = 80% (Note 4)
(LT1171) Duty Cycle = 50%
Duty Cycle = 50%
T
TJ < 25°C
≥ 25°C
J
Duty Cycle = 80% (Note 4)
(LT1172) Duty Cycle = 50%
Duty Cycle = 50%
T
TJ < 25°C
≥ 25°C
J
Duty Cycle = 80% (Note 4)
Supply Current Increase During Switch
IN
On-Time
SW
, output pin open, unless otherwise noted.
REF
1.224
1.214
l
l
1.244
1.244
1.264
1.274
350 750
1100
4400 6000
2400
7000
200 350
120
1.80
0.25 0.38
l 0.03 %/V
l
0.8
0.6
l
2.6 3.0 V
0.9 1.08
400
2.30
0.52
1.25
16.3 17.6
14.0
18.0
0.01 0.03 %/V
l
l
l
l
l
l
l
l
15
25
65
75
60
32
40
90
90
80
0.15
0.30
0.60
70
70
0.24
0.50
1.00
8
4
2
l
l
l
l
l
l
l
l
l
5
5
4
2.5
2.5
2.0
1.25
1.25
1.00
10
11
10
5.0
5.5
5.0
3.0
3.5
2.5
25 35 mA/A
88 85100 112
l
115
nA
nA
µmho
µmho
µA
µA
µA
µA
A/V
A/V
A/V
kHz
kHz
V
V
V
V
V
V
V
V
V
V
V
Ω
Ω
Ω
A
A
A
A
A
A
A
A
A
4
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For more information www.linear.com/LT1170
LT1170/LT1171/LT1172
(
)
)
)
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
DC
Maximum Switch Duty Cycle
MAX
≤ V
IN
≤ V
MAX
MAX
Shutdown Mode
Supply Current
Shutdown Mode
Threshold Voltage
Flyback Sense Delay Time (Note 5) 1.5 µs
3V ≤ V
V
= 0.05V
C
3V ≤ V
IN
, output pin open, unless otherwise noted.
REF
l
85 92 97 %
100 250 µA
l100 50150 250
300
mV
mV
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Minimum effective switch “on” time for the LT1170/LT1171/
LT1172 (in current limit only) is ≈ 0.6µs. This limits the maximum safe
input voltage during an output shorted condition. Buck mode and inverting
mode input voltage during an output shorted condition is limited to:
R
I
+ Vf
(
)
V
(max, output shorted) =
IN
buck and inverting mode
R = Inductor DC resistance
I
= 10A for LT1170, 5A for LT1171, and 2.5A for LT1172
L
Vf = Output catch diode forward voltage at I
t = 0.6µs, f = 100kHz switching frequency
Maximum input voltage can be increased by increasing R or Vf.
External current limiting such as that shown in AN19, Figure 39, will
provide protection up to the full supply voltage rating. C1 in Figure 39
should be reduced to 200pF.
15V +
L
f
t
(
(
L
Transformer designs will tolerate much higher input voltages because
leakage inductance limits rate of rise of current in the switch. These
designs must be evaluated individually to assure that current limit is well
controlled up to maximum input voltage.
Boost mode designs are never protected against output shorts because
the external catch diode and inductor connect input to output.
Note 3: Measured with V
2A for LT1171, and 1A for LT1172.
Note 4: For duty cycles (DC) between 50% and 80%, minimum guaranteed
switch current is given by I
(2 – DC) for the LT1171, and I
Note 5: Minimum input voltage for isolated flyback mode is 7V. V
for HV grade in fully isolated mode to avoid switch breakdown.
in hi clamp, VFB = 0.8V. ISW = 4A for LT1170,
C
= 3.33 (2 – DC) for the LT1170, I
LIM
= 0.833 (2 – DC) for the LT1172.
LIM
LIM
MAX
= 1.67
= 55V
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For more information www.linear.com/LT1170
5
LT1170/LT1171/LT1172
16
1.6
REFERENCE VOLTAGE CHANGE (mV)
1.250
FEEDBACK BIAS CURRENT (nA)
800
SUPPLY CURRENT (µA)
160
160
SUPPLY CURRENT (mA)
Typical perForMance characTerisTics
Switch Current Limit vs Duty Cycle* Minimum Input Voltage Switch Saturation Voltage
2.9
12
8
SWITCH CURRENT (A)
4
0
–55°C
125°C
* DIVIDE VERTICAL SCALE BY TWO FOR
LT1171, BY FOUR FOR LT1172.
30
20
DUTY CYCLE (%)
40
0
10
Line Regulation
5
4
3
2
1
0
TJ = –55°C
–1
–2
–3
–4
–5
10
0
20
INPUT VOLTAGE (V)
25°C
50
607080 90 100
TJ = 150°C
TJ = 25°C
30 40
1170/1/2 G01
50
1170/1/2 G04
2.8
2.7
2.6
2.5
MINIMUM INPUT VOLTAGE (V)
2.4
2.3
–75
Reference Voltage vs Temperature
1.248
1.246
1.244
1.242
1.240
1.238
REFERENCE VOLTAGE (V)
1.236
1.234
60
–75 –25
SWITCH CURRENT = I
SWITCH CURRENT = 0A
–50 0
–25
TEMPERATURE (°C)
–50 0
TEMPERATURE (°C)
50 150
25
50 150
25
MAX
100
125
75
1170/1/2 G02
1.4
1.2
1.0
0.8
0.6
0.4
SWITCH SATURATION VOLTAGE (V)
0.2
0
0
* DIVIDE CURRENT BY TWO FOR
LT1171, BY FOUR FOR LT1172.
2
1
SWITCH CURRENT (A)*
Feedback Bias Current
vs Temperature
700
600
500
400
300
200
100
100
125
75
1170/1/2 G05
0
–50 0
–75 –25
100°C
4 5 6 7
3
50 150
75
25
TEMPERATURE (°C)
150°C
–55°C
100
25°C
8
1170/1/2 G03
125
1170/1/2 G06
Supply Current vs Supply Voltage
(Shutdown Mode) Driver Current* vs Switch Current Supply Current vs Input Voltage*
TJ = 25°C
140
120
100
80
60
40
20
0
10 20
0
6
VC = 50mV
VC = 0V
30
SUPPLY VOLTAGE (V)
40
50
1170/1/2 G07
15
TJ = 25°C
140
120
100
80
60
DRIVER CURRENT (mA)
40
20
60
0
* AVERAGE LT1170 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.
0
1 2 3
TJ = –55°C
TJ = ≥ 25°C
SWITCH CURRENT (A)
4
1170/1/2 G08
5
14
NOTE THAT THIS CURRENT DOES NOT
13
INCLUDE DRIVER CURRENT, WHICH IS
12
A FUNCTION OF LOAD CURRENT AND
DUTY CYCLE.
11
10
9
8
7
6
5
10
0
* UNDER VERY LOW OUTPUT CURRENT CONDITIONS,
DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH
10% OR LESS.
20
INPUT VOLTAGE (V)
90% DUTY CYCLE
50% DUTY CYCLE
10% DUTY CYCLE
0% DUTY CYCLE
30 40
50
1170/1/2 G09
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60
For more information www.linear.com/LT1170
LT1170/LT1171/LT1172
TRANSCONDUCTANCE (µmho)
300
11
FEEDBACK VOLTAGE (mV)
500
1000
V
PIN CURRENT (µA)
TIME (µs)
23
Typical perForMance characTerisTics
Shutdown Mode Supply Current Error Amplifier Transconductance VC Pin Characteristics
200
180
160
140
120
100
80
60
SUPPLY CURRENT (µA)
40
20
0
102030
0
VC PIN VOLTAGE (mV)
TJ = 150°C
–55°C ≤ TJ ≤ 125°C
40
607080
50
90 100
1170/1/2 G10
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
–75 –25
–50 0
TEMPERATURE (°C)
∆I (V
gm =
∆V (FB PIN)
100
50 150
75
25
PIN)
C
125
1170/1/2 G11
VFB = 1.5V (CURRENT INTO VC PIN)
200
100
0
–100
PIN CURRENT (µA)
C
–200
V
–300
–400
VFB = 0.8V (CURRENT OUT OF VC PIN)
0.5
0 2.0
TJ = 25°C
1.5
1.0
VC PIN VOLTAGE (V)
2.5
1170/1/2 G12
Idle Supply Current vs Temperature
VC = 0.6V
10
9
8
V
7
6
5
4
IDLE SUPPLY CURRENT (mA)
3
2
1
–50 0
–75 –25
= 60V
SUPPLY
V
= 3V
SUPPLY
50 150
75
25
TEMPERATURE (°C)
100
125
1170/1/2 G13
Feedback Pin Clamp Voltage Switch “Off” Characteristics
450
400
350
300
250
200
150
100
50
0
0.1
0.3
0
0.4
0.2
FEEDBACK CURRENT (mA)
Shutdown Thresholds Flyback Blanking Time
400
CURRENT (OUT OF VC PIN)
350
300
250
200
150
PIN VOLTAGE (mV)
C
V
100
50
VC VOLTAGE IS REDUCED UNTIL
REGULATOR CURRENT DROPS
BELOW 300µA
0
–50 0
–75 –25
VOLTAGE
50 150
75
25
TEMPERATURE (°C)
–400
–350
–300
–250
–200
–150
–100
–50
125
1170/1/2 G16
0
100
2.2
2.0
C
1.8
1.6
1.4
1.2
1.0
–50 0
–75
–25
JUNCTION TEMPERATURE (°C)
–55°C
25°C
150°C
0.6
0.5
0.7
50 150
25
75
0.8
0.9 1.0
1170/1/2 G14
100
1170/1/2 G17
125
900
800
700
= 3V
102030
V
SUPPLY
= 15V
SWITCH VOLTAGE (V)
600
V
500
SUPPLY
400
300
SWITCH CURRENT (µA)
200
100
0
0
Isolated Mode Flyback
Reference Voltage
22
21
20
19
18
FLYBACK VOLTAGE (V)
17
16
15
–50 0
–75 –25
TEMPERATURE (°C)
V
SUPPLY
= 40V
40
607080
50
RFB = 500Ω
RFB = 1k
RFB = 10k
50 150
75
25
V
SUPPLY
= 55V
100
90 100
1170/1/2 G15
125
1170/1/2 G18
For more information www.linear.com/LT1170
117012fi
7
LT1170/LT1171/LT1172
TRANSCONDUCTANCE (µmho)
PHASE (DEG)
FEEDBACK PIN VOLTAGE (mV)
Typical perForMance characTerisTics
Transconductance of Error
Amplifier
7000
6000
5000
4000
3000
2000
1000
0
–1000
1k
10k 100k
FREQUENCY (Hz)
block DiagraM
V
IN
θ
g
m
1M 10M
1170/1/2 G19
–30
0
30
60
90
120
150
180
210
Normal/Flyback Mode Threshold on
Feedback Pin
500
490
480
470
460
450
440
430
420
410
400
FEEDBACK PIN VOLTAGE
(AT THRESHOLD)
FEEDBACK PIN CURRENT
–50
–25 25
0
SWITCH
16V
(AT THRESHOLD)
50
TEMPERATURE (°C)
OUT
75
100
125
1170/1/2 G20
–24
–22
FEEDBACK PIN CURRENT (µA)
–20
–18
–16
–14
–12
–10
–8
–6
–4
150
2.3V
REG
100kHz
OSC
MODE
SELECT
FB
–
ERROR
AMP
LOGIC DRIVER
COMP
V
C
FLYBACK
ERROR
AMP
5A, 75V
SWITCH
ANTI-
SAT
+
+
SHUTDOWN
CIRCUIT
1.24V
REF
†
ALWAYS CONNECT E1 TO THE GROUND PIN ON MINIDIP, 8- AND 16-PIN SURFACE MOUNT PACKAGES.
E1 AND E2 INTERNALLY TIED TO GROUND ON TO-3 AND TO-220 PACKAGES.
0.15V
(LT1170 AND LT1171 ONLY)
CURRENT
AMP
≈
GAIN 6
–
E1
0.02Ω
(0.04Ω
(0.16Ω
†
LT1172
LT1171)
LT1172)
0.16Ω
E2
1170/1/2 BD
8
117012fi
For more information www.linear.com/LT1170
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