LT1170-72 Datasheet

Linear Technology/Analog Devices

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Datasheet

LT1170/LT1171/LT1172
1
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For more information www.linear.com/LT1170
Typical applicaTion
FeaTures DescripTion
100kHz, 5A, 2.5A and 1.25A
High Efficiency Switching Regulators
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, con-
trol 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 exter-
nal 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.
Boost Converter (5V to 12V)
applicaTions
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
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.
Maximum Output Power*
1170/1/2 TA01
D1
MBR330
C2
1000µF
C1
1µF
R1
10.7k
1%
R2
1.24k
1%
LT1170
GND
VIN
5V
R3
1k
*REQUIRED IF INPUT LEADS 2" ** COILTRONICS 50-2-52
PULSE ENGINEERING 92114
VSW
FB
VC
OUTPUT
FILTER
L2
10µH
L1**
50µH
C3
100µF
12V
1A
C3*
100µF
+
+
INPUT VOLTAGE (V)
0
POWER (W) **
100
80
60
40
20
040
LT1170/1/2 TA02
10 20 30 50
* ROUGH GUIDE ONLY. BUCK MODE
POUT = (5A)(VOUT)
SPECIAL TOPOLOGIES DELIVER
MORE POWER.
** DIVIDE VERTICAL POWER SCALE
BY TWO FOR LT1171, BY FOUR
FOR LT1172.
BOOST
BUCK-BOOST
VO = 30V
FLYBACK
BUCK-BOOST
VO = 5V
LT1170
LT1170/LT1171/LT1172
2
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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
(Note 1)
pin conFiguraTion
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
1
2
3
4
8
7
6
5
TOP VIEW
GND
VC
FB
NC*
E2
VSW
E1
VIN
J8 PACKAGE
8-LEAD CERDIP
TJMAX = 125°C, θJA = 100°C/W
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
OBSOLETE
2
4
1
3
VSW VC
FB
CASE
IS GND
VIN
K PACKAGE
4-LEAD TO-3 METAL CAN
BOTTOM VIEW
LT1170MK: TJMAX = 150°C, θJC = 2°C/W, θJA = 35°C/W
LT1170CK: TJMAX = 100°C, θJC = 2°C/W, θJA = 35°C/W
LT1171MK: TJMAX = 150°C, θJC = 4°C/W, θJA = 35°C/W
LT1171CK: TJMAX = 100°C, θJC = 4°C/W, θJA = 35°C/W
LT1172MK: TJMAX = 150°C, θJC = 8°C/W, θJA = 35°C/W
LT1172CK: TJMAX = 100°C, θJC = 8°C/W, θJA = 35°C/W
Based on continuous operation.
TJMAX = 125°C for intermittent fault conditions.
OBSOLETE
N8 PACKAGE
8-LEAD PDIP
1
2
3
4
8
7
6
5
TOP VIEW
GND
VC
FB
NC*
E2
VSW
E1
VIN
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 100°C, θJA = 100°C/W (N)
TJMAX = 100°C, θJA = 120°C/W to 150°C/W
depending on board layout (S)
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
Q PACKAGE
5-LEAD DD
VIN
VSW
GND
FB
VC
FRONT VIEW
5
4
3
2
1
TAB IS
GND
TJMAX = 100°C, θJA = *°C/W
* 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.
TOP VIEW
SW PACKAGE
16-LEAD PLASTIC SO WIDE
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
NC
GND
VC
FB
NC
NC
NC
NC
NC
E2
VSW
E1
VIN
NC
NC
TJMAX = 100°C, θJA = 150°C/W
Based on continuous operation.
TJMAX = 125°C for intermittent fault conditions.
T PACKAGE
5-LEAD PLASTIC TO-220
VIN
VSW
GND
FB
VC
FRONT VIEW
5
4
3
2
1
TAB IS
GND
LT1170CT/LT1170HVCT: TJMAX =100°C, θJC = 2°C/W, θJA = 75°C/W
LT1171CT/LT1171HVCT: TJMAX =100°C, θJC = 4°C/W, θJA = 75°C/W
LT1172CT/LT1172HVCT: TJMAX =100°C, θJC = 8°C/W, θJA = 75°C/W
Based on continuous operation.
TJMAX = 125°C for intermittent fault conditions.
LT1170/LT1171/LT1172
3
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For more information www.linear.com/LT1170
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
LT1170/LT1171/LT1172
4
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For more information www.linear.com/LT1170
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 = VREF, output pin open, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VREF Reference Voltage Measured at Feedback Pin
VC = 0.8V
l
1.224
1.214
1.244
1.244
1.264
1.274
V
V
IBFeedback Input Current VFB = VREF
l
350 750
1100
nA
nA
gmError Amplifier Transconductance ∆IC = ±25µA
l
3000
2400
4400 6000
7000
µmho
µmho
Error Amplifier Source or Sink Current VC = 1.5V
l
150
120
200 350
400
µA
µA
Error Amplifier Clamp Voltage Hi Clamp, VFB = 1V
Lo Clamp, VFB = 1.5V
1.80
0.25
0.38
2.30
0.52
V
V
Reference Voltage Line Regulation 3V ≤ VIN ≤ VMAX
VC = 0.8V
l 0.03 %/V
AVError Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V 500 800 V/V
Minimum Input Voltage (Note 5) l2.6 3.0 V
IQSupply Current 3V ≤ VIN ≤ VMAX, VC = 0.6V 6 9 mA
Control Pin Threshold Duty Cycle = 0
l
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
VFB Flyback Reference Voltage (Note 5) IFB = 50µA
l
15.0
14.0
16.3 17.6
18.0
V
V
Change in Flyback Reference Voltage 0.05 ≤ IFB ≤ 1mA 4.5 6.8 9 V
Flyback Reference Voltage Line Regulation
(Note 5)
IFB = 50µA
7V ≤ VIN ≤ VMAX
0.01 0.03 %/V
Flyback Amplifier Transconductance (gm) ∆IC = ±10µA 150 300 650 µmho
Flyback Amplifier Source and Sink Current VC = 0.6V Source
IFB = 50µA Sink
l
l
15
25
32
40
70
70
µA
µA
BV Output Switch Breakdown Voltage 3V ≤ VIN ≤ VMAX, LT1170/LT1171/LT1172
ISW = 1.5mA LT1170HV/LT1171HV/LT1172HV
LT1172S8
l
l
l
65
75
60
90
90
80
V
V
V
VSAT Output Switch “On” Resistance (Note 3) LT1170
LT1171
LT1172
l
l
l
0.15
0.30
0.60
0.24
0.50
1.00
Ω
Ω
Ω
Control Voltage to Switch Current
T
ransconductance
LT1170
LT1171
LT1172
8
4
2
A/V
A/V
A/V
ILIM Switch Current Limit (LT1170) Duty Cycle = 50% TJ ≥ 25°C
Duty Cycle = 50% TJ < 25°C
Duty Cycle = 80% (Note 4)
l
l
l
5
5
4
10
11
10
A
A
A
(LT1171) Duty Cycle = 50% TJ ≥ 25°C
Duty Cycle = 50% TJ < 25°C
Duty Cycle = 80% (Note 4)
l
l
l
2.5
2.5
2.0
5.0
5.5
5.0
A
A
A
(LT1172) Duty Cycle = 50% TJ ≥ 25°C
Duty Cycle = 50% TJ < 25°C
Duty Cycle = 80% (Note 4)
l
l
l
1.25
1.25
1.00
3.0
3.5
2.5
A
A
A
∆IIN
∆ISW
Supply Current Increase During Switch
On-Time
25 35 mA/A
f Switching Frequency
l
88
85
100 112
115
kHz
kHz
LT1170/LT1171/LT1172
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SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
DCMAX Maximum Switch Duty Cycle l85 92 97 %
Shutdown Mode
Supply Current
3V ≤ VIN ≤ VMAX
VC = 0.05V
100 250 µA
Shutdown Mode
Threshold Voltage
3V ≤ VIN ≤ VMAX
l
100
50
150 250
300
mV
mV
Flyback Sense Delay Time (Note 5) 1.5 µs
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 = VREF, output pin open, unless otherwise noted.
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:
VIN (max, output shorted) =
15V +R
(
)
IL
(
)
+Vf
t
(
)
f
(
)
buck and inverting mode
R = Inductor DC resistance
IL = 10A for LT1170, 5A for LT1171, and 2.5A for LT1172
Vf = Output catch diode forward voltage at IL
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.
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 VC in hi clamp, VFB = 0.8V. ISW = 4A for LT1170,
2A for LT1171, and 1A for LT1172.
Note 4: For duty cycles (DC) between 50% and 80%, minimum guaranteed
switch current is given by ILIM = 3.33 (2 – DC) for the LT1170, ILIM = 1.67
(2 – DC) for the LT1171, and ILIM = 0.833 (2 – DC) for the LT1172.
Note 5: Minimum input voltage for isolated flyback mode is 7V. VMAX = 55V
for HV grade in fully isolated mode to avoid switch breakdown.
LT1170/LT1171/LT1172
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Typical perForMance characTerisTics
Line Regulation Reference Voltage vs Temperature
Feedback Bias Current
vs Temperature
Supply Current vs Supply Voltage
(Shutdown Mode) Driver Current* vs Switch Current Supply Current vs Input Voltage*
Switch Current Limit vs Duty Cycle* Minimum Input Voltage Switch Saturation Voltage
DUTY CYCLE (%)
0
SWITCH CURRENT (A)
16
12
8
4
040
1170/1/2 G01
20 30 50 60 70 80 90 100
25°C
125°C
–55°C
10
* DIVIDE VERTICAL SCALE BY TWO FOR
LT1171, BY FOUR FOR LT1172.
TEMPERATURE (°C)
–75
MINIMUM INPUT VOLTAGE (V)
–25 25 50 150
1170/1/2 G02
–50 0 75 100 125
2.9
2.8
2.7
2.6
2.5
2.4
2.3
SWITCH CURRENT = 0A
SWITCH CURRENT = IMAX
SWITCH CURRENT (A)*
0
SWITCH SATURATION VOLTAGE (V)
8
1170/1/2 G03
123
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
4 5 6 7
25°C
150°C
–55°C
100°C
* DIVIDE CURRENT BY TWO FOR
LT1171, BY FOUR FOR LT1172.
INPUT VOLTAGE (V)
0
REFERENCE VOLTAGE CHANGE (mV)
10 20 30 40
1170/1/2 G04
50
5
4
3
2
1
0
–1
–2
–3
–4
–5 60
TJ = 150°C
TJ = –55°C TJ = 25°C
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)
1170/1/2 G05
1.250
1.248
1.246
1.244
1.242
1.240
1.238
1.236
1.234
–75 –25 25 50 150
–50 0 75 100 125
TEMPERATURE (°C)
FEEDBACK BIAS CURRENT (nA)
1170/1/2 G06
800
700
600
500
400
300
200
100
0
–75 –25 25 50 150
–50 0 75 100 125
SUPPLY VOLTAGE (V)
0
10 20 30 40
140
120
100
80
60
40
20
0
50 60
1170/1/2 G07
VC = 50mV
VC = 0V
TJ = 25°C
SWITCH CURRENT (A)
0
DRIVER CURRENT (mA)
1 2 3
160
140
120
100
80
60
40
20
0
45
1170/1/2 G08
TJ = –55°C
TJ = ≥ 25°C
* AVERAGE LT1170 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (mA)
10 20 30 40
1170/1/2 G09
50
15
14
13
12
11
10
9
8
7
6
560
TJ = 25°C
NOTE THAT THIS CURRENT DOES NOT
INCLUDE DRIVER CURRENT, WHICH IS
A FUNCTION OF LOAD CURRENT AND
DUTY CYCLE.
90% DUTY CYCLE
50% DUTY CYCLE
10% DUTY CYCLE
0% DUTY CYCLE
* UNDER VERY LOW OUTPUT CURRENT CONDITIONS,
DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH
10% OR LESS.
LT1170/LT1171/LT1172
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Typical perForMance characTerisTics
Idle Supply Current vs Temperature Feedback Pin Clamp Voltage Switch “Off” Characteristics
Shutdown Thresholds Flyback Blanking Time
Isolated Mode Flyback
Reference Voltage
Shutdown Mode Supply Current Error Amplifier Transconductance VC Pin Characteristics
VC PIN VOLTAGE (mV)
0
SUPPLY CURRENT (µA)
200
180
160
140
120
100
80
60
40
20
0
40
1170/1/2 G10
10 20 30 50 60 70 80 90 100
TJ = 150°C
55°C ≤ TJ ≤ 125°C
TEMPERATURE (°C)
TRANSCONDUCTANCE (µmho)
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
1170/1/2 G11
–75 –25 25 50 150
–50 0 75 100 125
gm = I (VC PIN)
V (FB PIN)
VC PIN VOLTAGE (V)
300
200
100
0
–100
–200
–300
–400
1170/1/2 G12
VC PIN CURRENT (µA)
0 2.0
0.5 1.0 1.5 2.5
VFB = 1.5V (CURRENT INTO VC PIN)
VFB = 0.8V (CURRENT OUT OF VC PIN)
TJ = 25°C
TEMPERATURE (°C)
IDLE SUPPLY CURRENT (mA)
11
10
9
8
7
6
5
4
3
2
1
1170/1/2 G13
–75 –25 25 50 150
–50 0 75 100 125
VSUPPLY = 60V
VSUPPLY = 3V
VC = 0.6V
FEEDBACK CURRENT (mA)
0
FEEDBACK VOLTAGE (mV)
500
450
400
350
300
250
200
150
100
50
0
0.4
1170/1/2 G14
0.1 0.2 0.3 0.5 0.6 0.7 0.8 0.9 1.0
–55°C
25°C
150°C
SWITCH VOLTAGE (V)
0
SWITCH CURRENT (µA)
1000
900
800
700
600
500
400
300
200
100
0
40
1170/1/2 G15
10 20 30 50 60 70 80 90 100
VSUPPLY
= 55V
VSUPPLY
= 3V
VSUPPLY
= 15V
VSUPPLY
= 40V
TEMPERATURE (°C)
VC PIN VOLTAGE (mV)
1170/1/2 G16
400
350
300
250
200
150
100
50
0
–75 –25 25 50 150
–50 0 75 100 125
–400
–350
–300
–250
–200
–150
–100
–50
0
V
C
PIN CURRENT (µA)
CURRENT (OUT OF VC PIN)
VOLTAGE
VC VOLTAGE IS REDUCED UNTIL
REGULATOR CURRENT DROPS
BELOW 300µA
JUNCTION TEMPERATURE (°C)
–75
TIME (µs)
–25 25 50 150
1170/1/2 G17
–50 0 75 100 125
2.2
2.0
1.8
1.6
1.4
1.2
1.0
TEMPERATURE (°C)
FLYBACK VOLTAGE (V)
1170/1/2 G18
22
21
20
19
18
17
16
15
–75 –25 25 50 150
–50 0 75 100 125
RFB = 500Ω
RFB = 1k
RFB = 10k
LT1170/LT1171/LT1172
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Typical perForMance characTerisTics
block DiagraM
FREQUENCY (Hz)
1k
TRANSCONDUCTANCE (µmho)
7000
6000
5000
4000
3000
2000
1000
0
–1000 10k 100k
1170/1/2 G19
1M 10M
–30
0
30
60
90
120
150
180
210
PHASE (DEG)
θ
gm
TEMPERATURE (°C)
–50
FEEDBACK PIN VOLTAGE (mV)
500
490
480
470
460
450
440
430
420
410
400 050 75
1170/1/2 G20
–25 25 100 125 150
–24
–22
–20
–18
–16
–14
–12
–10
–8
–6
–4
FEEDBACK PIN CURRENT (µA)
FEEDBACK PIN CURRENT
(AT THRESHOLD)
FEEDBACK PIN VOLTAGE
(AT THRESHOLD)
Transconductance of Error
Amplifier
Normal/Flyback Mode Threshold on
Feedback Pin
1.24V
REF
1170/1/2 BD
ERROR
AMP
100kHz
OSC
2.3V
REG
VIN
FB
+
+
SHUTDOWN
CIRCUIT
VC
COMP
LOGIC DRIVER
ANTI-
SAT
FLYBACK
ERROR
AMP
16V
SWITCH
OUT
5A, 75V
SWITCH
0.02Ω
(0.04Ω
(0.16Ω
LT1171)
LT1172)
0.16Ω
CURRENT
AMP
GAIN 6
0.15V
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.
MODE
SELECT
E1E2
(LT1170 AND LT1171 ONLY)
LT1172
LT1170/LT1171/LT1172
9
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operaTion
The LT1170/LT1171/LT1172 are current mode switchers.
This means that switch duty cycle is directly controlled by
switch current rather than by output voltage. Referring to
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 voltage
is obtained by using the output of a voltage sensing er-
ror amplifier to set current trip level. This technique has
several advantages. First, it has immediate response to
input voltage variations, unlike ordinary switchers which
have notoriously poor line transient response. Second,
it reduces the 90° phase shift at midfrequencies in the
energy storage inductor
. This greatly simplifies closed
loop frequency compensation under widely varying input
voltage or output load conditions. Finally, it allows simple
pulse-by-pulse current limiting to provide maximum switch
protection under output overload or short conditions. A
low dropout internal regulator provides a 2.3V supply for
all internal circuitry on the LT1170/LT1171/LT1172. This
low dropout design allows input voltage to vary from 3V
to 60V with virtually no change in device performance. A
100kHz oscillator is the basic clock for all internal timing.
It turns “on” the output switch via the logic and driver
circuitry. Special adaptive anti-sat circuitry detects onset
of saturation in the power switch and adjusts driver current
instantaneously to limit switch saturation. This minimizes
driver dissipation and provides very rapid turnoff of the
switch.
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
LT1170/LT1171/LT1172 to disconnect the main error ampli-
fier output and connects the output of the flyback amplifier
to the comparator input. The L
T1170/L
T1171/LT1172 will
then regulate the value of the flyback pulse with respect
to the supply voltage.* This flyback pulse is directly pro-
portional to output voltage in the traditional transformer
coupled flyback topology regulator. By regulating the
amplitude of the flyback pulse, the output voltage can be
regulated with no direct connection between input and
output. The output is fully floating up to the breakdown
voltage of the transformer windings. Multiple floating
outputs are easily obtained with additional windings.
A special delay network inside the L
T1170/ LT1171/LT1172
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 func-
tions. It is used for frequency compensation, current limit
adjustment, soft-starting, and total regulator shutdown.
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
LT1170/LT1171/LT1172 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
Application Note 19 for full application details.
Extra Pins on the MiniDIP and Surface Mount
Packages
The 8- and 16-pin versions of the LT1172 have the emitters
of the power transistor brought out separately from the
ground pin. This eliminates errors due to ground pin voltage
drops and allows the user to reduce switch current limit
2:1 by leaving the second emitter (E2) disconnected. The
first emitter (E1) should always be connected to the ground
pin. Note that switch “on” resistance doubles when E2 is
left open, so efficiency will suffer somewhat when switch
currents exceed 300mA. Also, note that chip dissipation
will actually increase with E2 open during normal load
operation, even though dissipation in current limit mode
will decrease. See “Thermal Considerations” next.
Thermal Considerations When Using the MiniDIP and
SW Packages
The low supply current and high switch efficiency of the
LT1172 allow it to be used without a heat sink in most
applications when the TO-220 or TO-3 package is se-
lected. These packages are rated at 50°C/W and 35°C/W
respectively. The miniDIPs, however
, are rated at 100°C/W
in ceramic (J) and 130°C/W in plastic (N).
*See note under Block Diagram.
LT1170/LT1171/LT1172
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operaTion
Care should be taken for miniDIP applications to ensure that
the worst case input voltage and load current conditions
do not cause excessive die temperatures. The following
formulas can be used as a rough guide to calculate LT1172
power dissipation. For more details, the reader is referred
to Application Note 19 (AN19), “Efficiency Calculations”
section.
Average supply current (including driver current) is:
IIN ≈ 6mA + ISW (0.004 + DC/40)
ISW = switch current
DC = switch duty cycle
Switch power dissipation is given by:
PSW = (ISW)2 • (RSW)(DC)
RSW = LT1172 switch “on” resistance (1Ω maximum)
Total power dissipation is the sum of supply current times
input voltage plus switch power:
PD(TOT) = (IIN)(VIN) + PSW
In a typical example, using a boost converter to generate
12V at 0.12A from a 5V input, duty cycle is approximately
60%, and switch current is about 0.65A, yielding:
IIN = 6mA + 0.65(0.004 + DC/40) = 18mA
PSW = (0.65)2 • (1Ω)(0.6) = 0.25W
PD(TOT) = (5V)(0.018A) + 0.25 = 0.34W
Temperature rise in a plastic miniDIP would be 130°C/W
times 0.34W, or approximately 44°C. The maximum ambi-
ent temperature would be limited to 100°C (commercial
temperature limit) minus 44°C, or 56°C.
In most applications, full load current is used to calculate
die temperature. However, if overload conditions must
also be accounted for, four approaches are possible. First,
if loss of regulated output is acceptable under overload
conditions, the internal thermal limit of the LT1172 will
protect the die in most applications by shutting off switch
current. Thermal limit is not a tested parameter, however,
and should be considered only for noncritical applications
with temporary overloads. A second approach is to use the
larger TO-220 (T) or TO-3 (K) package which, even without
a heat sink, may limit die temperatures to safe levels under
overload conditions. In critical situations, heat sinking of
these packages is required; especially if overload conditions
must be tolerated for extended periods of time.
The third approach for lower current applications is to
leave the second switch emitter (miniDIP only) open. This
increases switch “on” resistance by 2:1, but reduces switch
current limit by 2:1 also, resulting in a net 2:1 reduction in
I2R switch dissipation under current limit conditions.
The fourth approach is to clamp the VC pin to a voltage
less than its internal clamp level of 2V. The LT1172 switch
current limit is zero at approximately 1V on the VC pin
and 2A at 2V on the VC pin. Peak switch current can be
externally clamped between these two levels with a diode.
See AN19 for details.
LT1170/LT1171/LT1172 Synchronizing
The LT1170/LT1171/LT1172 can be externally synchro-
nized in the frequency range of 120kHz to 160kHz. This
is accomplished as shown in the accompanying figures.
Synchronizing occurs when the VC pin is pulled to ground
with an external transistor. To avoid disturbing the DC
characteristics of the internal error amplifier, the width of
the synchronizing pulse should be under 0.3µs. C2 sets
the pulse width at 0.2µs. The effect of a synchronizing
pulse on the LT1170/LT1171/LT1172 amplifier offset can
be calculated from:
ΔVOS =
KT
q
tS
(
)
fS
(
)
IC+VC
R3
IC
KT
q=26mV at 25°C
tC = pulse width
fS = pulse frequency
IC = VC source current (≈200µA)
VC = operating VC voltage (1V to 2V)
R3 = resistor used to set mid-frequency “zero” in
frequency compensation network.
LT1170/LT1171/LT1172
11
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operaTion
With tS = 0.2µs, fS = 150kHz, VC = 1.5V, and R3 = 2k, offset
voltage shift is ≈ 3.8mV. This is not particularly bother-
some, but note that high offsets could result if R3 were
reduced to a much lower value. Also, the synchronizing
transistor must sink higher currents with low values of
R3, so larger drives may have to be used. The transistor
must be capable of pulling the VC pin to within 200mV of
ground to ensure synchronizing.
Synchronizing with Bipolar Transistor Synchronizing with MOS Transistor
1170/1/2 OP01
C2
39pF R1
3k
R2
2.2k
LT1170
GND
VIN
VC
C1
R3 2N2369
FROM 5V
LOGIC
1170/1/2 OP02
D1
1N4158
R2
2.2k
LT1170
GND
VIN
VC
C1
R3
FROM 5V
LOGIC
C2
100pF
D2
1N4158
* SILICONIX OR EQUIVALENT
VN2222*
Typical applicaTions
Flyback Converter
1170/1/2 TA03
D1
C1
2000µF
C4*
100µF
C2
0.15µF
R1
3.74k
R2
1.24k
VIN
20V TO 30V
R3
1.5k
*REQUIRED IF INPUT LEADS ≥ 2"
LT1170
VIN
VSW
FB
VC
OPTIONAL
FILTER
L2
5µH
C4
100µF
VOUT
5V
6A
VSNUB
CLAMP TURN-ON
SPIKE
PRIMARY FLYBACK VOLTAGE =
LT1170 SWITCH VOLTAGE
AREA “a” = AREA “b” TO MAINTAIN
ZERO DC VOLTS ACROSS PRIMARY
SECONDARY VOLTAGE
AREA “c” = AREA “d” TO MAINTAIN
ZERO DC VOLTS ACROSS SECONDARY
PRIMARY CURRENT
SECONDARY CURRENT
LT1170 SWITCH CURRENT
SNUBBER DIODE CURRENT
VOUT + Vf
N
0V
VIN
a
b
0V
c
d
VOUT + Vf
N • VIN
IIPRI
0
IPRI/N
IPRI
IPRI
t = (IPRI)(LL)
VSNUB
0
0
0
1
N* = 1/3
N*
D3
25V
1W
D2
MUR110
GND
+
+
LT1170/LT1171/LT1172
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Typical applicaTions
(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)
LCD Contrast Supply
C4
0.047µF
VOUT
–10V TO –26V
1170/1/2 TA04
R3
15k
OPTIONAL
SHUTDOWN
R2
100k
R1
200k
C1
1µF
TANTALUM
D1
1N914
C3
0.0047µF
C2***
2µF
TANTALUM
D2
VN2222
5V* L1**
50µH VBAT*
3V TO 20V
VIN
VC
FB
VSW
LT1172
E2
E1
GND
D3
*
**
***
D2, D3 = ER82.004 600mA SCHOTTKY. OTHER FAST SWITCHING TYPES MAY BE USED.
VIN AND BATTERY MAY BE TIED TOGETHER. MAXIMUM VALUE FOR VBAT IS EQUAL TO THE |NEGATIVE OUTPUT| + 1V. WITH HIGHER
BATTERY VOLTAGES, HIGHEST EFFICIENCY IS OBTAINED BY RUNNING THE LT1172 VIN PIN FROM 5V. SHUTTING OFF THE 5V SUPPLY
WILL AUTOMATICALLY TURN OFF THE LT1172. EFFICIENCY IS ABOUT 80% AT IOUT = 25mA.
R1, R2, R3 ARE MADE LARGE TO MINIMIZE BATTERY DRAIN IN SHUTDOWN, WHICH IS APPROXIMATELY VBAT /(R1 + R2 + R3).
FOR HIGH EFFICIENCY, L1 SHOULD BE MADE ON A FERRITE OR MOLYPERMALLOY CORE. PEAK INDUCTOR CURRENTS ARE ABOUT
600mA AT POUT = 0.7Ω. INDUCTOR SERIES RESISTANCE SHOULD BE LESS THAN 0.4Ω FOR HIGH EFFICIENCY.
OUTPUT RIPPLE IS ABOUT 200mVP-P TO 400mVP-P WITH C2 = 2µF TANTALUM. IF LOWER RIPPLE IS DESIRED, INCREASE C2, OR ADD
A 10Ω, 1µF TANTALUM OUTPUT FILTER.
+
+
Driving High Voltage FET
(for Off-Line Applications, See AN25)
External Current Limit
1170/1/2 TA05
VIN VSW
LT1170
GND
10V TO
20V
D1
+
D
GQ1
1170/1/2 TA06
VX
D1
LT1170
GND
R2
2V VC
R1
500Ω
LT1170/LT1171/LT1172
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Typical applicaTions
(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)
Negative-to-Positive Buck-Boost ConverterExternal Current Limit
Negative Buck Converter
C4*
100µF
VOUT
12V
2A
1170/1/2 TA07
R3
2.2k
C2
1000µF
D1
C1
0.22µF
Q1
VIN
VC
FB
VSW
LT1170
GND
OPTIONAL
INPUT FILTER
L3
VIN
–20V
REQUIRED IF INPUT LEADS ≥ 2"
PULSE ENGINEERING 92114, COILTRONICS 50-2-52
*
**
R2
1.24k
L1**
50µH
OPTIONAL
OUTPUT
FILTER
C3
L2
R1
11.3k
THIS CIRCUIT IS OFTEN USED TO CONVERT –48V TO 5V. TO GUARANTEE
FULL SHORT-CIRCUIT PROTECTION, THE CURRENT LIMIT CIRCUIT SHOWN
IN AN19, FIGURE 39, SHOULD BE ADDED WITH C1 REDUCED TO 200pF.
++
1170/1/2 TA08
R2
C2
VIN
VC
FB
VSW
LT1170
GND
VIN
NOTE THAT THE LT1170
GND PIN IS NO LONGER
COMMON TO VIN.
R1
1k
+
C1
1000pF
Q1
RS
C3*
100µF
–5.2V
4.5A
1170/1/2 TA09
R3
L1**
50µH
R1
4.64k
C2
1000µF
D1
C1
Q1
2N3906
VIN
VC
FB
VSW
LT1170
GND
OPTIONAL
INPUT FILTER
L3
VIN
–20V
LOAD
REQUIRED IF INPUT LEADS ≥ 2"
PULSE ENGINEERING 92114
COILTRONICS 50-2-52
*
**
R2
1.24k
R4
12k
OPTIONAL
OUTPUT
FILTER
C4
200µF
+
+
+
LT1170/LT1171/LT1172
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Typical applicaTions
Positive-to-Negative Buck-Boost Converter
C4
1µF
VIN
10V TO
30V
1170/1/2 TA10
R3
5k
C5
100µF*
D3
1N4001
C2
0.1µF
VIN
VC
FB
VSW
LT1170
GND
VOUT
–12V
2A
REQUIRED IF INPUT LEADS ≥ 2"
PULSE ENGINEERING 92114, COILTRONICS 50-2-52
*
**
R2
1.24k
L1**
50µH
R5
470Ω, 1W
TO AVOID STARTUP 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.
C3
2µF
D2
1N914 R4
47Ω
C1
1000µF
D1
R6
470Ω
R1
10.7k
+
+
+ +
High Efficiency Constant Current Charger
D2
MBR340
1170/1/2 TA11
INPUT VOLTAGE
> VBAT + 2V < 35V
C2
2.2µF
35V
TANTALUM
R7
22k
R8
1k
C3
0.47µF
V+
V
R4
1k
C4
200µF
25V BATTERY
2V TO 25V
L2*
10µH, 1A
L1
100µH, 1A
R5
0.05Ω
R3
25k
R2
1k
RUN = 0V
SHUTDOWN = 5V
* L2 REDUCES RIPPLE CURRENT INTO
THE BATTERY BY ABOUT 20:1.
IT MAY BE OMITTED IF DESIRED.
I = 1.244V R4
R3 • R5 = 1A AS SHOWN
CHRG
R6
78k
VIN
C
VFB
VSW
GND
D1
1N5819
C4
0.01µF
LT1006
+
+
LT1171
C1
200µF
35V
1A
2N3904
+ +
+
+
GND
2µF
1170/1/2 TA12
D1
1N914
33pF
3kV
10µF
TANT
R3
10k
50k
INTENSITY
ADJUST
1N5818 L1**
300µH
INPUT VOLTAGE
4.5V TO 20V
Q1,Q2 = BCP56 OR MPS650/561
COILTRONICS CTX300-4
SUMIDA 6345-020 OR COILTRONICS 110092-1
A MODIFICATION WILL ALLOW OPERATION DOWN TO 4.5V. CONSULT FACTORY.
*
**
***
C6
1µF
R1
560Ω
1k
LT1172
IN
V
VC
VSW
E2
E1
D2
1N914
LAMP
FB
L2***
0.02µF
A
B
Q1*
Q2*
+
+
Backlight CCFL Supply (see AN45 for details)
LT1170/LT1171/LT1172
15
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Typical applicaTions
Positive Buck Converter
C5*
100µF
V
IN
1170/1/2 TA13
R3
470Ω
5V, 4.5A
D2
1N914
C1
1µF
VIN
VC
FB
VSW
LT1170
GND
REQUIRED IF INPUT LEADS ≥ 2"
PULSE ENGINEERING 92114
COILTRONICS 50-2-52
*
**
R1
3.74k
L1**
50µH
R4
10Ω
C3
2.2µF
D1
r
R2
1.24k
C2
1µF
C4
1000µF
100mA
MINIMUM
D3
OPTIONAL
OUTPUT
FILTER
C5
200µF
L2
4µH
+
+
+
+
Negative Boost Regulator
C4*
470µF
1170/1/2 TA14
R3
3.3k
C3
10µF
D1
C2
0.22µF
VIN
VC
FB
LT1170
GND
VIN
–15V
REQUIRED IF INPUT LEADS ≥ 2"
*
R2
1.24k
D2
R1
27k
VSW
L1
50µH
C1
1000µF
RO
(MINIMUM
LOAD)
VOUT
–28V, 1A
+
+ +
Driving High Voltage NPN
1170/1/2 TA15
D2
C1
SETS IB (ON)
SETS IB (OFF)
*
**
R2**
VIN
VSW
LT1170
GND
D1
Q1
R1*
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Typical applicaTions
Forward Converter
1170/1/2 TA16
C1
2000µF
C3
R4
R2
1.24k
VIN
20V TO 30V
R3
LT1170
VIN
VSW
FB
VC
1N
D3
L1
25µH
C4
R6
330Ω
R5
1
C2 M
D2
D1 VOUT
5V, 6A
T1
Q1
D4
R1
3.74k
GND
+
High Efficiency 5V Buck Converter
+
VSW
FB
GND
VIN
VC
LT1170
+C1
330µF
35V
C6
0.02µF
C4
0.1µF
R1
680Ω C5
0.03µF
D1
MBR330p
C3
4.7µF
TANT
D2
1N4148
L1
50µH R2*
0.013Ω
C2
390µF
16V
VOUT
5V
3A**
+
×
MODE LOGIC
220pF
<0.3V = NORMAL MODE
>2.5V = SHUTDOWN
OPEN = BURST MODE
* R2 IS MADE FROM PC BOARD
COPPER TRACES.
** MAXIMUM CURRENT IS DETERMINED
BY THE CHOICE OF LT1070 FAMILY.
SEE APPLICATION SECTION.
V
IN
1170/1/2 TA17
OPTIONAL
OUTPUT
FILTER
100µF
16V
10µH
3A
+
VC
GND
MODE
DIODE
VOUT
VLIM
V+
LT1432
VIN
LT1170/LT1171/LT1172
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J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
J8 0801
.014 – .026
(0.360 – 0.660)
.200
(5.080)
MAX
.015 – .060
(0.381 – 1.524)
.125
3.175
MIN
.100
(2.54)
BSC
.300 BSC
(7.62 BSC)
.008 – .018
(0.203 – 0.457) 0 – 15
.005
(0.127)
MIN
.405
(10.287)
MAX
.220 – .310
(5.588 – 7.874)
1 2 34
8 7 6 5
.025
(0.635)
RAD TYP
.045 – .068
(1.143 – 1.650)
FULL LEAD
OPTION
.023 – .045
(0.584 – 1.143)
HALF LEAD
OPTION
CORNER LEADS OPTION
(4 PLCS)
.045 – .065
(1.143 – 1.651)
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
K Package
4-Lead TO-3 Metal Can
(Reference LTC DWG # 05-08-1311)
K4(TO-3) 0801
72°
18°
.490 – .510
(12.45 – 12.95)
R
.470 TP
P.C.D.
.167 – .177
(4.24 – 4.49)
R
.151 – .161
(3.84 – 4.09)
DIA 2 PLC
.655 – .675
(16.64 – 19.05)
1.177 – 1.197
(29.90 – 30.40)
.038 – .043
(0.965 – 1.09)
.060 – .135
(1.524 – 3.429)
.320 – .350
(8.13 – 8.89)
.420 – .480
(10.67 12.19)
.760 – .775
(19.30 – 19.69)
(OBSOLETE PACKAGE)
package DescripTion
Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.
LT1170/LT1171/LT1172
18
117012fi
For more information www.linear.com/LT1170
package DescripTion
Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.
N8 REV I 0711
.065
(1.651)
TYP
.045 – .065
(1.143 – 1.651)
.130 ±.005
(3.302 ±0.127)
.020
(0.508)
MIN
.018 ±.003
(0.457 ±0.076)
.120
(3.048)
MIN
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325 +.035
–.015
+0.889
–0.381
8.255
( )
1 2 34
87 65
.255 ±.015*
(6.477 ±0.381)
.400*
(10.160)
MAX
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.100
(2.54)
BSC
N Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510 Rev I)
LT1170/LT1171/LT1172
19
117012fi
For more information www.linear.com/LT1170
package DescripTion
Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.
Q(DD5) 0811 REV F
.028 – .038
(0.711 – 0.965)
TYP
.143 +.012
–.020
( )
3.632+0.305
–0.508
.067
(1.702)
BSC
.013 – .023
(0.330 – 0.584)
.095 – .115
(2.413 – 2.921)
.004 +.008
–.004
( )
0.102+0.203
–0.102
.050 ±.012
(1.270 ±0.305)
.059
(1.499)
TYP
.045 – .055
(1.143 – 1.397)
.165 – .180
(4.191 – 4.572)
.330 – .370
(8.382 – 9.398)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
15° TYP
.420
.350
.585
.090
.042
.067
RECOMMENDED SOLDER PAD LAYOUT
.325
.205
.080
.585
.090
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
.042
.067
.420
.276
.320
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.300
(7.620)
.075
(1.905)
.183
(4.648)
.060
(1.524)
.060
(1.524)
.256
(6.502)
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
Q Package
5-Lead Plastic DD Pak
(Reference LTC DWG # 05-08-1461 Rev F)
DETAIL A
DETAIL A
0° – 7° TYP0° – 7° TYP
LT1170/LT1171/LT1172
20
117012fi
For more information www.linear.com/LT1170
package DescripTion
Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 REV G 0212
.053 – .069
(1.346 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030
±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
LT1170/LT1171/LT1172
21
117012fi
For more information www.linear.com/LT1170
SW Package
16-Lead Plastic Small Outline (Wide .300 Inch)
(Reference LTC DWG # 05-08-1620)
S16 (WIDE) 0502
NOTE 3
.398 – .413
(10.109 – 10.490)
NOTE 4
16 15 14 13 12 11 10 9
1
N
2 3 4567 8
N/2
.394 – .419
(10.007 – 10.643)
.037 – .045
(0.940 – 1.143)
.004 – .012
(0.102 – 0.305)
.093 – .104
(2.362 – 2.642)
.050
(1.270)
BSC .014 – .019
(0.356 – 0.482)
TYP
0 – 8 TYP
NOTE 3
.009 – .013
(0.229 – 0.330)
.005
(0.127)
RAD MIN
.016 – .050
(0.406 – 1.270)
.291 – .299
(7.391 – 7.595)
NOTE 4
× 45°
.010 – .029
(0.254 – 0.737)
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
2. DRAWING NOT TO SCALE
3. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS
4. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
.420
MIN
.325 .005
RECOMMENDED SOLDER PAD LAYOUT
.045 .005
N
1 2 3 N/2
.050 BSC
.030 .005
TYP
package DescripTion
Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.
LT1170/LT1171/LT1172
22
117012fi
For more information www.linear.com/LT1170
T Package
5-Lead Plastic TO-220 (Standard)
(Reference LTC DWG # 05-08-1421)
T5 (TO-220) 0801
.028 – .038
(0.711 – 0.965)
.067
(1.70) .135 – .165
(3.429 – 4.191)
.700 – .728
(17.78 – 18.491)
.045 – .055
(1.143 – 1.397)
.095 – .115
(2.413 – 2.921)
.013 – .023
(0.330 – 0.584)
.620
(15.75)
TYP
.155 – .195*
(3.937 – 4.953)
.152 – .202
(3.861 – 5.131)
.260 – .320
(6.60 – 8.13)
.165 – .180
(4.191 – 4.572)
.147 – .155
(3.734 – 3.937)
DIA
.390 – .415
(9.906 – 10.541)
.330 – .370
(8.382 – 9.398)
.460 .500
(11.684 12.700)
.570 – .620
(14.478 – 15.748)
.230 – .270
(5.842 – 6.858)
BSC
SEATING PLANE
* MEASURED AT THE SEATING PLANE
package DescripTion
Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.
LT1170/LT1171/LT1172
23
117012fi
For more information www.linear.com/LT1170
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
G 3/10 Updated to Reactivate LT1172M from Obsoleted Parts List 2
H 6/16 Removed #PBF from MJ8 part number in first line 3
I 3/17 Corrected Flyback Amplifier Source and Sink Current units to µA from mA
Obsoleted LT1172M and LT1172MJ8
4
2, 3
(Revision history begins at Rev G)
LT1170/LT1171/LT1172
24
117012fi
For more information www.linear.com/LT1170
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
LINEAR TECHNOLOGY CORPORATION 1991
LT 0317 REV I • PRINTED IN USA
(408) 432-1900 FAX: (408) 434-0507 www.linear.com/LT1170
relaTeD parTs
Typical applicaTion
Positive Current Boosted Buck Converter
1170/1/2 TA18
C1
0.33µF
470Ω
2W
R7
1k
VIN
28V
R3
680Ω
LT1170
VIN
VSW
FB
VC
1: N
D2
R2
1.24k
C3
0.47µF
D1
VOUT
5V, 10A
N ≈ 0.25
R4
1.24k
GND
C5*
100µF
R6
470Ω
C6
0.002µF
+
C4
0.01µF
7
VIN
6
4
8
200pF
2
3
R5
5k
R1
5k C2
5000µF
* REQUIRED IF INPUT LEADS ≥ 2"
LM308
+
+
PART NUMBER DESCRIPTION COMMENTS
LT1070/LT1071/LT1072 5A/2.5A/1.25A High Efficiency Switching Regulators 40kHz, VIN to 60V, VSW to 75V
LT1074/LT1076 5.5A/2A Step-Down Switching Regulators 100kHz, Also for Positive-to-Negative Conversion
LT1082 1A, High Voltage, High Efficiency Switching Regulator VIN to 75V, VSW to 100V, Telecom
LT1268/LT1268B 7.5A, 150kHz Switching Regulators VIN to 30V, VSW to 60V
LT1269/LT1271 4A High Efficiency Switching Regulators 100kHz/60kHz, VIN to 30V, VSW to 60V
LT1270/LT1270A 8A and 10A High Efficiency Switching Regulators 60kHz, VIN to 30V, VSW to 60V
LT1370 500kHz High Efficiency 6A Switching Regulator High Power Boost, Flyback, SEPIC
LT1371 500kHz High Efficiency 3A Switching Regulator Good for Boost, Flyback, Inverting, SEPIC
LT1372/LT1377 500kHz and 1MHz High Efficiency 1.5A Switching Regulators Directly Regulates ±VOUT
LT1373 250kHz Low Supply Current High Efficiency 1.5A Switching Regulator Low 1mA Quiescent Current
LT1374 4A, 500kHz Step-Down Switching Regulator Synchronizable, VIN to 25V
LT1375/LT1376 1.5A, 500kHz Step-Down Switching Regulators Up to 1.25A Out from an SO-8
LT1425 Isolated Flyback Switching Regulator 6W Output, ±5% Regulation, No Optocoupler Needed
LT1507 500kHz Monolithic Buck Mode Switching Regulator 1.5A Switch, Good for 5V to 3.3V
LT1533 Ultralow Noise 1A Switching Regulator Push-Pull, <100µVP-P Output Noise

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