LT1171_15 [Linear]
100kHz, 5A, 2.5A and 1.25A High Efficiency Switching Regulators;
| 型号： | LT1171_15 |
| 厂家： | 
Linear |
| 描述： | 100kHz, 5A, 2.5A and 1.25A High Efficiency Switching Regulators |
| 文件： | 总24页 (文件大小：236K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1170/LT1171/LT1172
100kHz, 5A, 2.5A and 1.25A
High Efficiency Switching Regulators
FEATURES
DESCRIPTION
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,invertingand“Cuk.”Ahighcurrent,highefficiency
n
Wide Input Voltage Range: 3V to 60V
n
Low Quiescent Current: 6mA
Internal 5A Switch
n
(2.5A for LT1171, 1.25A for LT1172)
n
switch is included on the die along with all oscillator, con-
trol and protection circuitry. Integration of all functions
allowstheLT1170/LT1171/LT1172tobebuiltinastandard
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.
Shutdown Mode Draws Only 50μA Supply Current
n
Very Few External Parts Required
Self-Protected Against Overloads
n
n
Operates in Nearly All Switching Topologies
n
Flyback-Regulated Mode Has Fully Floating Outputs
n
Comes in Standard 5-Pin Packages
n
n
LT1172 Available in 8-Pin MiniDIP and
Surface Mount Packages
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.
Can Be Externally Synchronized
APPLICATIONS
n
Logic Supply 5V at 10A
n
5V Logic to 15V Op Amp Supply
n
Battery Upconverter
TheLT1170/LT1171/LT1172havemanyuniquefeaturesnot
found even on the vastly more difficult to use low power
controlchipspresentlyavailable.Theyuseadaptiveantisat
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.
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.
L, LT, LTC, LTM, Linear Technology, the Linear logo and SwitcherCAD are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
TYPICAL APPLICATION
Boost Converter (5V to 12V)
Maximum Output Power*
100
* ROUGH GUIDE ONLY. BUCK MODE
L1**
5V
L2
OUTPUT
FILTER
LT1170
P
= (5A)(V
)
50μH
OUT
OUT
10μH
SPECIAL TOPOLOGIES DELIVER
MORE POWER.
80
60
40
20
0
C3
100μF
** DIVIDE VERTICAL POWER SCALE
BY TWO FOR LT1171, BY FOUR
FOR LT1172.
BUCK-BOOST
= 30V
D1
V
O
V
IN
MBR330
12V
1A
BOOST
V
SW
LT1170/1/2 TA02
FLYBACK
+
R1
C2
1000μF
10.7k
LT1170
+
1%
C3*
100μF
FB
V
C
GND
BUCK-BOOST
R2
1.24k
1%
V
= 5V
R3
1k
C1
1μF
O
0
10
20
30
40
50
INPUT VOLTAGE (V)
*REQUIRED IF INPUT LEADS r 2"
** COILTRONICS 50-2-52
PULSE ENGINEERING 92114
1170/1/2 TA01
117012fg
1
LT1170/LT1171/LT1172
(Note 1)
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
Operating Junction Temperature Range
LT1170/LT1171/LT1172HV (Note 2).......................60V
LT1170/LT1171/LT1172 (Note 2)............................40V
Switch Output Voltage
LT1170M/LT1171M (OBSOLETE) ....... –55°C to 150°C
LT1172M............................................ –55°C to 125°C
LT1170/LT1171/LT1172HVC,
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
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
PIN CONFIGURATION
BOTTOM VIEW
V
V
TOP VIEW
SW
C
TOP VIEW
1
4
GND
1
2
3
4
E2
V
8
7
6
5
2
3
CASE
IS GND
GND
1
2
3
4
E2
V
8
7
6
5
V
C
SW
V
C
SW
FB
E1
V
V
FB
IN
FB
E1
V
K PACKAGE
4-LEAD TO-3 METAL CAN
NC*
IN
NC*
IN
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
LT1170MK: T
= 150°C, θ = 2°C/W, θ = 35°C/W
JC JA
JMAX
JMAX
J8 PACKAGE
LT1170CK: T
= 100°C, θ = 2°C/W, θ = 35°C/W
JC JA
8-LEAD CERDIP
LT1171MK: T
= 150°C, θ = 4°C/W, θ = 35°C/W
JC JA
JMAX
JMAX
JMAX
T
JMAX
= 100°C, θ = 100°C/W (N)
JA
JMAX
LT1171CK: T
LT1172MK: T
LT1172CK: T
= 100°C, θ = 4°C/W, θ = 35°C/W
JC JA
T
= 125°C, θ = 100°C/W
T
= 100°C, θ = 120°C/W to 150°C/W
JMAX
JA
JA
= 150°C, θ = 8°C/W, θ = 35°C/W
JC
JA
depending on board layout (S)
= 100°C, θ = 8°C/W, θ = 35°C/W
JMAX
JC JA
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
Based on continuous operation.
= 125°C for intermittent fault conditions.
* Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
T
JMAX
OBSOLETE
TOP VIEW
FRONT VIEW
NC
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
NC
E2
V
FRONT VIEW
5
4
3
2
1
V
V
5
4
3
2
1
V
V
GND
FB
IN
IN
SW
GND
SW
GND
FB
V
C
SW
V
FB
NC
NC
NC
E1
V
C
V
C
Q PACKAGE
5-LEAD DD
IN
T PACKAGE
5-LEAD PLASTIC TO-220
NC
NC
T
= 100°C, θ = *°C/W
JA
JMAX
LT1170CT/LT1170HVCT: T
LT1171CT/LT1171HVCT: T
LT1172CT/LT1172HVCT: T
=100°C, θ = 2°C/W, θ = 75°C/W
JC JA
JMAX
JMAX
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.
=100°C, θ = 4°C/W, θ = 75°C/W
JC
JC
JA
JA
SW PACKAGE
16-LEAD PLASTIC SO WIDE
=100°C, θ = 8°C/W, θ = 75°C/W
Based on continuous operation.
= 125°C for intermittent fault conditions.
T
T
= 100°C, θ = 150°C/W
JA
JMAX
JMAX
Based on continuous operation.
T
= 125°C for intermittent fault conditions.
JMAX
117012fg
2
LT1170/LT1171/LT1172
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
–55°C to 125°C
0°C to 100°C
LT1172MJ8#PBF
LT1172MJ8#TRPBF
LT1172CJ8#TRPBF
LT1170MK#TRPBF
LT1170CK#TRPBF
LT1171MK#TRPBF
LT1171CK#TRPBF
LT1172MK#TRPBF
LT1172CK#TRPBF
LT1172CN8#TRPBF
LT1172IN8#TRPBF
LT1172CS8#TRPBF
LT1172IS8#TRPBF
LT1170CQ#TRPBF
LT1170IQ#TRPBF
LT1170HVCQ#TRPBF
LT1171CQ#TRPBF
LT1171IQ#TRPBF
LT1171HVCQ#TRPBF
LT1171HVIQ#TRPBF
LT1172CQ#TRPBF
LT1172HVCQ#TRPBF
LT1172HVIQ#TRPBF
LT1172CSW#TRPBF
LT1170CQ#TRPBF
LT1170IT#TRPBF
8-Lead CERDIP
LT1172CJ8#PBF (OBSOLETE)
LT1170MK#PBF (OBSOLETE)
LT1170CK#PBF (OBSOLETE)
LT1171MK#PBF (OBSOLETE)
LT1171CK#PBF (OBSOLETE)
LT1172MK#PBF (OBSOLETE)
LT1172CK#PBF (OBSOLETE)
LT1172CN8#PBF
8-Lead CERDIP
4-Lead TO-3 Metal Can
4-Lead TO-3 Metal Can
4-Lead TO-3 Metal Can
4-Lead TO-3 Metal Can
4-Lead TO-3 Metal Can
4-Lead TO-3 Metal Can
8-Lead PDIP or 8-Lead Plastic SO
8-Lead PDIP or 8-Lead Plastic SO
8-Lead PDIP or 8-Lead Plastic SO
8-Lead PDIP or 8-Lead Plastic SO
5-Lead DD
–55°C to 125°C
0°C to 100°C
–55°C to 125°C
0°C to 100°C
–55°C to 125°C
0°C to 100°C
0°C to 100°C
LT1172IN8#PBF
–40°C to 100°C
0°C to 100°C
LT1172CS8#PBF
1172
LT1172IS8#PBF
1172I
–40°C to 100°C
0°C to 100°C
LT1170CQ#PBF
LT1170IQ#PBF
5-Lead DD
–40°C to 100°C
0°C to 100°C
LT1170HVCQ#PBF
LT1171CQ#PBF
5-Lead DD
5-Lead DD
0°C to 100°C
LT1171IQ#PBF
5-Lead DD
–40°C to 100°C
0°C to 100°C
LT1171HVCQ#PBF
LT1171HVIQ#PBF
5-Lead DD
5-Lead DD
–40°C to 100°C
0°C to 100°C
LT1172CQ#PBF
5-Lead DD
LT1172HVCQ#PBF
LT1172HVIQ#PBF
5-Lead DD
0°C to 100°C
5-Lead DD
–40°C to 100°C
0°C to 100°C
LT1172CSW#PBF
16-Lead Plastic SO Wide
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
5-Lead Plastic TO-220
LT1170CT#PBF
0°C to 100°C
LT1170IT#PBF
–40°C to 100°C
0°C to 100°C
LT1170HVCT#PBF
LT1170HVIT#PBF
LT1170HVCT#TRPBF
LT1170HVIT#TRPBF
LT1171CT#TRPBF
LT1171IT#TRPBF
–40°C to 100°C
0°C to 100°C
LT1171CT#PBF
LT1171IT#PBF
–40°C to 100°C
0°C to 100°C
LT1171HVCT#PBF
LT1171HVIT#PBF
LT1171HVCT#TRPBF
LT1171HVIT#TRPBF
LT1172CT#TRPBF
LT1172HVCT#TRPBF
–40°C to 100°C
0°C to 100°C
LT1172CT#PBF
LT1172HVCT#PBF
0°C to 100°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
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/
117012fg
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 = VREF, output pin open, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Reference Voltage
Measured at Feedback Pin
C
1.224 1.244
1.214 1.244
1.264
1.274
V
V
REF
V = 0.8V
l
l
l
l
I
Feedback Input Current
V
FB
= V
REF
350
750
1100
nA
nA
B
g
Error Amplifier Transconductance
Error Amplifier Source or Sink Current
Error Amplifier Clamp Voltage
Reference Voltage Line Regulation
ΔI = 25μA
C
3000
2400
4400
200
6000
7000
μmho
μmho
m
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
3V ≤ V ≤ V
C
l
l
l
l
0.03
%/V
IN
MAX
V = 0.8V
A
V
Error Amplifier Voltage Gain
Minimum Input Voltage (Note 5)
Supply Current
0.9V ≤ V ≤ 1.4V
500
800
2.6
6
V/V
V
C
3.0
9
I
Q
3V ≤ V ≤ V
, V = 0.6V
mA
IN
MAX
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
Flyback Reference Voltage (Note 5)
0.4
0.45
16.3
0.54
V
V
I
FB
= 50μA
15.0
14.0
17.6
18.0
V
V
FB
Change in Flyback Reference Voltage
0.05 ≤ I ≤ 1mA
4.5
6.8
9
V
FB
Flyback Reference Voltage Line Regulation
(Note 5)
I
= 50μA
0.01
0.03
%/V
FB
7V ≤ V ≤ V
IN
MAX
Flyback Amplifier Transconductance (g )
ΔI = 10μA
C
150
300
650
μmho
m
l
l
Flyback Amplifier Source and Sink Current V = 0.6V
Source
Sink
15
25
32
40
70
70
mA
mA
C
I
= 50μA
FB
l
l
l
BV
Output Switch Breakdown Voltage
3V ≤ V ≤ V
SW
,
LT1170/LT1171/LT1172
LT1170HV/LT1171HV/LT1172HV
LT1172S8
65
75
60
90
90
80
V
V
V
IN
MAX
I
= 1.5mA
l
l
l
V
SAT
Output Switch “On” Resistance (Note 3)
LT1170
LT1171
LT1172
0.15
0.30
0.60
0.24
0.50
1.00
Ω
Ω
Ω
Control Voltage to Switch Current
Transconductance
LT1170
LT1171
LT1172
8
4
2
A/V
A/V
A/V
l
l
l
I
Switch Current Limit (LT1170)
(LT1171)
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 4)
l
l
l
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 4)
l
l
l
(LT1172)
Duty Cycle = 50%
T ≥ 25°C
1.25
1.25
1.00
3.0
3.5
2.5
A
A
A
J
Duty Cycle = 50%
T < 25°C
J
Duty Cycle = 80% (Note 4)
ΔI
Supply Current Increase During Switch
On-Time
25
35
mA/A
IN
ΔI
f
SW
Switching Frequency
88
85
100
112
115
kHz
kHz
l
117012fg
4
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 = VREF, output pin open, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
92
MAX
97
UNITS
%
l
DC
Maximum Switch Duty Cycle
85
MAX
Shutdown Mode
Supply Current
3V ≤ V ≤ V
C
100
250
μA
IN
MAX
V = 0.05V
Shutdown Mode
Threshold Voltage
3V ≤ V ≤ V
100
50
150
1.5
250
300
mV
mV
IN
MAX
l
Flyback Sense Delay Time (Note 5)
μs
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.
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.
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:
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 in hi clamp, V = 0.8V. I = 4A for LT1170,
C
FB
SW
2A for LT1171, and 1A for LT1172.
Note 4: For duty cycles (DC) between 50% and 80%, minimum guaranteed
R I + Vf
(
)
(
)
L
V
(max, output shorted) =
switch current is given by I = 3.33 (2 – DC) for the LT1170, I = 1.67
15V +
IN
LIM
LIM
t f
( (
) )
buck and inverting mode
(2 – DC) for the LT1171, and I = 0.833 (2 – DC) for the LT1172.
LIM
R = Inductor DC resistance
I = 10A for LT1170, 5A for LT1171, and 2.5A for LT1172
L
Note 5: Minimum input voltage for isolated flyback mode is 7V. V
for HV grade in fully isolated mode to avoid switch breakdown.
= 55V
MAX
Vf = Output catch diode forward voltage at I
t = 0.6μs, f = 100kHz switching frequency
L
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.
117012fg
5
LT1170/LT1171/LT1172
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Current Limit vs Duty Cycle*
Minimum Input Voltage
Switch Saturation Voltage
2.9
2.8
2.7
2.6
2.5
2.4
2.3
16
12
8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
SWITCH CURRENT = I
MAX
150°C
100°C
25°C
–55°C
25°C
–55°C
125°C
SWITCH CURRENT = 0A
4
* DIVIDE VERTICAL SCALE BY TWO FOR
LT1171, BY FOUR FOR LT1172.
* DIVIDE CURRENT BY TWO FOR
LT1171, BY FOUR FOR LT1172.
0
70
0
10 20 30 40 50 60
80 90 100
100
125 150
–75 –50 –25
0
25 50 75
2
4
5
6
7
0
1
3
8
TEMPERATURE (°C)
DUTY CYCLE (%)
SWITCH CURRENT (A)*
1170/1/2 G01
1170/1/2 G02
1170/1/2 G03
Feedback Bias Current
vs Temperature
Reference Voltage vs Temperature
Line Regulation
5
4
1.250
1.248
1.246
1.244
1.242
1.240
1.238
1.236
1.234
800
700
600
500
400
300
200
100
0
3
T
= 150°C
J
2
1
0
T
= –55°C
J
T
= 25°C
J
–1
–2
–3
–4
–5
–75 –50 –25
0
25 50 75 100 125 150
0
10
30
40
50
60
–50
0
100
125 150
20
–75
–25
25 50 75
INPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
1170/1/2 G04
1170/1/2 G05
1170/1/2 G06
Supply Current vs Supply Voltage
(Shutdown Mode)
Driver Current* vs Switch Current
Supply Current vs Input Voltage*
15
14
13
160
140
120
100
80
160
140
120
100
80
T
= 25°C
T
= 25°C
J
J
NOTE THAT THIS CURRENT DOES NOT
INCLUDE DRIVER CURRENT, WHICH IS
12 A FUNCTION OF LOAD CURRENT AND
DUTY CYCLE.
11
T = –55°C
J
V
C
= 50mV
90% DUTY CYCLE
10
9
50% DUTY CYCLE
60
60
T
= ≥ 25°C
J
8
40
40
10% DUTY CYCLE
0% DUTY CYCLE
7
20
20
V
= 0V
C
6
0
0
5
0
1
2
3
4
0
10
30
40
50
1170/1/2 G09
60
30
SUPPLY VOLTAGE (V)
5
20
0
10
20
40
50
60
SWITCH CURRENT (A)
INPUT VOLTAGE (V)
1170/1/2 G08
1170/1/2 G07
* UNDER VERY LOW OUTPUT CURRENT CONDITIONS,
DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH
10% OR LESS.
* AVERAGE LT1170 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.
117012fg
6
LT1170/LT1171/LT1172
TYPICAL PERFORMANCE CHARACTERISTICS
Shutdown Mode Supply Current
Error Amplifier Transconductance
VC Pin Characteristics
300
200
200
180
160
140
120
100
80
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
$I (V PIN)
$V (FB PIN)
C
V
FB
= 1.5V (CURRENT INTO V PIN)
C
g
=
m
100
T
= 150°C
J
0
T
= 25°C
J
–100
–200
–300
–400
60
–55°C ≤ T ≤ 125°C
J
V
= 0.8V (CURRENT OUT OF V PIN)
C
FB
40
20
0
0
0
0.5
1.0
1.5
2.0
2.5
0
10 20 30 40 50 60
80
90 100
70
–75 –50 –25
0
25 50 75 100 125 150
V
PIN VOLTAGE (V)
V
PIN VOLTAGE (mV)
TEMPERATURE (°C)
C
C
1170/1/2 G10
1170/1/2 G12
1170/1/2 G11
Idle Supply Current vs Temperature
Feedback Pin Clamp Voltage
Switch “Off” Characteristics
11
10
9
500
450
400
350
300
250
200
150
100
50
1000
900
800
700
600
500
400
300
200
100
0
V
= 0.6V
C
–55°C
V
8
SUPPLY
= 40V
V
7
V
= 60V
= 3V
SUPPLY
= 15V
25°C
SUPPLY
V
6
SUPPLY
= 3V
V
SUPPLY
150°C
V
SUPPLY
5
= 55V
4
3
2
1
0
–75 –50 –25
0
25 50 75 100 125 150
0
0.1 0.2 0.3 0.4 0.5 0.6
0.8
0
10 20 30 40 50 60
80
90 100
0.7
0.9 1.0
70
TEMPERATURE (°C)
FEEDBACK CURRENT (mA)
SWITCH VOLTAGE (V)
1170/1/2 G13
1170/1/2 G14
1170/1/2 G15
Isolated Mode Flyback
Reference Voltage
Shutdown Thresholds
Flyback Blanking Time
2.2
23
22
21
20
19
18
17
16
15
400
350
300
250
200
150
100
50
–400
–350
–300
–250
–200
–150
–100
–50
CURRENT (OUT OF V PIN)
C
2.0
1.8
1.6
1.4
1.2
1.0
R
= 500ꢀ
FB
R
= 1k
FB
VOLTAGE
R
= 10k
FB
V
VOLTAGE IS REDUCED UNTIL
C
REGULATOR CURRENT DROPS
BELOW 300μA
0
0
–75 –50 –25
0
25 50 75 100 125 150
–75 –50 –25
0
25 50 75 100 125 150
–75 –50 –25
0
25 50 75 100 125 150
JUNCTION TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1170/1/2 G18
1170/1/2 G16
1170/1/2 G17
117012fg
7
LT1170/LT1171/LT1172
TYPICAL PERFORMANCE CHARACTERISTICS
Transconductance of Error
Amplifier
Normal/Flyback Mode Threshold on
Feedback Pin
–24
500
490
480
470
460
450
440
430
420
410
400
7000
6000
5000
4000
3000
2000
1000
0
–30
0
–22
–20
–18
–16
–14
–12
–10
–8
Q
30
FEEDBACK PIN VOLTAGE
(AT THRESHOLD)
60
g
m
90
120
150
180
210
FEEDBACK PIN CURRENT
(AT THRESHOLD)
–6
–1000
–4
150
1k
10k
100k
1M
10M
–50
50
100 125
–25
0
25
75
FREQUENCY (Hz)
TEMPERATURE (°C)
1170/1/2 G19
1170/1/2 G20
BLOCK DIAGRAM
SWITCH
OUT
V
IN
16V
2.3V
REG
FLYBACK
ERROR
AMP
LT1172
5A, 75V
SWITCH
100kHz
OSC
LOGIC
COMP
DRIVER
ANTI-
SAT
MODE
SELECT
FB
–
ERROR
AMP
V
C
+
+
0.02ꢀ
(0.04ꢀ LT1171)
(0.16ꢀ LT1172)
SHUTDOWN
CIRCUIT
CURRENT
0.16ꢀ
AMP
–
≈
GAIN
6
1.24V
REF
0.15V
(LT1170 AND LT1171 ONLY)
†
E1
E2
†
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.
1170/1/2 BD
117012fg
8
LT1170/LT1171/LT1172
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
eachoscillatorcycle. Itisturned“off”whenswitchcurrent
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-pulsecurrentlimitingtoprovidemaximumswitch
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
ofsaturationinthepowerswitchandadjustsdrivercurrent
instantaneously to limit switch saturation. This minimizes
driver dissipation and provides very rapid turnoff of the
switch.
AspecialdelaynetworkinsidetheLT1170/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
broughtoutexternally.Thispin(V )hasfourdifferentfunc-
C
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).Theerroramplifiersarecurrentoutput(g )types,
m
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 V pin is pulled to ground through a diode, placing the
C
LT1170/LT1171/LT1172 in an idle mode. Pulling the V pin
C
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
The8-and16-pinversionsoftheLT1172havetheemitters
of the power transistor brought out separately from the
groundpin.Thiseliminateserrorsduetogroundpinvoltage
drops and allows the user to reduce switch current limit
2:1 by leaving the second emitter (E2) disconnected. The
firstemitter(E1)shouldalwaysbeconnectedtotheground
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.
A 1.2V bandgap reference biases the positive input of the
erroramplifier.Thenegativeinputisbroughtoutforoutput
voltage sensing. This feedback pin has a second function;
when pulled low with an external resistor, it programs the
LT1170/LT1171/LT1172todisconnectthemainerrorampli-
fieroutputandconnectstheoutputoftheflybackamplifier
to the comparator input. The LT1170/LT1171/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.
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. TheminiDIPs, however, areratedat100°C/W
in ceramic (J) and 130°C/W in plastic (N).
*See note under Block Diagram.
117012fg
9
LT1170/LT1171/LT1172
OPERATION
largerTO-220(T)orTO-3(K)packagewhich,evenwithout
aheatsink, maylimitdietemperaturestosafelevelsunder
overload conditions. In critical situations, heat sinking of
thesepackagesisrequired;especiallyifoverloadconditions
must be tolerated for extended periods of time.
CareshouldbetakenforminiDIPapplicationstoensurethat
the worst case input voltage and load current conditions
do not cause excessive die temperatures. The following
formulascanbeusedasaroughguidetocalculateLT1172
power dissipation. For more details, the reader is referred
to Application Note 19 (AN19), “Efficiency Calculations”
section.
The third approach for lower current applications is to
leave the second switch emitter (miniDIP only) open. This
increasesswitch“on”resistanceby2:1,butreducesswitch
current limit by 2:1 also, resulting in a net 2:1 reduction in
Average supply current (including driver current) is:
I ≈ 6mA + I (0.004 + DC/40)
IN
SW
2
I R switch dissipation under current limit conditions.
I
SW
= switch current
The fourth approach is to clamp the V pin to a voltage
C
DC = switch duty cycle
less than its internal clamp level of 2V. The LT1172 switch
current limit is zero at approximately 1V on the V pin
C
Switch power dissipation is given by:
and 2A at 2V on the V pin. Peak switch current can be
C
2
P
= (I ) • (R )(DC)
SW
SW
SW
externally clamped between these two levels with a diode.
See AN19 for details.
R
= LT1172 switch “on” resistance (1Ω maximum)
SW
Total power dissipation is the sum of supply current times
input voltage plus switch power:
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.
P
= (I )(V ) + P
IN IN SW
D(TOT)
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:
Synchronizing occurs when the V pin is pulled to ground
C
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:
I = 6mA + 0.65(0.004 + DC/40) = 18mA
IN
2
P
P
= (0.65) • (1Ω)(0.6) = 0.25W
SW
= (5V)(0.018A) + 0.25 = 0.34W
D(TOT)
Temperature rise in a plastic miniDIP would be 130°C/W
times0.34W, orapproximately44°C. Themaximumambi-
ent temperature would be limited to 100°C (commercial
temperature limit) minus 44°C, or 56°C.
VC
R3
⎛
⎞
KT
q
⎛
⎞
t
f
I +
C
(
(
)
)
⎜
⎝
⎟
⎠
S
S
⎜
⎝
⎟
⎠
ΔVOS =
IC
KT
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
withtemporaryoverloads.Asecondapproachistousethe
= 26mV at 25°C
= pulse width
q
t
f
I
C
= pulse frequency
S
C
= V source current (≈200μA)
C
V = operating V voltage (1V to 2V)
C
C
R3 = resistor used to set mid-frequency “zero” in
frequency compensation network.
117012fg
10
LT1170/LT1171/LT1172
OPERATION
With t = 0.2μs, f = 150kHz, V = 1.5V, and R3 = 2k, offset
transistor must sink higher currents with low values of
R3, so larger drives may have to be used. The transistor
S
S
C
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
must be capable of pulling the V pin to within 200mV of
C
ground to ensure synchronizing.
Synchronizing with Bipolar Transistor
Synchronizing with MOS Transistor
V
IN
V
IN
LT1170
LT1170
V
GND
V
GND
C
C
C2
C2
D1
R1
3k
100pF
39pF
1N4158
R3
C1
R3
C1
VN2222*
2N2369
D2
1N4158
R2
2.2k
R2
2.2k
FROM 5V
LOGIC
FROM 5V
LOGIC
* SILICONIX OR EQUIVALENT
1170/1/2 OP02
1170/1/2 OP01
TYPICAL APPLICATIONS
Flyback Converter
CLAMP TURN-ON
SPIKE
OPTIONAL
FILTER
L2
5μH
V
SNUB
C4
100μF
V
+ Vf
OUT
N
a
PRIMARY FLYBACK VOLTAGE =
LT1170 SWITCH VOLTAGE
V
IN
N* = 1/3
D1
b
d
V
5V
6A
OUT
AREA “a” = AREA “b” TO MAINTAIN
ZERO DC VOLTS ACROSS PRIMARY
V
IN
0V
V
OUT
+ V
f
20V TO 30V
D3
25V
1W
N*
1
c
SECONDARY VOLTAGE
N • V
+
IN
C1
2000μF
AREA “c” = AREA “d” TO MAINTAIN
ZERO DC VOLTS ACROSS SECONDARY
0V
D2
MUR110
R1
3.74k
$I
V
I
IN
PRI
V
SW
FB
PRIMARY CURRENT
+
C4*
100μF
0
0
LT1170
I
/N
PRI
SECONDARY CURRENT
V
C
GND
I
PRI
R3
1.5k
R2
1.24k
LT1170 SWITCH CURRENT
0
0
C2
I
PRI
0.15μF
SNUBBER DIODE CURRENT
*REQUIRED IF INPUT LEADS ≥ 2"
(I )(L )
PRI
L
t =
V
SNUB
1170/1/2 TA03
117012fg
11
LT1170/LT1171/LT1172
TYPICAL APPLICATIONS
(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)
LCD Contrast Supply
5V*
L1**
50μH
V
*
BAT
3V TO 20V
V
IN
V
E2
E1
SW
+
C1
D1
1N914
1μF
LT1172
TANTALUM
R1
200k
R2
100k
V
OUT
FB
–10V TO –26V
V
GND
C
D2
C2***
2μF
R3
15k
C3
0.0047μF
D3
+
TANTALUM
OPTIONAL
SHUTDOWN
C4
0.047μF
VN2222
D2, D3 = ER82.004 600mA SCHOTTKY. OTHER FAST SWITCHING TYPES MAY BE USED.
*
V
AND BATTERY MAY BE TIED TOGETHER. MAXIMUM VALUE FOR V IS EQUAL TO THE |NEGATIVE OUTPUT| + 1V. WITH HIGHER
BAT
IN
BATTERY VOLTAGES, HIGHEST EFFICIENCY IS OBTAINED BY RUNNING THE LT1172 V PIN FROM 5V. SHUTTING OFF THE 5V SUPPLY
IN
WILL AUTOMATICALLY TURN OFF THE LT1172. EFFICIENCY IS ABOUT 80% AT I
= 25mA.
OUT
R1, R2, R3 ARE MADE LARGE TO MINIMIZE BATTERY DRAIN IN SHUTDOWN, WHICH IS APPROXIMATELY V
/(R1 + R2 + R3).
BAT
FOR HIGH EFFICIENCY, L1 SHOULD BE MADE ON A FERRITE OR MOLYPERMALLOY CORE. PEAK INDUCTOR CURRENTS ARE ABOUT
600mA AT P = 0.7ꢀ. INDUCTOR SERIES RESISTANCE SHOULD BE LESS THAN 0.4ꢀ FOR HIGH EFFICIENCY.
**
OUT
***
OUTPUT RIPPLE IS ABOUT 200mV TO 400mV WITH C2 = 2μF TANTALUM. IF LOWER RIPPLE IS DESIRED, INCREASE C2, OR ADD
P-P
P-P
A 10ꢀ, 1μF TANTALUM OUTPUT FILTER.
1170/1/2 TA04
Driving High Voltage FET
(for Off-Line Applications, See AN25)
External Current Limit
V
X
D
Q1
G
LT1170
D1
R2
V
IN
V
SW
≈ 2V
D1
V
GND
C
+
R1
500ꢀ
10V TO
20V
LT1170
GND
1170/1/2 TA06
1170/1/2 TA05
117012fg
12
LT1170/LT1171/LT1172
TYPICAL APPLICATIONS
(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)
Negative-to-Positive Buck-Boost Converter†
External Current Limit
L1**
50μH
L2
V
IN
OPTIONAL
OUTPUT
FILTER
V
C3
SW
FB
LT1170
+
–
D1
V
12V
2A
OUT
V
IN
V
V
SW
FB
IN
+
R1
V
C
GND
C2
1000μF
+
11.3k
C4*
LT1170
100μF
R1
1k
Q1
R2
C2
OPTIONAL
Q1
INPUT FILTER
V
C
GND
C1
1000pF
L3
R2
1.24k
R3
2.2k
C1
0.22μF
R
S
NOTE THAT THE LT1170
1170/1/2 TA08
V
IN
–20V
GND PIN IS NO LONGER
–
COMMON TO V
.
IN
* REQUIRED IF INPUT LEADS ≥ 2"
** PULSE ENGINEERING 92114, COILTRONICS 50-2-52
†
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 TA07
Negative Buck Converter
+
C2
1000μF
D1
LOAD
R1
4.64k
L1**
50μH
* REQUIRED IF INPUT LEADS ≥ 2"
** PULSE ENGINEERING 92114
COILTRONICS 50-2-52
V
IN
–5.2V
4.5A
V
SW
R4
12k
+
C3*
100μF
Q1
2N3906
LT1170
OPTIONAL
INPUT FILTER
FB
V
OPTIONAL
OUTPUT
FILTER
GND
C
+
C4
200μF
L3
C1
R3
R2
1.24k
V
IN
–20V
1170/1/2 TA09
117012fg
13
LT1170/LT1171/LT1172
TYPICAL APPLICATIONS
Positive-to-Negative Buck-Boost Converter
†
D3
†
R5
1N4001
V
470ꢀ, 1W
IN
10V TO
30V
* REQUIRED IF INPUT LEADS ≥ 2"
+
** PULSE ENGINEERING 92114, COILTRONICS 50-2-52
C5
†
TO AVOID STARTUP PROBLEMS FOR INPUT VOLTAGES
V
IN
100μF*
V
SW
BELOW 10V, CONNECT ANODE OF D3 TO V , AND
IN
REMOVE R5. C1 MAY BE REDUCED FOR LOWER OUTPUT
+
CURRENTS. C1 ≈ (500μF)(I ).
OUT
C4
1μF
LT1170
FOR 5V OUTPUTS, REDUCE R3 TO 1.5k, INCREASE C2 TO
0.3μF, AND REDUCE R6 TO 100ꢀ.
D2
R1
R4
47ꢀ
1N914
10.7k
FB
V
C
GND
+
+
†
R3
5k
C2
R2
1.24k
C3
2μF
C1
1000μF
R6
470ꢀ
D1
V
–12V
2A
0.1μF
OUT
L1**
50μH
1170/1/2 TA10
High Efficiency Constant Current Charger
1.244V • R4
R3 • R5
R3
25k
I
=
= 1A AS SHOWN
CHRG
INPUT VOLTAGE
> V + 2V < 35V
V
SW
BAT
* L2 REDUCES RIPPLE CURRENT INTO
THE BATTERY BY ABOUT 20:1.
D1
+
LT1171
V
IT MAY BE OMITTED IF DESIRED.
1N5819
R2
1k
–
+
V
LT1006
–
FB
IN
V
R4
1k
GND
C
C2
2.2μF
35V
+
+
C1
200μF
35V
C4
0.01μF
V
+
L1
L2*
C3
0.47μF
TANTALUM
100μH, 1A
10μH, 1A
R5
0.05ꢀ
1A
RUN = 0V
SHUTDOWN = 5V
2N3904
+
C4
200μF
25V
+
R6
78k
BATTERY
2V TO 25V
D2
MBR340
R8
1k
R7
22k
1170/1/2 TA11
Backlight CCFL Supply (see AN45 for details)
†
INPUT VOLTAGE
4.5V TO 20V
L2***
1k
33pF
3kV
L1**
300μH
LAMP
1N5818
A
Q1*
V
IN
V
SW
E2
D1
1N914
D2
1N914
0.02μF
+
50k
INTENSITY
ADJUST
10μF
TANT
LT1172
Q2*
R1
560ꢀ
R3
10k
B
E1
FB
GND
V
C
Q1,Q2 = BCP56 OR MPS650/561
COILTRONICS CTX300-4
SUMIDA 6345-020 OR COILTRONICS 110092-1
*
C6
1μF
1170/1/2 TA12
**
***
†
A MODIFICATION WILL ALLOW OPERATION DOWN TO 4.5V. CONSULT FACTORY.
2μF
117012fg
14
LT1170/LT1171/LT1172
TYPICAL APPLICATIONS
Positive Buck Converter
V
IN
* REQUIRED IF INPUT LEADS ≥ 2"
** PULSE ENGINEERING 92114
COILTRONICS 50-2-52
D3
L2
4μH
V
IN
V
SW
+
C3
OPTIONAL
OUTPUT
FILTER
C5
200μF
2.2μF
LT1170
D2
R1
+
1N914
3.74k
C5*
100μF
FB
V
GND
C
+
C2
1μF
R2
1.24k
R3
R4
10ꢀ
470ꢀ
L1**
50μH
C1
1μF
r
5V, 4.5A
+
C4
1000μF
100mA
MINIMUM
D1
1170/1/2 TA13
Negative Boost Regulator
D2
V
IN
V
SW
R1
27k
R
+
+
O
C1
1000μF
C3
10μF
LT1170
(MINIMUM
LOAD)
+
C4*
470μF
FB
V
GND
C
R2
1.24k
R3
3.3k
C2
0.22μF
L1
50μH
D1
V
V
IN
OUT
–28V, 1A
–15V
1170/1/2 TA14
* REQUIRED IF INPUT LEADS ≥ 2"
Driving High Voltage NPN
C1
D2
R2**
R1*
Q1
D1
V
IN
V
SW
LT1170
GND
* SETS I (ON)
B
** SETS I (OFF)
B
1170/1/2 TA15
117012fg
15
LT1170/LT1171/LT1172
TYPICAL APPLICATIONS
Forward Converter
L1
25μH
D1
V
OUT
T1
5V, 6A
1
M
N
C2
R4
+
C1
2000μF
D2
R1
3.74k
D3
V
IN
V
SW
FB
V
IN
D4
LT1170
20V TO 30V
R6
330ꢀ
V
GND
C
Q1
R2
1.24k
R3
C3
R5
1ꢀ
C4
1170/1/2 TA16
High Efficiency 5V Buck Converter
V
IN
10μH
3A
V
V
SW
IN
+
C1
330μF
35V
LT1170
+
OPTIONAL
OUTPUT
FILTER
FB
100μF
16V
V
GND
D2
1N4148
C
C6
0.02μF
C3
4.7μF
TANT
+
R1
680ꢀ
C5
0.03μF
L1
50μH
R2*
0.013ꢀ
C4
0.1μF
V
OUT
5V
s
390μF
16V
3A**
+
D1
MBR330p
C2
+
V
V
DIODE
C
V
V
V
IN
LIM
LT1432
GND
MODE
OUT
MODE LOGIC
220pF
* R2 IS MADE FROM PC BOARD
COPPER TRACES.
<0.3V = NORMAL MODE
>2.5V = SHUTDOWN
OPEN = BURST MODE
** MAXIMUM CURRENT IS DETERMINED
BY THE CHOICE OF LT1070 FAMILY.
SEE APPLICATION SECTION.
1170/1/2 TA17
117012fg
16
LT1170/LT1171/LT1172
PACKAGE DESCRIPTION
J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
.405
(10.287)
MAX
CORNER LEADS OPTION
(4 PLCS)
.005
(0.127)
MIN
6
5
4
8
7
2
.023 – .045
(0.584 – 1.143)
HALF LEAD
OPTION
.025
(0.635)
RAD TYP
.220 – .310
(5.588 – 7.874)
.045 – .068
(1.143 – 1.650)
FULL LEAD
OPTION
1
3
.200
.300 BSC
(5.080)
MAX
(7.62 BSC)
.015 – .060
(0.381 – 1.524)
.008 – .018
(0.203 – 0.457)
0° – 15°
.045 – .065
(1.143 – 1.651)
.125
3.175
MIN
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
.014 – .026
(0.360 – 0.660)
.100
(2.54)
BSC
J8 0801
K Package
4-Lead TO-3 Metal Can
(Reference LTC DWG # 05-08-1311)
1.177 – 1.197
(29.90 – 30.40)
.655 – .675
(16.64 – 19.05)
.760 – .775
(19.30 – 19.69)
.320 – .350
(8.13 – 8.89)
.470 TP
P.C.D.
.060 – .135
(1.524 – 3.429)
.151 – .161
(3.84 – 4.09)
DIA 2 PLC
.167 – .177
(4.24 – 4.49)
R
.420 – .480
(10.67 – 12.19)
.490 – .510
(12.45 – 12.95)
R
.038 – .043
(0.965 – 1.09)
72o
18o
K4(TO-3) 0801
(OBSOLETE PACKAGE)
117012fg
17
LT1170/LT1171/LT1172
PACKAGE DESCRIPTION
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400*
(10.160)
MAX
8
7
6
5
4
.255 .015*
(6.477 0.381)
1
2
3
.130 .005
.300 – .325
.045 – .065
(3.302 0.127)
(1.143 – 1.651)
(7.620 – 8.255)
.065
(1.651)
TYP
.008 – .015
(0.203 – 0.381)
.120
.020
(0.508)
MIN
(3.048)
MIN
+.035
.325
–.015
.018 .003
(0.457 0.076)
.100
(2.54)
BSC
+0.889
8.255
(
)
N8 1002
–0.381
NOTE:
INCHES
1. DIMENSIONS ARE
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
117012fg
18
LT1170/LT1171/LT1172
PACKAGE DESCRIPTION
Q Package
5-Lead Plastic DD Pak
(Reference LTC DWG # 05-08-1461)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
.060
(1.524)
.165 – .180
(4.191 – 4.572)
.256
(6.502)
.045 – .055
(1.143 – 1.397)
15° TYP
+.008
.004
–.004
.060
(1.524)
.059
(1.499)
TYP
.183
(4.648)
.330 – .370
(8.382 – 9.398)
+0.203
–0.102
0.102
(
)
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.067
(1.702)
BSC
.050 .012
(1.270 0.305)
.300
(7.620)
.013 – .023
(0.330 – 0.584)
+.012
.143
–.020
.028 – .038
+0.305
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
3.632
Q(DD5) 0502
(0.711 – 0.965)
(
)
–0.508
TYP
.420
.276
.080
.420
.350
.325
.205
.565
.565
.320
.090
.042
.090
.042
.067
.067
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
117012fg
19
LT1170/LT1171/LT1172
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
.045 .005
NOTE 3
.050 BSC
7
5
8
6
.245
MIN
.160 .005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 .005
TYP
1
3
4
2
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(MILLIMETERS)
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)
SO8 0303
117012fg
20
LT1170/LT1171/LT1172
PACKAGE DESCRIPTION
SW Package
16-Lead Plastic Small Outline (Wide .300 Inch)
(Reference LTC DWG # 05-08-1620)
.050 BSC .045 .005
.030 .005
TYP
.398 – .413
(10.109 – 10.490)
NOTE 4
15 14
12
10
9
N
16
N
13
11
.325 .005
.420
MIN
.394 – .419
(10.007 – 10.643)
NOTE 3
N/2
8
1
2
3
N/2
RECOMMENDED SOLDER PAD LAYOUT
2
3
5
7
1
4
6
.291 – .299
(7.391 – 7.595)
NOTE 4
.037 – .045
(0.940 – 1.143)
.093 – .104
(2.362 – 2.642)
.010 – .029
× 45°
(0.254 – 0.737)
.005
(0.127)
RAD MIN
0° – 8° TYP
.050
(1.270)
BSC
.004 – .012
.009 – .013
(0.102 – 0.305)
NOTE 3
(0.229 – 0.330)
.014 – .019
.016 – .050
(0.356 – 0.482)
TYP
(0.406 – 1.270)
NOTE:
1. DIMENSIONS IN
INCHES
(MILLIMETERS)
S16 (WIDE) 0502
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)
117012fg
21
LT1170/LT1171/LT1172
PACKAGE DESCRIPTION
T Package
5-Lead Plastic TO-220 (Standard)
(Reference LTC DWG # 05-08-1421)
.165 – .180
(4.191 – 4.572)
.147 – .155
(3.734 – 3.937)
DIA
.390 – .415
(9.906 – 10.541)
.045 – .055
(1.143 – 1.397)
.230 – .270
(5.842 – 6.858)
.570 – .620
(14.478 – 15.748)
.620
(15.75)
TYP
.460 – .500
(11.684 – 12.700)
.330 – .370
(8.382 – 9.398)
.700 – .728
(17.78 – 18.491)
.095 – .115
(2.413 – 2.921)
SEATING PLANE
.152 – .202
(3.861 – 5.131)
.155 – .195*
(3.937 – 4.953)
.260 – .320
(6.60 – 8.13)
.013 – .023
(0.330 – 0.584)
.067
BSC
.135 – .165
(3.429 – 4.191)
.028 – .038
(0.711 – 0.965)
(1.70)
* MEASURED AT THE SEATING PLANE
T5 (TO-220) 0801
117012fg
22
LT1170/LT1171/LT1172
REVISION HISTORY (Revision history begins at Rev G)
REV
DATE
DESCRIPTION
PAGE NUMBER
G
3/10
Updated to Reactivate LT1172M from Obsoleted Parts List
2
117012fg
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.
23
LT1170/LT1171/LT1172
TYPICAL APPLICATION
Positive Current Boosted Buck Converter
V
IN
28V
470ꢀ
2W
C3
0.47μF
R6
470ꢀ
C6
0.002μF
D2
V
IN
1: N
V
SW
FB
N ≈ 0.25
LT1170
R2
R7
1k
1.24k
D1
V
IN
V
GND
C
7
2
–
C4
0.01μF
R3
+
6
C5*
100μF
R5
5k
680ꢀ
LM308
3
+
C1
0.33μF
4
8
R4
1.24k
200pF
V
OUT
5V, 10A
R1
5k
+
C2
5000μF
* REQUIRED IF INPUT LEADS ≥ 2"
1170/1/2 TA18
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
40kHz, V to 60V, V to 75V
LT1070/LT1071/LT1072 5A/2.5A/1.25A High Efficiency Switching Regulators
IN
SW
LT1074/LT1076
LT1082
5.5A/2A Step-Down Switching Regulators
100kHz, Also for Positive-to-Negative Conversion
1A, High Voltage, High Efficiency Switching Regulator
7.5A, 150kHz Switching Regulators
V
IN
V
IN
to 75V, V to 100V, Telecom
SW
LT1268/LT1268B
LT1269/LT1271
LT1270/LT1270A
LT1370
to 30V, V to 60V
SW
4A High Efficiency Switching Regulators
100kHz/60kHz, V to 30V, V to 60V
IN SW
8A and 10A High Efficiency Switching Regulators
500kHz High Efficiency 6A Switching Regulator
500kHz High Efficiency 3A Switching Regulator
500kHz and 1MHz High Efficiency 1.5A Switching Regulators
60kHz, V to 30V, V to 60V
IN SW
High Power Boost, Flyback, SEPIC
LT1371
Good for Boost, Flyback, Inverting, SEPIC
LT1372/LT1377
LT1373
Directly Regulates
V
OUT
250kHz Low Supply Current High Efficiency 1.5A Switching Regulator
4A, 500kHz Step-Down Switching Regulator
1.5A, 500kHz Step-Down Switching Regulators
Isolated Flyback Switching Regulator
Low 1mA Quiescent Current
LT1374
Synchronizable, V to 25V
IN
LT1375/LT1376
LT1425
Up to 1.25A Out from an SO-8
6W Output, 5% Regulation, No Optocoupler Needed
1.5A Switch, Good for 5V to 3.3V
LT1507
500kHz Monolithic Buck Mode Switching Regulator
Ultralow Noise 1A Switching Regulator
LT1533
Push-Pull, <100μV Output Noise
P-P
117012fg
LT 0410 REV G • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
24
●
●
© LINEAR TECHNOLOGY CORPORATION 1991
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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