IC SWTCHNG REGULATOR HI-EFF 8DIP

LT1172CN8

Manufacturer Part NumberLT1172CN8
DescriptionIC SWTCHNG REGULATOR HI-EFF 8DIP
ManufacturerLinear Technology
TypeStep-Down (Buck), Step-Up (Boost), Inverting, Cuk, Flyback, Forward Converter
LT1172CN8 datasheet
 


Specifications of LT1172CN8

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output1.25 ~ 40 V
Current - Output1.25AFrequency - Switching100kHz
Voltage - Input3 ~ 40 VOperating Temperature0°C ~ 100°C
Mounting TypeThrough HolePackage / Case8-DIP (0.300", 7.62mm)
Power - Output100WLead Free Status / RoHS StatusContains lead / RoHS non-compliant
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FEATURES
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
TYPICAL APPLICATION
Boost Converter (5V to 12V)
L1**
5V
50 μ H
D1
MBR330
V
IN
V
SW
LT1170
+
C3*
100μF
FB
V
GND
C
R3
1k
C1
1μF
*REQUIRED IF INPUT LEADS 2"
** COILTRONICS 50-2-52
PULSE ENGINEERING 92114
100kHz, 5A, 2.5A and 1.25A
High Efficiency Switching Regulators
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, 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 and SwitcherCAD are registered
®
is also available.
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
Maximum Output Power*
100
L2
OUTPUT
LT1170
10μH
FILTER
80
C3
100μF
60
12V
BOOST
1A
+
R1
C2
10.7k
40
1000μF
1%
20
R2
1.24k
1%
0
0
1170/1/2 TA01
LT1170/LT1171/LT1172
* ROUGH GUIDE ONLY. BUCK MODE
P
= (5A)(V
OUT
OUT
SPECIAL TOPOLOGIES DELIVER
MORE POWER.
** DIVIDE VERTICAL POWER SCALE
BUCK-BOOST
BY TWO FOR LT1171, BY FOUR
V
= 30V
FOR LT1172.
O
FLYBACK
BUCK-BOOST
V
= 5V
O
10
20
30
40
50
INPUT VOLTAGE (V)
)
LT1170/1/2 TA02
117012fg
1

LT1172CN8 Summary of contents

  • Page 1

    ... L, LT, LTC, LTM, Linear Technology, the Linear logo and SwitcherCAD are registered ® is also available. trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Maximum Output Power* 100 L2 ...

  • Page 2

    LT1170/LT1171/LT1172 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, ...

  • Page 3

    ... LT1172MJ8#PBF LT1172MJ8#TRPBF LT1172CJ8#PBF (OBSOLETE) LT1172CJ8#TRPBF LT1170MK#PBF (OBSOLETE) LT1170MK#TRPBF LT1170CK#PBF (OBSOLETE) LT1170CK#TRPBF LT1171MK#PBF (OBSOLETE) LT1171MK#TRPBF LT1171CK#PBF (OBSOLETE) LT1171CK#TRPBF LT1172MK#PBF (OBSOLETE) LT1172MK#TRPBF LT1172CK#PBF (OBSOLETE) LT1172CK#TRPBF LT1172CN8#PBF LT1172CN8#TRPBF LT1172IN8#PBF LT1172IN8#TRPBF LT1172CS8#PBF LT1172CS8#TRPBF LT1172IS8#PBF LT1172IS8#TRPBF LT1170CQ#PBF LT1170CQ#TRPBF LT1170IQ#PBF LT1170IQ#TRPBF LT1170HVCQ#PBF LT1170HVCQ#TRPBF LT1171CQ#PBF LT1171CQ#TRPBF LT1171IQ#PBF LT1171IQ#TRPBF ...

  • Page 4

    LT1170/LT1171/LT1172 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER V Reference Voltage REF I Feedback Input Current B g Error Amplifier Transconductance m Error Amplifier Source or Sink Current Error Amplifier Clamp Voltage Reference Voltage Line Regulation ...

  • Page 5

    ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER DC Maximum Switch Duty Cycle MAX Shutdown Mode Supply Current Shutdown Mode Threshold Voltage Flyback Sense Delay Time (Note 5) Note 1: Stresses beyond those listed under Absolute Maximum ...

  • Page 6

    LT1170/LT1171/LT1172 TYPICAL PERFORMANCE CHARACTERISTICS Switch Current Limit vs Duty Cycle 25°C –55°C 8 125° DIVIDE VERTICAL SCALE BY TWO FOR LT1171, BY FOUR FOR LT1172 ...

  • Page 7

    TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Mode Supply Current 200 180 160 140 T = 150°C J 120 100 80 60 –55°C ≤ T ≤ 125° 100 V ...

  • Page 8

    LT1170/LT1171/LT1172 TYPICAL PERFORMANCE CHARACTERISTICS Transconductance of Error Amplifier 7000 6000 5000 4000 g 3000 2000 1000 0 –1000 1k 10k 100k FREQUENCY (Hz) BLOCK DIAGRAM V IN 2.3V REG 100kHz OSC MODE SELECT – FB ERROR AMP + 1.24V REF ...

  • Page 9

    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 ...

  • Page 10

    LT1170/LT1171/LT1172 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 ...

  • Page 11

    OPERATION With t = 0.2μ 150kHz 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 ...

  • Page 12

    LT1170/LT1171/LT1172 TYPICAL APPLICATIONS E2 E1 OPTIONAL VN2222 SHUTDOWN D2 ER82.004 600mA SCHOTTKY. OTHER FAST SWITCHING TYPES MAY BE USED AND BATTERY MAY BE TIED TOGETHER. MAXIMUM VALUE FOR V IN BATTERY VOLTAGES, HIGHEST EFFICIENCY IS OBTAINED ...

  • Page 13

    TYPICAL APPLICATIONS Negative-to-Positive Buck-Boost Converter C4* LT1170 100μF OPTIONAL INPUT FILTER V GND –20V * REQUIRED IF INPUT LEADS ≥ 2" PULSE ENGINEERING 92114, COILTRONICS 50-2-52 ** † THIS CIRCUIT IS OFTEN USED TO ...

  • Page 14

    LT1170/LT1171/LT1172 TYPICAL APPLICATIONS † D3 1N4001 470Ω LT1170 1μF V GND INPUT VOLTAGE > < 35V BAT D1 1N5819 2.2 μ F 200 μ F 35V 35V TANTALUM ...

  • Page 15

    TYPICAL APPLICATIONS 2.2μF + C5* 100μF + C4* 470μF L1 50μ –15V * REQUIRED IF INPUT LEADS ≥ 2" Positive Buck Converter * REQUIRED IF INPUT LEADS ≥ 2" ** PULSE ENGINEERING 92114 ...

  • Page 16

    LT1170/LT1171/LT1172 TYPICAL APPLICATIONS V IN 20V TO 30V GND 330μF 35V C6 0.02μF MBR330p MODE LOGIC <0.3V = NORMAL MODE >2.5V = SHUTDOWN OPEN = BURST MODE 16 Forward Converter ...

  • Page 17

    PACKAGE DESCRIPTION CORNER LEADS OPTION .045 – .068 (1.143 – 1.650) FULL LEAD OPTION .300 BSC (7.62 BSC) .008 – .018 (0.203 – 0.457) NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS .760 – .775 .320 – ...

  • Page 18

    LT1170/LT1171/LT1172 PACKAGE DESCRIPTION .300 – .325 (7.620 – 8.255) .008 – .015 (0.203 – 0.381) +.035 .325 –.015 ( ) +0.889 8.255 –0.381 NOTE: 1. DIMENSIONS ARE MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR ...

  • Page 19

    PACKAGE DESCRIPTION .060 .256 (1.524) (6.502) .060 .183 (1.524) (4.648) .075 (1.905) .300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK .067 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN INCH/(MILLIMETER) 2. DRAWING NOT ...

  • Page 20

    LT1170/LT1171/LT1172 PACKAGE DESCRIPTION .050 BSC .245 MIN .030 ±.005 TYP RECOMMENDED SOLDER PAD LAYOUT .010 – .020 (0.254 – 0.508) .008 – .010 (0.203 – 0.254) NOTE: 1. DIMENSIONS IN 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT ...

  • Page 21

    PACKAGE DESCRIPTION .030 ±.005 TYP N .420 MIN RECOMMENDED SOLDER PAD LAYOUT .291 – .299 (7.391 – 7.595) NOTE 4 .010 – .029 (0.254 – 0.737) .005 (0.127) RAD MIN .009 – .013 NOTE 3 (0.229 – ...

  • Page 22

    LT1170/LT1171/LT1172 PACKAGE DESCRIPTION .390 – .415 (9.906 – 10.541) .230 – .270 (5.842 – 6.858) .460 – .500 (11.684 – 12.700) .330 – .370 (8.382 – 9.398) .067 BSC .028 – .038 (1.70) (0.711 – 0.965 Package 5-Lead ...

  • Page 23

    ... Updated to Reactivate LT1172M from Obsoleted Parts List 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. ...

  • Page 24

    ... Directly Regulates ±V OUT Low 1mA Quiescent Current Synchronizable 25V 1.25A Out from an SO-8 6W Output, ±5% Regulation, No Optocoupler Needed 1.5A Switch, Good for 5V to 3.3V Push-Pull, <100μV Output Noise P-P LT 0410 REV G • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 1991 117012fg ...