View LT1271_125402.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LT1271/LT1269 4A High Efficiency Switching Regulators FEATURES
s s s s s s s s s
DESCRIPTIO
Wide Input Voltage Range 3.5V to 30V Low Quiescent Current: 7mA Internal 4A Switch Very Few External Parts Required Self Protected Against Overloads Shutdown Mode Draws Only 100A Supply Current Flyback Regulated Mode Has Fully Floating Outputs Comes in Standard 5-Pin Package Can Be Externally Synchronized (See LT1072 Data Sheet)
APPLICATI
s s s s s
S
Boost Converter High Efficiency Buck Converter PC Power Supply with Multiple Outputs Battery Up-Converter Negative-to-Positive Converter
The LT(R)1271 and LT1269 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) and slightly lower switch current, they can be operated in all standard switching configurations including buck, boost, flyback and inverting. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy to use and provides "bust proof" operation similar to that obtained with 3-pin linear regulators. The LT1271/LT1269 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current mode switching techniques, they provides excellent AC and DC load and line regulation. A patented adaptive antisat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100A typical for standby operation.
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation.
USER NOTE: This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1271/LT1269. Application circuits are included to show the capability of the LT1271/LT1269. A complete design manual (AN-19) 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 LT1271/LT1269 by factoring in the higher switch current rating and higher operating frequency.
TYPICAL APPLICATION
High Efficiency 5V Regulator with Burst ModeTM Operation
50
VIN 6.5V TO 25V VSW LT1271 FB VC 0.02F 680 0.1F 0.03F 4.7F TANT GND 1N4148 VIN
OUTPUT POWER (W)
EFFICIENCY 90% AT IOUT = 0.4A TO 1.5A
+
L1 25H TO 50H
0.015
MBR 330pF V+ VLIM LT1432 VOUT MODE GND
+
VOUT 5V, 3A 390F 16V
VC C1 200F 35V
DIODE
+
VIN
< 0.3V = NORMAL RUN MODE > 2.5V = SHUTDOWN OPEN = BURST MODE OPERATION
127/691 TA01
U
Maximum Output Power
40 BOOST BUCK-BOOST VO = 12V (INVERTING) 30 FLYBACK 20 BUCK-BOOST VO = 5V (INVERTING) 0 5 15 20 10 INPUT VOLTAGE (V) 25 30 10 0
1271/69 TA02
U
UO
BUCK MODE OUTPUT POWER (3.5A)(VOUT) TRANSFORMER TURNS RATIO MUST BE OPTIMUM TO ACHIEVE FULL POWER.
1
LT1271/LT1269 ABSOLUTE AXI U RATI GS
Operating Junction Temperature Range Operating .............................................. 0C to 100C Short Circuit ......................................... 0C to 125C Lead Temperature (Soldering, 10 sec.)................ 300C
Supply Voltage ....................................................... 30V Switch Output Voltage ............................................ 60V Feedback Pin Voltage (Transient, 1ms) ................ 15V Storage Temperature Range ................ - 65C to 150C
PACKAGE/ORDER I FOR ATIO
FRONT VIEW 5 4 3 2 1 VIN VSW GND FB VC
ORDER PART NUMBER
VSW 1
LT1271CQ LT1269CQ
POWER SWITCH
Q PACKAGE 5-LEAD PLASTIC DD TJ MAX = 100C, JC = 4C/W, JA = 30C/W* FRONT VIEW 5 4 3 2 1 T PACKAGE 5-LEAD PLASTIC TO-220 TJ MAX = 100C, JC = 4C/W, JA = 50C/W
*With device soldered to 1/2 square inch of 1oz copper over backside or internal layer ground plane. Consult factory for Industrial and Military grade parts.
VIN VSW GND FB VC
ORDER PART NUMBER LT1271CT LT1269CT
ELECTRICAL CHARACTERISTICS
SYMBOL VREF IB gm PARAMETER Reference Voltage Feedback Input Current Error Amplifier Transconductance Error Amplifier Source or Sink Current Error Amplifier Clamp Voltage Reference Voltage Line Regulation AV IQ Error Amplifier Voltage Gain Minimum Input Voltage (Note 3) Supply Current
VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
MIN
q q
CONDITIONS Measured at Feedback Pin VC = 0.8V VFB = VREF IC = 25A
q
VC = 1.5V
q
Hi Clamp, VFB = 1V Lo Clamp, VFB = 1.5V 3V VIN VMAX, VC = 0.8V 0.9V VC 1.4V
q q
3V VIN VMAX, VC = 0.6V
2
U
U
W
WW
U
W
TOP VIEW 20 VSW 19 VSW 18 NC 17 GND 16 GND 15 GND 14 GND 13 VIN 12 NC 11 NC POWER SWITCH
ORDER PART NUMBER LT1269CS
VSW 2 NC 3 GND 4 GND 5 GND 6 GND 7 AGND 8 VC 9 FB 10
SW PACKAGE 20-LEAD PLASTIC WIDE SO
WILL VARY FROM APPROXIMATELY 40C/W WITH 0.75 SQ. IN. OF 1 OZ. COPPER TO 46C/W WITH 0.33 SQ. IN. OF 1 OZ. COPPER
TYP 1.244 1.244 350
MAX 1.264 1.274 750 1100 6000 7000 350 400 2.3 0.52 0.03
UNITS V V nA nA mho mho A A V V %/V V/V
1.224 1.214
3000 2400 150 120 1.8 0.25
4400 200
0.38
500
800 2.8 7 3.0 10
V mA
LT1271/LT1269
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER Control Pin Threshold Normal/Flyback Threshold on Feedback Pin VFB VFB Flyback Reference Voltage Change in Flyback Reference Voltage Flyback Reference Voltage Line Regulation Flyback Amplifier Transconductance (gm) Flyback Amplifier Source and Sink Current BV VSAT Output Switch Breakdown Voltage Output Switch (Note 1) "On" Resistance Control Voltage to Switch Current Transconductance ILIM IIN ISW f DC (max) Switch Current Limit (Note 2) Supply Current Increase During Switch On-Time Switching Frequency Maximum Switch Duty Cycle Flyback Sense Delay Time Shutdown Mode Supply Current Shutdown Mode Threshold Voltage 3V VIN VMAX, VC = 0.05V 3V VIN VMAX
q
VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
MIN
q
CONDITIONS Duty Cycle = 0
TYP 0.9 0.45 16.3 6.8 0.01
MAX 1.08 1.25 0.54 17.6 18 8.5 0.03 650 70 70
UNITS V V V V V V %/V mho A A V
0.7 0.5 0.4
IFB = 50A
q
15 14 4.5
0.05 IFB 1mA IFB = 50A 3V VIN VMAX IC = 10A VC = 0.6V IFB = 50A 3V VIN VMAX ISW = 1.5mA Source Sink
q q q q
150 15 25 60
300 32 40 75 0.2 6.4
0.33
A/V
Duty Cycle = 50% Duty Cycle = 80%
q q
4 3.2 25
8 8 40 70 115 95 95 400 250 300
A A mA/A kHz kHz % % s A mV mV
LT1271 LT1269 LT1271 LT1269
q q
50 85 85 80
60 100 92 90 1.5 100
100 50
150
The q denotes the specifications which apply over the full operating temperature range. Note 1: Measured with VC in hi clamp, VFB = 0.8V.
Note 2: For duty cycles (DC) between 50% and 85%, minimum guaranteed switch current is given by ILIM = 2.67 (2 - DC). Note 3: Minimum input voltage.
3
LT1271/LT1269
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Current Limit vs Duty Cycle
12
SWITCH SATURATION VOLTAGE (V)
SWITCH CURRENT (A)
9
-55C 6 125C 3
0
0
10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%)
1271/69 G01
TYPICAL APPLICATI
OPTIONAL INTPUT FILTER L3 VIN -12V
4
UO
UW
Switch Saturation Voltage
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5
1271/69 G02
TJ = 25C
25C
SWITCH CURRENT (A)
S
Negative-to-Positive Buck-Boost Converter
L2 L1** 100H D1 MBR340 VSW C2 200F OPTIONAL OUTPUT FILTER C3
VIN
C4* 200F
+
+
x
Q1 2N3906
VOUT 12V, 1.5A R1 11.3k
LT1271
GND
VC
FB R3 2.2k R2 1.24k * REQUIRED IF INPUT LEADS 2" ** COILTRONICS CTX100-2-52
1271/69 TA04
x
C1 0.22F
LT1271/LT1269
TYPICAL APPLICATI UO S
Boost Converter (5V to 12V)
5V
100H*
VIN
VSW MBR330 12V 0.5A 10.7k FB 1k 1F
LT1271
GND
VC
+
1.24k
100F 25V
* COILTRONICS CTX100-2-52
1271/69 TA03
PACKAGE DESCRIPTIO
0.256 (6.502)
0.060 (1.524)
0.060 (1.524)
0.183 (4.648)
0.075 (1.905) 0.300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK +0.012 0.143 -0.020 0.057 - 0.077 (1.447 - 1.955) 0.028 - 0.038 (0.711 - 0.965) 0.013 - 0.023 (0.330 - 0.584)
U
Dimensions in inches (millimeters) unless otherwise noted.
Q Package 5-Lead Plastic DD Pak
(LTC DWG # 05-08-1461)
0.060 (1.524) TYP
0.390 - 0.415 (9.906 - 10.541) 15 TYP
0.165 - 0.180 (4.191 - 4.572)
0.045 - 0.055 (1.143 - 1.397) +0.008 0.004 -0.004
0.330 - 0.370 (8.382 - 9.398)
0.059 (1.499) TYP
(
+0.203 0.102 -0.102
)
0.095 - 0.115 (2.413 - 2.921) 0.050 0.012 (1.270 0.305)
(
+0.305 3.632 -0.508
)
Q(DD5) 0396
5
LT1271/LT1269
PACKAGE DESCRIPTIO U
Dimensions in inches (millimeters) unless otherwise noted.
T Package 5-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1421)
0.390 - 0.415 (9.906 - 10.541)
0.147 - 0.155 (3.734 - 3.937) DIA 0.230 - 0.270 (5.842 - 6.858)
0.165 - 0.180 (4.191 - 4.572)
0.045 - 0.055 (1.143 - 1.397)
0.460 - 0.500 (11.684 - 12.700)
0.570 - 0.620 (14.478 - 15.748) 0.330 - 0.370 (8.382 - 9.398) 0.700 - 0.728 (17.78 - 18.491)
0.620 (15.75) TYP
0.152 - 0.202 0.260 - 0.320 (3.861 - 5.131) (6.60 - 8.13)
0.095 - 0.115 (2.413 - 2.921)
0.013 - 0.023 (0.330 - 0.584) 0.057 - 0.077 (1.448 - 1.956) 0.028 - 0.038 (0.711 - 0.965) 0.135 - 0.165 (3.429 - 4.191) 0.155 - 0.195 (3.937 - 4.953)
T5 (TO-220) 0398
6
LT1271/LT1269
PACKAGE DESCRIPTIO U
Dimensions in inches (millimeters) unless otherwise noted.
SW Package 20-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.496 - 0.512* (12.598 - 13.005) 20 19 18 17 16 15 14 13 12 11
NOTE 1
0.394 - 0.419 (10.007 - 10.643)
0.291 - 0.299** (7.391 - 7.595) 0.010 - 0.029 x 45 (0.254 - 0.737)
1 0.093 - 0.104 (2.362 - 2.642)
2
3
4
5
6
7
8
9
10 0.037 - 0.045 (0.940 - 1.143)
0 - 8 TYP
0.009 - 0.013 (0.229 - 0.330)
NOTE 1 0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) TYP 0.014 - 0.019 (0.356 - 0.482) TYP
0.004 - 0.012 (0.102 - 0.305)
S20 (WIDE) 0396
NOTE: 1. 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 *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
LT1271/LT1269
TYPICAL APPLICATION
Negative Buck Converter
C3* 100F OPTIONAL INTPUT FILTER L3 10H VIN -8V TO -30V
RELATED PARTS
PART NUMBER LT1171 LT1370 LT1371 LT1372 LT1374 LT1376 DESCRIPTION 100kHz, 2.5A Boost Switching Regulator 500kHz, 6A Boost Switching Regulator 500kHz, 3A Boost Switching Regulator 500kHz, 1.5A Boost Switching Regulator 500kHz, 4.5A Buck Switching Regulator 500kHz, 1.5A Buck Switching Regulator COMMENTS Good for VIN Up to 40V 6A, 42V Internal Switch 3A, 42V Internal Switch, 90% Efficiency Also Regulates Negative Flyback Outputs VIN Up to 25V, SO-8 Package VIN Up to 25V, Uses 4.7H Inductor
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
x
D1 MBR735
C2 100F L1** 100H
+
R1 4.64k LOAD -5.2V AT 3.5A 12k
VIN
VSW
x
+
LT1271
Q1 2N3906 VC FB C1 R3 R2 1.24k OPTIONAL OUTPUT FILTER L2 4H
GND
+
C4 200F
* REQUIRED IF INPUT LEADS 2" ** COILTRONICS CTX100-2-52
1271/69 TA05
127169fb LT/TP 0798 2K REV B * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1992

▲Up To Search▲

Price & Availability of LT1271

	To Download LT1271 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .