LT1271CQ Linear Technology, LT1271CQ Datasheet

IC SWTCHNG REG 4A HI-EFF 5-DD

LT1271CQ

Manufacturer Part Number
LT1271CQ
Description
IC SWTCHNG REG 4A HI-EFF 5-DD
Manufacturer
Linear Technology
Type
Step-Down (Buck), Inverting, Flybackr
Datasheet

Specifications of LT1271CQ

Synchronous Rectifier
No
Number Of Outputs
1
Current - Output
4A
Frequency - Switching
60kHz
Voltage - Input
3.5 ~ 30 V
Operating Temperature
0°C ~ 100°C
Mounting Type
Surface Mount
Package / Case
D²Pak, TO-263 (5 leads + tab)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Voltage - Output
-
Power - Output
-
Internal Switch(s)
-

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FEATURE
A
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
PPLICATI
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 100 A Supply Current
Flyback Regulated Mode Has Fully Floating Outputs
Comes in Standard 5-Pin Package
Can Be Externally Synchronized (See LT1072 Data Sheet)
Boost Converter
High Efficiency Buck Converter
PC Power Supply with Multiple Outputs
Battery Up-Converter
Negative-to-Positive Converter
6.5V TO 25V
200 F
V
35V
IN
C1
High Efficiency 5V Regulator with Burst Mode
+
APPLICATION
S
O
U
0.02 F
0.1 F
S
680
V
FB
SW
V
C
MODE
V
LT1271
V
IN
C
0.03 F 4.7 F
DIODE
U
GND
LT1432
GND
V
330pF
TANT
IN
MBR
+
V
V
LIM
OUT
V
+
TO 50 H
25 H
L1
EFFICIENCY
AT I
< 0.3V = NORMAL RUN MODE
> 2.5V = SHUTDOWN
OPEN = BURST MODE OPERATION
1N4148
OUT
= 0.4A TO 1.5A
TM
0.015
Operation
90%
+
D
The LT
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 includ-
ing 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 ex-
tremely 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 pro-
vides 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 exter-
nally activated shutdown mode reduces total supply cur-
rent to 100 A typical for standby operation.
Burst Mode is a trademark of Linear Technology Corporation.
ESCRIPTIO
, LTC and LT are registered trademarks of Linear Technology Corporation.
127/691 TA01
390 F
16V
V
5V, 3A
OUT
®
1271 and LT1269 are monolithic high power
Switching Regulators
4A High Efficiency
U
50
40
30
20
10
0
0
BUCK MODE OUTPUT POWER
TRANSFORMER TURNS RATIO MUST BE
OPTIMUM TO ACHIEVE FULL POWER.
Maximum Output Power
5
BOOST
INPUT VOLTAGE (V)
LT1271/LT1269
10
FLYBACK
15
BUCK-BOOST
(INVERTING)
BUCK-BOOST
V
(INVERTING)
O
20
V
= 12V
O
(3.5A)(V
= 5V
25
1271/69 TA02
OUT
)
30
1

Related parts for LT1271CQ

LT1271CQ Summary of contents

Page 1

... A patented adaptive antisat switch drive allows very wide ranging load currents with no loss in efficiency. An exter- nally activated shutdown mode reduces total supply cur- rent to 100 A typical for standby operation. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. TM Operation ...

Page 2

... V Minimum Input Voltage (Note 3) I Supply Current Operating Junction Temperature Range Operating .............................................. 100 C Short Circuit ......................................... 125 C Lead Temperature (Soldering, 10 sec.)................ 300 ORDER PART NUMBER V SW LT1271CQ V SW LT1269CQ NC GND GND POWER SWITCH GND GND ORDER PART AGND V V NUMBER GND LT1271CT ...

Page 3

ELECTRICAL C HARA TERISTICS C SYMBOL PARAMETER Control Pin Threshold Normal/Flyback Threshold on Feedback Pin V Flyback Reference Voltage FB V Change in Flyback FB Reference Voltage Flyback Reference Voltage Line Regulation Flyback Amplifier Transconductance (gm) Flyback Amplifier Source and ...

Page 4

LT1271/LT1269 W U TYPICAL PERFOR A Switch Current Limit vs Duty Cycle 12 9 – 125 100 DUTY CYCLE (%) O U TYPICAL ...

Page 5

O U TYPICAL A PPLICATI PACKAGE DESCRIPTIO 0.060 0.256 (1.524) (6.502) 0.060 0.183 (1.524) (4.648) 0.075 (1.905) 0.300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK S Boost Converter (5V to 12V) 5V 100 ...

Page 6

LT1271/LT1269 PACKAGE DESCRIPTIO 0.390 – 0.415 (9.906 – 10.541) 0.460 – 0.500 (11.684 – 12.700) 0.057 – 0.077 0.028 – 0.038 (1.448 – 1.956) (0.711 – 0.965 Dimensions in inches (millimeters) unless otherwise noted. T Package 5-Lead Plastic ...

Page 7

... 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...

Page 8

... Internal Switch, 90% Efficiency Also Regulates Negative Flyback Outputs 25V, SO-8 Package 25V, Uses 4.7 H Inductor IN + LOAD R1 4.64k –5.2V AT 3.5A 12k Q1 2N3906 + OPTIONAL C4 OUTPUT 200 F FILTER 1271/69 TA05 Up to 40V IN 127169fb LT/TP 0798 2K REV B • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1992 ...

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