LINER LT1269CS 4a high efficiency switching regulator Datasheet

LT1271/LT1269
4A High Efficiency
Switching Regulators
U
DESCRIPTIO
FEATURES
■
■
■
■
■
■
■
■
■
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 100µA Supply Current
Flyback Regulated Mode Has Fully Floating Outputs
Comes in Standard 5-Pin Package
Can Be Externally Synchronized (See LT1072 Data Sheet)
UO
APPLICATI
■
■
■
■
■
S
Boost Converter
High Efficiency Buck Converter
PC Power Supply with Multiple Outputs
Battery Up-Converter
Negative-to-Positive Converter
The LT®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.
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.
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 100µA typical for standby operation.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
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TYPICAL APPLICATION
High Efficiency 5V Regulator with Burst ModeTM Operation
Maximum Output Power
50
VSW
VIN
FB
VC
GND
1N4148
0.02µF
680Ω
0.03µF 4.7µF
TANT
0.1µF
+
L1
25µH
TO 50µH
MBR
330pF
VC
C1
200µF
35V
+
DIODE
0.015Ω
+
VOUT
5V, 3A
390µF
16V
30
BUCK-BOOST
VO = 12V
(INVERTING)
FLYBACK†
20
BUCK-BOOST
VO = 5V
(INVERTING)
10
0
0
V+
5
15
20
10
INPUT VOLTAGE (V)
25
30
1271/69 TA02
VLIM
VIN
LT1432
†
VOUT
MODE
BOOST
40
EFFICIENCY ≈ 90%
AT IOUT = 0.4A TO 1.5A
LT1271
OUTPUT POWER (W)
VIN
6.5V TO 25V
BUCK MODE OUTPUT POWER ≈ (3.5A)(VOUT)
TRANSFORMER TURNS RATIO MUST BE
OPTIMUM TO ACHIEVE FULL POWER.
GND
< 0.3V = NORMAL RUN MODE
> 2.5V = SHUTDOWN
OPEN = BURST MODE OPERATION
127/691 TA01
1
LT1271/LT1269
W W
W
AXI U
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ABSOLUTE
RATI GS
Supply Voltage ....................................................... 30V
Switch Output Voltage ............................................ 60V
Feedback Pin Voltage (Transient, 1ms) ................ ±15V
Storage Temperature Range ................ – 65°C to 150°C
Operating Junction Temperature Range
Operating .............................................. 0°C to 100°C
Short Circuit ......................................... 0°C to 125°C
Lead Temperature (Soldering, 10 sec.)................ 300°C
W
U
U
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
FRONT VIEW
5
VIN
4
VSW
3
GND
2
FB
1
VC
TOP VIEW
LT1271CQ
LT1269CQ
Q PACKAGE
5-LEAD PLASTIC DD
TJ MAX = 100°C, θJC = 4°C/W, θJA = 30°C/W*
POWER
SWITCH
FRONT VIEW
5
VIN
4
VSW
3
GND
2
FB
1
VC
ORDER PART
NUMBER
ORDER PART
NUMBER
LT1271CT
LT1269CT
T PACKAGE
5-LEAD PLASTIC TO-220
TJ MAX = 100°C, θJC = 4°C/W, θJA = 50°C/W
VSW 1
20 VSW
VSW 2
19 VSW
NC 3
18 NC
GND 4
17 GND
GND 5
16 GND
GND 6
15 GND
GND 7
14 GND
AGND 8
13 VIN
VC 9
12 NC
FB 10
11 NC
LT1269CS
POWER
SWITCH
SW PACKAGE
20-LEAD PLASTIC WIDE SO
θ WILL VARY FROM APPROXIMATELY 40°C/W
WITH 0.75 SQ. IN. OF 1 OZ. COPPER TO 46°C/W
WITH 0.33 SQ. IN. OF 1 OZ. COPPER
*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.
ELECTRICAL CHARACTERISTICS
VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VREF
Reference Voltage
Measured at Feedback Pin
VC = 0.8V
1.224
1.214
1.244
1.244
1.264
1.274
V
V
350
750
1100
nA
nA
IB
Feedback Input Current
●
VFB = VREF
●
gm
AV
Error Amplifier
Transconductance
∆IC = ±25µA
Error Amplifier Source or
Sink Current
VC = 1.5V
Error Amplifier Clamp
Voltage
Hi Clamp, VFB = 1V
Lo Clamp, VFB = 1.5V
Reference Voltage Line
Regulation
3V ≤ VIN ≤ VMAX, VC = 0.8V
Error Amplifier Voltage Gain
0.9V ≤ VC ≤ 1.4V
Minimum Input Voltage (Note 3)
IQ
2
Supply Current
3000
2400
4400
●
6000
7000
µmho
µmho
150
120
200
●
350
400
µA
µA
2.3
0.52
V
V
0.03
%/V
1.8
0.25
●
500
●
3V ≤ VIN ≤ VMAX, VC = 0.6V
0.38
800
V/V
2.8
3.0
V
7
10
mA
LT1271/LT1269
ELECTRICAL CHARACTERISTICS
SYMBOL
VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
PARAMETER
CONDITIONS
Control Pin Threshold
Duty Cycle = 0
MIN
TYP
MAX
UNITS
0.7
0.5
0.9
1.08
1.25
V
V
0.4
0.45
0.54
V
15
14
16.3
17.6
18
V
V
4.5
6.8
8.5
V
0.01
0.03
%/V
150
300
650
µmho
●
●
15
25
32
40
70
70
µA
µA
●
60
75
●
Normal/Flyback Threshold
on Feedback Pin
VFB
Flyback Reference Voltage
IFB = 50µA
●
Change in Flyback
Reference Voltage
0.05 ≤ IFB ≤ 1mA
Flyback Reference Voltage
Line Regulation
IFB = 50µA
3V ≤ VIN ≤ VMAX
Flyback Amplifier
Transconductance (gm)
∆IC = ±10µA
Flyback Amplifier Source
and Sink Current
VC = 0.6V
IFB = 50µA
BV
Output Switch Breakdown
Voltage
3V ≤ VIN ≤ VMAX
ISW = 1.5mA
VSAT
Output Switch (Note 1)
“On” Resistance
VFB
Source
Sink
0.2
●
Control Voltage to Switch
Current Transconductance
V
0.33
6.4
ILIM
Switch Current Limit (Note 2)
Duty Cycle = 50%
Duty Cycle = 80%
∆IIN
∆ISW
Supply Current Increase
During Switch On-Time
f
Switching Frequency
LT1271
LT1269
DC (max)
Maximum Switch Duty Cycle
LT1271
LT1269
●
●
●
●
4
3.2
A/V
8
8
A
A
25
40
mA/A
50
85
60
100
70
115
kHz
kHz
85
80
92
90
95
95
%
%
Flyback Sense Delay Time
µs
1.5
Shutdown Mode
Supply Current
3V ≤ VIN ≤ VMAX, VC = 0.05V
Shutdown Mode
Threshold Voltage
3V ≤ VIN ≤ VMAX
The ● denotes the specifications which apply over the full operating
temperature range.
Note 1: Measured with VC in hi clamp, VFB = 0.8V.
●
Ω
100
50
100
400
µA
150
250
300
mV
mV
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
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Current Limit vs Duty Cycle
Switch Saturation Voltage
1.6
SWITCH SATURATION VOLTAGE (V)
SWITCH CURRENT (A)
12
9
–55°C
25°C
6
125°C
3
0
TJ = 25°C
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
10 20 30 40 50 60 70 80 90 100
DUTY CYCLE (%)
0
1
2
3
1271/69 G02
UO
S
Negative-to-Positive Buck-Boost Converter
L2
L1**
100µH
OPTIONAL
INTPUT
FILTER
VSW
C2
200µF
LT1271
VC
×
×
VOUT
12V, 1.5A
R1
11.3k
FB
R3
2.2k
VIN
–12V
+
C3
Q1
2N3906
GND
L3
4
+
OPTIONAL
OUTPUT
FILTER
D1
MBR340
VIN
C4*
200µF
5
SWITCH CURRENT (A)
1271/69 G01
TYPICAL APPLICATI
4
C1
0.22µF
R2
1.24k
* REQUIRED IF INPUT LEADS ≥ 2"
** COILTRONICS CTX100-2-52
1271/69 TA04
LT1271/LT1269
UO
TYPICAL APPLICATI
S
Boost Converter (5V to 12V)
5V
100µH*
VIN
VSW
MBR330
12V
0.5A
LT1271
10.7k
+
FB
VC
GND
1k
100µF
25V
1.24k
1µF
* COILTRONICS CTX100-2-52
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PACKAGE DESCRIPTIO
1271/69 TA03
Dimensions in inches (millimeters) unless otherwise noted.
Q Package
5-Lead Plastic DD Pak
(LTC DWG # 05-08-1461)
0.256
(6.502)
0.060
(1.524)
0.060
(1.524)
TYP
0.390 – 0.415
(9.906 – 10.541)
0.165 – 0.180
(4.191 – 4.572)
15° TYP
0.060
(1.524)
0.183
(4.648)
0.059
(1.499)
TYP
0.330 – 0.370
(8.382 – 9.398)
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
(
+0.008
0.004 –0.004
+0.203
0.102 –0.102
)
0.095 – 0.115
(2.413 – 2.921)
0.075
(1.905)
0.300
(7.620)
0.045 – 0.055
(1.143 – 1.397)
(
+0.012
0.143 –0.020
+0.305
3.632 –0.508
)
0.057 – 0.077
(1.447 – 1.955)
0.028 – 0.038
(0.711 – 0.965)
0.013 – 0.023
(0.330 – 0.584)
0.050 ± 0.012
(1.270 ± 0.305)
Q(DD5) 0396
5
LT1271/LT1269
U
PACKAGE DESCRIPTIO
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)
0.165 – 0.180
(4.191 – 4.572)
0.147 – 0.155
(3.734 – 3.937)
DIA
0.045 – 0.055
(1.143 – 1.397)
0.230 – 0.270
(5.842 – 6.858)
0.460 – 0.500
(11.684 – 12.700)
0.570 – 0.620
(14.478 – 15.748)
0.330 – 0.370
(8.382 – 9.398)
0.620
(15.75)
TYP
0.700 – 0.728
(17.78 – 18.491)
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
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PACKAGE DESCRIPTIO
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
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
0.291 – 0.299**
(7.391 – 7.595)
0.010 – 0.029 × 45°
(0.254 – 0.737)
1
2
3
4
5
6
7
8
9
0.093 – 0.104
(2.362 – 2.642)
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
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TYPICAL APPLICATION
Negative Buck Converter
D1
MBR735
+
OPTIONAL
INTPUT
FILTER
VIN
–8V TO –30V
×
VC
12k
FB
R3
×
–5.2V AT 3.5A
Q1
2N3906
OPTIONAL
OUTPUT
FILTER
C1
L3
10µH
LOAD
R1
4.64k
VSW
LT1271
GND
+
L1**
100µH
VIN
C3*
100µF
C2
100µF
R2
1.24k
+
C4
200µF
L2
4µH
* REQUIRED IF INPUT LEADS ≥ 2"
** COILTRONICS CTX100-2-52
1271/69 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1171
100kHz, 2.5A Boost Switching Regulator
Good for VIN Up to 40V
LT1370
500kHz, 6A Boost Switching Regulator
6A, 42V Internal Switch
LT1371
500kHz, 3A Boost Switching Regulator
3A, 42V Internal Switch, 90% Efficiency
LT1372
500kHz, 1.5A Boost Switching Regulator
Also Regulates Negative Flyback Outputs
LT1374
500kHz, 4.5A Buck Switching Regulator
VIN Up to 25V, SO-8 Package
LT1376
500kHz, 1.5A Buck Switching Regulator
VIN Up to 25V, Uses 4.7µH Inductor
8
Linear Technology Corporation
127169fb LT/TP 0798 2K REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 1992
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