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LT1269CSW#PBF

P1-P3P4-P6P7-P8
1
LT1271/LT1269
4A High Efficiency
Switching Regulators
TYPICAL APPLICATION
U
D
U
ESCRIPTIO
S
F
EA
T
U
RE
■
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)
U
S
A
O
PP
L
IC
AT
I
■
Boost Converter
■
High Efficiency Buck Converter
■
PC Power Supply with Multiple Outputs
■
Battery Up-Converter
■
Negative-to-Positive Converter
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.
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 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 100µA typical for standby operation.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
INPUT VOLTAGE (V)
0
0
OUTPUT POWER (W)
10
20
30
5
10
15 20
1271/69 TA02
25
40
50
30
BOOST
BUCK-BOOST
V
O
= 5V
(INVERTING)
FLYBACK
†
BUCK-BOOST
V
O
= 12V
(INVERTING)
BUCK MODE OUTPUT POWER
≈
(3.5A)(V
OUT
)
TRANSFORMER TURNS RATIO MUST BE
OPTIMUM TO ACHIEVE FULL POWER.
†
Maximum Output Power
V
SW
FB
GND
V
IN
V
C
LT1271
C1
200µF
35V
0.02µF
0.1µF
680Ω
0.03µF
4.7µF
TANT
1N4148
L1
25µH
TO 50µH
0.015Ω
390µF
16V
V
OUT
5V, 3A
<0.3V = NORMAL RUN MODE
>2.5V = SHUTDOWN
OPEN = BURST MODE OPERATION
V
IN
6.5V TO 25V
127/691 TA01
V
C
V
IN
MODE
V
OUT
V
LIM
V
+
LT1432
GND
DIODE
MBR
330pF
EFFICIENCY
≈
90%
AT I
OUT
= 0.4A TO 1.5A
+
+
+
High Efficiency 5V Regulator with Burst Mode
TM
Operation
2
LT1271/LT1269
A
U
G
W
A
W
U
W
ARB
S
O
LU
T
EXI T
I
S
Operating Junction Temperature Range
Operating.............................................. 0°C to 100°C
Short Circuit ......................................... 0°C to 125°C
Lead Temperature (Soldering, 10 sec.)................ 300°C
Supply Voltage ....................................................... 30V
Switch Output Voltage ............................................ 60V
Feedback Pin Voltage (Transient, 1ms) ................ ±15V
Storage Temperature Range ................ –65°C to 150°C
WU
U
PACKAGE
/
O
RDER I FOR ATIO
ORDER PART
NUMBER
V
IN
V
SW
GND
FB
V
C
T PACKAGE
5-LEAD PLASTIC TO-220
FRONT VIEW
5
4
3
2
1
T
J MAX
= 100°C, θ
JC
= 4°C/W, θ
JA
= 50°C/W
Q PACKAGE
5-LEAD PLASTIC DD
FRONT VIEW
V
IN
V
SW
GND
FB
V
C
5
4
3
2
1
T
J MAX
= 100°C, θ
JC
= 4°C/W, θ
JA
= 30°C/W*
LT1271CQ
LT1269CQ
ORDER PART
NUMBER
LT1271CT
LT1269CT
ORDER PART
NUMBER
LT1269CS
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
1
2
3
4
5
6
7
8
9
10
TOP VIEW
SW PACKAGE
20-LEAD PLASTIC WIDE SO
20
19
18
17
16
15
14
13
12
11
V
SW
V
SW
NC
GND
GND
GND
GND
AGND
V
C
FB
V
SW
V
SW
NC
GND
GND
GND
GND
V
IN
NC
NC
POWER
SWITCH
POWER
SWITCH
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
Reference Voltage Measured at Feedback Pin 1.224 1.244 1.264 V
V
C
= 0.8V ● 1.214 1.244 1.274 V
I
B
Feedback Input Current V
FB
= V
REF
350 750 nA
● 1100 nA
gm Error Amplifier ∆I
C
= ±25µA 3000 4400 6000 µmho
Transconductance
● 2400 7000 µmho
Error Amplifier Source or V
C
= 1.5V 150 200 350 µA
Sink Current ● 120 400 µA
Error Amplifier Clamp Hi Clamp, V
FB
= 1V 1.8 2.3 V
Voltage Lo Clamp, V
FB
= 1.5V 0.25 0.38 0.52 V
Reference Voltage Line 3V ≤ V
IN
≤ V
MAX,
V
C
= 0.8V ● 0.03 %/V
Regulation
A
V
Error Amplifier Voltage Gain 0.9V ≤ V
C
≤ 1.4V 500 800 V/V
Minimum Input Voltage (Note 3) ● 2.8 3.0 V
I
Q
Supply Current 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.6V 7 10 mA
V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF,
switch pin open, unless otherwise noted.
E
LECTR
IC
AL C CHARA TERIST
ICS
*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.
3
LT1271/LT1269
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Control Pin Threshold Duty Cycle = 0 0.7 0.9 1.08 V
● 0.5 1.25 V
Normal/Flyback Threshold 0.4 0.45 0.54 V
on Feedback Pin
V
FB
Flyback Reference Voltage I
FB
= 50µA 15 16.3 17.6 V
● 14 18 V
V
FB
Change in Flyback 0.05 ≤ I
FB
≤ 1mA 4.5 6.8 8.5 V
Reference Voltage
Flyback Reference Voltage I
FB
= 50µA 0.01 0.03 %/V
Line Regulation 3V ≤ V
IN
≤ V
MAX
Flyback Amplifier ∆I
C
= ±10µA 150 300 650 µmho
Transconductance (gm)
Flyback Amplifier Source V
C
= 0.6V Source ● 15 32 70 µA
and Sink Current I
FB
= 50µA Sink ● 25 40 70 µA
BV Output Switch Breakdown 3V ≤ V
IN
≤ V
MAX
● 60 75 V
Voltage I
SW
= 1.5mA
V
SAT
Output Switch (Note 1) ● 0.2 0.33 Ω
“On” Resistance
Control Voltage to Switch 6.4 A/V
Current Transconductance
I
LIM
Switch Current Limit (Note 2) Duty Cycle = 50% ● 48A
Duty Cycle = 80%
● 3.2 8 A
∆I
IN
Supply Current Increase 25 40 mA/A
∆I
SW
During Switch On-Time
f Switching Frequency LT1271 ● 50 60 70 kHz
LT1269
● 85 100 115 kHz
DC (max) Maximum Switch Duty Cycle LT1271 85 92 95 %
LT1269 80 90 95 %
Flyback Sense Delay Time 1.5 µs
Shutdown Mode 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.05V 100 400 µA
Supply Current
Shutdown Mode 3V ≤ V
IN
≤ V
MAX
100 150 250 mV
Threshold Voltage
● 50 300 mV
E
LECTR
IC
AL C CHARA TERIST
ICS
V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF,
switch pin open, unless otherwise noted.
The ● denotes the specifications which apply over the full operating
temperature range.
Note 1: Measured with V
C
in hi clamp, V
FB
= 0.8V.
Note 2: For duty cycles (DC) between 50% and 85%, minimum
guaranteed switch current is given by I
LIM
= 2.67 (2 – DC).
Note 3: Minimum input voltage.
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LT1269CSW#PBF

Mfr. #:
Buy LT1269CSW#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 4A Hi Eff Sw Regs
Lifecycle:
New from this manufacturer.
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