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LT1371IR#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
1
LT1371
500kHz High Efficiency
3A Switching Regulator
The LT
®
1371 is a monolithic high frequency current mode
switching regulator. It can be operated in all standard
switching configurations including boost, buck, flyback,
forward, inverting and “Cuk.” A 3A high efficiency switch
is included on the die, along with all oscillator, control and
protection circuitry.
The LT1371 typically consumes only 4mA quiescent
current and has higher efficiency than previous parts.
High frequency switching allows for very small inductors
to be used.
New design techniques increase flexibility and maintain
ease of use. Switching is easily synchronized to an exter-
nal logic level source. A logic low on the Shutdown pin
reduces supply current to 12µA. Unique error amplifier
circuitry can regulate positive or negative output voltage
while maintaining simple frequency compensation tech-
niques. Nonlinear error amplifier transconductance re-
duces output overshoot on start-up or overload recovery.
Oscillator frequency shifting protects external compo-
nents during overload conditions.
DESCRIPTION
U
■
Faster Switching with Increased Efficiency
■
Uses Small Inductors: 4.7µH
■
All Surface Mount Components
■
Low Minimum Supply Voltage: 2.7V
■
Quiescent Current: 4mA Typ
■
Current Limited Power Switch: 3A
■
Regulates Positive or Negative Outputs
■
Shutdown Supply Current: 12µA Typ
■
Easy External Synchronization
■
Boost Regulators
■
Laptop Computer Supplies
■
Multiple Output Flyback Supplies
■
Inverting Supplies
APPLICATIONS
U
TYPICAL APPLICATION
U
5V to 12V Boost Converter
OUTPUT CURRENT (A)
0.01
50
EFFICIENCY (%)
60
70
80
90
0.1 1
LT1371 • TA02
100
V
IN
= 5V
12V Output Efficiency
LT1371
V
IN
V
C
5V
GND
FB
LT1371 • TA01
V
SW
S/S
L1*
4.7µH
C1**
22µF
25V
C4**
22µF
25V
× 2
C2
0.047µF
C3
0.0047µF
R3
2k
R2
6.19k
1%
R1
53.6k
1%
V
OUT
†
12V
D1
MBRS330T3
ON
OFF
*
**
COILCRAFT DO3316P-472 (4.7µH),
DO3316P-103 (10µH) OR 
SUMIDA CD104-100MC (10µH)
AVX TPSD226M025R0200
+ +
L1
4.7µH
10µH
I
OUT
0.7A
0.8A
†
MAX I
OUT
FEATURES
, LTC and LT are registered trademarks of Linear Technology Corporation.
2
LT1371
A
U
G
W
A
W
U
W
ARB
S
O
LU
T
EXI T
I
S
Supply Voltage ....................................................... 30V
Switch Voltage
LT1371 ............................................................... 35V
LT1371HV .......................................................... 42V
S/S, SHDN, SYNC Pin Voltage ................................ 30V
Feedback Pin Voltage (Transient, 10ms) .............. ±10V
Feedback Pin Current........................................... 10mA
Negative Feedback Pin Voltage
(Transient, 10ms)............................................. ±10V
Operating Ambient Temperature Range ...... 0°C to 70°C
Operating Junction Temperature Range
Commercial .......................................... 0°C to 125°C
Industrial ......................................... –40°C to 125°C
Short Circuit ......................................... 0°C to 150°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
E
LECTR
IC
AL C CHARA TERIST
ICS
V
IN
= 5V, V
C
= 0.6V, V
FB
= V
REF
, V
SW
, S/S, SHDN, SYNC and NFB pins open, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
Reference Voltage Measured at Feedback Pin 1.230 1.245 1.260 V
V
C
= 0.8V ● 1.225 1.245 1.265 V
I
FB
Feedback Input Current V
FB
= V
REF
250 550 nA
● 900 nA
Reference Voltage Line Regulation 2.7V ≤ V
IN
≤ 25V, V
C
= 0.8V ● 0.01 0.03 %/V
WU
U
PACKAGE
/
O
RDER I FOR ATIO
T
JMAX
= 125°C, θ
JA
= 30°C/W
R PACKAGE
7-LEAD PLASTIC DD
FRONT VIEW
TAB
IS
GND
V
IN
S/S
V
SW
GND
NFB
FB
V
C
7
6
5
4
3
2
1
ORDER PART
NUMBER
WITH PACKAGE SOLDERED TO 0.5 INCH
2
COPPER
AREA OVER BACKSIDE GROUND PLANE OR INTERNAL
POWER PLANE. θ
JA
CAN VARY FROM 20°C/W TO
>40°C/W DEPENDING ON MOUNTING TECHNIQUE
ORDER PART
NUMBER
T7 PACKAGE
7-LEAD TO-220
V
IN
S/S
V
SW
GND
NFB
FB
V
C
FRONT VIEW
7
6
5
4
3
2
1
TAB
IS
GND
T
JMAX
= 125°C, θ
JA
= 50°C/W, θ
JC
= 4°C/W
ORDER PART
NUMBER
T
JMAX
= 125°C, θ
JA
= 50°C/W
θ
JA
WILL VARY FROM APPROXIMATELY 40°C/W WITH
0.75 INCH
2
OF 1 OZ COPPER TO 50°C/W WITH 0.33 INCH
2
OF 1 OZ COPPER ON A DOUBLE-SIDED BOARD
1
2
3
4
5
6
7
8
9
10
TOP VIEW
SW PACKAGE
20-LEAD PLASTIC SO WIDE
20
19
18
17
16
15
14
13
12
11
V
C
FB
NFB
GND
GND
GND
GND
SHDN
SYNC
V
IN
V
SW
NC
V
SW
GND
GND
GND
GND
NC
NC
GND
LT1371CR
LT1371HVCR
LT1371IR
LT1371HVIR
LT1371CT7
LT1371HVCT7
LT1371IT7
LT1371HVIT7
LT1371CSW
LT1371HVCSW
LT1371ISW
LT1371HVISW
Consult factory for Military grade parts.
3
LT1371
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
NFB
Negative Feedback Reference Voltage Measured at Negative Feedback Pin –2.540 –2.490 –2.440 V
Feedback Pin Open, V
C
= 0.8V ● –2.570 – 2.490 – 2.410 V
I
NFB
Negative Feedback Input Current V
NFB
= V
NFR
● –45 –30 –15 µA
Negative Feedback Reference Voltage 2.7V ≤ V
IN
≤ 25V, V
C
= 0.8V ● 0.01 0.05 %/V
Line Regulation
g
m
Error Amplifier Transconductance ∆I
C
= ±25µA 1100 1500 1900 µmho
● 700 2300 µmho
Error Amplifier Source Current V
FB
= V
REF
– 150mV, V
C
= 1.5V ● 120 200 350 µA
Error Amplifier Sink Current V
FB
= V
REF
+ 150mV, V
C
= 1.5V ● 1400 2400 µA
Error Amplifier Clamp Voltage High Clamp, V
FB
= 1V 1.70 1.95 2.30 V
Low Clamp, V
FB
= 1.5V 0.25 0.40 0.52 V
A
V
Error Amplifier Voltage Gain 500 V/V
V
C
Pin Threshold Duty Cycle = 0% 0.8 1 1.25 V
f Switching Frequency 2.7V ≤ V
IN
≤ 25V 450 500 550 kHz
0°C ≤ T
J
≤ 125°C ● 430 500 580 kHz
–40°C ≤ T
J
≤ 0°C (I Grade) 400 580 kHz
Maximum Switch Duty Cycle ● 85 95 %
Switch Current Limit Blanking Time 130 260 ns
BV Output Switch Breakdown Voltage LT1371 ● 35 47 V
LT1371HV
0° C ≤ T
J
≤ 125°C ● 42 47 V
–40°C ≤ T
J
≤ 0°C (I Grade) 40 V
V
SAT
Output Switch ON Resistance I
SW
= 2A ● 0.25 0.45 Ω
I
LIM
Switch Current Limit Duty Cycle = 50% ● 3.0 3.8 5.4 A
Duty Cycle = 80% (Note 1)
● 2.6 3.4 5.0 A
∆I
IN
Supply Current Increase During Switch ON Time 15 25 mA/A
∆I
SW
Control Voltage to Switch Current 4A/V
Transconductance
Minimum Input Voltage ● 2.4 2.7 V
I
Q
Supply Current 2.7V ≤ V
IN
≤ 25V ● 4 5.5 mA
Shutdown Supply Current 2.7V ≤ V
IN
≤ 25V, V
S/S
≤ 0.6V
0° C ≤ T
J
≤ 125°C ● 12 30 µA
–40°C ≤ T
J
≤ 0°C (I Grade) 50 µA
Shutdown Threshold 2.7V ≤ V
IN
≤ 25V ● 0.6 1.3 2 V
Shutdown Delay ● 51225µs
S/S or SHDN Pin Input Current 0V ≤ V
S/S
or V
SHDN
≤ 5V ● –10 15 µA
Synchronization Frequency Range ● 600 800 kHz
E
LECTR
IC
AL C CHARA TERIST
ICS
V
IN
= 5V, V
C
= 0.6V, V
FB
= V
REF
, V
SW
, S/S, SHDN, SYNC and NFB pins open, unless otherwise noted.
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: For duty cycles (DC) between 50% and 90%, minimum
guaranteed switch current is given by I
LIM
= 1.33 (2.75 – DC).
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

LT1371IR#TRPBF

Mfr. #:
Buy LT1371IR#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 500kHz Hi Eff 3A Sw Reg
Lifecycle:
New from this manufacturer.
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