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LT1076CT#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
LT1074/LT1076
1
sn1074 1074fds
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
Step-Down Switching
Regulator
The LT
®
1074 is a 5A (LT1076 is rated at 2A) monolithic
bipolar switching regulator which requires only a few
external parts for normal operation. The power switch, all
oscillator and control circuitry, and all current limit com-
■
Buck Converter with Output Voltage Range of 2.5V
to 50V
■
Tapped-Inductor Buck Converter with 10A Output
at 5V
■
Positive-to-Negative Converter
■
Negative Boost Converter
■
Multiple Output Buck Converter
■
5A Onboard Switch (LT1074)
■
Operates Up to 60V Input
■
100kHz Switching Frequency
■
Greatly Improved Dynamic Behavior
■
Available in Low Cost 5 and 7-Lead Packages
■
Only 8.5mA Quiescent Current
■
Programmable Current Limit
■
Micropower Shutdown Mode
ponents, are included on the chip. The topology is a classic
positive “buck” configuration but several design innova-
tions allow this device to be used as a positive-to-negative
converter, a negative boost converter, and as a flyback
converter. The switch output is specified to swing 40V
below ground, allowing the LT1074 to drive a tapped-
inductor in the buck mode with output currents up to 10A.
The LT1074 uses a true analog multiplier in the feedback
loop. This makes the device respond nearly instanta-
neously to input voltage fluctuations and makes loop gain
independent of input voltage. As a result, dynamic behav-
ior of the regulator is significantly improved over previous
designs.
On-chip pulse by pulse current limiting makes the LT1074
nearly bust-proof for output overloads or shorts. The input
voltage range as a buck converter is 8V to 60V, but a self-
boot feature allows input voltages as low as 5V in the
inverting and boost configurations.
The LT1074 is available in low cost TO-220 or DD packages
with frequency pre-set at 100kHz and current limit at 6.5A
(LT1076 = 2.6A). A 7-pin TO-220 package is also available
which allows current limit to be adjusted down to zero. In
addition, full micropower shutdown can be programmed.
See Application Note 44 for design details.
A fixed 5V output, 2A version is also available. See LT1076-5.
Buck Converter Efficiency
Basic Positive Buck Converter
+
+
V
SW
V
IN
V
C
GND
FB
LT1074
5V
5A
C1
500
µF
R1
2.8k
1%
R2
2.21k
1%
MBR745*
10V TO 40V
C3
†
200µF
R3
2.7k
C2
0.01
µF
L1**
50µH (LT1074)
100
µH (LT1076)
USE MBR340 FOR LT1076
COILTRONICS #50-2-52 (LT1074)
#100-1-52 (LT1076)
PULSE ENGINEERING, INC.
#PE-92114 (LT1074)
#PE-92102 (LT1076)
HURRICANE #HL-AK147QQ (LT1074)
#HL-AG210LL (LT1076)
RIPPLE CURRENT RATING ≥ I
OUT
/2
*
**
†
LT1074•TA01
25V
OUTPUT LOAD CURRENT (A)
0
EFFICIENCY (%)
60
70
80
90
1234
LT1074•TPC27
5
6
100
50
L = 50µH TYPE 52 CORE
DIODE = MBR735
V = 5V, V = 15V
OUT IN
V = 12V, V = 20V
OUT IN
LT1074
LT1074/LT1076
2
sn1074 1074fds
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
(Note 1)
*Assumes package is soldered to 0.5 IN
2
of 1 oz. copper over internal ground plane or over back side plane.
LT1076CQ
LT1076IQ
LT1076CR
LT1076IR
LT1076HVCR
LT1076HVIR
LT1074CT7
LT1074HVCT7
LT1074IT7
LT1074HVIT7
LT1076CT7
LT1076HVCT7
LT1074CT
LT1074HVCT
LT1074IT
LT1074HVIT
LT1076CT
LT1076HVCT
LT1076IT
LT1076HVIT
LT1074CK
LT1074HVCK
LT1074MK
LT1074HVMK
LT1076CK
LT1076HVCK
LT1076MK
LT1076HVMK
Input Voltage
LT1074/ LT1076 .................................................. 45V
LT1074HV/LT1076HV ......................................... 64V
Switch Voltage with Respect to Input Voltage
LT1074/ LT1076 .................................................. 64V
LT1074HV/LT1076HV ......................................... 75V
Switch Voltage with Respect to Ground Pin (V
SW
Negative)
LT1074/LT1076 (Note 7) ..................................... 35V
LT1074HV/LT1076HV (Note 7) ........................... 45V
Feedback Pin Voltage..................................... –2V, +10V
Shutdown Pin Voltage (Not to Exceed V
IN
) .............. 40V
I
LIM
Pin Voltage (Forced) ............................................ 5.5V
Maximum Operating Ambient Temperature Range
Commercial .................................................0°C to 70°C
Industrial ................................................ –40°C to 85°C
Military (OBSOLETE) ..................... –55°C to 125°C
Maximum Operating Junction Temperature Range
Commercial ............................................... 0°C to 125°C
Industrial .............................................. –40°C to 125°C
Military (OBSOLETE) .................... –55°C to 150°C
Maximum Storage Temperature ............... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)...................... 300°C
ORDER PART
NUMBER
ORDER PART
NUMBER
LT1076: θ
JC
= 4°C, θ
JA
= 30°C/W
LT1076: θ
JC
= 4°C, θ
JA
= 30°C/W
LT1074: θ
JC
= 2.5°C, θ
JA
= 50°C/W
LT1076: θ
JC
= 4°C, θ
JA
= 50°C/W
LT1074: θ
JC
= 2.5°C, θ
JA
= 35°C/W
LT1076: θ
JC
= 4°C, θ
JA
= 35°C/W
LT1074: θ
JC
= 2.5°C, θ
JA
= 50°C/W
LT1076: θ
JC
= 4°C, θ
JA
= 50°C/W
Q PACKAGE
5-LEAD PLASTIC DD
FRONT VIEW
V
IN
V
SW
GND
V
C
FB/SENSE
5
4
3
2
1
R PACKAGE
7-LEAD PLASTIC DD
FRONT VIEW
SHDN
V
C
FB/SENSE
GND
I
LIM
V
SW
V
IN
7
6
5
4
3
2
1
2
4
1
3
V
C
V
IN
V
SW
CASE
IS GND
FB
K PACKAGE
4-LEAD TO-3 METAL CAN
BOTTOM VIEW
T PACKAGE
5-LEAD PLASTIC TO-220
LEADS ARE FORMED STANDARD FOR
STRAIGHT LEADS, ORDER FLOW 06
V
IN
V
SW
GND
V
C
FB
FRONT VIEW
5
4
3
2
1
T7 PACKAGE
7-LEAD PLASTIC TO-220
SHDN
V
C
FB
GND
I
LIM
V
SW
V
IN
FRONT VIEW
7
6
5
4
3
2
1
TAB IS
GND
TAB IS
GND
TAB IS
GND
TAB IS
GND
Consult LTC Marketing for parts specified with wider operating temperature ranges.
OBSOLETE PACKAGE
Consider the T5 Package for Alternate Source
LT1074/LT1076
3
sn1074 1074fds
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. T
j
= 25°C, V
IN
= 25V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch “On” Voltage (Note 2) LT1074 I
SW
= 1A, T
j
≥ 0°C 1.85 V
I
SW
= 1A, T
j
< 0°C 2.1 V
I
SW
= 5A, T
j
≥ 0°C 2.3 V
I
SW
= 5A, T
j
< 0°C 2.5 V
LT1076 I
SW
= 0.5A ● 1.2 V
I
SW
= 2A ● 1.7 V
Switch “Off” Leakage LT1074 V
IN
≤ 25V, V
SW
= 0 5 300 µA
V
IN
= V
MAX,
V
SW
= 0 (Note 8) 10 500 µA
LT1076 V
IN
= 25V, V
SW
= 0 150 µA
V
IN
= V
MAX,
V
SW
= 0 (Note 8) 250 µA
Supply Current (Note 3) V
FB
= 2.5V, V
IN
≤ 40V ● 8.5 11 mA
40V < V
IN
< 60V ● 912 mA
V
SHUT
= 0.1V (Device Shutdown) (Note 9) ● 140 300 µA
Minimum Supply Voltage Normal Mode ● 7.3 8 V
Startup Mode (Note 4)
● 3.5 4.8 V
Switch Current Limit (Note 5) LT1074 I
LIM
Open ● 5.5 6.5 8.5 A
R
LIM
= 10k (Note 6) 4.5 A
R
LIM
= 7k (Note 6) 3 A
LT1076 I
LIM
Open ● 2 2.6 3.2 A
R
LIM
= 10k (Note 6) 1.8 A
R
LIM
= 7k (Note 6) 1.2 A
Maximum Duty Cycle ● 85 90 %
Switching Frequency 90 100 110 kHz
T
j
≤ 125°C ● 85 120 kHz
T
j
> 125°C ● 85 125 kHz
V
FB
= 0V through 2kΩ (Note 5) 20 kHz
Switching Frequency Line Regulation 8V ≤ V
IN
≤ V
MAX
(Note 8) ● 0.03 0.1 %/V
Error Amplifier Voltage Gain (Note 7) 1V ≤ V
C
≤ 4V 2000 V/V
Error Amplifier Transconductance 3700 5000 8000 µmho
Error Amplifier Source and Sink Current Source (V
FB
= 2V) 100 140 225 µA
Sink (V
FB
= 2.5V) 0.7 1 1.6 mA
Feedback Pin Bias Current V
FB
= V
REF
● 0.5 2 µA
Reference Voltage V
C
= 2V ● 2.155 2.21 2.265 V
Reference Voltage Tolerance V
REF
(Nominal) = 2.21V ±0.5 ±1.5 %
All Conditions of Input Voltage, Output
● ±1 ±2.5 %
Voltage, Temperature and Load Current
Reference Voltage Line Regulation 8V ≤ V
IN
≤ V
MAX
(Note 8) ● 0.005 0.02 %/V
V
C
Voltage at 0% Duty Cycle 1.5 V
Over Temperature
● –4 mV/°C
Multiplier Reference Voltage 24 V
Shutdown Pin Current V
SH
= 5V ● 51020 µA
V
SH
≤ V
THRESHOLD
(≅2.5V) ● 50 µA
Shutdown Thresholds Switch Duty Cycle = 0 ● 2.2 2.45 2.7 V
Fully Shut Down
● 0.1 0.3 0.6 V
Thermal Resistance Junction to Case LT1074 2.5 °C/W
LT1076 4.0 °C/W
ELECTRICAL CHARACTERISTICS
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LT1076CT#PBF

Mfr. #:
Buy LT1076CT#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 2A Step-Down Switching Reg
Lifecycle:
New from this manufacturer.
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