_______________General Description
The MXL1074/MXL1076 are monolithic, bipolar, pulse-
width modulation (PWM), switch-mode DC-DC regulators
optimized for step-down applications. The MXL1074 is
rated at 5A, while the MXL1076 is rated at 2A. Few exter-
nal components are needed for standard operation
because the power switch, oscillator, and control circuitry
are all on-chip. Employing a classic buck topology, these
regulators perform high-current step-down functions, but
can also be configured as an inverter, a negative boost
converter, or a flyback converter.
The regulators have excellent dynamic and transient-
response characteristics, while featuring cycle-by-cycle
current limiting to protect against overcurrent faults and
short-circuit output faults. The MXL1074/MXL1076 also
have a wide 8V to 40V input range in the step-down
configuration. In inverting and step-up configurations,
the input can be as low as 5V.
The MXL1074/MXL1076 are available in a 5-pin TO-220
package. The devices have a preset 100kHz oscillator
frequency and a preset current limit of 6.5A for the
MXL1074, and 2.6A for the MXL1076. The MXL1074/
MXL1076 are pin compatible with the LT1074/LT1076.
________________________Applications
Distributed Power from High-Voltage Buses
High-Current, High-Voltage Step-Down Applications
High-Current Inverter
Negative Step-Up Converter
Multiple-Output Step-Down Converter
Isolated DC-DC Conversion
____________________________Features
o
Input Range:
Up to 40V
o
5A On-Chip Power Switch (MXL1074)
2A On-Chip Power Switch (MXL1076)
o
Adjustable Output:
2.5V to 35V
o
100kHz Switching Frequency
o
Excellent Dynamic Characteristics
o
Few External Components
o
8.5mA Quiescent Current
o
TO-220 Package
______________Ordering Information
MXL1074/MXL1076
5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
________________________________________________________________
Maxim Integrated Products
1
INPUT
8V TO 40V
220F
2.7k
0.01F
GND
V
C
V
IN
FB
V
SW
MBR745
50H
OUTPUT
5V AT 5A
2.8k
2.21k
470F
MXL1074
__________________________________________________Typical Operating Circuits
Call toll free 1-800-998-8800 for free samples or literature.
19-0102; Rev 3; 9/95
PART
TEMP. RANGE
PIN-PACKAGE
MXL1074
CT
0C to +70C
5 TO-220
MXL1074ET
-40C to +85C
5 TO-220
5A STEP-DOWN CONVERTER
MXL1076
CT
0C to +70C
5 TO-220
MXL1076ET
-40C to +85C
5 TO-220
INPUT
8V TO 40V
220F
2.7k
0.01F
GND
V
C
V
IN
FB
V
SW
MBR745
100H
OUTPUT
5V AT 2A
2.8k
2.21k
470F
MXL1076
2A STEP-DOWN CONVERTER
V
IN
GND
FB
V
SW
V
C
MXL1074
MXL1076
5
4
3
2
1
5-PIN TO-220
FRONT VIEW
CASE IS CONNECTED TO GROUND. STANDARD PACKAGE HAS
STAGGERED LEADS. CONTACT FACTORY FOR STRAIGHT LEADS.
___________________Pin Configuration
MXL1074/MXL1076
5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
2
_______________________________________________________________________________________
Input Voltage ..........................................................................45V
Switch Voltage with Respect to Input Voltage .......................50V
Switch Voltage with Respect to Ground Pin (V
SW
negative)
(Note 1) ..............................................................................35V
Feedback Pin Voltage ...............................................-0.3V, +10V
Operating Temperature Ranges
MXL1074CT/MXL1076CT ...................................0C to +70C
MXL1074ET/MXL1076ET .................................-40C to +85C
Junction Temperature Ranges
MXL1074CT/MXL1076CT .................................0C to +125C
MXL1074ET/MXL1076ET ...............................-40C to +125C
Storage Temperature Range .............................-65C to +160C
Lead Temperature (soldering, 10sec) .............................+300C
ELECTRICAL CHARACTERISTICS
(V
IN
= 25V, T
j
= T
MIN
to T
MAX
, unless otherwise noted.)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
5.5
6.5
8.5
MXL1074
Switch-Current Limit (Note 5)
3.5
5.0
Minimum Supply Voltage
3.5
4.8
V
7.3
8.0
Normal Mode
mA
8.5
11
Supply Current (Note 3)
MIN
TYP
MAX
CONDITIONS
PARAMETER
A
2
2.6
3.2
MXL1076
UNITS
V
FB
= 2.5V, V
IN
40V
0.03
0.1
20
V
FB
= grounded through 2k
(Note 5)
Switching Frequency
85
120
kHz
90
100
110
%
85
90
Maximum Duty Cycle
T
j
= +25C
T
j
+125C
T
j
= +25C
8V
V
IN
40V
Switching Frequency Line
Regulation
%/V
ABSOLUTE MAXIMUM RATINGS
V
8.0
40.0
Input Supply Voltage Range
Start-Up Mode (Note 4)
T
j
0C
T
j
< 0C
MXL1076
MXL1074
1.7
I
SW =
2A
1.2
I
SW =
0.5A
2.50
T
j
< 0C
2.30
T
j
0C
I
SW
= 5A
2.10
T
j
< 0C
V
1.85
T
j
0C
I
SW
= 1A
Switch-On Voltage (Note 2)
MXL1076
MXL1074
250
T
j
= +25C
V
IN
= 40V, V
SW
= 0V
150
T
j
= +25C
V
IN
25V, V
SW
= 0V
10
500
T
j
= +25C
V
IN
= 40V, V
SW
= 0V
A
5
300
T
j
= +25C
V
IN
25V, V
SW
= 0V
Switch-Off Leakage
Note 1:
Do not exceed switch-to-input voltage limitation.
Note 2:
For switch currents between 1A and 5A, maximum switch on voltage can be calculated via linear interpolation.
Note 3:
By setting the feedback pin (FB) to 2.5V, the V
C
pin is forced to its low clamp level and the switch duty cycle is forced to
zero, approximating the zero load condition.
Note 4:
For proper regulation, total voltage from V
IN
to ground must be
8V after start-up.
Note 5:
To avoid extremely short switch-on times, the switch frequency is internally scaled down when V
FB
is less than 1.3V. Switch
current limit is tested with V
FB
adjusted to give a 1s minimum switch-on time.
Note 6:
Guaranteed, not production tested.
MXL1074/MXL1076
5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 25V, T
j
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
T
j
= +25C
Error-Amplifier Voltage Gain
1V
V
C
4V
2000
V/V
Error-Amplifier
Transconductance
C/W
2.5
MXL1074
4.0
MXL1076
Thermal Resistance Junction
to Case (Note 6)
V
1.5
T
j
= +25C
0.5
1.5
T
j
= +25C
VREF (nominal) = 2.21V
mV/C
-4
T
j
= T
MIN
to T
MAX
V
C
Voltage at 0% Duty Cycle
%/V
0.005
0.02
8V
V
IN
40V
Reference Voltage Line
Regulation
%
1
2.5
All conditions of input voltage, output voltage,
temperature and load current
Reference Voltage Tolerance
V
2.155
2.210
2.265
V
C
= 2V
Reference Voltage
A
0.5
2
V
FB
= VREF
Feedback Pin Bias Current
mA
0.6
1.0
1.7
T
j
= +25C
V
FB
= 2.5V
Error-Amplifier Sink Current
A
100
140
225
T
j
= +25C
V
FB
= 2V
Error-Amplifier Source Current
mho
3000
5000
9000
T
j
= +25C
UNITS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
4
___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
1995 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products
MXL1074/MXL1076
5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
________________________________________________________Package Information
E
J3
F
B
DIM
A
B
C1
D
E
e
F
H1
J1
J2
J3
L
L1
L2
P
Q
MIN
0.140
0.015
0.014
0.560
0.380
0.045
0.230
0.080
0.170
0.327
0.170
0.260
0.700
0.139
0.100
MAX
0.190
0.040
0.022
0.650
0.420
0.055
0.270
0.115
0.185
0.335
0.200
0.340
0.720
0.161
0.120
MIN
3.56
0.38
0.41
14.23
9.66
1.14
5.85
2.04
4.32
8.31
4.32
6.60
17.78
3.54
2.54
MAX
4.82
1.01
0.50
16.51
10.66
1.39
6.85
2.92
4.70
8.51
5.08
8.64
18.29
4.08
3.04
INCHES
MILLIMETERS
e
21-005-
5-PIN TO-220
(STAGGERED LEAD)
PACKAGE
1.70 BSC
0.067 BSC
P
H1
Q
D
A
L2
J1
L1
L
C1
J2
E
F
B
DIM
A
B
C1
D
E
e
F
H1
J1
L
P
Q
MIN
0.140
0.015
0.014
0.560
0.380
0.045
0.230
0.080
0.500
0.139
0.100
MAX
0.190
0.040
0.022
0.650
0.420
0.055
0.270
0.115
0.580
0.161
0.120
MIN
3.56
0.38
0.41
14.23
9.66
1.14
5.85
2.04
12.70
3.54
2.54
MAX
4.82
1.01
0.50
16.51
10.66
1.39
6.85
2.92
14.73
4.08
3.04
INCHES
MILLIMETERS
e
21-4737-
5-PIN TO-220
(STRAIGHT LEAD)
PACKAGE
1.70 BSC
0.067 BSC
P
H1
Q
D
A
J1
C1
L
CONTACT FACTORY FOR AVAILABILITY
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