19-0107; Rev 3; 9/95
5A/2A Step-Down, PWM,
Switch-Mode DC-DC Regulators
_______________General Description
The MAX724/MAX726 are monolithic, bipolar, pulse-
width modulation (PWM), switch-mode DC-DC regula-
tors optimized for step-down applications. The
MAX724 is rated at 5A, and the MAX726 at 2A. Few
external components are needed for standard opera-
tion 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 invert-
ers, negative boost converters, or flyback converters.
These 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 MAX724/MAX726 also
have a wide 8V to 40V input range in the buck step-
down configuration. In inverting and boost configura-
tions, the input can be as low as 5V.
The MAX724/MAX726 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 (MAX724)
or 2.6A (MAX726).
___________________________Features
o
Input Range: Up to 40V
o
5A On-Chip Power Switch (MAX724)
2A On-Chip Power Switch (MAX726)
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
MAX724/MAX726
______________Ordering Information
PART
MAX724CCK
MAX724ECK
MAX726CCK
MAX726ECK
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
5 TO-220
5 TO-220
5 TO-220
5 TO-220
_______________________Applications
Distributed Power from High-Voltage Buses
High-Current, High-Voltage Step-Down Applications
High-Current Inverter
Negative Boost Converter
Multiple-Output Buck Converter
Isolated DC-DC Conversion
__________Typical Operating Circuit
__________________Pin Configuration
FRONT VIEW
INPUT
8V TO 40V
V
IN
220µF
V
SW
50µH
MBR745
FB
2.21k
GND
0.01µF
OUTPUT
5V AT 5A
2.8k
470µF
MAX724
V
C
2.7k
MAX724
MAX726
5
4
3
2
1
V
IN
V
SW
GND
V
C
FB
5-PIN TO-220
CASE IS CONNECTED TO GROUND.
STANDARD PACKAGE HAS STAGGERED LEADS.
CONTACT FACTORY FOR STRAIGHT LEADS.
5A STEP-DOWN CONVERTER
________________________________________________________________
Maxim Integrated Products
1
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