MAX746 Maxim, MAX746 Datasheet

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MAX746

Manufacturer Part Number
MAX746
Description
High-Efficiency / PWM / Step-Down / N-Channel DC-DC Controller
Manufacturer
Maxim
Datasheet
19-0192; Rev 1; 11/93
High-Efficiency, PWM, Step-Down,
_______________General Description
The MAX746 is a high-efficiency, high-current, step-down
DC-DC power-supply controller that drives external N-chan-
nel FETs. It provides 93% to 96% efficiency from a 6V supply
voltage with load currents ranging from 50mA up to 3A. It
uses a pulse-width-modulating (PWM) current-mode control
scheme to provide precise output regulation and low output
noise. The MAX746's 4V to 15V input voltage range, fixed
TM
5V/adjustable (Dual-Mode
) output, and adjustable current
limit make this device ideal for a wide range of applications.
High efficiency is maintained with light loads due to a propri-
etary automatic pulse-skipping control (Idle-Mode
that minimizes switching losses by reducing the switching fre-
quency at light loads. The low 950µA quiescent current and
ultra-low 1.4µA shutdown current further extend battery life.
External components are protected by the MAX746's cycle-
by-cycle current limit. The MAX746 also features a 2V ±1.5%
reference, a comparator for low-battery detection or level
translating, and soft-start and shutdown capability.
The MAX747—discussed in a separate data sheet—
functions similarly to the MAX746, but drives P-channel logic
level FETs.
________________________Applications
5V-to-3.3V Green PC Applications
Notebook/Laptop Computers
Personal Digital Assistants
Battery-Operated Equipment
Cellular Phones
__________Typical Operating Circuit
INPUT 6V TO 15V
V+
AV+
CP
MAX746
HIGH
CS
SHDN
EXT
ON/OFF
LOW-BATTERY
DETECTOR INPUT
LBI
OUT
LBO
REF
SS
CC
FB
AGND
GND
™Dual-Mode and Idle-Mode are trademarks of Maxim Integrated Products.
________________________________________________________________ Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
N-Channel DC-DC Controller
____________________________Features
93% to 96% Efficiency for 50mA to 3A
Output Currents
4V to 15V Input Voltage Range
Low 950µA Supply Current
1.4µA Shutdown Current
Drives External N-Channel FETs
Fixed-Frequency Current-Mode PWM (Heavy Loads)
Idle-Mode PFM (Light Loads)
TM
) scheme
Cycle-by-Cycle Current Limiting
2V ±1.5% Accurate Reference Output
Adjustable Soft-Start
Undervoltage Lockout
Precision Comparator for Power-Fail or
Low-Battery Warning
______________Ordering Information
PART
MAX746CPE
MAX746CSE
MAX746C/D
MAX746EPE
MAX746ESE
MAX746MJE
* Contact factory for dice specifications.
__________________Pin Configuration
TOP VIEW
40m
LBO
LBI
SS
OUTPUT
39 H
REF
5V
SHDN
440 F
FB
CC
LOW-BATTERY
DETECTOR OUTPUT
AV+
TEMP. RANGE
PIN-PACKAGE
0°C to +70°C
16 Plastic DIP
0°C to +70°C
16 Narrow SO
0°C to +70°C
Dice*
-40°C to +85°C
16 Plastic DIP
-40°C to +85°C
16 Narrow SO
-55°C to +125°C
16 CERDIP
GND
1
16
V+
2
15
CP
3
14
MAX746
HIGH
4
13
EXT
5
12
6
AGND
11
CS
7
10
8
9
OUT
DIP/SO
1

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