MAX746 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – High-Efficiency, PWM, Step-Down, N-Channel DC-DC Controller

19-0192; Rev 1; 11/93
High-Efficiency, PWM, Step-Down,
N-Channel DC-DC Controller
_______________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
5V/adjustable (Dual-Mode^TM) 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^TM) scheme
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
REF
SS
OUT
LBO
CC FB AGNDGND
40mΩ
39µH
OUTPUT
5V
440µF
LOW-BATTERY
DETECTOR OUTPUT
____________________________Features
o 93% to 96% Efficiency for 50mA to 3A
Output Currents
o 4V to 15V Input Voltage Range
o Low 950µA Supply Current
o 1.4µA Shutdown Current
o Drives External N-Channel FETs
o Fixed-Frequency Current-Mode PWM (Heavy Loads)
o Idle-Mode PFM (Light Loads)
o Cycle-by-Cycle Current Limiting
o 2V ±1.5% Accurate Reference Output
o Adjustable Soft-Start
o Undervoltage Lockout
o Precision Comparator for Power-Fail or
Low-Battery Warning
______________Ordering Information
PART
TEMP. RANGE
MAX746CPE
0°C to +70°C
MAX746CSE
0°C to +70°C
MAX746C/D
0°C to +70°C
MAX746EPE
-40°C to +85°C
MAX746ESE
-40°C to +85°C
MAX746MJE
-55°C to +125°C
* Contact factory for dice specifications.
PIN-PACKAGE
16 Plastic DIP
16 Narrow SO
Dice*
16 Plastic DIP
16 Narrow SO
16 CERDIP
__________________Pin Configuration
TOP VIEW
LBO ₁
LBI 2
SS ₃
REF ₄
SHDN 5
FB 6
CC ₇
AV+ ₈
MAX746
16 ^GND
15 V+
14 CP
13 HIGH
12 EXT
11 AGND
10 CS
9 OUT
™Dual-Mode and Idle-Mode are trademarks of Maxim Integrated Products.
DIP/SO
________________________________________________________________ Maxim Integrated Products 1
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