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MAX747CSD+

P1-P3P4-P6P7-P9P10-P12
_______________General Description
The MAX747 high-efficiency, high-current, step-down
controller drives external P-channel FETs. It provides
90% to 95% efficiency from a 6V supply with load
currents ranging from 50mA up to 2.5A. It uses a
pulse-width-modulating (PWM) current-mode control
scheme to provide precise output regulation and low
output noise. The MAX747’s 4V to 15V input voltage
range, a fixed 5V/adjustable (Dual-Mode™) output, and
a current limit set with an external resistor make this
device ideal for a wide range of applications.
High efficiency is maintained with light loads due to a
proprietary dual-control (Idle-Mode™) scheme that
minimizes switching losses by reducing the switching
frequency at light loads. The low 800µA quiescent
current and ultra-low 0.6µA shutdown current further
extend battery life.
External components are protected by the MAX747’s
cycle-by-cycle current limit. The MAX747 also features a
2V ±1.5% reference, a comparator for low-battery
detection or level translating, as well as soft-start and
shutdown capability.
The MAX746, discussed in a separate data sheet,
functions similarly to the MAX747, but it drives N-channel
logic level FETs on the high side.
________________________Applications
Notebook Power Supplies
Personal Digital Assistants
Battery-Operated Equipment
Cellular Phones
5V to 3.3V Green PC Applications
____________________________Features
♦ 90% to 95% Efficiency for 50mA to 2.5A
Output Currents
♦ 4V to 15V Input Voltage Range
♦ Low 800µA Supply Current
♦ 0.6µA Shutdown Current
♦ Drives External P-Channel FETs
♦ Cycle-by-Cycle Current Limiting
♦ 2V ±1.5% Accurate Reference Output
♦ Adjustable Soft-Start
♦ Precision Comparator for Power-Fail or
Low-Battery Warning
______________Ordering Information
* Contact factory for dice specifications.
MAX747
High-Efficiency PWM, Step-Down
P-Channel DC-DC Controller
________________________________________________________________
Maxim Integrated Products
1
OUTPUT
5V
2.3A
INPUT
6V TO 15V
AV+
EXT
OUT
GND
430µF
REF
MAX747
CS
SHDN
ON/OFF
LBI
LOW-BATTERY
DETECTOR
INPUT
V+
LOW-BATTERY
DETECTOR
OUTPUT
AGNDFBCCSS
LBO
5OmΩ
5OµH
P
0.1µF
100µF
__________________Pin Configuration
SS
1
2
3
4
14
13
12
11
GND
CC
FB
AV+
LBI
DIP/SO
TOP VIEW
MAX747
5
6
7
10
9
8
OUT
AGND
REF
SHDN
LBO
V+
EXT
CS
__________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.
19-0171; Rev 1; 9/93
PART TEMP. RANGE PIN-PACKAGE
MAX747CPD 0°C to +70°C 14 Plastic DIP
MAX747CSD 0°C to +70°C 14 Narrow SO
MAX747C/D 0°C to +70°C Dice*
MAX747EPD -40°C to +85°C 14 Plastic DIP
MAX747ESD -40°C to +85°C 14 Narrow SO
MAX747MJD -55°C to +125°C 14 CERIDIP
™ Dual-Mode and Idle-Mode are trademarks of Maxim Integrated Products.
MAX747
High-Efficiency PWM, Step-Down
P-Channel DC-DC Controller
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Supply Voltage V+, AV+ to GND..............................-0.3V to 17V
AGND to GND..........................................................-0.3V to 0.3V
All Other Pins................................................-0.3V to (V+ + 0.3V)
Reference Current (I
REF
) ....................................................±2mA
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 10.00mW/°C above +70°C) ..........800mW
SO (derate 8.33mW/°C above +70°C).........................667mW
CERDIP (derate 9.09mW/°C above +70°C).................727mW
Operating Temperature Ranges:
MAX747C_D .......................................................0°C to +70°C
MAX747E_D.....................................................-40°C to +85°C
MAX747MJD..................................................-55°C to +125°C
Junction Temperature
MAX747C_D/E_D.........................................................+150°C
MAX747MJD ...............................................................+175°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
ELECTRICAL CHARACTERISTICS
(V+ = 10V, I
LOAD
= 0mA, I
REF
= 0mA, T
A
= 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.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range V+ For regulated outputs 415V
Output Voltage V
OUT
V+ = 6V to 15V, 0V < V+ - CS < 0.125V, FB = 0V
(includes line and load regulation)
4.85 5.08 5.25 V
Feedback Voltage
1.96 2.00 2.04
V
V+ = 6V to 15V, FB = 0V 0.05
Line Regulation
V+ = 4V to 15V, external feedback mode 0.1
%V
Load Regulation 0V < V+ - CS < 0.125V 1.3 2.5 %
Efficiency Circuit of Figure 1, I
LOAD
= 0.5A to 2.5A 91 %
OUT Leakage Current V
OUT
= 5V 50 80 µA
FB Input Logic Low For dual-mode switchover 40 mV
FB Input Leakage Current FB = 2V 0.1 100 nA
Reference Voltage I
REF
= 0µA
1.97 2.00 2.03
V
Reference Load Regulation I
REF
= 0µA to 100µA 920mV
Soft-Start Source Current SS = 0V 1 µA
Soft-Start Fault Current SS = 2V 100 500 µA
Operating, V+ = 15V 0.95 1.3
Operating, V+ = 10V 0.8
mA
Supply Current
Shutdown mode 0.6 20 µA
Oscillator Frequency f
OSC
MAX747C 85 100 115
kHz
Maximum Duty Cycle V+ = 6V 91 96 %
CS Amp I
LIM
Threshold V
LIMIT
V+ - CS 125 150 175 mV
EXT Output High I
EXT
= -1mA (sourcing) V+ – 0.1 V
EXT Output Low I
EXT
= 1mA (sinking) 0.25 V
EXT Sink Current V
EXT
= 7.5V 110 mA
EXT Source Current V
EXT
= 2.5V 170 mA
CC Impedance 24 kΩ
LBI Threshold Voltage V
TH
LBI falling
1.97 2.00 2.03
V
LBI Input Leakage Current LBI = 2.5V 100 nA
SHDN Input Voltage Low V
IL
0.4 V
SHDN Input Voltage High V
IH
2.0 V
SHDN Input Leakage Current SHDN = 10V 0.1 100 nA
V
REF
LBO Output Leakage Current V+ = 15V, LBO = 15V, LBI = 2.5V 1 µA
LBO Output Voltage Low I
SINK
= 0.5mA 0.4 V
MAX747C
MAX747EM 1.96 2.00 2.04
MAX747E/M 80 100 120
MAX747C
MAX747E/M 1.96 2.00 2.04
V+ - CS = 0V, external
feedback mode
MAX747C
MAX747E/M 1.95 2.00 2.05
MAX747
High-Efficiency PWM, Step-Down
P-Channel DC-DC Controller
_______________________________________________________________________________________
3
0
-75
SUPPLY CURRENT vs.
TEMPERATURE
1
MAX747-TOC1
TEMPERATURE (°C)
3
2
4
-50 -25 0 25 50 75 100 125
V
IN
= 9V
V
OUT
= 5V
SCHOTTKY DIODE
LEAKAGE EXCLUDED
ENTIRE
CIRCUIT
SUPPLY CURRENT (mA)
0.6
5
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
0.7
MAX747-TOC2
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
13
0.9
0.8
71115
1.0
9
2
0.4
CONTINUOUS-CONDUCTION MODE BOUNDARY
AND CORRESPONDING PEAK INDUCTOR CURRENT (V
OUT
= 3.3V)
6
MAX747-TOC3
OUTPUT CURRENT (A)
SUPPLY VOLTAGE (V)
1.2
14
10
0.6 1.0 1.4
18
0.8
CONTINUOUS
CONDUCTION
REGION
V
OUT
= 3.3V
L = 33µH
R
SENSE
= 50mΩ
DISCONTINUOUS
CONDUCTION
REGION
PEAK
INDUCTOR
CURRENT
0.4
0.8
1.6
1.2
2.0
PEAK INDUCTOR CURRENT (A)
5
0.5
CONTINUOUS-CONDUCTION MODE BOUNDARY
AND CORRESPONDING PEAK INDUCTOR CURRENT (V
OUT
= 5V)
9
MAX747-TOC4
OUTPUT CURRENT (A)
SUPPLY VOLTAGE (V)
13
11
0.7 1.3
15
1.10.9
CONTINUOUS
CONDUCTION
REGION
PEAK INDUCTOR
CURRENT
V
OUT
= 5V
L = 50µH
R
SENSE
= 50mΩ
DISCONTINUOUS
CONDUCTION
REGION
PEAK INDUCTOR CURRENT (A)
7
0.4
0.8
1.6
1.2
2.0
100
70
0.01 0.1 10
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5V)
80
90
MAX1747-TOC7
OUTPUT CURRENT (A)
EFFICIENCY (%)
1
V
IN
= 12V
V
IN
= 9V
V
IN
= 6V
3
0
0.01 0.1 10
PEAK INDUCTOR CURRENT vs.
OUTPUT CURRENT (V
OUT
= 5V)
1
2
MAX747-TOC5
OUTPUT CURRENT (A)
PEAK INDUCTOR CURRENT (A)
1
V
IN
= 12V
V
IN
= 9V
V
IN
= 6V
3
0
0.01 0.1 10
PEAK INDUCTOR CURRENT vs.
OUTPUT CURRENT (V
OUT
= 3.3V)
1
2
MAX747-TOC6
OUTPUT CURRENT (A)
PEAK INDUCTOR CURRENT (A)
1
V
IN
= 9V
V
IN
= 6V
V
IN
= 5V
100
70
0.01 0.1 10
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
80
90
MAX747-TOC8
OUTPUT CURRENT (A)
EFFICIENCY (%)
1
V
IN
= 6V
V
IN
= 9V
V
IN
= 12V
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, V+ = 9V, T
A
= +25°C, unless otherwise noted.)
P1-P3P4-P6P7-P9P10-P12

MAX747CSD+

Mfr. #:
Buy MAX747CSD+
Manufacturer:
Maxim Integrated
Description:
Switching Controllers Integrated Circuits (ICs)
Lifecycle:
New from this manufacturer.
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