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Part: MAX747CSD
Category:
Power Management
-> Battery Management
Description: MAX747 High-Efficiency, Pwm, Step-down Controller (External P-channel Driver)
Company: Maxim Integrated Products
Datasheet: Download MAX747CSD datasheet File size : 404 kB
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Datasheet text preview:
19-0171; Rev 1; 9/93
High-Efficiency PWM, Step-Down P-Channel DC-DC Controller
_______________General Description
The MAX747 high-efficiency, high-current, step-down controller drives external P-channel FETs. It provides 9 0 % to 95% efficiency from a 6V supply with load c u r r e n t s 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-ModeTM) 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 p r o p r i e t a r y dual-control (Idle-ModeTM) scheme that minimizes switching losses by reducing the switching f r e q u e n c y 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 2 V ±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.
____________________________Features
o 90% to 95% Efficiency for 50mA to 2.5A Output Currents o 4V to 15V Input Voltage Range o Low 800µA Supply Current o 0.6µA Shutdown Current o Drives External P-Channel FETs o Cycle-by-Cycle Current Limiting o 2V ±1.5% Accurate Reference Output o Adjustable Soft-Start o Precision Comparator for Power-Fail or Low-Battery Warning
MAX747
______________Ordering Information
PART MAX747CPD MAX747CSD MAX747C/D MAX747EPD MAX747ESD MAX747MJD TEMP. RANGE 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C -55°C to +125°C PIN-PACKAGE 14 Plastic DIP 14 Narrow SO Dice* 14 Plastic DIP 14 Narrow SO 14 CERIDIP
* Contact factory for dice specifications.
________________________Applications
Notebook Power Supplies Personal Digital Assistants Battery-Operated Equipment Cellular Phones 5V to 3.3V Green PC Applications
__________Typical Operating Circuit
6 INPUT V TO 15V V+ AV+ 5Om
100µF
MAX747
CS EXT P 5OµH OU5 PUT T 2V .3A
__________________Pin Configuration
T O P VIEW
ON/OFF SHDN
430µF
LBI SS REF SHDN FB CC
1 2 3 4 5 6
14 LBO 13 GND
OUT LOW-BATTERY D ETECTOR I NPUT LBI 0.1µF
MAX747
12 V+ 11 EXT 10 AGND 9 8 CS OUT
REF SS
LBO CC FB AGND GND
D LOW-BATTERY OETECTOR UTPUT
AV+ 7
DIP/SO
TM Dual-Mode and Idle-Mode are trademarks of Maxim Integrated Products.
________________________________________________________________ Maxim Integrated Products 1
Call toll free 1-800-998-8800 for free samples or literature.
High-Efficiency PWM, Step-Down P-Channel DC-DC Controller MAX747
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 (IREF) ....±2mA Continuous Power Dissipation (TA = +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
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.
ELECTRICAL CHARACTERISTICS
(V+ = 10V, ILOAD = 0mA, IREF = 0mA, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER Input Voltage Range Output Voltage Feedback Voltage Line Regulation Load Regulation Efficiency OUT Leakage Current FB Input Logic Low FB Input Leakage Current Reference Voltage Reference Load Regulation Soft-Start Source Current Soft-Start Fault Current Supply Current Oscillator Frequency Maximum Duty Cycle CS Amp ILIM Threshold EXT Output High EXT Output Low EXT Sink Current EXT Source Current CC Impedance LBI Threshold Voltage LBO Output Voltage Low LBI Input Leakage Current LBO Output Leakage Current SHDN Input Voltage Low SHDN Input Voltage High SHDN Input Leakage Current 2 SYMBOL CONDITIONS V+ For regulated outputs V+ = 6V to 15V, 0V < V+ - CS < 0.125V, FB = 0V VOUT (includes line and load regulation) V+ - CS = 0V, external MAX747C feedback mode MAX747E/M V+ = 6V to 15V, FB = 0V V+ = 4V to 15V, external feedback mode 0V < V+ - CS < 0.125V Circuit of Figure 1, ILOAD = 0.5A to 2.5A VOUT = 5V For dual-mode switchover FB = 2V MAX747C VREF IREF = 0µA MAX747E/M IREF = 0µA to 100µA SS = 0V SS = 2V Operating, V+ = 15V Operating, V+ = 10V Shutdown mode MAX747C fOSC MAX747E/M V+ = 6V VLIMIT V+ - CS IEXT = -1mA (sourcing) IEXT = 1mA (sinking) VEXT = 7.5V VEXT = 2.5V VTH LBI falling MAX747C MAX747EM MIN 4 4.85 1.96 1.95 TYP 5.08 2.00 2.00 0.05 1.3 91 50 0.1 2.00 2.00 9 1 500 0.95 0.8 0.6 100 100 96 150 MAX 15 5.25 2.04 2.05 0.1 2.5 80 40 100 2.03 2.04 20 UNITS V V V %V % % µA mV nA V mV µA µA mA µA kHz % mV V V mA mA k V V nA µA V V nA
1.97 1.96
100
1.3 20 115 120 175 0.25
85 80 91 125 V+ 0.1
1.97 1.96
110 170 24 2.00 2.00
ISINK = 0.5mA LBI = 2.5V V+ = 15V, LBO = 15V, LBI = 2.5V VIL VIH SHDN = 10V 2.0 0.1
2.03 2.04 0.4 100 1 0.4 100
_______________________________________________________________________________________
High-Efficiency PWM, Step-Down P-Channel DC-DC Controller
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, V+ = 9V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX747-TOC1
MAX747
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX747-TOC2
PEAK INDUCTOR CURRENT vs. OUTPUT CURRENT (VOUT = 5V)
MAX747-TOC5
4 VIN = 9V VOUT = 5V SUPPLY CURRENT (mA) 3
1.0
3 PEAK INDUCTOR CURRENT (A)
SUPPLY CURRENT (mA)
0.9
2
2 CENTIRE IRCUIT 1 SCHOTTKY DIODE LEAKAGE EXCLUDED 0 -75 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C)
0.8
1
VIN = 12V VIN = 9V VIN = 6V
0.7
0.6 5 7 9 11 13 15 SUPPLY VOLTAGE (V)
0 0.01
0.1
1
10
OUTPUT CURRENT (A)
PEAK INDUCTOR CURRENT vs. OUTPUT CURRENT (VOUT = 3.3V)
MAX747-TOC6
EFFICIENCY vs. OUTPUT CURRENT (VOUT = 5V)
VIN = 6V
MAX1747-TOC7
EFFICIENCY vs. OUTPUT CURRENT (VOUT = 3.3V)
MAX747-TOC8
3 PEAK INDUCTOR CURRENT (A)
100
100
VIN = 6V EFFICIENCY (%) EFFICIENCY (%) 2 90 VIN = 9V 90 VIN = 9V VIN = 12V 80
VIN = 9V 1 VIN = 6V VIN = 5V 0 0.01
80
VIN = 12V
0.1
1
10
70 0.01
0.1
1
10
70 0.01
0.1
1
10
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
CONTINUOUS-CONDUCTION MODE BOUNDARY AND CORRESPONDING PEAK INDUCTOR CURRENT (VOUT = 3.3V)
MAX747-TOC3
CONTINUOUS-CONDUCTION MODE BOUNDARY AND CORRESPONDING PEAK INDUCTOR CURRENT (VOUT = 5V)
C DISCONTINUOUS RONDUCTION EGION PEAK INDUCTOR CURRENT VOUT = 5V L = 50µH RSENSE = 50m
MAX747-TOC4
18 VOUT = 3.3V L = 33µH RSENSE = 50m SUPPLY VOLTAGE (V) 14 C DISCONTINUOUS RONDUCTION EGION I PEAK NDUCTOR C URRENT CONTINUOUS RONDUCTION EGION
2.0 PEAK INDUCTOR CURRENT (A)
15
2.0 PEAK INDUCTOR CURRENT (A)
13 SUPPLY VOLTAGE (V)
1.6
1.6
11 9
10
1.2
1.2
6
0.8
7
CONTINUOUS RONDUCTION EGION
0.8
2 0.4 0.6 0.8 1.0 1.2 1.4 OUTPUT CURRENT (A)
0.4
5 0.5 0.7 0.9 1.1 1.3 OUTPUT CURRENT (A)
0.4
_______________________________________________________________________________________
3
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