Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Holder SOIC 16

__________________General Description

The MAX730A/MAX738A/MAX744A are 5V-output

CMOS, step-down switching regulators. The MAX738A/

MAX744A accept inputs from 6V to 16V and deliver

750mA. The MAX744A guarantees 500mA load capa-

bility for inputs above 6V and has tighter oscillator fre-

quency limits for low-noise (radio) applications. The

MAX730A accepts inputs between 5.2V and 11V and

delivers 450mA for inputs above 6V. Typical efficien-

cies are 85% to 96%. Quiescent supply current is

1.7mA and only 6µA in shutdown.

Pulse-width modulation (PWM) current-mode control

provides precise output regulation and excellent tran-

sient responses. Output voltage accuracy is guaran-

teed to be ±5% over line, load, and temperature varia-

tions. Fixed-frequency switching allows easy filtering of

output ripple and noise, as well as the use of small

external components. These regulators require only a

single inductor value to work in most applications, so

no inductor design is necessary.

The MAX730A/MAX738A/MAX744A also feature cycle-

by-cycle current limiting, overcurrent limiting, undervolt-

age lockout, and programmable soft-start protection.

___________________________Applications

Portable Instruments

Cellular Phones and Radios

Personal Communicators

Distributed Power Systems

Computer Peripherals

________________________________Features

♦ 750mA Load Currents (MAX738A/MAX744A)

♦ High-Frequency, Current-Mode PWM

♦ 159kHz to 212.5kHz Guaranteed Oscillator

Frequency Limits (MAX744A)

♦ 85% to 96% Efficiencies

♦ 1.7mA Quiescent Current

♦ 6µA Shutdown Supply Current

♦ Single Preselected Inductor Value,

No Component Design Required

♦ Overcurrent, Soft-Start, and Undervoltage

Lockout Protection

♦ Cycle-by-Cycle Current Limiting

♦ 8-Pin DIP/SO Packages (MAX730A)

_________________Ordering Information

Ordering Information continued at end of data sheet.

*Contact factory for dice specifications.

MAX730A/MAX738A/MAX744A

5V, Step-Down,

Current-Mode PWM DC-DC Converters

________________________________________________________________

Maxim Integrated Products

TOP VIEW

V+

GND

OUT

REF

MAX730A

MAX738A

MAX744A

DIP

SHDN

Pin Configurations continued on last page.

_________________Pin Configurations

MAX738A

MAX744A

INPUT

6V TO 16V

V+

OUT

GNDSS

REF

SHDNON/OFF

33µH

OUTPUT

100µF

68µF

__________Typical Operating Circuit

19-0165; Rev 2; 1/96

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

PART TEMP. RANGE PIN-PACKAGE

MAX730ACPA

0°C to +70°C 8 Plastic DIP

MAX730ACSA 0°C to +70°C 8 SO

MAX730AC/D 0°C to +70°C Dice*

MAX730AEPA 8 Plastic DIP

MAX730AESA -40°C to +85°C 8 SO

-40°C to +85°C

MAX730AMJA -55°C to +125°C 8 CERDIP

Summary of content (16 pages)

PAGE 1
9-0165; Rev 2; 1/96 5V, Step-Down, Current-Mode PWM DC-DC Converters ________________________________Features The MAX730A/MAX738A/MAX744A are 5V-output CMOS, step-down switching regulators. The MAX738A/ MAX744A accept inputs from 6V to 16V and deliver 750mA. The MAX744A guarantees 500mA load capability for inputs above 6V and has tighter oscillator frequency limits for low-noise (radio) applications. The MAX730A accepts inputs between 5.2V and 11V and delivers 450mA for inputs above 6V.
PAGE 2
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters ABSOLUTE MAXIMUM RATINGS Pin Voltages V+ (MAX730A) ......................................................+12V, -0.3V V+ (MAX738A/MAX744A) .....................................+18V, -0.3V LX (MAX730A) .................................(V+ - 12V) to (V+ + 0.3V) LX (MAX738A/MAX744A) ................(V+ - 21V) to (V+ + 0.3V) OUT .................................................................................±25V SS, CC, SHDN .............
PAGE 3
5V, Step-Down, Current-Mode PWM DC-DC Converters (Circuit of Figure 3, V+ = 9V for the MAX730A, V+ = 12V for the MAX738A/MAX744A, ILOAD = 0mA, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER CONDITIONS MAX730A MIN TYP MAX ILOAD = 0mA to 300mA Load Regulation MAX738A MIN TYP MAX MAX744A MIN TYP MAX 0.0005 0.0005 90 90 87 87 0.0005 ILOAD = 0mA to 750mA V+ = 9.0V, ILOAD = 300mA Efficiency 92 V+ = 12V, ILOAD = 750mA 1.7 Supply Current (includes switch current) 3.0 1.7 3.0 1.
PAGE 4
__________________________________________Typical Operating Characteristics (Circuit of Figure 3, TA = +25°C, unless otherwise noted.) MAX730A EFFICIENCY vs. OUTPUT CURRENT 100 100 (NOTES 3, 6) (NOTES 3, 6) (NOTE 3) 90 V+ = 5.5V 80 V+ = 7V V+ = 9V 70 V+ = 6V 80 V+ = 8V V+ = 12V 60 200 400 600 800 OUTPUT CURRENT (mA) V+ = 12.0V 0 MAXIMUM OUTPUT CURRENT vs.
PAGE 5
V, Step-Down, Current-Mode PWM DC-DC Converters MAX730A OSCILLATOR FREQUENCY vs. TEMPERATURE OSCILLATOR FREQUENCY vs. SUPPLY VOLTAGE 220 240 (NOTE 3) MAX730A OSCILLATOR FREQUENCY (kHz) OSCILLATOR FREQUENCY (kHz) 210 200 190 MAX744A 180 170 160 220 200 V+ = 11.0V V+ = 5.5V 180 160 140 V+ = 7.0V V+ = 9.0V MAX738A 150 4 6 8 10 12 SUPPLY VOLTAGE (V) 14 0 -60 -40 -20 0 16 20 40 60 80 100 120 140 160 TEMPERATURE (°C) MAX744A OSCILLATOR FREQUENCY vs.
PAGE 6
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters ____________________________Typical Operating Characteristics (continued) (Circuit of Figure 3, TA = +25°C, unless otherwise noted.
PAGE 7
5V, Step-Down, Current-Mode PWM DC-DC Converters MAX730A LOAD-TRANSIENT RESPONSE MAX738A/MAX744A LOAD-TRANSIENT RESPONSE A A 750mA 300mA B B 50mA 20mA 50ms/div 50ms/div A: VOUT, 50mV/div, DC-COUPLED B: IOUT, 200mA/div, 20mA TO 300mA A: VOUT, 50mV/div, DC-COUPLED B: IOUT, 500mA/div, 50mA TO 750mA V+ = 9V V+ = 12V ______________________________________________________________Pin Description PIN 8-PIN DIP/SO 16-PIN WIDE SO NAME FUNCTION 1 2 SHDN 2 3 REF 3 7 SS Soft-Start.
PAGE 8
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters _________________Detailed Description The MAX730A/MAX738A/MAX744A switch-mode regulators use a current-mode pulse-width-modulation (PWM) control system coupled with a simple step-down (buck) regulator topography. They convert an unregulated DC voltage from 5.2V to 11V for the MAX730A, and from 6V to 16V for the MAX738A/MAX744A.
PAGE 9
5V, Step-Down, Current-Mode PWM DC-DC Converters MAX730A/MAX738A/MAX744A Table 1. Typical Soft-Start Times MAX730A CIRCUIT CONDITIONS SOFT-START TIME (ms) vs. C1 (µF) R1 (kΩ) V+ (V) IOUT (mA) C4 (µF) C1 = 0.01 C1 = 0.047 C1 = 0.1 C1 = 0.
PAGE 10
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters VIN = +6.0V TO +16.0V SHDN C2 C3* 1µF V+ OVERCURRENT COMPARATOR SLOPE COMPENSATION BIAS GEN Σ OUT C5 330pF RAMP GEN RSENSE ERROR AMP F/F CC R Q S 1.23V BANDGAP R1 510k CURRENT SENSE AMP PWM COMPARATOR D1 1N5817 REF OSC C6 0.01µF 1M ±35% L1 LX SS CLAMP SS VOUT = +5V C4* MAX730A MAX738A MAX744A UNDERVOLTAGE LOCKOUT C1 0.1µF VUVLO GND *SEE TABLE 2 FOR COMPONENT VALUES AND SUPPLIERS Figure 1.
PAGE 11
5V, Step-Down, Current-Mode PWM DC-DC Converters Production Method MAX730AC/MAX738AC/MAX744AC Commercial Temp. Range Inductors L1 = 33µH to 100µH Surface Mount Sumida (708) 956-0666 CD54-101KC (MAX730AC) CD105-101KC (MAX738AC/MAX744AC) Coiltronics (407) 241-7876 CTX100 series MAX730AE/M, MAX738AE/M, MAX744AE/M Wide Temp. Range Capacitors Inductors Capacitors L1 = 33µH C3 = 68µF, 16V C4 = 100µF, 6.
PAGE 12
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters FROM SHDN R1 510k SS CLAMP SS 1M ±35% C1 1.23V MAX730A MAX738A MAX744A Figure 2. Block Diagram of Soft-Start Circuitry MAX730A +5.2V TO +11.0V MAX738A/MAX744A +6.0V TO +16.0V OPTIONAL LOWPASS OUTPUT FILTER C2 1µF L2 25µH C3* 8 1 SHDN OUTPUT V+ LX 7 D1 1N5817 MAX730A MAX738A OUT 5 MAX744A R1 510k 3 C1 0.1µF SS GND 6 CC 4 FILTER OUTPUT C7 2.
PAGE 13
5V, Step-Down, Current-Mode PWM DC-DC Converters MAX730A/MAX738A/MAX744A MAX730 EVALUATION KIT Figure 4. DIP PC Layout, Through-Hole Component Placement Diagram (1x scale) Figure 5. DIP PC Layout, Component Side (1x scale) Figure 6. DIP PC Layout, Solder Side (1x scale) Figure 7.
PAGE 14
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters ____Pin Configurations (continued) __Ordering Information (continued) TOP VIEW SHDN 1 REF 2 MAX730A SS 3 CC 4 8 V+ 7 LX 6 GND 5 OUT SO V+ 1 16 V+ SHDN 2 15 V+ REF 3 14 LX MAX738A MAX744A N.C. 4 N.C. 5 PART TEMP.
PAGE 15
5V, Step-Down, Current-Mode PWM DC-DC Converters DIM D1 A A1 A2 A3 B B1 C D D1 E E1 e eA eB L α E E1 D A3 A A2 L A1 INCHES MAX MIN 0.200 – – 0.015 0.175 0.125 0.080 0.055 0.022 0.016 0.065 0.050 0.012 0.008 0.390 0.348 0.035 0.005 0.325 0.300 0.280 0.240 0.100 BSC 0.300 BSC 0.400 – 0.150 0.115 15˚ 0˚ MILLIMETERS MIN MAX – 5.08 0.38 – 3.18 4.45 1.40 2.03 0.41 0.56 1.27 1.65 0.20 0.30 8.84 9.91 0.13 0.89 7.62 8.26 6.10 7.11 2.54 BSC 7.62 BSC – 10.16 2.92 3.
PAGE 16
MAX730A/MAX738A/MAX744A 5V, Step-Down, Current-Mode PWM DC-DC Converters ___________________________________________Package Information (continued) DIM E1 D E B2 A A B B1 B2 C D E E1 e L L1 Q S S1 α S S1 INCHES MAX MIN 0.200 – 0.023 0.014 0.065 0.038 0.045 0.023 0.015 0.008 0.405 – 0.310 0.220 0.320 0.290 0.100 BSC 0.200 0.125 – 0.150 0.060 0.015 0.055 – – 0.005 15˚ 0˚ MILLIMETERS MIN MAX – 5.08 0.36 0.58 0.97 1.65 0.58 1.14 0.20 0.38 – 10.29 5.59 7.87 7.37 8.13 2.54 BSC 3.18 5.08 3.81 – 0.38 1.