Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - DC/DC voltage regulator Holder SOIC 8

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________________________________________________________________ Maxim Integrated Products 1

_______________General Description

The MAX639/MAX640/MAX653 step-down switching

regulators provide high efficiency over a wide range of

load currents, delivering up to 225mA. A current-limiting

pulse-frequency-modulated (PFM) control scheme gives

the devices the benefits of pulse-width-modulated

(PWM) converters (high efficiency at heavy loads), while

using only 10µA of supply current (vs. 2mA to 10mA for

PWM converters). The result is high efficiency over a

wide range of loads.

The MAX639/MAX640/MAX653 input range is 4V to

11.5V, and the devices provide lower preset output volt-

ages of 5V, 3.3V, and 3V, respectively. Or, the output

can be user-adjusted to any voltage from 1.3V to the

input voltage.

The MAX639/MAX640/MAX653 have an internal 1A power

MOSFET switch, making them ideal for minimum-compo-

nent, low- and medium-power applications. For increased

output drive capability, use the MAX649/MAX651/MAX652

step-down controllers, which drive an external P-channel

FET to deliver up to 5W.

________________________Applications

9V Battery to 5V, 3.3V, or 3V Conversion

High-Efficiency Linear Regulator Replacement

Portable Instruments and Handy-Terminals

5V-to-3.3V Converters

____________________________Features

♦ High Efficiency for a Wide Range of Load Currents

♦ 10µA Quiescent Current

♦ Output Currents Up to 225mA

♦ Preset or Adjustable Output Voltage:

5.0V (MAX639)

3.3V (MAX640)

3.0V (MAX653)

♦ Low-Battery Detection Comparator

♦ Current-Limiting PFM Control Scheme

______________Ordering Information

Ordering Information continued on last page.

*Contact factory for dice specifications.

MAX639/MAX640/MAX653

5V/3.3V/3V/Adjustable, High-Efficiency,

Low I

, Step-Down DC-DC Converters

19-4505; Rev 4; 7/05

PART TEMP RANGE PIN-PACKAGE

MAX639CPA

0°C to +70°C 8 Plastic DIP

MAX639CSA 0°C to +70°C 8 SO

MAX639C/D 0°C to +70°C Dice*

MAX639

MAX640

MAX653

DIP/SO

TOP VIEW

VFB

SHDN

V+

VOUT

LBO

LBI

GND

__________________Pin Configuration

GND

MAX639

SHDN

VOUT

LBO

LOW-BATTERY

DETECTOR

OUTPUT

ON/OFF

LBI

LOW-BATTERY

DETECTOR

INPUT

OUTPUT

225mA

INPUT

5.5V TO 11.5V

V+

VFB

__________Typical Operating Circuit

MAX639ESA -40°C to +85°C 8 SO

MAX639EPA -40°C to +85°C 8 Plastic DIP

MAX639MJA -55°C to +125°C 8 CERDIP

Summary of content (13 pages)

PAGE 1
9-4505; Rev 4; 7/05 5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters ____________________________Features The MAX639/MAX640/MAX653 step-down switching regulators provide high efficiency over a wide range of load currents, delivering up to 225mA. A current-limiting pulse-frequency-modulated (PFM) control scheme gives the devices the benefits of pulse-width-modulated (PWM) converters (high efficiency at heavy loads), while using only 10µA of supply current (vs.
PAGE 2
MAX639/MAX640/MAX653 5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters ABSOLUTE MAXIMUM RATINGS V+...........................................................................................12V LX .........................................................(V+ - 12V) to (V+ + 0.3V) LBI, LBO, VFB, SHDN, VOUT........................-0.3V to (V+ + 0.3V) LX Output Current (Note 1) ......................................................1A LBO Output Current ..................................
PAGE 3
5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters MAX639/MAX640/MAX653 ELECTRICAL CHARACTERISTICS (continued) (V+ = 9V for the MAX639, V+ = 5V for the MAX640/MAX653, ILOAD = 0mA, TA = TMIN to TMAX, typical values are at TA = +25°C, unless otherwise noted.) CONDITIONS V+ = 9V, TA = +25°C, MAX639/MAX640/MAX653 PARAMETER LX Switch On-Resistance MAX 1.5 UNITS V+ = 6V, TA = TMIN to TMAX, MAX639 2.5 Ω V+ = 4V, TA = TMIN to TMAX, MAX640/MAX653 2.8 LX Switch Leakage V+ = 11.
PAGE 4
_____________________________Typical Operating Characteristics (continued) (Circuit of Figure 3, internal feedback, L = 100µH, TA = +25°C, unless otherwise noted.) EFFICIENCY vs. INPUT VOLTAGE IOUT = 100mA 80 MAX639, V+ = 6V MAX640, V+ = 4.3V MAX653, V+ = 4V 70 L = 470µH IOUT = 25mA MAX639 95 EFFICIENCY (%) EFFICIENCY (%) 90 100 MAX639 95 EFFICIENCY (%) L = 100µH MAX639-05 100 MAX639-4 100 EFFICIENCY vs. INPUT VOLTAGE 90 MAX640 MAX639-06 EFFICIENCY vs.
PAGE 5
V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters START-UP TIME (ms) 8 V+ = 9.0V 6 4 6 MEASURED FROM THE RISING EDGE OF V+ OR SHDN TO (VOUT = 5.0V) L = 470µH. 30 START-UP TIME (ms) MEASURED FROM THE RISING EDGE OF V+ OR SHDN TO (VOUT = 3.3V)(MAX640) OR (VOUT = 3.0V)(MAX653). THE START-UP TIME DIFFERENCE BETWEEN THE MAX640 AND THE MAX653 IS NEGLIGIBLE. 8 V+ = 5.5V 40 MAX639-13 MEASURED FROM THE RISING EDGE OF V+ OR SHDN TO (VOUT = 5V). V+ = 5.0V 4 V+ = 5.5V 20 V+ = 9.
PAGE 6
MAX639/MAX640/MAX653 5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters _____________________________Typical Operating Characteristics (continued) (Circuit of Figure 3, internal feedback, L = 100µH, TA = +25°C, unless otherwise noted.
PAGE 7
5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters PIN NAME FUNCTION 1 VOUT 2 LBO 3 LBI 4 GND 5 LX Drain of a PMOS power switch that has its source connected to V+. LX drives the external inductor, which provides current to the load. 6 V+ Positive Supply-Voltage Input. Should not exceed 11.5V 7 VFB 8 SHDN Sense Input for regulated-output operation. Internally connected to an on-chip voltage divider and to the variable duty-cycle, on-demand oscillator.
PAGE 8
MAX639/MAX640/MAX653 5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters Figure 2 shows what happens to the ideal circuit of Figure 1 if the switch turns on with a 66% duty cycle and V+ = 3/2 VOUT. The inductor current rises more slowly than it falls because the magnitude of the voltage applied during tON is less than that applied during tOFF. Varying the duty cycle and switching frequency keeps the peak current constant as input voltage varies.
PAGE 9
5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters Shutdown Mode Bringing SHDN below 0.8V places the MAX639/ MAX640/MAX643 in shutdown mode. LX becomes high impedance, and the voltage at VOUT falls to zero. The time required for the output to rise to its nominal regulated voltage when brought out of shutdown (start-up time) depends on the inductor value, input voltage, and load current (see the Start-Up Time vs. Output Current graph in the Typical Operating Characteristics).
PAGE 10
MAX639/MAX640/MAX653 5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters INPUT +4.0V TO +11.5V 6 8 CIN 100µF LX V+ L = 100µH 5 OUTPUT COUT 100µF 1N5817 SHDN MAX639 VOUT MAX640 MAX653 1 R3 MAX639 MAX640 MAX653 VFB 7 GND 4 LBI 3 R4 Figure 4. Adjustable-Output Operation Figure 5. Through-Hole PC Layout and Component Placement Diagram for Standard Step-Down Application (Top-Side View) Step 3: L = 50 / IPEAK. L will be in µH. Do not use an inductor of less than 100µH.
PAGE 11
5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters SHDN LX 5 MAX639 MAX640 1 MAX653 VOUT L = 100µH 1N5817 COUT 100µF GND 4 VFB 7 MAX639 FG02 CIN 100µF MAXIMUM OUTPUT CURRENT (mA) VIN 8 TA = +25°C L = 100µH MAX639 140 120 MAX639/MAX640/MAX653 160 6 V+ 100 80 60 40 20 -5V -3.3V OR -3V 0 0 1 3 2 4 5 V+ (V) Figure 7. Maximum Current Capability of Figure 6 Circuit 87.0 MAX639 FG02 capacitor, even when the switch is off.
PAGE 12
MAX639/MAX640/MAX653 5V/3.
PAGE 13
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) DIM A A1 B C e E H L N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS MAX639/MAX640/MAX653 5V/3.