Maxim MAX8805Y, MAX8640ZEXT18+T Datasheet

General Description

The MAX8640Y/MAX8640Z step-down converters are
optimized for applications where small size, high effi­ciency, and low output ripple are priorities. They utilize
a proprietary PWM control scheme that optimizes the
switching frequency for high efficiency with small exter­nal components and maintains low output ripple volt­age at all loads. The MAX8640Z switches at up to
4MHz to allow a tiny 1µH inductor and 2.2µF output
capacitor. The MAX8640Y switches at up to 2MHz for
higher efficiency while still allowing small 2.2µH and

4.7µF components. Output current is guaranteed up to
500mA, while typical quiescent current is 24µA.
Factory-preset output voltages from 0.8V to 2.5V elimi­nate external feedback components.

Internal synchronous rectification greatly improves effi­ciency and replaces the external Schottky diode
required in conventional step-down converters. Internal
fast soft-start eliminates inrush current so as to reduce
input capacitor requirements.

The MAX8640Y/MAX8640Z are available in the tiny 6­pin, SC70 lead-free package (2.0mm x 2.1mm footprint,

1.1mm max height).

Applications

Microprocessor/DSP Core Power

I/O Power

Cell Phones, PDAs, DSCs, MP3s

Other Handhelds Where Space Is Limited

Features

♦ Tiny 6-Pin SC70 Package
♦ 500mA Guaranteed Output Current
♦ 4MHz or 2MHz PWM Switching Frequency
♦ Tiny External Components: 1µH/2.2µF or

2.2µH/4.7µF

♦ 24µA Quiescent Current
♦ Factory Preset Outputs from 0.8V to 2.5V
♦ ±1% Initial Accuracy
♦ Low Output Ripple at All Loads
♦ Ultrasonic Skip Mode Down to 1mA Loads
♦ Ultra-Fast Line- and Load-Transient Response
♦ Fast Soft-Start Eliminates Inrush Current

MAX8640Y/MAX8640Z

500mA, 4MHz/2MHz Synchronous

Step-Down DC-DC Converters in SC70

________________________________________________________________ Maxim Integrated Products 1

19-3997; Rev 0; 5/06

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Ordering Information

PART*

PIN­PACKAGE

PKG

CODE

TOP

MARK

MAX8640YEXT08+T 6 SC70-6 X6S-1

ACQ

MAX8640YEXT11+T 6 SC70-6 X6S-1

ACR

MAX8640YEXT12+T 6 SC70-6 X6S-1

ACS

MAX8640YEXT13+T 6 SC70-6 X6S-1

ACG

MAX8640YEXT15+T 6 SC70-6 X6S-1

ADD

MAX8640YEXT16+T 6 SC70-6 X6S-1

ADB

MAX8640YEXT18+T 6 SC70-6 X6S-1

ACI

MAX8640YEXT19+T 6 SC70-6 X6S-1

ACH

MAX8640YEXT25+T 6 SC70-6 X6S-1

ACJ

GND

OUT

1

+

6IN

5 GND

LX

MAX8640Y
MAX8640Z

SC70

TOP VIEW

2

34

SHDN

Pin Configuration

L1

1μH OR 2.2μH

C2

2.2μF OR

4.7μF

C1

2.2μF

OUT

LX

GND

IN

SHDN

ON/OFF

MAX8640Y
MAX8640Z

INPUT

2.7V TO 4.9V

OUTPUT

0.8V TO 2.5V

UP TO 500mA

Typical Operating Circuit

Ordering Information continued and Selector Guide appears
at end of data sheet.

*Contact factory for availability of each version.
+Denotes lead-free package.

Note: All devices are specified over the -40°C to +85°C
operating temperature range.

MAX8640Y/MAX8640Z

500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters in SC70

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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.

IN to GND .................................................................-0.3V to +6V

LX, OUT, SHDN to GND ..............................-0.3V to (V

IN

+ 0.3V)

LX Current (Note 1) ........................................................0.8A

RMS

OUTPUT Short Circuit to GND ...................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

6-Pin SC70 (derate 3.1mW/°C above +70°C)..............245mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(VIN= 3.6V, SHDN = IN, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 2)

PARAMETER

SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Range V

IN

2.7 4.9 V

UVLO Threshold UVLO VIN rising, 100mV hysteresis 2.44 2.6 2.70 V

No load, no switching 24 48

TA = +25°C 0.01 0.1

Supply Current I

CC

SHDN = GND

T

A

= +85°C 0.1

µA

Output Voltage Range V

OUT

Factory preset 0.8 2.5 V

I

LOAD

= 0mA, TA = +25°C -1 0 +1

Output Voltage Accuracy
(Falling Edge)

I

LOAD

= 0mA, TA = -40°C to +85°C -2 +2

%

Output Load Regulation
(Voltage Positioning)

Equal to inductor DC resistance R

L

V/A

V

IH

VIN = 2.7V to 4.9V 1.4

SHDN Logic Input Level

V

IL

VIN = 2.7V to 4.9V 0.4

V

TA = +25°C 0.001 1

SHDN Logic Input Bias Current I

IH,IL

VIN = 4.9V,
SHDN = GND or IN

T

A

= +85°C 0.01

µA

Peak Current Limit I

LIMP

pFET switch 590 770 1400 mA

Valley Current Limit I

LIMN

nFET rectifier 450 650 1300 mA

Rectifier Off-Current Threshold I

LXOFF

nFET rectifier 10 40 70 mA

R

ONP

pFET switch, ILX = -40mA 0.6 1.2

On-Resistance

R

ONN

nFET rectifier, ILX = 40mA 0.35 0.7

Ω

TA = +25°C 0.1 1

LX Leakage Current I

LXLKG

V

IN

= 4.9V, LX = GND

to IN, SHDN = GND

T

A

= +85°C 1

µA

t

ON(MIN

)

95

Minimum On and Off Times

t

OFF(MIN

)

95

ns

Thermal Shutdown +160 °C

Thermal-Shutdown Hysteresis 20 °C

Note 1: LX has internal clamp diodes to IN and GND. Applications that forward bias these diodes should not exceed the IC’s package

power-dissipation limit.

Note 2: All devices are 100% production tested at T

A

= +25°C. Limits over the operating temperature range are guaranteed by design.

MAX8640Y/MAX8640Z

500mA, 4MHz/2MHz Synchronous

Step-Down DC-DC Converters in SC70

_______________________________________________________________________________________ 3

Typical Operating Characteristics

(VIN= 3.6V, V

OUT

= 1.5V, MAX8640Z, L = Murata LQH32CN series, TA= +25°C, unless otherwise noted.)

EFFICIENCY vs. LOAD CURRENT

1.8V OUTPUT

LOAD CURRENT (mA)

EFFICIENCY (%)

MAX8640Y/Z toc01

0

10

20

30

40

50

60

70

80

90

100

0.1 1 10 100 1000

MAX8640YEXT18

NO-LOAD SUPPLY CURRENT

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (μA)

MAX8640Y/Z toc02

2.9 3.3 3.7 4.1 4.5 4.9

5

10

15

20

25

30

35

MAX8640ZEXT15

MAX8640YEXT18

SWITCHING FREQUENCY

vs. LOAD CURRENT

LOAD CURRENT (mA)

SWITCHING FREQUENCY (MHz)

MAX8640Y/Z toc03

0 100 200 300 400 500

0.1

1

10

MAX8640ZEXT15

MAX8640YEXT18

OUTPUT VOLTAGE vs. LOAD CURRENT

(VOLTAGE POSITIONING)

LOAD CURRENT (mA)

OUTPUT VOLTAGE (V)

MAX8640Y/Z toc04

0 100 200 300 400 500

1.30

1.35

1.40

1.45

1.50

1.55

MAX8640ZEXT15

I

LX

V

LX

V

OUT

200mA/div

2V/div

20mV/div
(AC-COUPLED)

10μs/div

LIGHT-LOAD SWITCHING WAVEFORMS

(I

OUT

= 1mA)

MAX8640Y/Z toc05

I

LX

V

LX

V

OUT

200mA/div

2V/div
0V

0mA

20mV/div
(AC-COUPLED)

200ns/div

MEDIUM-LOAD SWITCHING WAVEFORMS

(I

OUT

= 40mA)

MAX8640Y/Z toc06

I

LX

V

LX

V

OUT

200mA/div

2V/div

0V

0mA

20mV/div
(AC-COUPLED)

200ns/div

HEAVY-LOAD SWITCHING WAVEFORMS

(I

OUT

= 300mA)

MAX8640Y/Z toc07