_______________General Description

The MAX777L/MAX778L/MAX779L are pulse-skipping DC-DC

converters that step up from low-voltage inputs (1V guaran-

teed). They require only three external components—an induc-

tor (typically 22µH) and two capacitors. The MAX777L delivers

a 5V output, the MAX778L generates pin-selectable voltages of

3.0V or 3.3V, and the MAX779L output can be adjusted from

2.5V to 6V through an external resistive divider.

need for an external catch diode, and permits regulation even

when the input is greater than the output. Also, unlike those in

other step-up converters, the MAX777L/MAX778L/MAX779L’s

ing the output from the source. This eliminates the current drain

associated with conventional step-up converters when off or in

shutdown.

High-frequency operation (up to 150kHz) allows the use of

small, surface-mount inductors with values of 10µH or less.

Supply current is 190µA under no load and only 20µA in stand-

by mode; supply voltage can range from 1V to 4.5V (1 to 3

cells). With a 2V input, the devices typically deliver 200mA at

5V, or 300mA at 3V.

For fully specified devices designed for step-up/step-down

applications (where the input can be above or below the out-

put), refer to the MAX877L/MAX878L/MAX879L data sheet.

________________________Applications

Single Battery-Cell (1V), Step-Up Voltage Conversion

Efficient, High-Power Step-Up Regulation from

Low Input Voltages

Pagers

Portable Instruments & Hand-Held Terminals

Notebook and Palmtop Computers

____________________________Features

o 1V to 4.5V Input Guarantees Start-Up Under Load

o Up to 210mA Output

o Load Fully Disconnected in Shutdown

o 82% Efficiency

o Output in Regulation with Input Voltage above

Output Voltage

o Internal 1A Power Switch and Active Rectifier

o Adjustable Current Limit Allows Low-Cost

Inductors

o 190µA No Load Supply Current

o 20µA Shutdown Supply Current

o 3V/3.3V (MAX778L), 5V (MAX777L), and

Adjustable (MAX779L) Output Voltage

______________Ordering Information

Ordering Information continued at end of data sheet.

**Contact factory for availability and processing to MIL-STD-883.

Low-Voltage Input, 3V/3.3V/5V/

Adjustable Output, Step-Up DC-DC Converters

________________________________________________________________

Maxim Integrated Products

1

1

2

3

4

DIP/SO

TOP VIEW

MAX777L

MAX778L

MAX779L

8

7

6

5

SHDN

OUT

LX

ILIM

IN

AGND

PGND

__________________Pin Configuration

INPUT

1V TO 4.5V

IN

ILIM

SHDN

100µF

OUTPUT

5V

AGND

MAX777L

LX

OUT

PGND

22µH

ON/OFF

22

µF

1

2

7

4

3

6

5

__________Typical Operating Circuit

19-0186; Rev 2; 7/96

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

PART

TEMP. RANGE

PIN-PACKAGE

MAX777LCPA

0°C to +70°C

8 Plastic DIP

MAX777LCSA

0°C to +70°C

8 SO

MAX777LC/D

0°C to +70°C

Dice*

MAX777LMJA

-55°C to +125°C

8 CERDIP**

MAX777LESA

-40°C to +85°C

8 SO

MAX777LEPA

-40°C to +85°C

8 Plastic DIP

Active Rectifier is a trademark of Maxim Integrated Products.

EVALUATION

KIT MANUAL

FOLLOWS

DATA

SHEET