Rainbow-electronics MAX859 User Manual download pdf

_______________General Description

The MAX856–MAX859 are high-efficiency, CMOS, step-

up, DC-DC switching regulators for small, low input volt-

age or battery-powered systems. The MAX856/MAX858

accept a positive input voltage between 0.8V and V

OUT

and convert it to a higher, pin-selectable output voltage of

3.3V or 5V. The MAX857/MAX859 adjustable versions

accept 0.8V to 6.0V input voltages and generate higher

adjustable output voltages in the 2.7V to 6.0V range.

Typical efficiencies are greater than 85%. Typical quies-

cent supply current is 25µA (1µA in shutdown).

The MAX856–MAX859 combine ultra-low quiescent supply

current and high efficiency to give maximum battery life. An

internal MOSFET power transistor permits high switching

frequencies. This benefit, combined with internally set peak

inductor current limits, permits the use of small, low-cost

inductors. The MAX856/MAX857 have a 500mA peak

inductor current limit. The MAX858/MAX859 have a 125mA

peak inductor current limit.

________________________Applications

3.3V to 5V Step-Up Conversion

Palmtop Computers

Portable Data-Collection Equipment

Personal Data Communicators/Computers

Medical Instrumentation

2-Cell & 3-Cell Battery-Operated Equipment

Glucose Meters

____________________________Features

♦ 0.8V to 6.0V Input Supply Voltage

♦ 0.8V Typ Start-Up Supply Voltage

♦ 85% Efficiency at 100mA

♦ 25µA Quiescent Current

♦ 1µA Shutdown Mode

♦ 125mA and 500mA Switch-Current Limits Permit

Use of Low-Cost Inductors

♦ Up to 500kHz Switching Frequency

♦ ±1.5% Reference Tolerance Over Temperature

♦ Low-Battery Detector (LBI/LBO)

♦ 8-Pin SO and µMAX Packages

______________Ordering Information

Ordering Information continued at end of data sheet.

* Dice are tested at T

= +25°C only.

†

Contact factory for availability.

MAX856–MAX859

3.3V/5V or Adjustable-Output,

Step-Up DC-DC Converters

________________________________________________________________

Maxim Integrated Products

GND

OUT

LBI

LBO

REF

3/5

SHDN

MAX856

MAX858

SO/µMAX

TOP VIEW

GND

OUT

LBI

LBO

REF

SHDN

MAX857

MAX859

SO/µMAX

__________________Pin Configuration

MAX856

SHDN

3/5

REF

GND

OUT

INPUT

0.8V TO V

OUT

1N5817

OUTPUT

5V AT 100mA

OR

3.3V AT 125mA

LBO

68µF

47µH

LOW-BATTERY

DETECTOR OUTPUT

ON/OFF

3V/5V SELECT

LBI

LOW-BATTERY

DETECTOR

INPUT

__________Typical Operating Circuit

19-0211; Rev 4; 5/96

PART TEMP. RANGE PIN-PACKAGE

MAX856CSA

0°C to +70°C 8 SO

MAX856CUA 0°C to +70°C 8 µMAX

MAX856C/D 0°C to +70°C Dice*

MAX856ESA -40°C to +85°C 8 SO

MAX856MJA -55°C to +125°C 8 CERDIP

†

MAX857CSA

0°C to +70°C 8 SO

MAX857CUA 0°C to +70°C 8 µMAX

MAX857C/D

0°C to +70°C Dice*

MAX857ESA -40°C to +85°C 8 SO

MAX857MJA -55°C to +125°C 8 CERDIP

†

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

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

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Summary of Contents

Page 1 - Step-Up DC-DC Converters

_______________General DescriptionThe MAX856–MAX859 are high-efficiency, CMOS, step-up, DC-DC switching regulators for small, low input volt-age or ba

Page 2

MAX856–MAX8593.3V/5V or Adjustable-Output, Step-Up DC-DC Converters10 ________________________________________________________________________________

Page 3