Rainbow-electronics MAX1688 Manual de usuario descargar pdf (Pagina 1)

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

For small orders, phone 1-800-835-8769.

General Description

The MAX1687/MAX1688 step-up DC-DC converters deliv-

er up to 2W from a single Li-Ion or three NiMH cells. The

devices are ideal for burst-load applications such as GSM

cell phones and wireless LANs, where the RF power

amplifiers require short, high current bursts. The

MAX1687/MAX1688 reduce battery surge current by slow-

ly charging a reservoir capacitor, which supplies the nec-

essary peak energy for the load current burst. As a result,

the peak battery current is limited, thus maximizing battery

life and minimizing battery voltage sag and transient dips.

An internal synchronous rectifier provides over 90% con-

version efficiency and eliminates the need for an external

Schottky diode. A logic shutdown mode reduces the shut-

down current to only 3µA. The devices can be disabled

during current bursts (RF transmit mode) to eliminate

switching noise.

The switching frequency of the MAX1687/MAX1688, con-

trolled by the selected inductor, can exceed 1MHz. Two

external resistors set the output voltage from 1.25V to 6V.

The MAX1687 controls peak battery current, while the

MAX1688 features a more advanced, adaptive constant-

recharge-time algorithm that maximizes battery life. The

MAX1687/MAX1688 are available in thin 16-pin TSSOP

(1.1mm max height) or standard 8-pin SO packages.

Applications

GSM Phones

Wireless Handsets

PC Cards (PCMCIA)

Features

♦ Low 450mA Peak Battery Current

Provides 2A, 5V GSM Burst

♦ 90% Efficiency

♦ Internal Power MOSFETs and Current-Sense

Resistor

♦ Output Disconnects from Input During Shutdown

♦ 3µA Shutdown Current

♦ Precise Voltage-Controlled Current Limit

(MAX1687)

♦ Adaptive Constant-Recharge-Time Capability

(MAX1688)

♦ 1.25V to 6V Adjustable Output

♦ 2.7V to 6V Input Range

(1 Li-Ion cell or 3 NiMH cells)

♦ Switching Frequency Can Exceed 1MHz

♦ Standby Mode Disables DC-DC During

Transmission Burst

♦ Low Inrush Current at Start-Up

MAX1687

†

/MAX1688

†

Step-Up DC-DC Converters with

Precise, Adaptive Current Limit for GSM

________________________________________________________________

Maxim Integrated Products

IN OUT

OUT

LX2

PGND

AGND

TOP VIEW

MAX1687

MAX1688

TSSOP

LX1

LIM [CHG]

REF

N.C.

[ ] ARE FOR MAX1688

MAX1687

MAX1688

OUT

UP TO 6V

OUT

LX1 LX2

2.7V TO 6V

OFF

0 TO 1V

CONTROL INPUT

1 Li-lon

3 NiMH

3 ALKALINE

(LIM)

REF

[CHG]

( ) ARE FOR MAX1687

[ ] ARE FOR MAX1688

GND

Typical Operating Circuit

19-1426; Rev 0; 2/99

PART*

MAX1687EUE

MAX1687ESA

MAX1688EUE

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

16 TSSOP

8 SO

16 TSSOP

Pin Configurations

Ordering Information

MAX1688ESA -40°C to +85°C

8 SO

Pin Configurations continued at end of data sheet.

†

Patent pending

U.S. and foreign patents pending.

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

1 2 3 4 5 6 ... 11 12

/MAX1688 1
MAX1687/MAX1688 10

Indice de contenidos

Pagina 1 - /MAX1688

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.For small orders, phone 1-800-835-8769.General Descript

Pagina 2

MAX1687/MAX1688Step-Up DC-DC Converters with Precise, Adaptive Current Limit for GSM10 _______________________________________________________________

Pagina 3