Rainbow-electronics MAX1655 Manual de usuario descargar pdf

_______________General Description

The MAX1649/MAX1651 BiCMOS, step-down, DC-DC

switching controllers provide high efficiency over loads

ranging from 1mA to more than 2.5A. A unique, current-

limited pulse-frequency-modulated (PFM) control scheme

gives these devices the benefits of pulse-width-modula-

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

while using only 100µA of supply current (vs. 2mA to

10mA for PWM converters). Dropout performance down

to 300mV is provided by a high switch duty cycle (96.5%)

and a low current-sense threshold (110mV).

A high switching frequency (up to 300kHz) allows these

devices to use miniature external components.

The MAX1649/MAX1651 have dropout voltages less

than 0.3V at 500mA and accept input voltages up to

16V. Output voltages are preset at 5V (MAX1649), or

3.3V (MAX1651). They can also be adjusted to any

voltage from 1.5V to the input voltage by using two

resistors.

These step-down controllers drive external P-channel

MOSFETs at loads greater than 12.5W. If less power is

required, use the MAX639/MAX640/MAX653 step-down

converters with on-chip FETs, which allow up to a

225mA load current.

________________________Applications

PDAs

High-Efficiency Step-Down Regulation

5V-to-3.3V Green PC Applications

Battery-Powered Applications

____________________________Features

♦ More than 90% Efficiency (10mA to 1.5A Loads)

♦ More than 12.5W Output Power

♦ Less than 0.3V Dropout Voltage at 500mA

♦ 100µA Max Quiescent Supply Current

♦ 5µA Max Shutdown Supply Current

♦ 16V Max Input Voltage

♦ 5V (MAX1649), 3.3V (MAX1651), or Adjustable

Output Voltage

♦ Current-Limited Control Scheme

♦ Up to 300kHz Switching Frequency

♦ Up to 96.5% Duty Cycle

______________Ordering Information

* Dice are tested at T

= +25°C.

MAX1649/MAX1651

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

Low-Dropout, Step-Down DC-DC Controllers

________________________________________________________________

Maxim Integrated Products

GND

EXT

V+

REF

SHDN

OUT

DIP/SO

TOP VIEW

MAX1649

MAX1651

__________________Pin Configuration

__________Typical Operating Circuit

Call toll free 1-800-998-8800 for free samples or literature.

19-0305; Rev 2; 9/95

PART TEMP. RANGE PIN-PACKAGE

MAX1649CPA

0°C to +70°C 8 Plastic DIP

MAX1649CSA 0°C to +70°C 8 SO

MAX1649C/D 0°C to +70°C Dice*

MAX1649EPA -40°C to +85°C 8 Plastic DIP

MAX1649ESA -40°C to +85°C 8 SO

MAX1651

V+

CSSHDN

FB GND

ON/OFF

EXT

REF

OUT

OUTPUT

3.3V

INPUT

3.6V TO 16V

MAX1651CPA

0°C to +70°C 8 Plastic DIP

MAX1651CSA 0°C to +70°C 8 SO

MAX1651C/D 0°C to +70°C Dice*

MAX1651EPA -40°C to +85°C 8 Plastic DIP

MAX1651ESA -40°C to +85°C 8 SO

1 2 3 4 5 6 ... 11 12

MAX1649/MAX1651 1

Indice de contenidos

Pagina 1 - MAX1649/MAX1651

_______________General DescriptionThe MAX1649/MAX1651 BiCMOS, step-down, DC-DCswitching controllers provide high efficiency over loadsranging from 1mA

Pagina 2

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers10 _____________________________________________________

Pagina 3

Input Bypass CapacitorThe input bypass capacitor reduces peak currentsdrawn from the voltage source, and also reduces theamount of noise at the voltag

Pagina 4

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses arei

Pagina 5

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers2 ______________________________________________________

Pagina 6

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers________________________________________________________

Pagina 7

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers4 ______________________________________________________

Pagina 8

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers________________________________________________________

Pagina 9

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers6 ______________________________________________________

Pagina 10

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers________________________________________________________

Pagina 11

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers8 ______________________________________________________

Pagina 12

MAX1649/MAX16515V/3.3V or Adjustable, High-Efficiency,Low-Dropout, Step-Down DC-DC Controllers________________________________________________________

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