Rainbow-electronics MAX1627 User Manual download pdf

_______________General Description

The MAX1626/MAX1627 step-down DC-DC switching

controllers provide high efficiency over loads ranging

from 1mA to more than 2A. A unique current-limited,

pulse-frequency-modulated (PFM) control scheme

operates with up to a 100% duty cycle, resulting in very

low dropout voltages. This control scheme eliminates

minimum load requirements and reduces the supply

current under light loads to 90µA (versus 2mA to 10mA

for common pulse-width modulation controllers).

These step-down controllers drive an external P-chan-

nel MOSFET, allowing design flexibility for applications

to 12W or higher. Soft-start reduces current surges dur-

ing start-up. A high switching frequency (up to 300kHz)

and operation in continuous-conduction mode allow the

use of tiny surface-mount inductors. Output capacitor

requirements are also reduced, minimizing PC board

area and system costs.

The output voltage is preset at 5V or 3.3V for the

MAX1626 and adjustable for the MAX1627. Input volt-

ages can be up to 16.5V. The MAX1626/MAX1627 are

functional upgrades for the MAX1649/MAX1651.

________________________Applications

PCMCIA Power Supplies

Personal Digital Assistants

Hand-Held Computers

Portable Terminals

Low-Cost Notebook Computer Supplies

5V to 3.3V Green PC Applications

High-Efficiency Step-Down Regulation

Minimum-Component DC-DC Converters

Battery-Powered Applications

____________________________Features

♦ Low Dropout Voltage

♦ 100% Maximum Duty Cycle

♦ Soft-Start Limits Start-Up Current

♦ Efficiency >90% (3mA to 2A Loads)

♦ Output Power >12.5W

♦ 90µA Max Quiescent Current

♦ 1µA Max Shutdown Current

♦ Up to 300kHz Switching Frequency

♦ 16.5V Max Input Voltage

♦ Output Voltage: 5V/3.3V (MAX1626)

Adjustable (MAX1627)

♦ Current-Limited Control Scheme

MAX1626/MAX1627

5V/3.3V or Adjustable, 100% Duty-Cycle,

High-Efficiency, Step-Down DC-DC Controllers

________________________________________________________________

Maxim Integrated Products

MAX1626

V+

CSSHDN

GND

3/5

ON/OFF

EXT

REF

OUT

OUTPUT

3.3V

INPUT

3.3V to 16.5V

__________________Pin Configuration

GND

EXT

V+

REF

SHDN

3/5 (FB)

OUT

( ) ARE FOR MAX1627

SO



TOP VIEW

MAX1626

MAX1627

__________Typical Operating Circuit

19-1075; Rev 0; 6/96

PART

MAX1626C/D

MAX1626ESA

MAX1627C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

Dice*

8 SO

Dice*

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

______________Ordering Information

* Dice are tested at T

= +25°C.

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

MAX1627ESA -40°C to +85°C 8 SO

1 2 3 4 5 6 ... 15 16

Summary of Contents

Page 1 - MAX1626/MAX1627

_______________General DescriptionThe MAX1626/MAX1627 step-down DC-DC switchingcontrollers provide high efficiency over loads rangingfrom 1mA to more

Page 2

MAX1626/MAX1627With high inductor values, the MAX1626/MAX1627 willbegin continuous-conduction operation at a lower frac-tion of the full load (see Det

Page 3

Diode SelectionThe MAX1626/MAX1627’s high switching frequencydemands a high-speed rectifier. Schottky diodes, suchas the 1N5817–1N5822 family or surfa

Page 4

MAX1626/MAX1627current feedback signal and causing jitter. 0.47µF isrecommended. Increase the value as necessary inhigh-power applications. Bypass REF

Page 5

________________________ApplicationsThe MAX1626/MAX1627 typical operating circuits(Figures 1 and 8) are designed to output 2A at a 5Voutput voltage. T

Page 6

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers14 ________________________________________________

Page 7

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers___________________________________________________

Page 8

DIMAA1BCEeHLMIN0.0530.0040.0140.0070.1500.2280.016MAX0.0690.0100.0190.0100.1570.2440.050MIN1.350.100.350.193.805.800.

Page 9

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers2 _________________________________________________

Page 10

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers___________________________________________________

Page 11

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers4 _________________________________________________

Page 12

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers___________________________________________________

Page 13

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers6 _________________________________________________

Page 14

MAX1626/MAX16275V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers___________________________________________________

Page 15 - SUBSTRATE CONNECTED TO V+

MAX1626/MAX1627EXT Drive Voltage RangeEXT swings from V+ to GND and provides the gatedrive for an external P-channel power MOSFET. A high-er supply vo

Page 16 - (0.150 in.)

least 100 times FB’s input bias current. Capacitor CR2is used to compensate the MAX1627 for even switch-ing. Values between 0pF and 330pF work for man

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Rainbow-electronics MAX1627 User Manual

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Summary of Contents

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