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_______________General Description

The MAX845 provides an isolated power supply small

enough to fit in thin PCMCIA cards and space-sensitive

applications. It drives a low-profile center-tapped trans-

former primary from a 5V or 3.3V DC power supply. The

secondary can be wound to provide any isolated posi-

tive or negative voltage at powers up to 750mW.

The MAX845 consists of an oscillator followed by a tog-

gle flip-flop. The flip-flop generates two 50% duty-cycle

square waves, which are complementary at half the

oscillator frequency (450kHz, min). These two signals

drive the ground-referenced N-channel power switch-

es. Internal circuitry ensures break-before-make action

between the two switches.

A low-power shutdown disables both the switches and

the oscillator, reducing power consumption. An evalua-

tion kit (MAX845EVKIT-MM) is available to evaluate low-

profile 5V 40mA and 5V 100mA applications.

________________________Applications

PCMCIA Modem Cards

Isolated Data Acquisition

Isolated Interface Power Supply

Noise-Immunity Communications Interface

Bridging Ground Differences

Medical Equipment

Process Control

Low-Power LAN Networks

____________________________Features

o Transformer Driver for Ultra-Thin 5V-µs Transformers

o Isolated DC-to-DC Power Supply for PCMCIA

Applications

o 450kHz Minimum Switching Frequency

o Ultra-Low Input Supply Current Ripple

o Single +5V or +3.3V Supply

o 5µW Low-Power Shutdown Mode

o 8-Pin SO and µMAX Packages

o Low Output Ripple Permits Miniature Output

Capacitors

Isolated Transformer Driver

for PCMCIA Applications

________________________________________________________________

Maxim Integrated Products

1

1

2

3

4

8

7

6

5

D2

GND2

N.C.

SD

FS

GND1

D1

SO/

µMAX

TOP VIEW

MAX845

___________________Pin Configuration

MAX845

D1

D2

FS

GND1

GND2

1

8

46

27

3

SD

FREQUENCY

SELECT

C2

C1

C3

5V @ 150mA

OUTPUT

5V

ON / OFF

T1

CR2

CR1

__________Typical Operating Circuit

19-0372; Rev 4; 10/97

PART

MAX845C/D

MAX845EUA

-40°C to +85°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

Dice*

8 µMAX

EVALUATION

KIT

AVAILABLE

*Contact factory for dice specifications.

_______________Ordering Information

MAX845ESA

-40°C to +85°C

8 SO