General Description

The MAX7389/MAX7390 replace ceramic resonators,

crystals, and supervisory functions for microcontrollers

in 3.3V and 5V applications.

The MAX7389/MAX7390 provide a clock source, reset,

and watchdog functions. The watchdog timer is pin pro-

grammable and provides watchdog timeout values in

the 16ms to 2048ms range. The MAX7389 provides a

separate watchdog output that is used as a status indi-

cator or to control safety-critical system elements.

The MAX7390 features a clock-speed select that

reduces the output frequency by half. This functionality

allows the microcontroller to operate at reduced power

and may be used to extend the time available to per-

form housekeeping tasks, such as writing data to flash

during a power failure.

The MAX7389/MAX7390 clock outputs are factory pro-

grammed to a frequency in the 1MHz to 16MHz range.

Four standard frequencies are available. Other frequen-

cies are available upon request. The maximum operating

supply current is 5.5mA with a clock frequency of 12MHz.

Unlike typical crystal and ceramic resonator oscillator

circuits, the MAX7389/MAX7390 are resistant to EMI

and vibration, and operate reliably at high tempera-

tures. The high-output drive current and absence of

high-impedance nodes make the oscillator invulnerable

to dirty or humid operating conditions.

package. The MAX7389/MAX7390 standard operating

temperature range is from -40°C to +125°C.

Applications

White Goods

Handheld Products

Automotive

Portable Equipment

Appliances and Controls

Microcontroller Systems

Features

♦ Robust Microcontroller Clock and Supervisor in a

Single Package

♦ Integrated Reset and Watchdog Functions

♦ Pin-Programmable Watchdog Timeout

♦ Speed Select

♦ +2.7V to +5.5V Operation

♦ Factory-Trimmed Oscillator

♦ Reset Valid Down to 1.1V Supply Voltage

♦ ±10mA Clock-Output Drive Current

♦ ±4% Total Accuracy for -40°C to +125°C

♦ ±2.75% Total Accuracy for 0°C to +85°C

♦ 5.5mA Operating Current (12MHz Version)

♦ -40°C to +125°C Temperature Range

♦ 8-Pin µMAX Surface-Mount Package

♦ 1MHz to 16MHz Factory Preset Frequency

Microcontroller Clock Generator with

Watchdog

________________________________________________________________ Maxim Integrated Products

1

19-3897; Rev 1; 2/06

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

RST/RST

TOP VIEW

µMAX

WDI

WDO

GND

1

2

8

7

CLOCK

WDS1

WDS2

3

4

6

5

MAX7389

Pin Configurations

Ordering Information

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX7389srff

-40

8 µMAX

U8-1

MAX7390srff

-40

8 µMAX

U8-1

Note: “s” is a placeholder for the reset output type. Insert the

symbol found in Table 3 in the place of “s.” “r” is a placeholder

for the power-on reset (POR) voltage. Insert the symbol found in

Table 2 in the place of “r.” “ff” is a placeholder for the nominal

output frequency. Insert the symbol found in Table 4 in the

place of “ff.” For example, MAX7389CMTP describes a device

with 4.38V reset level, open-collector RST output, and a clock

output frequency of 8MHz.

Typical Application Circuit, Functional Diagram, and Selector

Guide appear at end of data sheet.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

WDI

SPEED

GND

1

2

8

7

CLOCK

RST/RST

WDS1

WDS2

TOP VIEW

3

4

6

5

MAX7390

µMAX