General Description

The MAX7391 replaces ceramic resonators, crystals,

and supervisory functions for microcontrollers in 3.3V

and 5V applications.

The MAX7391 provides a clock source, reset, and

power-fail functions. The programmable power-fail func-

tion provides early warning of power failure and is con-

supply to the device.

The clock output can be switched between normal and

half-speed operation. This functionality allows the micro-

controller to operate at reduced power and may be

used to extend the time available to perform house-

keeping tasks, such as writing data to flash during a

power failure. Connecting the power-fail output to the

SPEED input reduces clock speed automatically during

power-fail events.

The MAX7391 clock output is factory programmed to a

frequency in the 1MHz to 16MHz range. Four standard

frequencies are available. Other frequencies are avail-

able upon request. The maximum operating supply cur-

rent is 5.5mA (typ) with a clock frequency of 12MHz.

Unlike typical crystal and ceramic resonator oscillator

circuits, the MAX7391 is resistant to EMI and vibration,

and operates reliably at high temperatures. The high-

output drive current and absence of high-impedance

nodes make the oscillator invulnerable to dirty or humid

operating conditions.

The MAX7391 standard operating temperature range is

from -40°C to +125°C.

Applications

White Goods

Automotive

Appliances and Controls

Handheld Products

Portable Equipment

Microcontroller Systems

Features

♦ Robust Microcontroller Clock and Supervisory

Functions in a Single Package

♦ Integrated Reset and Power-Fail Functions

♦ 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 Accurac for 0°C to +85°C

♦ 5.5mA Operating Current (12MHz Version)

♦ -40°C to +125°C Temperature Range

♦ Surface-Mount Package

♦ 1MHz to 16MHz Factory Preset Frequency Range

Speed-Switching Clock Generator

with Power Fail

________________________________________________________________ Maxim Integrated Products

1

19-3981; Rev 0; 1/06

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.

SPEED

PFO

GND

1

2

8

7

CLOCK

RST/RST

N.C.

PFI

TOP VIEW

µMAX

3

4

6

5

MAX7391

Pin Configuration

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

PKG

CODE

MAX7391srff

-40°C to +125°C

8 µMAX

U8-1

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

symbol found in Table 2 in the place of “s.” “r” is a placeholder

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

Table 1 in the place of “r.” “ff” is a placeholder for the nominal

output frequency. Insert the symbol found in Table 3 in the

place of “ff.” For example, MAX7391CMTP 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.