MAX7391 Datasheet, PDF (1/10 Pages) Maxim Integrated Products – Speed-Switching Clock Generator with Power Fail

19-3981; Rev 0; 1/06
Speed-Switching Clock Generator
with Power Fail
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-
figurable to detect either an external voltage or the V_CC
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 is available in an 8-pin µMAX^® package.
The MAX7391 standard operating temperature range is
from -40°C to +125°C.
White Goods
Automotive
Appliances and Controls
Handheld Products
Portable Equipment
Microcontroller Systems
Applications
Typical Application Circuit, Functional Diagram, and Selector
Guide appear at end of data sheet.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
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
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.
Pin Configuration
TOP VIEW
PFI 1
V_CC 2
N.C. 3
GND 4
MAX7391
8 CLOCK
7 RST/RST
6 SPEED
5 PFO
µMAX
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