19-3897; Rev 1; 2/06
Microcontroller Clock Generator with
Watchdog
General Description
The MAX7389/MAX7390 replace ceramic resonators,
crystals, and supervisory functions for microcontrollers
in 3.3V and 5V applications.
Features
♦ Robust Microcontroller Clock and Supervisor in a
Single Package
♦ Integrated Reset and Watchdog Functions
♦ Pin-Programmable Watchdog Timeout
♦ Speed Select
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.
♦ +2.7V to +5.5V Operation
♦ Factory-Trimmed Oscillator
♦ Reset Valid Down to 1.1V Supply Voltage
♦ ±1ꢀmꢁ Clock-Output Drive Current
♦ ±±4 Total ꢁccuracy ꢂor -±ꢀ0C to +1250C
♦ ±2.754 Total ꢁccuracy ꢂor ꢀ0C to +ꢃ50C
♦ 5.5mꢁ Operating Current (12MHz Version)
♦ -±ꢀ0C to +1250C Temperature Range
♦ ꢃ-Pin µMꢁX Surꢂace-Mount Package
♦ 1MHz to 16MHz Factory Preset Frequency
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.
Ordering Information
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.
PIN-
PꢁCKꢁGE
PKG
CODE
PꢁRT
TEMP RꢁNGE
MꢁX73ꢃ9srff
MꢁX739ꢀsrff
-40oC to +125oC
-40oC to +125oC
8 µMAX
8 µMAX
U8-1
U8-1
The MAX7389/MAX7390 are available in an 8-pin µMAX®
package. The MAX7389/MAX7390 standard operating
temperature range is from -40°C to +125°C.
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.
Applications
White Goods
Automotive
Handheld Products
Portable Equipment
Typical Application Circuit, Functional Diagram, and Selector
Guide appear at end of data sheet.
Appliances and Controls Microcontroller Systems
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations
TOP VIEW
TOP VIEW
V
1
2
3
4
8
7
6
5
CLOCK
CC
V
1
2
3
4
8
7
6
5
CLOCK
RST/RST
WDI
CC
RST/RST
WDS1
WDS2
GND
WDS1
WDS2
GND
MAX7389
MAX7390
WDI
WDO
SPEED
µMꢁX
µMꢁX
________________________________________________________________ Maxim Integrated Products
1
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.