19-3896; Rev 1; 1/06
System Monitoring Oscillator with
Watchdog and Power Fail
General Description
Features
The MAX7387/MAX7388 replace ceramic resonators,
crystals, and supervisory functions for microcontrollers
in 3.3V and 5V applications.
♦ Robust Microcontroller Clock and Supervisor in a
Single Package
♦ Integrated Reset, Watchdog, and Power-Fail
The MAX7387/MAX7388 provide a clock source together
with integrated reset, watchdog, and power-fail func-
tions. The watchdog timer is pin programmable and
provides watchdog timeout values in the 16ms to
2048ms range. The power-fail output provides early
warning of power failure. The power-fail threshold on the
MAX7388 is internally set. The MAX7387 also provides
a separate watchdog output that is used as a status
indicator or to control safety-critical system elements.
Functions
♦ Pin-Programmable Watchdog Timeout
♦ +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
♦ -±ꢀ0C to +1250C Temperature Range
The MAX7387/MAX7388 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 (max) with a clock frequency of
12MHz.
♦ ꢃ- and 1ꢀ-Pin µMꢁX Surꢂace-Mount Packages
♦ 5.5mꢁ Operating Current (12MHz)
Unlike typical crystal and ceramic resonator oscillator
circuits, the MAX7387/MAX7388 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.
♦ 1MHz to 16MHz Factory Preset Frequency
Ordering Information
PꢁRT
TEMP RꢁNGE PIN-PꢁCKꢁGE PKG CODE
MꢁX73ꢃ7srff -40oC to +125oC 10 µMAX
MꢁX73ꢃꢃsrff -40oC to +125oC 8 µMAX
U10-2
U8-1
The MAX7387/MAX7388 are available in 10-pin and 8-pin
µMAX® packages, respectively. The MAX7387/MAX7388
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, MAX7387CMTP 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
Appliances and Controls Microcontroller Systems
Typical Application Circuit, Functional Diagram, and Selector
Guide appear at end of data sheet.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations
TOP VIEW
TOP VIEW
PFI
1
2
3
4
5
10 CLOCK
V
1
2
3
4
8
7
6
5
CLOCK
RST/RST
WDI
CC
V
CC
9
8
7
6
RST/RST
WDI
WDS1
WDS2
GND
MAX7387
MAX7388
WDS1
WDS2
GND
PFO
PFO
WDO
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.