Microcontroller Clock Generator
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 sepa-
rate watchdog output that is used as a status indicator 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 perform 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 temperatures. The
high-output drive current and absence of high-impedance
nodes make the oscillator invulnerable to dirty or humid
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.
●●Appliances and Controls ●●Microcontroller Systems
µMAX is a registered trademark of Maxim Integrated Products, Inc.
●● Robust Microcontroller Clock and Supervisor in a
●● 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
-40oC to +125oC 8 µMAX
-40oC to +125oC 8 µMAX
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 nomi-
nal 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.
19-3897; Rev 2; 4/14