May 11, 2006
• Selectable watchdog timer
—Select 200ms, 600ms, 1.4s, off
• Low VCC detection and reset assertion
—Five standard reset threshold voltages
nominal 4.62V, 4.38V, 2.92V, 2.68V, 1.75V
—Adjust low VCC reset threshold voltage using
special programming sequence
—Reset signal valid to VCC = 1V
• Low power CMOS
—12µA typical standby current, watchdog on
—800nA typical standby current watchdog off
—3mA active current
• 400kHz I2C interface
• 1.8V to 5.5V power supply operation
• Available packages
—8 Ld SOIC
—8 Ld MSOP
• Pb-free plus anneal available (RoHS compliant)
These devices combine three popular functions,
Power-on Reset Control, Watchdog Timer, and Supply
Voltage Supervision. This combination lowers system
cost, reduces board space requirements, and
Applying power to the device activates the power-on
reset circuit which holds RESET/RESET active for a
period of time. This allows the power supply and oscilla-
tor to stabilize before the processor can execute code.
The Watchdog Timer provides an independent
protection mechanism for microcontrollers. When the
microcontroller fails to restart a timer within a select-
able time out interval, the device activates the
RESET/RESET signal. The user selects the interval
from three preset values. Once selected, the interval
does not change, even after cycling the power.
The device’s low VCC detection circuitry protects the
user’s system from low voltage conditions, resetting the
system when VCC falls below the minimum VCC trip
point. RESET/RESET is asserted until VCC returns to
proper operating level and stabilizes. Five industry stan-
dard VTRIP thresholds are available; however, Intersil’s
unique circuits allow the threshold to be reprogrammed
to meet custom requirements, or to fine-tune the thresh-
old for applications requiring higher precision.
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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