• Selectable watchdog timer
  • Select 200ms, 600ms, 1.4s, off
• Low V_CC detection and reset assertion
  • Five standard reset threshold voltages nominal 4.62V, 4.38V, 2.92V, 2.68V, 1.75V
  • Adjust low V_CC reset threshold voltage using special programming sequence
  • Reset signal valid to V_CC = 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 increases reliability.

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 oscillator 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 selectable 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 V_CC detection circuitry protects the user's system from low voltage conditions, resetting the system when V_CC falls below the minimum V_CC trip point. RESET/RESET is asserted until V_CC returns to proper operating level and stabilizes. Five industry standard V_TRIP thresholds are available; however, Intersil's unique circuits allow the threshold to be reprogrammed to meet custom requirements, or to fine-tune the threshold for applications requiring higher precision.