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 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 standard VTRIP

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.

Features

• 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 available (RoHS compliant)