X4003

X4003/X4005 CPU Supervisor 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-lead SOIC —8-lead MSOP DESCRIPTION These devices combine three popular functions, Poweron 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 minim...