Built-in inadvertent write protection 1,000,000 Program/Erase cycles Manual reset capability 100 year data retention 8-pin DIP, SOIC, TSSOP, MSOP or TDFN

The CAT1026 and CAT1027 are complete memory and supervisory solutions for microcontroller-based systems. A 2k-bit serial EEPROM memory and a system power supervisor with brown-out protection are integrated together in low power CMOS technology. Memory interface is via 400kHz I2C bus. The CAT1026 and CAT1027 provide a precision VCC sense circuit with five reset threshold voltage options that support 5V, 3.3V and 3V systems. The power supply monitor and reset circuit protects memory and systems controllers during power up/down and against brownout conditions. If power supply voltages are out of tolerance reset signals become active preventing the system microcontroller, ASIC, or peripherals from operating. used as an input for push-button manual reset capability. The CAT1026 and CAT1027 provide an auxiliary voltage sensor input, VSENSE, which is used to monitor a second system supply. The auxiliary high impedance comparator drives the open drain output, VLOW, whenever the sense voltage is below 1.25V threshold. The CAT1027 is designed with a 1.6 second watchdog timer circuit that resets a system to a known state if software or a hardware glitch halts or "hangs" the system. The CAT1027 features a watchdog timer interrupt input, WDI.

The on-chip 2k-bit EEPROM memory features a 16-byte page. In addition, hardware data protection is provided by a VCC sense circuit that prevents writes to memory whenever VCC falls below the reset threshold or until VCC reaches the The CAT1026 features two open drain reset outputs: reset threshold during power up. one (RESET) drives high and the other (RESET) drives Available packages include an 8-pin DIP, 8-pin SOIC, 8low whenever VCC falls below the threshold. Reset pin TSSOP, 8-pin TDFN and 8-pin MSOP. The TDFN outputs become inactive typically 200 ms after the package thickness is 0.8mm maximum. TDFN footprint is supply voltage exceeds the reset threshold value. With 3x3mm. both active high and low reset signals, interface to microcontrollers and other ICs is simple. CAT1027 has only a RESET output. In addition, the RESET pin can be

RESET/RESET: RESET OUTPUTS (RESET CAT1026 Only) These are open drain pins and RESET can be used as a manual reset trigger input. By forcing a reset condition on the pin the device will initiate and maintain a reset condition. The RESET pin must be connected through a pull-down resistor, and the RESET pin must be connected through a pull-up resistor. SDA: SERIAL DATA ADDRESS The bidirectional serial data/address pin is used to transfer all data into and out of the device. The SDA pin is an open drain output and can be wire-ORed with other open drain or open collector outputs. SCL: SERIAL CLOCK Serial clock input. VSENSE: AUXILIARY VOLTAGE MONITOR INPUT The VSENSE input is a second voltage monitor which is compared against CAT1026 and CAT1027 internal reference voltage of 1.25V typically. Whenever the input voltage is lower than 1.25V, the open drain VLOW output will be driven low. An external resistor divider is used to set the voltage level to be sensed. Connect VSENSE to VCC if unused. VLOW: AUXILIARY VOLTAGE MONITOR OUTPUT This open drain output goes low when VSENSE is less than 1.25V and goes high when VSENSE exceeds the reference voltage. WDI (CAT1027 Only): WATCHDOG TIMER INTERRUPT Watchdog Timer Interrupt Input is used to reset the watchdog timer. If a transition from high to low or low to high does not occur every 1.6 seconds, the RESET outputs will be driven active.

Active Low Reset Input/Output Ground Serial Data/Address Clock Input Active High Reset Output (CAT1026 only) Power Supply Auxiliary Voltage Monitor Input Auxiliary Voltage Monitor Output Watchdog Timer Interrupt (CAT1027 only)

Device Manual Reset Input Pin Watchdog Monitor Pin SDA WDI Write Protection Pin Independent Auxiliary Voltage Sense RESET: Active High and LOW EEPROM

For supervisory circuits with embedded 16k EEPROM, please refer to the CAT1161, CAT1162 and CAT1163 data sheets.