MCP795W1X/MCP795W2X Battery-Backed SPI Real-Time Clock/Calendar with Enhanced Features Device Selection Table User Memory EEPROM Protected 64-Byte Battery-Backed SRAM Part Number (Kbits) EEPROM 1 Kbit or 2 Kbit EEPROM: - Software write-protect MCP795W10 1 Blank - Page write up to 8 bytes MCP795W20 2 Blank - Endurance: 1M erase/write cycles MCP795W11 1 EUI-48 128-Bit Protected EEPROM Area: MCP795W21 2 EUI-48 - Robust write unlock sequence MCP795W12 1 EUI-64 - EUI-48 MAC address (MCP795WX1) MCP795W22 2 EUI-64 - EUI-64 MAC address (MCP795WX2) Timekeeping Features Operating Ranges Real-Time Clock/Calendar (RTCC): - Hours, minutes, seconds, hundredth of SPI Serial Interface: seconds, day of week, date, month, year - SPI clock rate up to 5 MHz - Leap year compensated to 2399 Temperature Range: - 12/24-hour modes - Industrial (I): -40C to +85C Oscillator for 32.768 kHz Crystals: - Optimized for 6-9 pF crystals Packages On-Chip Digital Trimming/Calibration: 14-Lead SOIC and TSSOP - 1 ppm resolution - 259 ppm range Package Types (not to scale) Dual Programmable Alarms Clock Output Function with Selectable Frequency SOIC/TSSOP Power-Fail Timestamp: - Time logged on switchover to and from Battery X1 1 14 VCC mode X2 2 13 CLKOUT Low-Power Features VBAT 3 12 EVHS Wide Voltage Range: - Operating voltage range of 1.8V to 3.6V 4 11 WDO EVLS - Backup voltage range of 1.3V to 3.6V Low Typical Timekeeping Current: IRQ 5 10 SCK - Operating from VCC: 1.2 A at 3.0V CS 6 9 SI - Operating from VBAT: 1.0 A at 3.0V 7 8 Automatic Switchover to Battery Backup VSS SO Enhanced Features Programmable Watchdog Timer: - Dedicated output pin - Cleared via SPI bus or EVHS input Dual Configurable Event Detect Modules: - High-Speed Digital Event Detect for program- mable pulse count detection - Low-Speed Event Detect for programmable switch debouncing 2011-2016 Microchip Technology Inc. DS20002280D-page 1MCP795W1X/MCP795W2X The MCP795WX1 and MCP795WX2 are Description pre-programmed with EUI-48 and EUI-64 addresses, The MCP795WXX Real-Time Clock/Calendar (RTCC) respectively. Custom programming is also available. tracks time using internal counters for hours, minutes, Two event detect modules are included on the seconds, hundredth of seconds, days, months, years MCP795WXX. The high-speed event detect module and day of week. Alarms can be configured on all counters up to and including months. For usage and will generate an interrupt after a programmable configuration, the MCP795WXX supports SPI number of pulses have been detected. The low-speed communications up to 5 MHz. event detect module can be used to debounce mechanical switches and includes a selectable The MCP795WXX is designed to operate using a 32.768kHz tuning fork crystal with external crystal debounce period. load capacitors. On-chip digital trimming can be used The MCP795WXX also features an integrated to adjust for frequency variance caused by crystal Watchdog Timer peripheral. This allows applications to tolerance and temperature. improve system robustness by moving this SRAM and timekeeping circuitry are powered from the functionality outside of the microcontroller. backup supply when main power is lost, allowing the The MCP795WXX has versatile output options. There device to maintain accurate time and the SRAM contents. The times when the device switches over to is a dedicated pin for outputting a selectable frequency the backup supply and when primary power returns square wave or for use as a general purpose output. are both logged by the power-fail timestamp. Additionally, the alarms can be assigned to either the Watchdog Timer interrupt output or the event detect The MCP795WXX features 128 bits of EEPROM interrupt output. which is only writable after an unlock sequence, making it ideal for storing a unique ID or other critical information. FIGURE 1-1: TYPICAL APPLICATION SCHEMATIC VCC VCC VCC 14 VCC C 1 X1 X1 6 CS C 10 2 X2 SCK X2 9 3 SI VBAT VBAT MCP795WXX PIC MCU 8 SO 4 MCLR WDO 5 12 IRQ EVHS EVHS 13 11 CLKOUT EVLS EVLS VSS 7 DS20002280D-page 2 2011-2016 Microchip Technology Inc. 32.768 KHZ