MCP7952X/MCP7951X 3V SPI Real-Time Clock Calendar with Battery Switchover Device Selection Table User Memory: SRAM EEPROM 64-Byte Battery-Backed SRAM Part Number Unique ID (Bytes) (Kbits) 2 Kbit and 1 Kbit EEPROM Memory: MCP79520 64 2 Blank - Software block write-protect (, , or entire array) MCP79510 64 1 Blank - Write Page mode (up to 8 bytes) MCP79521 64 2 EUI-48 - Endurance: 1M erase/write cycles MCP79511 64 1 EUI-48 128-Bit Unique ID in Protected Area of EEPROM: MCP79522 64 2 EUI-64 - Available blank or preprogrammed MCP79512 64 1 EUI-64 - EUI-48 or EUI-64 MAC address Timekeeping Features: - Unlock sequence for user programming Real-Time Clock/Calendar: Operating Ranges: - Hours, Minutes, Seconds, Hundredth of Seconds, Day of Week, Month, Year, Leap SPI Clock Speed up to 5 MHz Year Operating Temperature Ranges: Crystal Oscillator requires External 32,768 kHz - Industrial (I Temp): -40C to +85C. Tuning Fork Crystal and Load Capacitors. Packages include 10-Lead MSOP and TDFN Clock Out Function: - 1Hz, 4.096 kHz, 8.192 kHz, 32.768 kHz Package Types (not to scale) 2 Programmable Alarms MSOP/TDFN Programmable open drain output Alarm or Interrupt X1 1 10 Vcc On-Chip Digital Trimming/Calibration: X2 2 9 MFP - +/- 255 PPM range in 1 PPM steps VBAT 3 8 SCK Power-Fail Time-Stamp Battery Switchover: 4 7 SO CS - Logs time when VCC fails and VCC is restored 5 6 SI VSS Low-Power Features: Wide Operating Voltage: Note: MCP795XX is used in this document as a -VCC: 1.8V to 3.6V generic part number for the MCP7951X, MCP7952X devices. -VBAT: 1.3V to 3.6V Low Operating Current: -VCC Standby Current < 1uA 3V -VBAT Timekeeping Current: <700nA 1.8V Automatic Battery Switchover from VCC to VBAT: - Backup power for timekeeping and SRAM retention 2012 Microchip Technology Inc. Preliminary DS22300A-page 1 MCP795XXMCP7952X/MCP7951X Description: The MCP795XX is a low-power Real-Time Clock/ Calendar (RTCC) that uses digital trimming compen- sation for an accurate clock/calendar, an interrupt out- put to support alarms and events, a power sense circuit that automatically switches to the backup sup- ply, nonvolatile memory for safe data storage and sev- eral enhanced features that support system requirements. Along with a low-cost 32,768 kHz crystal, this RTCC tracks time using several internal registers and then communicates the data over a 5 MHz SPI bus that is fast enough to support a programmable millisecond alarm. The device is fully accessible through the serial inter- CC is between 1.8V and 3.6V, but can face, while V operate down to 1.3V through the backup supply con- nected to the VBAT input for timekeeping and SRAM retention only. As part of the power sense circuit, a time saver function is implemented to store the time when main power is lost and again, when power is restored to log the duration of a power failure. Along with the on-board serial EEPROM and battery- backed SRAM, a 128-bit protected space is available for a unique ID. This space can be ordered preprogrammed with a MAC address, or blank for the user to program. This clock/calendar automatically adjusts for months with fewer than 31 days including corrections for leap years. The clock operates in either 24-hour or 12-hour format with AM/PM indicator and settable alarm(s). Using the external crystal, the MFP pin can be set to generate a number of output frequencies. FIGURE 1-1: BLOCK DIAGRAM X1 VCC CLKOUT Divider OSC X2 MFP EEPROM VBAT SCK ID CS SO SRAM SPI VSS SI TIME-STAMP DS22300A-page 2 Preliminary 2012 Microchip Technology Inc. VBAT ALARMS SWITCHOVER