STMicroelectronics | M41T93SMY6F

It has built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the clock operations can be supplied by a small lithium.

Features:

• Ultra-low battery supply current of 365 nA
• Factory calibrated accuracy ±5 ppm guaranteed after 2 reflows (SOX18)
  • Much better accuracies achievable using built-in programmable analog and digital calibration circuits
• 2.0 V to 5.5 V clock operating voltage
• Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
• Automatic switchover and reset output circuitry (fixed reference)
  • M41T93S: VCC = 3.0 V to 5.5 V (2.85 V ≤ VRST ≤ 3.00 V)
• Compatible with SPI bus serial interface (supports SPI mode 0 [CPOL = 0, CPHA = 0])
• Programmable alarm with interrupt function (valid even during battery backup mode)
• Optional 2nd programmable alarm available
• Square wave output (defaults to 32 KHz on power-up) RESET (RST) output
• Watchdog timer
• Programmable 8-bit counter/timer
• 7 bytes of battery-backed user SRAM
• Battery low flag
• Low operating current of 80 μA
• Oscillator stop detection
• Battery or SuperCap™ backup
• Operating temperature of –40 °C to +85 °C
• Package options include:
• a 16-lead QFN or an 18-lead embedded crystal SOIC
• RoHS compliance: lead-free components are compliant with the RoHS directive