DS1341/DS1342 Real-Time Clocks

By Maxim Integrated 133

DS1341/DS1342 Real-Time Clocks

Maxim Integrated's DS1341 and DS1342 low-current, real-time clocks (RTCs) are timekeeping devices that provide an extremely low standby current, which permits longer life from a power supply. The DS1341 and DS1342 support high-ESR crystals, which broaden the pool of usable crystals for the devices. The DS1341 uses a 6 pF crystal, while the DS1342 uses a 12.5 pF crystal. These devices are accessed through an I²C serial interface. Other features include two time-of-day alarms, two interrupt outputs, a programmable square-wave output, and a serial bus timeout mechanism.

The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either 24 hr or 12 hr format with an AM/PM indicator.

The DS1341/DS1342 each includes an input for synchronization. When a reference clock (e.g., 60Hz power line or GPS 1PPS) is present at the CLKIN pin and the enable external clock input bit (ECLK) is set to 1, the DS1341/DS1342 RTCs are frequency-locked to the external clock. The clock accuracy is determined by the external source. In case of external clock failure, the clock is switched to the crystal oscillator.

The devices are available in lead(Pb)-free/RoHS-compliant, 8-pin µSOP or TDFN packages. The devices support a -40°C to +85°C extended temperature range.

  • Low Timekeeping Current of 250 nA (typical)
  • Compatible with crystal ESR up to 100 kΩ
  • Use crystals with CL = 6 pF (DS1341) or CL= 12.5 pF (DS1342)
  • +1.8 V to +5.5 V operating voltage range
  • Maintain time down to +1.15 V (typical)
  • Fast (400 kHz) I²C interface
  • Bus timeout for lockup-free operation
  • RTC counts seconds, minutes, hours, day, date, month, and year with leap year compensation valid through 2099
  • External clock source for synchronization clock reference (e.g., 32 kHz, 50 Hz/60 Hz power line, GPS 1 PPS)
  • Two time-of-day alarm with two interrupt outputs
  • Programmable square-wave output
  • Industrial temperature range (-40°C to +85°C)
  • Small, 8-Pin µSOP or TDFN packages
  • Automotive
  • Medical
  • Point of sale (POS)
  • Portable audio
  • Portable instruments
  • Telematics

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