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Low-Current SPI/3-Wire RTCs

Compatible with Any 32.768kHz Crystal

Product Details

Key Features

Parametric specs for Timekeeping & Real-Time Clocks
Interface 3-Wire
SPI
VSUPPLY (V) 1.71 to 5.5
Date/ Time Format (hh = sec/100) YY-MM-DD/ HH:MM:SS
Time Keeping Current (nA) (typ) 250
CL (pF) 6
Memory Type NV SRAM
Memory Size (Bytes) 96
Time of Day Alarms 2
Package/Pins TDFN/14
TSSOP/20
Budgetary
Price (See Notes)
2.26
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Simplified Block Diagram

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Parameters

Parametric specs for Timekeeping & Real-Time Clocks
Interface 3-Wire
SPI
VSUPPLY (V) 1.71 to 5.5
Date/ Time Format (hh = sec/100) YY-MM-DD/ HH:MM:SS
Time Keeping Current (nA) (typ) 250
CL (pF) 6
Memory Type NV SRAM
Memory Size (Bytes) 96
Time of Day Alarms 2
Package/Pins TDFN/14
TSSOP/20
Budgetary
Price (See Notes)
2.26

Key Features

  • Low Timekeeping Current of 250nA (typ)
  • Compatible with Crystal ESR Up to 100kΩ
  • Versions Available to Support Either 6pF or 12.5pF Crystals
  • RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap Year Compensation Valid Through 2099
  • Power-Fail and Switch Circuitry
  • Three Operating Voltages
    • 1.8V ±5%
    • 3.0V ±10%
    • 3.3V ±10%
  • Trickle-Charge Capability
  • Maintain Time Down to 1.15V (typ)
  • Support Motorola SPI Modes 1 and 3, or Standard 3-Wire Interface
  • Burst Mode for Reading/Writing Successive Addresses in Clock/RAM
  • 96-Byte Battery-Backed NV RAM for Data Storage
  • Two Time-of-Day Alarms with Two Interrupt Outputs
  • Industrial Temperature Range
  • 20-Pin TSSOP or 14-Pin TDFN Package

Applications/Uses

  • Embedded Timestamping
  • Handheld Devices
  • Medical
  • Telematics

Description

The DS1343/DS1344 low-current real-time clocks (RTCs) are timekeeping devices that provide an extremely low standby current, permitting longer life from a backup supply source. The devices also support high-ESR crystals, broadening the pool of usable crystals for the devices. 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-hour or 12-hour format with an active-low AM/PM indicator.

Address and data are transferred serially through an SPI™ or 3-wire interface. Two programmable time-of-day alarms are provided. Each alarm can generate an interrupt on a combination of seconds, minutes, hours, and day. Don't-care states can be inserted into one or more fields if it is desired for them to be ignored for the alarm condition. The time-of-day alarms can be programmed to assert two different interrupt outputs, or they can be combined to assert one common interrupt output. Both interrupt outputs operate when the device is powered by either VCC or VBAT.

The devices are available in a lead-free/RoHS-compliant, 20-pin TSSOP or 14-pin TDFN package, and support a -40°C to +85°C extended industrial temperature range.

Simplified Block Diagram

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .