DS1393:Low-Voltage SPI/3-Wire RTCs with Trickle Charger

Low-Voltage SPI/3-Wire RTCs with Trickle Charger have the Broadest Feature Set and the Smallest Footprint in Their Class

The low-voltage serial-peripheral interface (SPI™) DS1390/DS1391/DS1394 and the low-voltage 3-wire DS1392/DS1393 real-time clocks (RTCs) are clocks/calendars that provide hundredths of a second, 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 the 24-hour or 12-hour format with an AM/PM indicator. One programmable time-of-day alarm is provided. A temperature-compensated voltage reference monitors the status of VCC and automatically disables the bus interface and switches to the backup supply if a power failure is detected. On the DS1390, a single open drain output provides a CPU interrupt or a square wave at one of four selectable frequencies. The DS1391 replaces the SQW/active-low INT pin with an active-low RST output/debounced input. The DS1390, DS1391, and DS1394 are programmed serially through an SPI-compatible, bidirectional bus. The DS1392 and DS1393 communicate over a 3-wire serial bus, and the extra pin is used for either a separate interrupt pin or an active-low RST output/debounced input. All five devices are available in a 10-pin µSOP package, and are rated over the industrial temperature range.

Key Features
  • Real-Time Clock Counts Hundredths of Seconds, Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap-Year Compensation Valid Up to 2100
  • Output Pin Configurable as Interrupt or Square Wave with Programmable Frequency of 32.768kHz, 8.192kHz, 4.096kHz, or 1Hz (DS1390/DS1393/DS1394 Only)
  • One Time-of-Day Alarm
  • Power-Fail Detect and Switch Circuitry
  • Reset Output/Debounced Input (DS1391/DS1393)
  • Separate SQW and INT Output (DS1392)
  • Trickle-Charge Capability
  • SPI Supports Modes 0 and 2 (DS1394)
  • SPI Supports Modes 1 and 3 (DS1390/DS1391)
  • 3-Wire Interface (DS1392/DS1393)
  • 4MHz at 3.0V and 3.3V
  • 1MHz at 1.8V
  • Three Operating Voltages: 1.8V ±5%, 3.0V ±10%, and 2.97 to 5.5V (DS1394: 3.3V ±10%)
  • Industrial Temperature Range: -40°C to +85°C
DS1390, DS1391, DS1392, DS1393, DS1394: Functional Diagram
DS1390, DS1391, DS1392, DS1393, DS1394: Functional Diagram
  • Embedded Time Stamping
  • GPS/Telematics Devices
  • Handheld Devices
  • Medical Devices
titleDownload file
DS1390-DS1394 Data SheetDS1390-DS1394.pdf
Part NumberInterfaceVSUPPLY
Time Keeping Current
Memory TypeTime of Day AlarmsFunctionsPackage/PinsBudgetary
typSee Notes
5006None1RTCµMAX/10$1.50 @1k
µMAX/10$1.50 @1k
µMAX/10$1.50 @1k
µMAX/10$1.73 @1k
µMAX/10$1.55 @1k
Quality and Environmental Data
Related Products
  • DS1305:Serial Alarm Real-Time Clock
  • MAX6901:3-Wire Serial RTC in a TDFN
  • MAX6902:SPI-Compatible RTC in a TDFN
  • DS1306:Serial Alarm Real-Time Clock
  • DS1302:Trickle-Charge Timekeeping Chip
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
DS1393U-18No Longer AvailableDS1393U-18+µMAX,;10 pin;15.4 mm²-40°C to +85°CNo
DS1393U-18+Last Time BuyµMAX,;10 pin;15.4 mm²-40°C to +85°CLead Free
DS1393U-18+T&RActiveµMAX,;10 pin;15.4 mm²-40°C to +85°CLead Free
DS1393U-3+ActiveµMAX,;10 pin;15.4 mm²-40°C to +85°CLead Free
DS1393U-33No Longer AvailableDS1393U-33+µMAX,;10 pin;15.4 mm²-40°C to +85°CNo
DS1393U-33+ActiveµMAX,;10 pin;15.4 mm²-40°C to +85°CLead Free
DS1390-DS1394.pdf DS1394
Tips for Writing Bulletproof Real-Time Clock Control Code DS3234
State Machine Logic in Binary-Coded Decimal (BCD)-Formatted Real-Time Clocks DS3234
Oscillator Design Considerations for Low-Current Applications DS17885
Selecting a Backup Source for Real-Time Clocks DS3234
Using the DS32kHz with Maxim Real-Time Clocks DS17885
Lithium Coin-Cell Batteries: Predicting an Application Lifetime DS9034PCX
Design Considerations for Maxim Real-Time Clocks DS3234
Using the Dallas Tricklecharge Timekeeper DS1672
Crystal Considerations with Maxim Real-Time Clocks (RTCs) DS3234
DS1393.pdf DS1393
DS1390-DS1394.pdf DS1394