DS1388Z-3+

Real Time Clock Overview

The DS1388Z-3+ is an I2C real-time clock, supervisor, and EEPROM device from Analog Devices/Maxim Integrated. It provides a clock/calendar with hundredths-of-seconds resolution, a programmable watchdog timer, power-supply monitor with reset, and 512 bytes of EEPROM. Operating at a nominal VCC of 3.0V (range 2.7V to 3.3V), it supports fast-mode I2C communication up to 400kHz. The device features automatic power-fail detection and switching to a backup supply (VBACKUP) ranging from 1.3V to 5.5V. It includes integrated trickle-charge capability for backup sources and operates within a temperature range of -40°C to +85°C in an 8-pin SO package.

Real Time Clock Feature Summary

• I2C RTC with Calendar: Counts hundredths of seconds, seconds, minutes, hours, day, date, month, and year with leap-year compensation valid up to 2100.
• Supervisor Functions: Programmable watchdog timer (0.01–99.99s), automatic power-fail detect and switch circuitry, and reset output with pushbutton reset input capability.
• 512 Bytes EEPROM: Non-volatile memory divided into two 256-byte blocks for data storage.
• Trickle Charger: Integrated circuit for charging backup supplies, configurable via resistor and diode selection.

Real Time Clock Applications

• Portable Instruments
• Point-of-Sale Equipment
• Network Interface Cards
• Wireless Equipment

Real Time Clock Procurement Notes

Verify the specific voltage variant when ordering. The suffix '3' indicates a 3.0V nominal operating voltage (2.7V to 3.3V). Ensure the design accounts for the 8-pin SO package dimensions and thermal characteristics. Confirm that the I2C bus pull-up resistors are correctly sized for the 400kHz fast-mode operation specified in the datasheet.

Real Time Clock Selection Notes

Select the DS1388Z-3+ when a 3.0V primary supply is available. For 5.0V systems, use the DS1388Z-5+. For 3.3V systems tolerant of wider ranges, consider the DS1388Z-33+. All variants share identical pinouts and functional features, differing only in recommended DC operating conditions and power-fail thresholds.

Real Time Clock Part Context

The DS1388Z-3+ belongs to the DS1388 family of multifunction RTC supervisors. It integrates timekeeping, supervision, and non-volatile storage in a single component. The 'Z' denotes lead-free/RoHS compliance, and the '+' indicates the specific voltage grade. This part replaces older discrete RTC and supervisor solutions by consolidating functions into one IC.

Real Time Clock Replacement Considerations

Direct pin-compatible replacements include other DS1388 variants (DS1388Z-5+, DS1388Z-33+) if voltage levels allow. Verify that any substitute maintains the 512-byte EEPROM capacity and I2C interface compatibility. No other specific cross-reference part numbers are confirmed in the provided documentation.