DS1388Z-33+

Real Time Clock Overview

The DS1388Z-33+ is an I2C real-time clock, supervisor, and EEPROM device manufactured by Analog Devices Inc./Maxim Integrated. It integrates a clock/calendar, programmable watchdog timer, power-supply monitor with reset, and 512 bytes of EEPROM. The clock supports hundredths of seconds, seconds, minutes, and hours in 12-hour or 24-hour formats, with automatic leap year correction through 2100. Operating at a nominal VCC of 3.3V (range 2.97V to 3.63V), it features fast 400kHz I2C interface, automatic power-fail detection, and integrated trickle-charge capability for backup supplies. It operates within a temperature range of -40°C to +85°C.

Real Time Clock Feature Summary

• Integrates RTC, supervisor, and 512-byte EEPROM in a single 8-pin SOIC package.
• Supports fast-mode I2C interface up to 400kHz.
• Includes programmable watchdog timer (0.01s to 99.99s) and power-fail detect circuitry.
• Features integrated trickle charger for backup supply maintenance.

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 required for the design, as the Z-33 suffix denotes a 3.3V nominal operating voltage. Confirm that the system's primary supply remains within the 2.97V to 3.63V range to ensure proper operation of the internal voltage reference and comparator circuits. Ensure the I2C bus pull-up resistors are selected appropriately for the 400kHz speed requirement.

Real Time Clock Selection Notes

Select the DS1388Z-33+ when a 3.3V logic level is required for the primary supply. Compare against DS1388Z-5+ for 5V systems or DS1388Z-3+ for 3.0V systems. Consider the 512-byte EEPROM capacity and the need for a watchdog timer when evaluating this component against simpler RTC-only devices. Verify crystal load capacitance requirements (6pF typical) for accurate timing.

Real Time Clock Part Context

The DS1388 series combines timekeeping, memory, and supervision functions. The Z-33 variant specifically targets 3.3V applications, distinguishing it from the 5V (Z-5) and 3.0V (Z-3) counterparts. All variants share the same pinout and functional architecture, differing primarily in their recommended DC operating conditions for VCC and power-fail thresholds.

Real Time Clock Replacement Considerations

Direct replacements include DS1388Z-5+ for 5V systems and DS1388Z-3+ for 3.0V systems, provided the supply voltage matches. Other Maxim Integrated RTCs like the DS1340 lack the integrated EEPROM and watchdog features, requiring additional components for equivalent functionality.