DS1394U-33+

Real Time Clock Overview

The DS1394U-33+ is a low-voltage serial peripheral interface (SPI) real-time clock/calendar manufactured by Analog Devices Inc./Maxim Integrated. It provides hundredths of a second, seconds, minutes, hours, day, date, month, and year information with automatic leap-year compensation valid up to the year 2100. The device operates within an industrial temperature range of -40°C to +85°C and supports supply voltages from 2.97V to 5.5V. Key electrical parameters include a typical standby current of 175µA at VCC=3.3V and a maximum active supply current of 2mA. It features a programmable time-of-day alarm, power-fail detection circuitry, and trickle-charging capability for backup sources.

Real Time Clock Feature Summary

• SPI-compatible bidirectional bus supporting Modes 0 and 2
• Real-time clock with calendar and leap-year compensation valid to 2100
• Programmable square-wave output at 32.768kHz, 8.192kHz, 4.096kHz, or 1Hz
• Power-fail detect and switch circuitry with trickle-charge capability

Real Time Clock Applications

• Hand-held devices
• GPS/Telematics devices
• Embedded time stamping
• Medical devices

Real Time Clock Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm RoHS compliance status and check for end-of-life notifications or obsolescence notices prior to procurement. Ensure ordering suffixes match specific voltage and package requirements.

Real Time Clock Selection Notes

Select this model when SPI Mode 0 or 2 compatibility is required, as opposed to Modes 1 and 3 used by other variants in the series. Ensure the system design accommodates the 10-pin µSOP package dimensions. Verify that the application requires the specific SQW/INT pin configuration available on the DS1394.

Real Time Clock Part Context

This component belongs to the DS1390–DS1394 family of low-voltage RTCs. While sharing core timing functions, the DS1394 is distinct due to its support for SPI Modes 0 and 2 and its specific SQW/INT pin arrangement. It differs from the DS1391 which utilizes an RST output/debounced input instead of the square wave/interrupt pin.

Real Time Clock Replacement Considerations

Public confirmed substitute part numbers are not provided in the source material.