DS1338C-18#

Real Time Clock Overview

The DS1338C-18# is a low-power serial real-time clock (RTC) and calendar integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It features full binary-coded decimal (BCD) timekeeping with leap-year compensation valid up to the year 2100, alongside 56 bytes of battery-backed NV SRAM. The device operates on a supply voltage range of 1.71V to 5.5V with a maximum standby current of 100µA at 1.89V. It utilizes an I²C interface for data transfer and includes an integrated 32.768kHz crystal within its 16-SOIC package. The component supports industrial temperatures from -40°C to +85°C.

Real Time Clock Feature Summary

• Integrated 32.768kHz crystal in 16-SOIC package
• Automatic power-fail detection and switching to VBAT
• I²C serial interface supporting standard and fast modes
• Programmable square-wave output signal

Real Time Clock Applications

• Handhelds (GPS, POS Terminal)
• Consumer Electronics (Set-Top Box, Digital Recording)
• Office Equipment (Fax/Printer, Copier)
• Medical (Glucometer, Medicine Dispenser)
• Telecommunications (Router, Switcher, Server)

Real Time Clock Procurement Notes

Verify that the ordering suffix '#' indicates a RoHS-compliant device which may include lead exempt under RoHS requirements. Confirm the specific voltage variant matches the application needs, as the '18' suffix denotes the 1.71V–5.5V operating range. Ensure the 16-SOIC package dimensions align with the PCB footprint constraints.

Real Time Clock Selection Notes

Select this part when space savings are critical due to the integrated crystal option. The 1.8V nominal supply version is suitable for low-voltage systems requiring operation down to 1.71V. Consider the 100µA maximum standby current for battery-powered designs. Verify that the I²C bus speed requirements are met by the standard or fast mode capabilities.

Real Time Clock Part Context

This component belongs to the DS1338 family of serial RTCs. The 'C' designation specifically identifies the package variant containing the integrated crystal, distinguishing it from the Z and U series which require external crystals. The '#18' suffix specifies the electrical characteristics for the lower voltage operating range compared to the '-3' or '-33' variants.

Real Time Clock Replacement Considerations

DS1338Z-18+T&R

Real Time Clock FAQ

What is the function of the integrated crystal in the DS1338C?

The DS1338C integrates a standard 32,768Hz quartz tuning-fork crystal within the package, eliminating the need for external oscillator components and saving board space.

How does the device handle power failures?

The DS1338C includes a built-in power-sense circuit that detects power failures and automatically switches to the backup supply (VBAT), maintaining time and date operation without interruption.

What is the accuracy of the DS1338C at nominal conditions?

At nominal VCC and +25°C, the typical accuracy of the DS1338C is approximately 10ppm.