DS12R885S-33+

Real Time Clock Overview

The DS12R885S-33+ is a real-time clock (RTC) and calendar IC manufactured by Analog Devices Inc./Maxim Integrated. It operates within a supply voltage range of 2.97V to 3.63V and supports an industrial temperature range from -40°C to +85°C. The device features a multiplexed byte-wide parallel interface compatible with both Intel and Motorola bus timing modes. It includes 114 bytes of battery-backed static RAM, automatic leap-year compensation, and a time-of-day alarm. Power management is handled by an integrated circuit that detects primary power failure and switches to a backup supply via the VBACKUP pin, which supports rechargeable batteries or super capacitors through a constant-voltage trickle charger.

Real Time Clock Feature Summary

• Multiplexed Parallel Interface: Supports selectable Intel or Motorola bus timing for flexible system integration.
• Nonvolatile Memory: Includes 114 bytes of general-purpose battery-backed NV SRAM with a dedicated clear input.
• Power Management: Features automatic power-fail detection and switching, plus an always-enabled trickle charger for VBACKUP sources.
• Calendar Functions: Counts seconds, minutes, hours, day, date, month, and year with automatic leap-year correction to 2100.

Real Time Clock Applications

• Embedded Systems
• Utility Meters
• Security Systems
• Network Hubs, Bridges, and Routers

Real Time Clock Procurement Notes

Verify the specific ordering suffix '-33+' to confirm the 3.3V operating voltage range (2.97V to 3.63V). Ensure the package type matches the required footprint, as this part number corresponds to the 24-SOIC surface-mount package. Confirm RoHS compliance status if required by local regulations, indicated by the '+' suffix in the manufacturer's nomenclature.

Real Time Clock Selection Notes

Select the DS12R885S-33+ when a parallel interface is preferred over serial alternatives like I2C or SPI. This component is suitable for systems requiring direct memory-mapped access to RTC registers and NV RAM. Ensure the host microcontroller supports the required multiplexed address/data bus timing. Verify that the available space on the PCB accommodates the 24-pin SOIC package dimensions.

Real Time Clock Part Context

The DS12R885 series serves as a functional drop-in replacement for the legacy DS12885 RTC. It belongs to a family that includes variants with integrated crystals and batteries, such as the DS12CR887 (EDIP module) and DS12R887 (BGA module). While the base DS12R885 requires external components for oscillation and backup power, the integrated modules simplify design by encapsulating these elements within the package.

Real Time Clock Replacement Considerations

Public confirmed substitute part numbers are not provided in the source material. Designers should verify pin compatibility and electrical specifications carefully when considering alternative RTCs from other manufacturers.