DS1685Q-5

Real Time Clock Overview

The DS1685Q-5 is a real-time clock (RTC) IC designed as a successor to the industry-standard DS1287. It provides timekeeping and calendar functions with Y2K compliance, operating at +5V with an industrial temperature range of -40°C to +85°C. The device features a multiplexed address/data bus interface and includes 242 bytes of battery-backed NV SRAM. Key capabilities include a 64-bit silicon serial number, power-control circuitry for system wake-up, and a 32kHz square-wave output. It supports leap-year compensation valid through 2099 and is housed in a 28-pin PLCC package.

Real Time Clock Feature Summary

• Y2K compliant timekeeping with leap-year compensation valid through 2099
• 242 bytes of user-accessible nonvolatile RAM divided into two banks
• Integrated 64-bit silicon serial number for unique identification
• Power-control circuitry enabling system power-on via alarm or kickstart input

Real Time Clock Applications

• Embedded systems requiring precise timekeeping
• Utility meters needing data retention during power loss
• Security systems with alarm logging capabilities
• Network hubs, bridges, and routers for timestamping

Real Time Clock Procurement Notes

Verify component authenticity and lead-free status, indicated by the '+' suffix in the part number. Confirm that the PLCC package matches the target PCB footprint. Ensure the voltage supply aligns with the +5V specification for this specific variant. Check for any end-of-life notices or obsolescence warnings from Analog Devices/Maxim Integrated before finalizing procurement plans.

Real Time Clock Selection Notes

Select the DS1685Q-5 when an industrial temperature range (-40°C to +85°C) is required alongside a +5V supply. Choose this PLCC package version if surface-mount assembly with a quad flat package is preferred over DIP or SOIC options. Ensure the design accommodates the multiplexed bus interface and external crystal requirements specified in the datasheet.

Real Time Clock Part Context

The DS1685Q-5 belongs to the DS1685 family of 3V/5V real-time clocks manufactured by Analog Devices Inc./Maxim Integrated. It serves as a drop-in replacement for older DS1285, DS1385, DS1485, and DS1585 RTCs while offering enhanced features like NV SRAM and silicon serial numbers. The 'Q' designation specifically identifies the 28-pin PLCC package variant within this product line.

Real Time Clock Replacement Considerations

Direct substitutes include other variants in the DS1685 family such as DS1685EN-5+ (TSSOP package) or DS1685S-5+ (SOIC package), provided the pinout compatibility is verified. For legacy replacements, consider DS1285 or DS1385 equivalents, though feature sets may differ.