DS1685-5-IND Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The DS1685-5-IND is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This 24-DIP through-hole device provides 242 bytes of NVSRAM, alarm capability, square wave output, and Y2K compliance. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations. Substitute parts maintain functional compatibility through equivalent electrical specifications and interface characteristics while offering improved availability and compliance status.

Substiute Parts

DS1685-5-IND

Analog Devices Inc./Maxim IntegratedIn Stock: 1004DS1685-5-IND Datasheet

Current PartRFQ

BQ4802YDWR

Texas InstrumentsIn Stock: 1873BQ4802YDWR Datasheet

MFR RecommendedRFQ

DP8573AV/NOPB

Texas InstrumentsIn Stock: 4247DP8573AV/NOPB Datasheet

MFR RecommendedRFQ

M48T08-100PC1

STMicroelectronicsIn Stock: 1683M48T08-100PC1 Datasheet

MFR RecommendedRFQ

M48T08Y-10MH1F

STMicroelectronicsIn Stock: 1165M48T08Y-10MH1F Datasheet

MFR RecommendedRFQ

M48T18-100PC1

STMicroelectronicsIn Stock: 1462M48T18-100PC1 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the DS1685-5-IND is determined by the following critical parameters:

Electrical Compatibility:

• Supply voltage range: 4.5V ~ 5.5V (primary requirement)
• Parallel interface architecture
• Time format: HH:MM:SS with 12/24 hour capability
• Date format: YY-MM-DD-dd structure
• Real-time clock and calendar functionality

Functional Compatibility:

• Alarm capability
• Leap year support
• Operating temperature range overlap: minimum -40°C or better, maximum 85°C or better

Mechanical Considerations:

• Through-hole mounting preferred for direct PCB replacement
• Surface-mount alternatives acceptable with appropriate socket or adapter solutions
• Package footprint compatibility assessment required for specific applications

The five substitute parts listed (BQ4802YDWR, DP8573AV/NOPB, M48T08-100PC1, M48T08Y-10MH1F, M48T18-100PC1) meet these core electrical and functional requirements while offering active product status and improved compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

For Direct Through-Hole Replacement (Preferred): M48T08-100PC1 and M48T18-100PC1 are the primary candidates. Both maintain through-hole 28-DIP module packaging compatible with standard PCB layouts. M48T08-100PC1 operates within 0°C ~ 70°C, while M48T18-100PC1 provides identical thermal range. Both are ROHS3 compliant and active products with established supply chains.

For Extended Temperature Range (-40°C ~ 85°C): DP8573AV/NOPB matches the original operating temperature specification and maintains active product status with ROHS3 compliance. Surface-mount 28-LCC packaging requires socket or adapter implementation for through-hole applications.

For Surface-Mount Applications: BQ4802YDWR (28-SOIC) and M48T08Y-10MH1F (28-SOP with SNAPHAT) provide surface-mount alternatives with active status and ROHS3 compliance. BQ4802YDWR offers reduced timekeeping current (1.5mA typical) compared to the original specification.

Compliance Consideration: All substitute parts are ROHS3 compliant, addressing the RoHS non-compliance status of the DS1685-5-IND. This compliance improvement is significant for new designs and systems requiring regulatory adherence.

Frequently Asked Questions (FAQ)

Q: Can M48T08-100PC1 or M48T18-100PC1 directly replace DS1685-5-IND on existing PCBs? A: Both parts use 28-DIP module packaging with 0.600" (15.24mm) spacing, matching the original 24-DIP footprint spacing. Pin-to-pin compatibility requires verification against specific schematic requirements, as the 28-DIP package contains additional pins compared to the 24-DIP original. Pinout mapping is essential before implementation.

Q: What is the primary difference between M48T08-100PC1 and M48T18-100PC1? A: Both parts share identical electrical specifications, operating temperature range (0°C ~ 70°C), and 28-DIP module packaging. The primary distinction is the base product number designation (M48T08 versus M48T18), which may reflect different memory configurations or internal architecture. Functional compatibility for clock/calendar applications is equivalent.

Q: Why do some substitutes have narrower operating temperature ranges (0°C ~ 70°C) compared to the original (-40°C ~ 85°C)? A: Operating temperature range is a fundamental design specification. Parts specified for 0°C ~ 70°C are not suitable for applications requiring -40°C ~ 85°C operation. DP8573AV/NOPB maintains the extended temperature range and is the appropriate selection for such applications.

Q: Is DP8573AV/NOPB suitable for through-hole PCB mounting? A: DP8573AV/NOPB uses 28-LCC (J-Lead) surface-mount packaging. Through-hole implementation requires a surface-mount-to-DIP adapter socket or custom PCB redesign. Direct through-hole mounting is not possible without mechanical adaptation.

Q: What is the significance of ROHS3 compliance on all substitute parts? A: ROHS3 compliance indicates adherence to Restriction of Hazardous Substances regulations, restricting lead and other hazardous materials. The original DS1685-5-IND is RoHS non-compliant. All substitutes meet current environmental and regulatory standards, making them suitable for applications with compliance requirements.

Q: How does the 1µA timekeeping current of DP8573AV/NOPB compare to the 3mA specification of DS1685-5-IND? A: The DP8573AV/NOPB exhibits significantly lower battery-backed timekeeping current (1µA versus 3mA), resulting in extended battery life during power-loss conditions. This represents an improvement over the original specification and is advantageous for battery-dependent applications.

Q: Are there pin-count differences between the original 24-DIP and substitute 28-DIP packages? A: Yes. The DS1685-5-IND uses 24-DIP packaging, while all listed substitutes use 28-pin packages (28-SOIC, 28-LCC, or 28-DIP module). The additional pins must be accounted for in PCB layout and schematic design. Unused pins typically require connection to ground or power according to manufacturer datasheets.