DS1687-5 Equivalent & Substitute Parts

Part Overview

The DS1687-5 is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This 24-DIP through-hole module 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 must maintain functional compatibility across timing, memory, interface, and voltage parameters while accommodating packaging and compliance differences.

Substiute Parts

DS1687-5

Analog Devices Inc./Maxim IntegratedIn Stock: 1432DS1687-5 Datasheet

Current PartRFQ

DS1687-5+

Analog Devices Inc./Maxim IntegratedIn Stock: 1365DS1687-5+ Datasheet

DirectRFQ

BQ3285S-SB2

Texas InstrumentsIn Stock: 1987BQ3285S-SB2 Datasheet

MFR RecommendedRFQ

M48T35AV-10PC1

STMicroelectronicsIn Stock: 1390M48T35AV-10PC1 Datasheet

MFR RecommendedRFQ

M48T35Y-70PC1

STMicroelectronicsIn Stock: 3110M48T35Y-70PC1 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the DS1687-5 is based on the following critical parameters:

Primary Compatibility Criteria:

• Parallel interface requirement
• Time format support (12/24 hour)
• Date format support (YY-MM-DD-dd)
• Operating temperature range (0°C ~ 70°C)
• Supply voltage compatibility (4.5V ~ 5.5V primary operation)

Secondary Compatibility Criteria:

• NVSRAM presence for data retention
• Alarm and square wave output functionality
• Through-hole or surface-mount packaging options
• RoHS and REACH compliance status

Substitute parts are grouped into two categories:

Category 1: Direct Functional Equivalent (Same Package) DS1687-5+ maintains identical electrical specifications, package form factor (24-DIP), and feature set while offering active product status and improved compliance (ROHS3 Compliant, REACH Unaffected).

Category 2: Functional Equivalents with Package Variation BQ3285S-SB2 (Texas Instruments, 24-SOIC surface mount), M48T35AV-10PC1 (STMicroelectronics, 28-DIP through hole, 3V supply), and M48T35Y-70PC1 (STMicroelectronics, 28-DIP through hole, 4.5V ~ 5.5V supply) provide clock/calendar functionality with parallel interface but require PCB layout modifications due to different package geometries and pin counts.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (No PCB Modification): DS1687-5+ is the primary substitute when PCB layout and component footprint cannot be modified. This part maintains identical package geometry (24-DIP), electrical specifications, and feature set while providing active product status and ROHS3 compliance. Selection of DS1687-5+ eliminates obsolescence risk and improves supply chain availability.

For New Designs or PCB Redesign Scenarios: M48T35Y-70PC1 (STMicroelectronics) is suitable for applications requiring 4.5V ~ 5.5V supply operation with 28-DIP through-hole mounting. This part offers active product status, ROHS3 compliance, and REACH unaffected status. PCB layout modification is required due to 28-pin configuration versus 24-pin original.

M48T35AV-10PC1 (STMicroelectronics) is suitable only for applications where primary supply voltage is 3V ~ 3.6V. This part requires both PCB layout modification (28-DIP) and voltage supply redesign.

For Surface-Mount Applications: BQ3285S-SB2 (Texas Instruments) provides clock/calendar functionality in 24-SOIC surface-mount package. This substitution requires PCB redesign and is applicable only to new designs or systems undergoing surface-mount conversion. The part maintains 4.5V ~ 5.5V supply compatibility and active product status.

All substitute parts maintain parallel interface compatibility, date/time format support, and operating temperature range alignment with the original DS1687-5 specification.

Frequently Asked Questions (FAQ)

Q: Can DS1687-5+ be used as a direct drop-in replacement for DS1687-5? A: Yes. DS1687-5+ maintains identical package geometry (24-DIP Module, 0.600" spacing), pin configuration, electrical specifications (4.5V ~ 5.5V supply, 3mA timekeeping current), and functional features (Alarm, NVSRAM, Square Wave Output, Y2K). No PCB modification is required.

Q: What is the primary difference between DS1687-5 and DS1687-5+? A: DS1687-5+ is the active production variant of the same base product (DS1687). The main differences are product status (Active vs. Obsolete), RoHS compliance (ROHS3 Compliant vs. RoHS non-compliant), and REACH status (REACH Unaffected vs. REACH Affected). Electrical and functional specifications are identical.

Q: Why do M48T35 series parts require PCB modification? A: M48T35AV-10PC1 and M48T35Y-70PC1 use 28-DIP package configuration versus the 24-DIP of DS1687-5. The additional 4 pins and different pin assignments require PCB layout redesign. Additionally, M48T35AV-10PC1 operates at 3V ~ 3.6V supply, requiring voltage supply circuit modification.

Q: Is BQ3285S-SB2 compatible with existing DS1687-5 PCB layouts? A: No. BQ3285S-SB2 uses 24-SOIC surface-mount package versus 24-DIP through-hole. While pin count is identical, the package footprint is fundamentally different, requiring PCB redesign. This substitution is applicable only to new designs or systems undergoing surface-mount conversion.

Q: What are the memory differences between DS1687-5 and substitute parts? A: DS1687-5 provides 242 bytes NVSRAM. BQ3285S-SB2 provides 114 bytes NVSRAM. M48T35 series parts do not specify memory size in provided documentation. Applications requiring specific NVSRAM capacity must verify compatibility with substitute part specifications.

Q: Are all substitute parts RoHS3 compliant? A: Yes. DS1687-5+ (Analog Devices), BQ3285S-SB2 (Texas Instruments), M48T35AV-10PC1 (STMicroelectronics), and M48T35Y-70PC1 (STMicroelectronics) are all ROHS3 Compliant and REACH Unaffected, providing improved environmental and regulatory compliance compared to the obsolete DS1687-5.

Q: Can M48T35AV-10PC1 operate at 5V supply voltage? A: No. M48T35AV-10PC1 is specified for 3V ~ 3.6V supply operation only. Applications requiring 4.5V ~ 5.5V supply must use M48T35Y-70PC1 or DS1687-5+.

Q: What is the timekeeping current difference between DS1687-5 and M48T35 series? A: DS1687-5 draws 3mA @ 5V during timekeeping. M48T35 series parts draw 2mA @ 3V ~ 3.6V (M48T35AV-10PC1) or 2mA @ 4.75V ~ 5.5V (M48T35Y-70PC1), providing lower power consumption in their respective voltage ranges.