DS1685SN-5 Real Time Clock IC: Equivalent & Substitute Parts

Part Overview

The DS1685SN-5 is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This device provides 242 bytes of NVSRAM, parallel interface connectivity, and features including alarm capability, square wave output, and Y2K compliance. The DS1685SN-5 is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations. Substitute parts are selected based on functional equivalence in clock/calendar operation, memory capacity, interface type, and electrical specifications.

Substiute Parts

DS1685SN-5

Analog Devices Inc./Maxim IntegratedIn Stock: 940DS1685SN-5 Datasheet

Current PartRFQ

DS1685SN-5+

Analog Devices Inc./Maxim IntegratedIn Stock: 979DS1685SN-5+ Datasheet

DirectRFQ

M48T08-150PC1

STMicroelectronicsIn Stock: 1658M48T08-150PC1 Datasheet

MFR RecommendedRFQ

M48T37Y-70MH1F

STMicroelectronicsIn Stock: 2256M48T37Y-70MH1F Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the DS1685SN-5 is based on the following critical parameters: Clock/Calendar functionality type, parallel interface requirement, memory capacity (242B), time and date format support (HH:MM:SS with 12/24 hour format and YY-MM-DD-dd date format), supply voltage range (4.5V ~ 5.5V), and operating temperature range (-40°C ~ 85°C). Package type and mounting method are secondary considerations when electrical and functional specifications align.

The substitute parts are grouped into two categories:

Direct Functional Equivalent (Same Package): DS1685SN-5+ maintains identical electrical specifications, memory capacity, interface type, and packaging (24-SOIC surface mount), differing only in product status (Active vs. Obsolete) and RoHS compliance level.

Functional Equivalents (Alternative Packages): M48T08-150PC1 and M48T37Y-70MH1F provide Clock/Calendar functionality with parallel interface and compatible voltage specifications. These parts differ in package type (28-DIP through-hole and 44-BSOP surface mount respectively) and operating temperature ranges, requiring design consideration for mechanical and thermal compatibility.

Parameter Comparison

Engineering Selection Recommendations

DS1685SN-5+ (Direct Equivalent): This part is the primary substitute for the obsolete DS1685SN-5. It maintains identical electrical specifications, memory capacity, interface type, and 24-SOIC surface mount packaging. The DS1685SN-5+ is Active in product status and ROHS3 compliant, making it suitable for new designs and legacy system replacements without PCB modification.

M48T08-150PC1 (Through-Hole Alternative): This STMicroelectronics Timekeeper® series part provides Clock/Calendar functionality with parallel interface and compatible voltage specifications. The 28-DIP through-hole package requires different PCB footprint and assembly process compared to the surface mount DS1685SN-5. Operating temperature range is limited to 0°C ~ 70°C, which is narrower than the original part. This substitute is applicable for systems with through-hole assembly requirements or legacy board designs.

M48T37Y-70MH1F (Surface Mount Alternative): This STMicroelectronics Timekeeper® series part provides Clock/Calendar functionality in a 44-BSOP surface mount package. Voltage supply range (4.5V ~ 5.5V) and timekeeping current specifications align with the original part. Operating temperature range is limited to 0°C ~ 70°C. This substitute requires PCB redesign due to different package footprint and pin count. ROHS3 compliance and Active product status support new design implementation.

Frequently Asked Questions (FAQ)

Q: Can DS1685SN-5+ be used as a direct replacement for DS1685SN-5 without PCB modification?

A: Yes. DS1685SN-5+ maintains identical package type (24-SOIC surface mount), pin configuration, electrical specifications, and functional features. No PCB redesign is required. The primary difference is product status (Active vs. Obsolete) and RoHS compliance level.

Q: What are the key differences between M48T08-150PC1 and the original DS1685SN-5?

A: M48T08-150PC1 differs in three areas: (1) Package type is 28-DIP through-hole versus 24-SOIC surface mount, requiring PCB footprint redesign; (2) Operating temperature range is 0°C ~ 70°C versus -40°C ~ 85°C, limiting use in extended temperature applications; (3) Time format supports 24-hour only versus 12/24-hour selectable format.

Q: Is M48T37Y-70MH1F compatible with existing DS1685SN-5 designs?

A: M48T37Y-70MH1F provides functional Clock/Calendar equivalence with parallel interface and compatible voltage specifications. However, the 44-BSOP package differs from the 24-SOIC package, requiring PCB redesign and different assembly process. Operating temperature range is limited to 0°C ~ 70°C. Electrical compatibility exists, but mechanical redesign is necessary.

Q: What is the significance of RoHS compliance in substitute part selection?

A: DS1685SN-5 is RoHS non-compliant, while all substitute parts (DS1685SN-5+, M48T08-150PC1, M48T37Y-70MH1F) are ROHS3 compliant. For new designs and systems subject to RoHS regulations, compliant substitutes are required. For legacy system maintenance, RoHS status may not be a constraint depending on application and regulatory requirements.

Q: Can operating temperature range differences affect substitute part selection?

A: Yes. DS1685SN-5 operates from -40°C ~ 85°C, while M48T08-150PC1 and M48T37Y-70MH1F operate from 0°C ~ 70°C. For applications requiring extended temperature operation below 0°C or above 70°C, these substitutes are not suitable. DS1685SN-5+ maintains the original -40°C ~ 85°C range and is the appropriate choice for extended temperature requirements.

Q: What packaging considerations apply when selecting between substitute parts?

A: DS1685SN-5+ uses 24-SOIC surface mount (identical to original). M48T08-150PC1 uses 28-DIP through-hole, requiring different assembly equipment and PCB design. M48T37Y-70MH1F uses 44-BSOP surface mount, requiring PCB redesign due to different footprint and pin count. Package selection depends on existing assembly capabilities and PCB layout constraints.