DS1689S Equivalent & Substitute Parts

Part Overview

The DS1689S is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality manufactured by Analog Devices Inc./Maxim Integrated. This 28-SOIC surface mount device provides parallel interface timekeeping with 114 bytes of NVSRAM, supporting dual voltage supplies (2.7V–3.3V and 4.5V–5.5V) with battery backup capability. The DS1689S is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing system support.

Substiute Parts

DS1689S

Analog Devices Inc./Maxim IntegratedIn Stock: 6164DS1689S Datasheet

Current PartRFQ

BQ4802YDW

BenchmarqIn Stock: 1824BQ4802YDW Datasheet

MFR RecommendedRFQ

BQ4845S-A4TR

Texas InstrumentsIn Stock: 910BQ4845S-A4TR Datasheet

MFR RecommendedRFQ

M48T02-150PC1

STMicroelectronicsIn Stock: 1525M48T02-150PC1 Datasheet

MFR RecommendedRFQ

M48T08-100PC1

STMicroelectronicsIn Stock: 1683M48T08-100PC1 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the DS1689S is determined by the following critical parameters:

• Package Type & Mounting: 28-SOIC surface mount form factor with compatible pin pitch (0.295"–0.337" width tolerance)
• Interface Type: Parallel interface for direct pin compatibility
• Time/Date Format: HH:MM:SS (12/24 hr) and YY-MM-DD-dd format support
• Voltage Supply Range: Compatibility with 4.5V–5.5V main supply and battery backup voltage ranges
• Operating Temperature: 0°C–70°C range
• Product Status: Active status preferred for long-term availability

The substitute parts are grouped into two categories:

Category A - Surface Mount 28-SOIC (Direct Package Match):

• BQ4802YDW (Benchmarq)
• BQ4845S-A4TR (Texas Instruments)

Category B - Through Hole 24-DIP and 28-DIP (Package Variant):

• M48T02-150PC1 (STMicroelectronics, 24-DIP)
• M48T08-100PC1 (STMicroelectronics, 28-DIP)

Parameter Comparison

Engineering Selection Recommendations

For Surface Mount Applications (Direct Package Compatibility):

BQ4845S-A4TR is the preferred substitute for the DS1689S in new designs. This Texas Instruments part maintains the 28-SOIC surface mount package, supports parallel interface with HH:MM:SS (12/24 hr) and YY-MM-DD-dd date format, and operates within the 0°C–70°C temperature range. The BQ4845S-A4TR holds active product status, ROHS3 compliance, and MSL rating of 1 (Unlimited), providing superior long-term availability and environmental compliance compared to the obsolete DS1689S.

BQ4802YDW (Benchmarq) provides an alternative surface mount option with active product status and compatible parallel interface. However, RoHS and MSL specifications are not provided for this part.

For Through Hole Applications (Package Variant):

M48T08-100PC1 (STMicroelectronics, 28-DIP) is suitable for through hole designs requiring 28-pin configuration. This part maintains parallel interface, HH:MM:SS (24 hr) time format, and YY-MM-DD-dd date format. It holds active product status, ROHS3 compliance, and MSL rating of 1 (Unlimited).

M48T02-150PC1 (STMicroelectronics, 24-DIP) is applicable for designs using 24-pin through hole configuration with similar compliance and availability characteristics.

Compliance Considerations:

All substitute parts except BQ4802YDW provide ROHS3 compliance, addressing the RoHS non-compliant status of the obsolete DS1689S. All substitute parts maintain MSL rating of 1 (Unlimited) or equivalent, improving handling and storage flexibility compared to the DS1689S MSL rating of 3 (168 Hours).

Frequently Asked Questions (FAQ)

Q: Can BQ4845S-A4TR directly replace DS1689S in existing designs?

A: BQ4845S-A4TR is compatible for designs using 28-SOIC surface mount packages with parallel interface. Both parts support HH:MM:SS (12/24 hr) and YY-MM-DD-dd date format. However, verify that your PCB layout accommodates the 0.295" width of the BQ4845S-A4TR versus the 0.337" width of the DS1689S, as SOIC package width tolerance may require minor layout adjustments.

Q: What is the key difference between surface mount and through hole substitute options?

A: Surface mount substitutes (BQ4802YDW, BQ4845S-A4TR) maintain the 28-SOIC package form factor of the DS1689S and are suitable for PCBs designed for surface mount assembly. Through hole substitutes (M48T02-150PC1, M48T08-100PC1) use 24-DIP or 28-DIP packages and require through hole PCB footprints, making them suitable only for designs with through hole capability.

Q: Does the DS1689S support 24-hour time format only?

A: No. The DS1689S supports both 12-hour and 24-hour time formats (HH:MM:SS 12/24 hr). The M48T02-150PC1 and M48T08-100PC1 support 24-hour format only, which may require firmware or software adjustment if your application relies on 12-hour format selection.

Q: Are there battery backup voltage differences between substitutes?

A: Yes. The DS1689S supports battery backup voltage of 2.5V–3.7V. BQ4802YDW supports 2.4V–4V, and BQ4845S-A4TR supports 2.3V–4V. The M48T02-150PC1 and M48T08-100PC1 do not specify battery backup voltage. Verify your battery supply voltage is compatible with the selected substitute part.

Q: Which substitute offers the best long-term availability?

A: BQ4845S-A4TR and both STMicroelectronics parts (M48T02-150PC1, M48T08-100PC1) hold active product status, ensuring long-term availability. All three provide ROHS3 compliance and MSL rating of 1 (Unlimited), supporting extended production lifecycles.

Q: What is the impact of lower timekeeping current in BQ4802YDW and BQ4845S-A4TR?

A: Both BQ4802YDW and BQ4845S-A4TR specify 1.5mA (Typ) @ 4.5V–5.5V timekeeping current, compared to 3mA @ 5V for the DS1689S. Lower current consumption reduces power dissipation and extends battery life in battery-backed applications, providing a functional advantage over the original part.