DS1685QN-3 Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The DS1685QN-3 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 DS1685QN-3 is classified as obsolete, making identification of active equivalent parts essential for new designs and ongoing production support. Substitute parts must maintain functional compatibility across timing accuracy, memory capacity, interface type, and operating voltage specifications.

Substiute Parts

DS1685QN-3

Analog Devices Inc./Maxim IntegratedIn Stock: 974DS1685QN-3 Datasheet

Current PartRFQ

DS1685QN-3+

Analog Devices Inc./Maxim IntegratedIn Stock: 1138DS1685QN-3+ Datasheet

DirectRFQ

BQ4802LYDW

Texas InstrumentsIn Stock: 1993BQ4802LYDW Datasheet

MFR RecommendedRFQ

DP8573AVX/NOPB

National SemiconductorIn Stock: 1484DP8573AVX/NOPB Datasheet

MFR RecommendedRFQ

M48T201V-85MH1F

STMicroelectronicsIn Stock: 1609M48T201V-85MH1F Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the DS1685QN-3 is determined by the following critical parameters:

Primary Compatibility Criteria:

• Interface type (Parallel required)
• Time and date format support (HH:MM:SS 12/24 hr, YY-MM-DD-dd)
• Operating voltage range overlap (minimum 2.7V supply capability)
• Operating temperature range (minimum -40°C to 85°C coverage)
• Package compatibility (28-pin surface mount preferred)
• Product status (Active preferred for ongoing availability)

Secondary Considerations:

• Memory capacity (242B baseline)
• Feature set (Alarm, Square Wave Output, Y2K support)
• RoHS compliance status
• Current consumption during timekeeping operation

Substitute parts are grouped into two categories: direct equivalents from the same manufacturer (DS1685QN-3+) and cross-manufacturer alternatives (BQ4802LYDW, DP8573AVX/NOPB, M48T201V-85MH1F) that meet the core electrical and functional requirements.

Parameter Comparison

Engineering Selection Recommendations

DS1685QN-3+ (Direct Equivalent) The DS1685QN-3+ is the primary substitute for the obsolete DS1685QN-3. Both parts share identical electrical specifications, functional features, and 28-LCC package configuration. The DS1685QN-3+ maintains active product status and achieves ROHS3 compliance, making it suitable for new designs and production continuity. Pin-for-pin compatibility and matching memory capacity (242B) eliminate design modifications.

BQ4802LYDW (Texas Instruments) The BQ4802LYDW provides parallel interface RTC functionality with compatible time/date formats and operating voltage range (2.7V ~ 3.6V). Package differs to 28-SOIC, requiring PCB layout adjustment. Operating temperature range is restricted to 0°C ~ 70°C, limiting use in extended temperature applications. Lower timekeeping current (1.5mA typical) offers power efficiency advantage. ROHS3 compliant and active product status support modern supply chain requirements.

DP8573AVX/NOPB (National Semiconductor) The DP8573AVX/NOPB maintains 28-LCC package compatibility and full operating temperature range (-40°C ~ 85°C). Primary supply voltage requirement is 4.5V ~ 5.5V, incompatible with 2.7V ~ 3.7V designs. Parallel interface and date/time format support enable functional substitution in 5V systems only. Extremely low timekeeping current (1µA @ 5V) provides significant power advantage in battery-backed applications.

M48T201V-85MH1F (STMicroelectronics) The M48T201V-85MH1F operates within compatible voltage range (3V ~ 3.6V) and maintains full feature set including Y2K support and square wave output. Package configuration is 44-BSOP, requiring significant PCB redesign and additional SNAPHAT connector requirement. Operating temperature range is restricted to 0°C ~ 70°C. ROHS3 compliant with active product status. Suitable only for applications where package change is feasible.

Frequently Asked Questions (FAQ)

Q: Can DS1685QN-3+ be used as a direct replacement for DS1685QN-3? A: Yes. The DS1685QN-3+ is electrically and functionally identical to the DS1685QN-3, with matching pin configuration, memory capacity, voltage specifications, and operating temperature range. No design modifications are required.

Q: What is the primary limitation of BQ4802LYDW as a substitute? A: The BQ4802LYDW uses 28-SOIC packaging instead of 28-LCC, requiring PCB layout changes. Additionally, the operating temperature range is limited to 0°C ~ 70°C, making it unsuitable for applications requiring -40°C operation.

Q: Is DP8573AVX/NOPB compatible with 3V supply designs? A: No. The DP8573AVX/NOPB requires 4.5V ~ 5.5V supply voltage and is not compatible with 2.7V ~ 3.7V designs. It is suitable only for 5V system applications.

Q: What are the package considerations for M48T201V-85MH1F? A: The M48T201V-85MH1F uses 44-BSOP packaging with SNAPHAT connector requirement, compared to the 28-LCC package of the DS1685QN-3. This requires significant PCB redesign and is recommended only when package change is acceptable.

Q: Which substitute offers the best power efficiency? A: The DP8573AVX/NOPB provides the lowest timekeeping current at 1µA @ 5V, followed by BQ4802LYDW at 1.5mA typical. Both DS1685QN-3+ and M48T201V-85MH1F consume 2mA during timekeeping operation.

Q: Are all substitute parts RoHS compliant? A: DS1685QN-3+ (ROHS3), BQ4802LYDW (ROHS3), and M48T201V-85MH1F (ROHS3) are RoHS compliant. DP8573AVX/NOPB RoHS status is not specified in available documentation.

Q: What is the recommended substitute for new designs? A: DS1685QN-3+ is the recommended primary choice due to identical specifications and pin compatibility. For applications requiring different voltage or temperature ranges, evaluate BQ4802LYDW (3.3V systems, 0°C ~ 70°C) or DP8573AVX/NOPB (5V systems only).