DS1643-70+ Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The DS1643-70+ is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality and 8KB of Nonvolatile Static RAM (NVSRAM), manufactured by Analog Devices Inc./Maxim Integrated. This device operates in the 4.5V to 5.5V supply range and is packaged in a 28-DIP module format for through-hole mounting. The DS1643-70+ is classified as obsolete, making equivalent substitute parts necessary for ongoing system maintenance, redesigns, and new production applications requiring compatible RTC functionality.

Substiute Parts

DS1643-70+

Analog Devices Inc./Maxim IntegratedIn Stock: 977DS1643-70+ Datasheet

Current PartRFQ

BQ3285S-SB2

Texas InstrumentsIn Stock: 1987BQ3285S-SB2 Datasheet

MFR RecommendedRFQ

DP8573AVX/NOPB

National SemiconductorIn Stock: 1484DP8573AVX/NOPB Datasheet

MFR RecommendedRFQ

M48T02-70PC1

STMicroelectronicsIn Stock: 1276M48T02-70PC1 Datasheet

MFR RecommendedRFQ

M48T201Y-70MH1F

STMicroelectronicsIn Stock: 2083M48T201Y-70MH1F Datasheet

MFR RecommendedRFQ

M48T35AV-10PC1

STMicroelectronicsIn Stock: 1390M48T35AV-10PC1 Datasheet

MFR RecommendedRFQ

M48T37V-10MH1F

STMicroelectronicsIn Stock: 1945M48T37V-10MH1F Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the DS1643-70+ is determined by the following critical parameters:

• Voltage Supply Range: 4.5V ~ 5.5V (primary operating voltage)
• Interface Type: Parallel (data communication method)
• Time/Date Format: HH:MM:SS (24 hr) and YY-MM-DD-dd (functional compatibility)
• Mounting Type: Through Hole or Surface Mount (physical integration)
• Package Compatibility: 28-DIP or equivalent pin-count packages
• Product Status: Active or Obsolete (availability for procurement)
• RoHS Compliance: ROHS3 Compliant (regulatory requirement)

The substitute parts listed below maintain compatibility across these core parameters while offering variations in memory size, additional features (alarm, watchdog timer, supervisor), and alternative packaging formats. Substitutes are grouped by mounting type and package configuration to facilitate direct or adapter-based integration into existing designs.

Parameter Comparison

Engineering Selection Recommendations

For Direct Through-Hole Replacement (28-DIP Package):

M48T02-70PC1 and M48T35AV-10PC1 are the primary through-hole substitutes. M48T02-70PC1 maintains the 4.5V ~ 5.5V supply voltage range and 0°C ~ 70°C operating temperature identical to the DS1643-70+, with active product status and ROHS3 compliance. M48T35AV-10PC1 operates at a reduced voltage range (3V ~ 3.6V) and is suitable only for systems redesigned for lower supply voltages.

For Surface Mount Integration:

BQ3285S-SB2 (24-SOIC) and DP8573AVX/NOPB (28-LCC) provide surface-mount alternatives with 4.5V ~ 5.5V supply compatibility. DP8573AVX/NOPB extends the operating temperature range to -40°C ~ 85°C, suitable for industrial applications. M48T201Y-70MH1F and M48T37V-10MH1F (44-BSOP packages) offer enhanced feature sets including alarm, watchdog timer, and supervisor functions, though they require SNAPHAT socket adapters for integration.

Compliance and Availability:

All recommended substitutes maintain ROHS3 compliance. M48T02-70PC1, M48T201Y-70MH1F, M48T35AV-10PC1, and M48T37V-10MH1F are STMicroelectronics Timekeeper® series devices with active product status, ensuring long-term availability. BQ3285S-SB2 (Texas Instruments) and DP8573AVX/NOPB (National Semiconductor) are also active products with established supply chains.

Frequently Asked Questions (FAQ)

Q: Can the DS1643-70+ be directly replaced with any of these substitutes without PCB modification?

A: M48T02-70PC1 and M48T35AV-10PC1 are pin-compatible 28-DIP through-hole packages and can be used as direct replacements if voltage supply requirements are met. M48T02-70PC1 is preferred for systems maintaining 4.5V ~ 5.5V supply. Surface-mount alternatives (BQ3285S-SB2, DP8573AVX/NOPB, M48T201Y-70MH1F, M48T37V-10MH1F) require PCB redesign or adapter solutions.

Q: What is the primary difference between M48T02-70PC1 and M48T35AV-10PC1?

A: M48T02-70PC1 operates at 4.75V ~ 5.5V supply voltage, matching the original DS1643-70+ 5V system design. M48T35AV-10PC1 operates at 3V ~ 3.6V and is intended for low-voltage applications. Both are 28-DIP through-hole packages with identical pinouts.

Q: Are the 44-BSOP packages (M48T201Y-70MH1F and M48T37V-10MH1F) compatible with existing 28-DIP sockets?

A: No. The 44-BSOP packages require SNAPHAT socket adapters for integration into 28-DIP footprints. These are surface-mount packages with different pin configurations and require dedicated PCB layout or adapter hardware.

Q: What additional features do the STMicroelectronics Timekeeper® substitutes provide?

A: M48T02-70PC1 provides basic clock/calendar functionality. M48T201Y-70MH1F adds alarm, square wave output, supervisor, and watchdog timer functions. M48T35AV-10PC1 and M48T37V-10MH1F include alarm and watchdog timer capabilities. These features are backward-compatible and do not interfere with basic clock/calendar operation.

Q: Which substitute is recommended for industrial temperature range applications?

A: DP8573AVX/NOPB (National Semiconductor) operates across -40°C ~ 85°C, extending beyond the standard 0°C ~ 70°C range. This device is suitable for industrial and automotive environments requiring wider temperature tolerance.

Q: Are all substitutes RoHS compliant?

A: M48T02-70PC1, M48T201Y-70MH1F, M48T35AV-10PC1, M48T37V-10MH1F, and BQ3285S-SB2 are ROHS3 compliant. DP8573AVX/NOPB RoHS status is not specified in available documentation.

Q: What is the Moisture Sensitivity Level (MSL) significance for these parts?

A: MSL 1 (Unlimited) parts such as M48T02-70PC1, M48T35AV-10PC1, and BQ3285S-SB2 have no moisture sensitivity restrictions and can be stored indefinitely. MSL 3 (168 Hours) parts such as M48T201Y-70MH1F and M48T37V-10MH1F must be used within 168 hours of moisture exposure and require controlled storage conditions.