DS1501WS Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The DS1501WS is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This device features 256B parallel NVSRAM, alarm capability, leap year support, square wave output, and watchdog timer functionality in a 28-SOIC surface mount package. The DS1501WS is classified as obsolete, making identification of functionally equivalent substitute components essential for ongoing system support, design updates, and production continuity.

Substiute Parts

DS1501WS

Analog Devices Inc./Maxim IntegratedIn Stock: 8668DS1501WS Datasheet

Current PartRFQ

BQ4802LYPWR

Texas InstrumentsIn Stock: 28912BQ4802LYPWR Datasheet

MFR RecommendedRFQ

M48T08-100PC1

STMicroelectronicsIn Stock: 1683M48T08-100PC1 Datasheet

MFR RecommendedRFQ

M48T18-100PC1

STMicroelectronicsIn Stock: 1462M48T18-100PC1 Datasheet

MFR RecommendedRFQ

M48T58Y-70MH1F

STMicroelectronicsIn Stock: 2289M48T58Y-70MH1F Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the DS1501WS is determined by the following critical parameters:

Primary Compatibility Criteria:

• Parallel interface architecture
• Clock/Calendar functionality with time and date format support (HH:MM:SS and YY-MM-DD-dd)
• Operating temperature range: 0°C ~ 70°C
• Surface mount or through-hole mounting capability
• 28-pin package configuration
• Watchdog timer and leap year support

Secondary Compatibility Considerations:

• Supply voltage compatibility (3V ~ 3.6V primary supply or 4.5V ~ 5.5V alternative)
• Battery backup voltage range
• Timekeeping current consumption
• Product status (active vs. obsolete)
• RoHS compliance status

The substitute parts identified below maintain functional equivalence through parallel interface architecture and core clock/calendar features. Package form factors vary (28-SOIC, 28-TSSOP, 28-DIP) to accommodate different PCB design requirements and mounting technologies.

Parameter Comparison

Engineering Selection Recommendations

BQ4802LYPWR (Texas Instruments)

• Active product status with ROHS3 compliance
• Surface mount 28-TSSOP package with reduced footprint (0.173" width vs. 0.295" for DS1501WS)
• Supply voltage range 2.7V ~ 3.6V encompasses DS1501WS operating range
• Lower timekeeping current consumption (1.5mA typical vs. 4mA maximum)
• Supports both 12/24-hour time format
• Recommended for new designs requiring low-power operation and compact PCB layout

M48T08-100PC1 (STMicroelectronics)

• Active product status with ROHS3 compliance
• Through-hole 28-DIP package for legacy or prototype applications
• Supply voltage 4.75V ~ 5.5V requires voltage regulation if 3V supply is primary
• Timekeeper® series designation indicates established reliability
• Suitable for systems with 5V supply architecture

M48T18-100PC1 (STMicroelectronics)

• Active product status with ROHS3 compliance
• Through-hole 28-DIP package configuration
• Supply voltage 4.5V ~ 5.5V with lower minimum threshold than M48T08-100PC1
• Timekeeper® series designation
• Appropriate for 5V systems with flexible supply tolerance

M48T58Y-70MH1F (STMicroelectronics)

• Active product status with ROHS3 compliance
• Surface mount 28-SOIC package with SNAPHAT Sockets (0.337" width)
• Supply voltage 4.5V ~ 5.5V
• Timekeeper® series designation
• Moisture sensitivity level 3 (168 hours) requires controlled storage conditions
• Closest package form factor to DS1501WS for direct PCB layout compatibility

Frequently Asked Questions (FAQ)

Q: Can BQ4802LYPWR directly replace DS1501WS on existing PCBs? A: BQ4802LYPWR uses 28-TSSOP package versus DS1501WS 28-SOIC package. While both are surface mount with 28 pins, the pin pitch and footprint differ. PCB layout modification is required. Electrical compatibility exists within the 2.7V ~ 3.6V supply range.

Q: What is the primary difference between M48T08-100PC1 and M48T18-100PC1? A: Both are through-hole 28-DIP packages with identical footprints. M48T18-100PC1 operates at 4.5V ~ 5.5V minimum supply, while M48T08-100PC1 requires 4.75V ~ 5.5V. M48T18-100PC1 provides wider supply voltage tolerance for 5V systems.

Q: Is M48T58Y-70MH1F suitable for high-humidity manufacturing environments? A: M48T58Y-70MH1F has Moisture Sensitivity Level 3 (168 hours), requiring controlled storage and handling. This is more restrictive than DS1501WS (MSL 1, unlimited). Standard ESD and moisture control procedures must be followed during assembly.

Q: Which substitute part has the lowest power consumption? A: BQ4802LYPWR has the lowest timekeeping current at 1.5mA typical at 2.7V ~ 3.6V, compared to DS1501WS at 4mA maximum. This represents a 62.5% reduction in timekeeping power consumption.

Q: Are all substitute parts RoHS compliant? A: BQ4802LYPWR, M48T08-100PC1, M48T18-100PC1, and M48T58Y-70MH1F are all ROHS3 compliant. DS1501WS is RoHS non-compliant. Compliance requirements for your application determine which substitute is appropriate.

Q: Can I use a 5V-rated substitute in a 3V system? A: M48T08-100PC1, M48T18-100PC1, and M48T58Y-70MH1F require 4.5V ~ 5.5V supply and are not suitable for 3V systems without voltage regulation. BQ4802LYPWR (2.7V ~ 3.6V) is the only substitute compatible with 3V supply architecture.

Q: What is the functional difference between DS1501WS and its substitutes regarding timekeeping features? A: All substitute parts support parallel interface, clock/calendar functionality, 24-hour time format, YY-MM-DD-dd date format, and 0°C ~ 70°C operating temperature. BQ4802LYPWR adds 12-hour format option. Feature set differences are minimal; primary distinctions are package form factor, supply voltage, and power consumption.