DS1501WS/T&R Equivalent & Substitute Parts

Part Overview

The DS1501WS/T&R is a Real Time Clock (RTC) IC with Clock/Calendar functionality manufactured by Analog Devices Inc./Maxim Integrated. This 28-SOIC surface mount device provides 256 bytes of parallel interface memory with integrated timekeeping, alarm, leap year compensation, non-volatile SRAM, square wave output, and watchdog timer capabilities. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations. Substitute parts are selected based on matching functional parameters: parallel interface, 28-pin package compatibility, clock/calendar functionality, alarm capability, leap year support, and compatible operating temperature range.

Key Parameters

Parameter	DS1501WS/T&R
Manufacturer	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete
Type	Clock/Calendar
Interface	Parallel
Package / Case	28-SOIC (0.295", 7.50mm Width)
Mounting Type	Surface Mount
Memory Size	256B
Time Format	HH:MM:SS (24 hr)
Date Format	YY-MM-DD-dd
Voltage - Supply	3V ~ 3.6V
Voltage - Supply, Battery	2.5V ~ 3.7V
Current - Timekeeping (Max)	4mA @ 3V ~ 3.6V
Operating Temperature	0°C ~ 70°C
Features	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K
RoHS Status	RoHS non-compliant
REACH Status	REACH Unaffected

Substitute Part Grouping Explanation

Substitute parts for the DS1501WS/T&R are selected based on the following critical parameters that determine functional compatibility:

Primary Substitution Criteria:

Clock/Calendar functionality with parallel interface
28-pin package configuration (SOIC or DIP variants)
Alarm and leap year support
Compatible operating temperature range (0°C ~ 70°C minimum)
Surface mount or through-hole mounting options

Secondary Compatibility Factors:

Supply voltage range (3V ~ 5.5V acceptable for system integration)
Time and date format support (HH:MM:SS and YY-MM-DD-dd)
Current consumption during timekeeping operation
Product status (active parts preferred for long-term availability)
RoHS and REACH compliance status

Substitutes are grouped into two categories: direct surface mount replacements (BQ4802YDWR) and alternative package options (M48T02-70PC1, M48T35Y-70PC1, M48T35AV-10PC1, M48T37V-10MH1F) that maintain functional equivalence while offering different mounting technologies and voltage specifications.

Parameter Comparison

Parameter	DS1501WS/T&R	BQ4802YDWR	M48T02-70PC1	M48T35Y-70PC1	M48T35AV-10PC1	M48T37V-10MH1F	DP8573AVX/NOPB
Manufacturer	Analog Devices Inc./Maxim Integrated	Texas Instruments	STMicroelectronics	STMicroelectronics	STMicroelectronics	STMicroelectronics	National Semiconductor
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
Type	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar
Interface	Parallel	Parallel	Parallel	Parallel	Parallel	Parallel	Parallel
Package / Case	28-SOIC (0.295", 7.50mm Width)	28-SOIC (0.295", 7.50mm Width)	24-DIP Module (0.600", 15.24mm)	28-DIP Module (0.600", 15.24mm)	28-DIP Module (0.600", 15.24mm)	44-BSOP (0.337", 8.56mm Width)	28-LCC (J-Lead)
Mounting Type	Surface Mount	Surface Mount	Through Hole	Through Hole	Through Hole	Surface Mount	Surface Mount
Time Format	HH:MM:SS (24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (24 hr)	HH:MM:SS (24 hr)	HH:MM:SS (24 hr)	HH:MM:SS (24 hr)	HH:MM:SS:hh (12/24 hr)
Date Format	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd
Voltage - Supply	3V ~ 3.6V	4.5V ~ 5.5V	4.75V ~ 5.5V	4.5V ~ 5.5V	3V ~ 3.6V	3V ~ 3.6V	4.5V ~ 5.5V
Voltage - Supply, Battery	2.5V ~ 3.7V	2.4V ~ 4V	Not specified	Not specified	Not specified	Not specified	2.2V ~ 5.1V
Current - Timekeeping (Max)	4mA @ 3V ~ 3.6V	1.5mA (Typ) @ 4.5V ~ 5.5V	3mA @ 4.7V ~ 5.5V	2mA @ 4.75V ~ 5.5V	2mA @ 3V ~ 3.6V	2mA @ 3V ~ 3.6V	1µA @ 5V
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	-40°C ~ 85°C
Features	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	Alarm, Daylight Savings, Leap Year, Supervisor, Watchdog Timer	Leap Year	Leap Year	Leap Year	Alarm, Leap Year, Watchdog Timer	Alarm, Leap Year
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not specified
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	Not specified

Engineering Selection Recommendations

BQ4802YDWR (Texas Instruments) is the primary direct substitute for surface mount applications. It maintains the 28-SOIC package footprint and provides equivalent clock/calendar functionality with alarm and watchdog timer features. The part is active and ROHS3 compliant. Supply voltage differs at 4.5V ~ 5.5V, requiring circuit redesign for 3V operation. Current consumption is lower at 1.5mA typical.

M48T35Y-70PC1 (STMicroelectronics) offers through-hole 28-DIP mounting with 4.5V ~ 5.5V supply voltage, leap year support, and active product status. This option suits legacy board designs requiring through-hole components and is ROHS3 compliant.

M48T35AV-10PC1 (STMicroelectronics) provides through-hole 28-DIP mounting with 3V ~ 3.6V supply voltage matching the original part specification. This variant maintains voltage compatibility while offering active product status and ROHS3 compliance.

M48T37V-10MH1F (STMicroelectronics) is a surface mount 44-BSOP option with 3V ~ 3.6V supply voltage, alarm, leap year, and watchdog timer features. This part requires SNAPHAT adapter and is suitable for applications requiring additional functionality or pin count flexibility.

M48T02-70PC1 (STMicroelectronics) is a 24-DIP through-hole option with 4.75V ~ 5.5V supply voltage and leap year support. This part is suitable for legacy designs with 24-pin DIP footprints.

DP8573AVX/NOPB (National Semiconductor) provides 28-LCC J-Lead surface mount packaging with extended operating temperature range (-40°C ~ 85°C) and superior current consumption (1µA @ 5V). Supply voltage is 4.5V ~ 5.5V. This option is suitable for industrial temperature applications.

Selection should prioritize product status (active parts for long-term availability), supply voltage compatibility with existing circuit design, package mounting technology (surface mount vs. through-hole), and RoHS compliance requirements.

Frequently Asked Questions (FAQ)

Q: Can BQ4802YDWR directly replace DS1501WS/T&R on the same PCB?

A: BQ4802YDWR maintains the 28-SOIC surface mount package and pin footprint compatibility. However, the supply voltage differs: BQ4802YDWR requires 4.5V ~ 5.5V while DS1501WS/T&R operates at 3V ~ 3.6V. Direct PCB replacement requires circuit redesign to accommodate the higher supply voltage.

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

A: Surface mount substitutes (BQ4802YDWR, M48T37V-10MH1F, DP8573AVX/NOPB) use SOIC, BSOP, or LCC packages for modern PCB assembly. Through-hole substitutes (M48T02-70PC1, M48T35Y-70PC1, M48T35AV-10PC1) use DIP packages for legacy board designs and manual insertion assembly. Package selection depends on PCB design and manufacturing capability.

Q: Which substitute maintains the 3V ~ 3.6V supply voltage of the original part?

A: M48T35AV-10PC1 and M48T37V-10MH1F both operate at 3V ~ 3.6V, matching the original DS1501WS/T&R supply voltage specification. M48T35AV-10PC1 is a 28-DIP through-hole option, while M48T37V-10MH1F is a 44-BSOP surface mount option.

Q: Are all substitute parts RoHS compliant?

A: All STMicroelectronics and Texas Instruments substitutes listed are ROHS3 compliant. The original DS1501WS/T&R is RoHS non-compliant. DP8573AVX/NOPB RoHS status is not specified in available documentation.

Q: What is the functional difference between parts with different feature sets?

A: DS1501WS/T&R includes NVSRAM, square wave output, and Y2K features. BQ4802YDWR adds daylight savings and supervisor functions. M48T37V-10MH1F includes alarm and watchdog timer. M48T02-70PC1, M48T35Y-70PC1, and M48T35AV-10PC1 provide basic leap year support. DP8573AVX/NOPB includes alarm functionality. Feature availability depends on specific application requirements.

Q: Which substitute offers the lowest power consumption?

A: DP8573AVX/NOPB provides the lowest timekeeping current at 1µA @ 5V. BQ4802YDWR offers 1.5mA typical @ 4.5V ~ 5.5V. M48T35Y-70PC1, M48T35AV-10PC1, and M48T37V-10MH1F all consume 2mA @ their respective supply voltages.

Q: Can M48T02-70PC1 be used as a substitute despite having a 24-pin package instead of 28-pin?

A: M48T02-70PC1 is a 24-DIP package, which differs from the 28-pin requirement. This part is functionally equivalent for clock/calendar operation but requires PCB redesign to accommodate the different pin count and package footprint. It is suitable only for new designs or boards with 24-DIP footprints.

Q: What is the operating temperature range difference between substitutes?

A: Most substitutes operate at 0°C ~ 70°C, matching the original part. DP8573AVX/NOPB extends the range to -40°C ~ 85°C, making it suitable for industrial and extended temperature applications.

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