RTC-7301SF:B3 Equivalent & Substitute Parts

Part Overview

The RTC-7301SF:B3 is a Real Time Clock (RTC) IC manufactured by EPSON, designed for clock/calendar applications with parallel interface. This device provides time and date tracking with alarm functionality and leap year support in a 24-SOP surface mount package. The part is currently obsolete, making equivalent and substitute components necessary for system redesign, legacy support, or inventory replacement in new production runs.

Key Parameters

Parameter	RTC-7301SF:B3
Manufacturer	EPSON
Category	Clock/Timing
Type	Clock/Calendar
Interface	Parallel
Package / Case	24-SOP (0.213", 5.40mm Width)
Voltage - Supply	2.4V ~ 5.5V
Time Format	HH:MM:SS (24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year
Operating Temperature	-40°C ~ 85°C
Current - Timekeeping (Max)	1µA ~ 2µA @ 3V ~ 5V
Mounting Type	Surface Mount
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the RTC-7301SF:B3 is determined by the following critical parameters:

Interface Compatibility: All substitute parts must support parallel interface for direct pin-level compatibility with existing PCB designs.

Voltage Supply Range: The original part operates across 2.4V ~ 5.5V. Substitute parts must either match this range or operate within a subset that covers the system's supply voltage.

Time and Date Format: All substitutes must support HH:MM:SS (24-hour) time format and YY-MM-DD-dd date format to maintain firmware compatibility.

Core Features: Alarm and leap year functionality are required features present in all qualified substitutes.

Package and Mounting: Surface mount packages are preferred for modern PCB assembly. Pin count and physical dimensions must be evaluated against PCB layout constraints.

Operating Temperature Range: The original part's -40°C ~ 85°C range is suitable for industrial applications. Substitutes with narrower ranges (0°C ~ 70°C) are acceptable for commercial-grade applications only.

RoHS Compliance: All substitute parts must maintain ROHS3 compliance to meet regulatory requirements.

Parameter Comparison

Part Number	Manufacturer	Package / Case	Voltage - Supply	Time Format	Date Format	Features	Operating Temperature	Current - Timekeeping (Max)	Product Status	RoHS Status
RTC-7301SF:B3	EPSON	24-SOP (0.213", 5.40mm)	2.4V ~ 5.5V	HH:MM:SS (24 hr)	YY-MM-DD-dd	Alarm, Leap Year	-40°C ~ 85°C	1µA ~ 2µA @ 3V ~ 5V	Obsolete	ROHS3 Compliant
BQ4802LYPWR	Texas Instruments	28-TSSOP (0.173", 4.40mm)	2.7V ~ 3.6V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Daylight Savings, Leap Year, Supervisor, Watchdog Timer	0°C ~ 70°C	1.5mA (Typ) @ 2.7V ~ 3.6V	Active	ROHS3 Compliant
DP8573AVX/NOPB	National Semiconductor	28-LCC (J-Lead)	4.5V ~ 5.5V	HH:MM:SS:hh (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year	-40°C ~ 85°C	1µA @ 5V	Active	Not Specified
DS12885N+	Analog Devices Inc./Maxim Integrated	24-DIP (0.600", 15.24mm)	4.5V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output	-40°C ~ 85°C	15mA @ 4.5V ~ 5.5V	Active	ROHS3 Compliant
DS12885S+	Analog Devices Inc./Maxim Integrated	24-SOIC (0.295", 7.50mm)	4.5V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output	0°C ~ 70°C	15mA @ 4.5V ~ 5.5V	Active	ROHS3 Compliant
DS12R885S-33+	Analog Devices Inc./Maxim Integrated	24-SOIC (0.295", 7.50mm)	2.97V ~ 3.63V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Square Wave Output, Trickle-Charger	-40°C ~ 85°C	2mA @ 2.97V ~ 3.63V	Active	ROHS3 Compliant
DS1501WZ+	Analog Devices Inc./Maxim Integrated	28-SOIC (0.295", 7.50mm)	3V ~ 3.6V	HH:MM:SS (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	0°C ~ 70°C	4mA @ 3V ~ 3.6V	Active	ROHS3 Compliant
DS1501WZN+	Analog Devices Inc./Maxim Integrated	28-SOIC (0.295", 7.50mm)	3V ~ 3.6V	HH:MM:SS (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	-40°C ~ 85°C	4mA @ 3V ~ 3.6V	Active	ROHS3 Compliant
DS1501YZN+	Analog Devices Inc./Maxim Integrated	28-SOIC (0.295", 7.50mm)	4.5V ~ 5.5V	HH:MM:SS (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	-40°C ~ 85°C	5mA @ 4.5V ~ 5.5V	Active	ROHS3 Compliant
DS1501YZN+T&R	Analog Devices Inc./Maxim Integrated	28-SOIC (0.295", 7.50mm)	4.5V ~ 5.5V	HH:MM:SS (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	-40°C ~ 85°C	5mA @ 4.5V ~ 5.5V	Active	ROHS3 Compliant
DS1554P-70+	Analog Devices Inc./Maxim Integrated	34-PowerCap™ Module	4.5V ~ 5.5V	HH:MM:SS (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Watchdog Timer, Y2K	0°C ~ 70°C	6mA @ 5V	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Pin-Compatible Replacement (24-Pin Surface Mount):

DS12885S+ and DS12R885S-33+ are the closest functional equivalents in 24-SOIC packaging. DS12885S+ operates at 4.5V ~ 5.5V with -40°C ~ 85°C temperature range matching the original specification. DS12R885S-33+ provides a narrower voltage range (2.97V ~ 3.63V) but maintains the full industrial temperature range and includes trickle-charger functionality.

For 5V Supply Systems:

DP8573AVX/NOPB, DS12885N+, DS12885S+, DS1501YZN+, DS1501YZN+T&R, and DS1554P-70+ all support 4.5V ~ 5.5V supply voltage. DS12885N+ is a through-hole 24-DIP option for legacy PCB designs. DS1501 series parts offer extended memory (256B) and additional features including watchdog timer and Y2K support.

For 3V Supply Systems:

BQ4802LYPWR, DS1501WZ+, and DS1501WZN+ operate within 3V supply ranges. BQ4802LYPWR (2.7V ~ 3.6V) includes supervisor and watchdog timer features. DS1501WZ+ and DS1501WZN+ both support 3V ~ 3.6V with identical feature sets; DS1501WZN+ extends operating temperature to -40°C ~ 85°C for industrial applications.

For Industrial Temperature Range (-40°C ~ 85°C):

DP8573AVX/NOPB, DS12885N+, DS12R885S-33+, DS1501WZN+, DS1501YZN+, DS1501YZN+T&R maintain the original -40°C ~ 85°C operating range. All are ROHS3 compliant.

For Commercial Temperature Range (0°C ~ 70°C):

BQ4802LYPWR, DS12885S+, DS1501WZ+, and DS1554P-70+ operate within 0°C ~ 70°C. These are suitable for non-industrial applications where temperature constraints are less stringent.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with a different pin count?

A: Pin count changes require PCB redesign. The original RTC-7301SF:B3 uses 24 pins. Direct replacements maintaining 24-pin configuration (DS12885S+, DS12R885S-33+) require minimal layout changes. Parts with different pin counts (28-pin, 34-pin) necessitate full schematic and PCB revision.

Q: What is the difference between 24-SOIC and 24-SOP packaging?

A: Both are surface mount packages with similar footprints and pin spacing. 24-SOIC (Small Outline Integrated Circuit) and 24-SOP (Small Outline Package) are functionally equivalent for PCB assembly purposes. Verify exact dimensions with component datasheets before PCB layout finalization.

Q: Does the substitute part need to support both 12-hour and 24-hour time formats?

A: The original RTC-7301SF:B3 operates exclusively in 24-hour format. Substitute parts offering 12/24-hour selectable formats (DS12885 series, BQ4802LYPWR) provide flexibility but must be configured for 24-hour operation to maintain firmware compatibility.

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts except DP8573AVX/NOPB are explicitly ROHS3 compliant. DP8573AVX/NOPB RoHS status is not specified in available documentation. Verify compliance requirements with your procurement and regulatory teams before selection.

Q: What is the impact of different timekeeping current specifications?

A: The original part draws 1µA ~ 2µA during timekeeping. Substitute parts range from 1µA (DP8573AVX/NOPB) to 6mA (DS1554P-70+). Higher current consumption affects battery backup runtime. For battery-backed applications, select parts with lower timekeeping current (DP8573AVX/NOPB, BQ4802LYPWR, DS12R885S-33+).

Q: Can I use DS1501 series parts as direct replacements?

A: DS1501 series parts (DS1501WZ+, DS1501WZN+, DS1501YZN+, DS1501YZN+T&R) are 28-pin SOIC packages with extended memory (256B) and additional features. They require PCB redesign due to different pin count and layout. These are suitable for new designs or major system revisions where additional functionality is beneficial.

Q: What does "Tape & Reel (T&R)" packaging mean?

A: Tape & Reel packaging (DS1501YZN+T&R) is standard for high-volume automated assembly. Cut Tape (CT) and Digi-Reel packaging (BQ4802LYPWR) are alternatives for lower-volume or mixed-component orders. Packaging choice does not affect electrical performance.

Q: Which substitute part is best for a new design?

A: For new designs, select from active product status parts with ROHS3 compliance. DS1501 series (particularly DS1501YZN+ or DS1501YZN+T&R) offer modern features including NVSRAM, watchdog timer, and Y2K support. For cost-sensitive applications, DS12885S+ provides core functionality with proven reliability.

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