RA-8565SA:B PURE SN Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The RA-8565SA:B PURE SN is an EPSON Real Time Clock (RTC) IC with Clock/Calendar functionality, I2C interface, and 14-SOIC surface mount packaging. This part operates across a wide supply voltage range (1.8V to 5.5V) with ultra-low timekeeping current consumption (1µA to 1.8µA @ 3V to 5V) and supports alarm functionality. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing system support, redesigns, and new production requirements.

Key Parameters

Parameter	RA-8565SA:B PURE SN
Manufacturer	EPSON
Type	Clock/Calendar
Interface	I2C
Time Format	HH:MM:SS
Date Format	YY-MM-DD-dd
Voltage Supply Range	1.8V ~ 5.5V
Current - Timekeeping (Max)	1µA ~ 1.8µA @ 3V ~ 5V
Operating Temperature	-40°C ~ 125°C
Package / Case	14-SOIC (0.197", 5.00mm Width)
Mounting Type	Surface Mount
Features	Alarm
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the RA-8565SA:B PURE SN is determined by the following critical parameters:

Primary Substitution Criteria:

I2C or 2-Wire Serial interface compatibility
Clock/Calendar functionality with HH:MM:SS time format and YY-MM-DD-dd date format
Supply voltage range overlap (minimum 1.8V to 5.5V compatibility)
Alarm feature availability
Surface mount packaging with compatible pin count and footprint dimensions
Operating temperature range that meets or exceeds -40°C to 125°C

Substitution Groups:

Group 1: Direct EPSON Equivalents (14-SOIC Package)

RX-8025SA:AC0 provides the closest functional match with identical 14-SOIC packaging, I2C interface, and alarm functionality. Extended supply voltage range (1.7V ~ 5.5V) and leap year support offer enhanced capability. Operating temperature limited to -40°C ~ 85°C.

Group 2: Compact Alternatives (8-Pin Packages)

1337DVGI (Renesas, 8-TSSOP), BU9873F-GTE2 (Rohm, 8-SOIC), and BU9873FVT-GE2 (Rohm, 8-TSSOP) reduce pin count and package size while maintaining I2C interface, alarm, and leap year features. These parts operate within 1.8V ~ 5.5V supply range with comparable timekeeping current. Package footprint differs significantly from the original 14-SOIC.

Group 3: Maxim/Analog Devices Solutions (8-SOIC and 16-SOIC)

DS1307+ (8-DIP through-hole), DS1307ZN+T&R (8-SOIC), DS1338Z-3+ (8-SOIC), DS1338Z-33+ (8-SOIC), and DS1338C-18# (16-SOIC) offer I2C interface with NVSRAM, leap year, and square wave output. DS1307 series requires 4.5V ~ 5.5V supply (narrower range). DS1338 series supports lower voltage operation (1.71V ~ 5.5V for DS1338C-18#, 2.7V ~ 5.5V for DS1338Z-3+, 3V ~ 5.5V for DS1338Z-33+). DS1388Z-33+T&R adds EEPROM, supervisor, trickle-charger, and watchdog timer functions with 512B memory.

Parameter Comparison

Part Number	Manufacturer	Package / Case	Interface	Voltage Supply	Current - Timekeeping (Max)	Operating Temp	Features	Product Status
RA-8565SA:B PURE SN	EPSON	14-SOIC (5.00mm)	I2C	1.8V ~ 5.5V	1µA ~ 1.8µA @ 3V ~ 5V	-40°C ~ 125°C	Alarm	Obsolete
RX-8025SA:AC0	EPSON	14-SOIC (5.00mm)	I2C, 2-Wire Serial	1.7V ~ 5.5V	1.2µA ~ 1.8µA @ 3V ~ 5V	-40°C ~ 85°C	Alarm, Leap Year	Active
1337DVGI	Renesas Electronics	8-TSSOP (3.00mm)	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	Alarm, Leap Year, Square Wave Output	Active
BU9873F-GTE2	Rohm Semiconductor	8-SOIC (4.40mm)	I2C, 2-Wire Serial	1.8V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	-40°C ~ 85°C	Alarm, Leap Year	Not For New Designs
BU9873FVT-GE2	Rohm Semiconductor	8-TSSOP (4.40mm)	I2C, 2-Wire Serial	1.8V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	-40°C ~ 85°C	Alarm, Leap Year	Not For New Designs
DS1307+	Analog Devices Inc./Maxim Integrated	8-DIP (7.62mm)	I2C, 2-Wire Serial	4.5V ~ 5.5V	200µA @ 5V	0°C ~ 70°C	Leap Year, NVSRAM, Square Wave Output	Active
DS1307ZN+T&R	Analog Devices Inc./Maxim Integrated	8-SOIC (3.90mm)	I2C, 2-Wire Serial	4.5V ~ 5.5V	200µA @ 5V	-40°C ~ 85°C	Leap Year, NVSRAM, Square Wave Output	Active
DS1338C-18#	Analog Devices Inc./Maxim Integrated	16-SOIC (7.50mm)	I2C, 2-Wire Serial	1.71V ~ 5.5V	100µA @ 1.89V	-40°C ~ 85°C	Leap Year, NVSRAM, Square Wave Output	Active
DS1338Z-3+	Analog Devices Inc./Maxim Integrated	8-SOIC (3.90mm)	I2C, 2-Wire Serial	2.7V ~ 5.5V	200µA @ 3.3V	-40°C ~ 85°C	Leap Year, NVSRAM, Square Wave Output	Active
DS1338Z-33+	Analog Devices Inc./Maxim Integrated	8-SOIC (3.90mm)	I2C, 2-Wire Serial	3V ~ 5.5V	125µA ~ 200µA @ 3.63V ~ 5.5V	-40°C ~ 85°C	Leap Year, NVSRAM, Square Wave Output	Active
DS1388Z-33+T&R	Analog Devices Inc./Maxim Integrated	8-SOIC (3.90mm)	I2C, 2-Wire Serial	2.97V ~ 3.63V	150µA @ 2.97V ~ 3.63V	-40°C ~ 85°C	EEPROM, Leap Year, Supervisor, Trickle-Charger, Watchdog Timer	Active

Engineering Selection Recommendations

For Direct Replacement (Identical Footprint): RX-8025SA:AC0 is the primary substitute for the RA-8565SA:B PURE SN. Both parts use 14-SOIC packaging with identical physical dimensions (0.197", 5.00mm width). RX-8025SA:AC0 is active product status with ROHS3 compliance and REACH affected designation. The operating temperature range is reduced to -40°C ~ 85°C compared to the original -40°C ~ 125°C specification. Supply voltage range extends to 1.7V minimum, providing broader low-voltage compatibility. Leap year support is an additional feature not present in the original part.

For Compact Redesigns (Reduced Pin Count): 1337DVGI (Renesas), BU9873F-GTE2, and BU9873FVT-GE2 (Rohm) reduce package complexity to 8-pin configurations. These parts require PCB layout redesign due to different footprints. 1337DVGI offers the lowest timekeeping current (0.6µA @ 1.3V ~ 1.8V) and is active product status. BU9873 variants are marked "Not For New Designs" and should be avoided for new development. All three maintain I2C interface and alarm functionality with -40°C ~ 85°C operating range.

For Extended Feature Integration: DS1338 series (DS1338Z-3+, DS1338Z-33+, DS1338C-18#) and DS1388Z-33+T&R add NVSRAM, square wave output, and additional supervisory functions. DS1338C-18# in 16-SOIC package supports the widest supply voltage range (1.71V ~ 5.5V) among Maxim solutions. DS1388Z-33+T&R includes EEPROM, supervisor, trickle-charger, and watchdog timer, suitable for applications requiring enhanced power management and data retention. All Maxim parts are active product status with ROHS3 compliance.

For Legacy Through-Hole Applications: DS1307+ in 8-DIP package provides through-hole mounting for legacy board designs. This part requires 4.5V ~ 5.5V supply voltage (narrower range than the original) and operates at 0°C ~ 70°C. Higher timekeeping current (200µA @ 5V) compared to the original specification.

Frequently Asked Questions (FAQ)

Q: Can RX-8025SA:AC0 be used as a direct drop-in replacement for RA-8565SA:B PURE SN? A: Yes, RX-8025SA:AC0 is a direct footprint replacement. Both parts use 14-SOIC (0.197", 5.00mm width) surface mount packaging with identical pin assignments. However, the operating temperature range is reduced from -40°C ~ 125°C to -40°C ~ 85°C. Verify that your application does not require operation above 85°C.

Q: What is the key difference between the 14-SOIC EPSON parts and the 8-pin alternatives? A: The 14-SOIC package (RA-8565SA:B PURE SN and RX-8025SA:AC0) provides more pins for additional functionality and signal routing. The 8-pin alternatives (1337DVGI, BU9873 variants, DS1338Z series) reduce package size and pin count, requiring PCB redesign. Pin-to-pin compatibility does not exist between these package types.

Q: Which substitute part has the lowest power consumption? A: 1337DVGI (Renesas) offers the lowest timekeeping current at 0.6µA @ 1.3V ~ 1.8V. This is significantly lower than the original RA-8565SA:B PURE SN (1µA ~ 1.8µA @ 3V ~ 5V). However, 1337DVGI requires a different 8-TSSOP package footprint.

Q: Are all substitute parts ROHS3 compliant? A: Yes, all listed substitute parts are ROHS3 compliant. RX-8025SA:AC0 is additionally marked as REACH Affected. Verify REACH compliance requirements for your specific application and region.

Q: What is the difference between DS1338Z-3+, DS1338Z-33+, and DS1338C-18#? A: These are all Maxim DS1338 variants with different supply voltage ranges and packages. DS1338Z-3+ supports 2.7V ~ 5.5V in 8-SOIC. DS1338Z-33+ supports 3V ~ 5.5V in 8-SOIC. DS1338C-18# supports the widest range (1.71V ~ 5.5V) in 16-SOIC package. All include NVSRAM and square wave output. Select based on your supply voltage requirements and available PCB space.

Q: Can I use DS1307+ as a substitute for the RA-8565SA:B PURE SN? A: DS1307+ is functionally compatible but has significant limitations. It requires 4.5V ~ 5.5V supply (narrower than the original 1.8V ~ 5.5V), operates at 0°C ~ 70°C (narrower than -40°C ~ 125°C), and consumes 200µA timekeeping current (higher than the original 1µA ~ 1.8µA). Use only if your application meets these stricter requirements. DS1307+ is through-hole 8-DIP package, requiring board redesign.

Q: Should I use BU9873F-GTE2 or BU9873FVT-GE2 for new designs? A: Both Rohm BU9873 variants are marked "Not For New Designs." Avoid these parts for new product development. Use RX-8025SA:AC0, 1337DVGI, or Maxim DS1338 series instead, which are all active product status.

Q: What additional features does DS1388Z-33+T&R provide compared to DS1338Z-33+? A: DS1388Z-33+T&R adds EEPROM (512B memory), supervisor, trickle-charger, and watchdog timer functions. However, it has a narrower supply voltage range (2.97V ~ 3.63V) compared to DS1338Z-33+ (3V ~ 5.5V). Use DS1388Z-33+T&R only if your application requires these additional power management and data retention features and operates within the specified voltage range.

Q: Is the RA-8565SA:B PURE SN still available for purchase? A: The RA-8565SA:B PURE SN is obsolete product status. Inventory may be available from authorized distributors, but long-term supply is not guaranteed. Plan for migration to active substitute parts such as RX-8025SA:AC0 or Maxim DS1338 series for ongoing production support.

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