RA-8565SA:B3 Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The RA-8565SA:B3 is an EPSON Real Time Clock (RTC) IC with integrated clock/calendar functionality, I2C 2-wire serial interface, and alarm capabilities. This 14-SOIC surface mount device operates across 1.8V to 5.5V supply range with ultra-low timekeeping current of 1µA to 1.8µA at 3V to 5V. The part is marked as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications requiring RTC functionality with I2C interface compatibility.

Key Parameters

Parameter	RA-8565SA:B3
Manufacturer	EPSON
Category	Clock/Timing - RTC
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Package	14-SOIC (0.209", 5.30mm Width)
Mounting Type	Surface Mount
Voltage Supply	1.8V ~ 5.5V
Current - Timekeeping (Max)	1µA ~ 1.8µA @ 3V ~ 5V
Operating Temperature	-40°C ~ 125°C
Time Format	HH:MM:SS (24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year
Product Status	Obsolete
RoHS Status	ROHS Compliant

Substitute Part Grouping Explanation

Substitution for the RA-8565SA:B3 is determined by the following critical parameters:

Primary Compatibility Criteria:

Interface: I2C, 2-Wire Serial (mandatory)
Time/Date Format: HH:MM:SS and YY-MM-DD-dd support (mandatory)
Features: Alarm and Leap Year support (mandatory)
Voltage Supply Range: Minimum 1.8V to 5.5V overlap (mandatory)
Operating Temperature: -40°C minimum and 85°C or higher maximum (mandatory)
Mounting Type: Surface Mount (mandatory)

Secondary Considerations:

Package form factor (SOIC, TSSOP, or module variants acceptable with PCB layout adjustment)
Current consumption during timekeeping operation
Memory size and additional features (SRAM, trickle charger, watchdog timer)
Product status (Active preferred over obsolete or not-for-new-designs)

The substitute parts listed below meet the primary compatibility criteria and represent functionally equivalent alternatives across different package options and feature sets.

Parameter Comparison

Parameter	RA-8565SA:B3	DS1337S+T&R	DS1339U-33+T&R	DS1338U-18+	DS3232MZ+TRL	ISL12022MIBZ-TR5421
Manufacturer	EPSON	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Renesas Electronics
Interface	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial
Package	14-SOIC	8-SOIC	8-TSSOP/MSOP	8-TSSOP/MSOP	8-SOIC	20-SOIC
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Voltage Supply	1.8V ~ 5.5V	1.8V ~ 5.5V	2.97V ~ 5.5V	1.71V ~ 5.5V	2.3V ~ 4.5V	2.7V ~ 5.5V
Time Format	HH:MM:SS (24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (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
Features	Alarm, Leap Year	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Leap Year, NVSRAM, Square Wave Output	Alarm, Leap Year, Square Wave Output, SRAM	Alarm, Daylight Savings, Leap Year, SRAM
Operating Temperature	-40°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Current - Timekeeping (Max)	1µA ~ 1.8µA @ 3V ~ 5V	0.6µA @ 1.3V ~ 1.8V	200µA @ 5.5V	100µA @ 1.89V	175µA @ 2.3V ~ 4.5V	14µA ~ 15µA @ 3V ~ 5V
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

DS1337S+T&R - Recommended for direct functional replacement with minimal design changes. Active product status with ROHS3 compliance. Operates across full 1.8V to 5.5V range matching the RA-8565SA:B3. 8-SOIC package requires PCB layout modification from 14-SOIC footprint. Lowest timekeeping current at 0.6µA in low voltage operation. Suitable for battery-backed applications.

DS1339U-33+T&R - Active product with trickle-charger feature for enhanced battery backup capability. Voltage supply minimum of 2.97V limits low-voltage applications below 3V. 8-TSSOP package offers smaller footprint than original 14-SOIC. ROHS3 compliant with high inventory availability (22,908 pcs).

DS1338U-18+ - Active product with widest voltage supply range (1.71V to 5.5V) and NVSRAM feature. 8-TSSOP package. ROHS3 compliant. Suitable for ultra-low voltage applications. Timekeeping current of 100µA at 1.89V.

DS3232MZ+TRL - Active product with integrated SRAM (236B) and square wave output. Voltage supply range 2.3V to 4.5V limits high-voltage applications above 4.5V. 8-SOIC package. ROHS3 compliant with high inventory (32,573 pcs). Suitable for applications requiring additional memory.

ISL12022MIBZ-TR5421 - Active product from Renesas with daylight savings feature and 128B SRAM. 20-SOIC package requires significant PCB layout modification. Voltage supply 2.7V to 5.5V. ROHS3 compliant with highest inventory (57,600 pcs). Suitable for applications requiring extended features and memory.

Frequently Asked Questions (FAQ)

Q: Can I directly replace RA-8565SA:B3 with any of these substitutes without firmware changes?

A: All listed substitutes maintain I2C 2-wire serial interface compatibility and support identical time/date formats (HH:MM:SS and YY-MM-DD-dd). However, register maps and command structures may differ between manufacturers. Firmware validation is required to confirm register address compatibility and feature access methods.

Q: What is the primary limitation when substituting to smaller packages like 8-SOIC or 8-TSSOP?

A: The RA-8565SA:B3 uses 14-SOIC packaging while most substitutes use 8-SOIC or 8-TSSOP packages. This requires PCB footprint redesign and re-layout. Pin count reduction from 14 to 8 pins means some functionality may be consolidated or eliminated. Verify pin assignments and signal routing compatibility before PCB modification.

Q: Which substitute offers the best low-power performance for battery-backed applications?

A: DS1337S+T&R provides the lowest timekeeping current at 0.6µA when operating at 1.3V to 1.8V, making it optimal for extended battery life. DS1339U-33+T&R includes integrated trickle-charger for automatic battery charging. ISL12022MIBZ-TR5421 offers 14µA to 15µA at 3V to 5V with daylight savings support.

Q: Are all substitutes RoHS compliant?

A: Yes. All listed substitutes carry ROHS3 compliance certification, meeting current environmental and hazardous substance restrictions. The original RA-8565SA:B3 is ROHS compliant.

Q: What is the operating temperature difference between the main part and substitutes?

A: The RA-8565SA:B3 operates to 125°C maximum, while all listed substitutes operate to 85°C maximum. Applications requiring operation above 85°C cannot use these substitutes without thermal management modifications or alternative component selection.

Q: Can I use ISL12022MIBZ-TR5421 as a drop-in replacement?

A: No. The ISL12022MIBZ-TR5421 uses 20-SOIC packaging versus the original 14-SOIC, requiring complete PCB redesign. However, it provides additional features including daylight savings support and 128B SRAM, making it suitable for enhanced functionality applications with design flexibility.

Q: Which substitute has the highest inventory availability?

A: ISL12022MIBZ-TR5421 has the highest inventory at 57,600 pcs. DS3232MZ+TRL follows with 32,573 pcs. DS1339U-33+T&R has 22,908 pcs. All three offer reliable supply for production applications.

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