RX-8564LC:B0 PURE SN Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The RX-8564LC:B0 PURE SN is an EPSON Real Time Clock (RTC) IC with integrated clock/calendar functionality, I2C 2-Wire Serial interface, and 12-pin TFSOJ surface mount packaging. This device operates across a wide supply voltage range of 1.8V to 5.5V with ultra-low timekeeping current consumption of 0.65µA to 0.8µA at 2V to 5V. The part is Active status and ROHS3 compliant with unlimited moisture sensitivity rating.

Substitute parts are necessary when the RX-8564LC:B0 is unavailable, when alternative packaging formats are required for specific PCB layouts, or when design requirements demand different feature sets such as additional memory, trickle-charger functionality, or enhanced alarm capabilities while maintaining core RTC clock/calendar functionality.

Key Parameters

Parameter	RX-8564LC:B0 PURE SN
Manufacturer	EPSON
Category	Clock/Timing - RTC Clock/Calendar
Interface	I2C, 2-Wire Serial
Voltage Supply Range	1.8V ~ 5.5V
Current - Timekeeping (Max)	0.65µA ~ 0.8µA @ 2V ~ 5V
Operating Temperature	-40°C ~ 85°C
Time Format	HH:MM:SS (24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year
Package / Case	12-TFSOJ (0.094", 2.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)
Product Status	Active

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following core parameters:

Primary Compatibility Criteria:

I2C 2-Wire Serial interface (mandatory)
RTC Clock/Calendar functionality with HH:MM:SS time format and YY-MM-DD-dd date format
Operating temperature range -40°C to 85°C
Surface mount technology
ROHS3 compliance
Supply voltage overlap with 1.8V ~ 5.5V range

Secondary Considerations:

Timekeeping current consumption (lower is preferred for battery-backed applications)
Package form factor (different packages acceptable if PCB layout permits)
Feature set (Alarm, Leap Year support required; additional features such as Square Wave Output, Trickle-Charger, or NVSRAM are optional enhancements)
Product status (Active preferred; Not For New Designs acceptable for legacy applications)

Substitute parts are grouped by their ability to meet these criteria while potentially offering different packaging, enhanced features, or alternative manufacturers within the same functional category.

Parameter Comparison

Part Number	Manufacturer	Interface	Voltage Supply	Timekeeping Current (Max)	Package / Case	Time Format	Features	Product Status
RX-8564LC:B0 PURE SN	EPSON	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.65µA ~ 0.8µA @ 2V ~ 5V	12-TFSOJ (0.094", 2.40mm)	HH:MM:SS (24 hr)	Alarm, Leap Year	Active
1337AGDVGI	Renesas Electronics	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.3µA @ 1.3V ~ 1.8V	8-TSSOP (0.118", 3.00mm)	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output	Active
AB-RTCMC-32.768KHZ-AIGZ-S7-T	Abracon LLC	I2C, 2-Wire Serial	1V ~ 4.4V	0.4µA ~ 0.95µA @ 1V ~ 4.4V	8-WCDFN	HH:MM:SS:hh (24 hr)	Alarm, Leap Year, Watchdog Timer	Active
BQ32000DR	Texas Instruments	I2C, 2-Wire Serial	3V ~ 3.6V	100µA @ 3.3V	8-SOIC (0.154", 3.90mm)	HH:MM:SS (24 hr)	Leap Year, Square Wave Output, Trickle-Charger	Active
BU9873FVT-GE2	Rohm Semiconductor	I2C, 2-Wire Serial	1.8V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	8-TSSOP (0.173", 4.40mm)	HH:MM:SS (12/24 hr)	Alarm, Leap Year	Not For New Designs
DS1308U-18+T	Analog Devices Inc./Maxim	I2C, 2-Wire Serial	1.71V ~ 5.5V	100µA @ 200µA @ 1.89V ~ 5.5V	8-TSSOP (0.118", 3.00mm)	HH:MM:SS (12/24 hr)	Leap Year, NVSRAM, Square Wave Output	Active
DS1308U-33+T	Analog Devices Inc./Maxim	I2C, 2-Wire Serial	3V ~ 5.5V	125µA ~ 200µA @ 3V ~ 5.5V	8-TSSOP (0.118", 3.00mm)	HH:MM:SS (12/24 hr)	Leap Year, NVSRAM, Square Wave Output	Active
DS1337+	Analog Devices Inc./Maxim	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	8-DIP (0.300", 7.62mm)	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output	Active
DS1337U+T&R	Analog Devices Inc./Maxim	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	8-TSSOP (0.118", 3.00mm)	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output	Active
DS1338Z-33+	Analog Devices Inc./Maxim	I2C, 2-Wire Serial	3V ~ 5.5V	125µA ~ 200µA @ 3.63V ~ 5.5V	8-SOIC (0.154", 3.90mm)	HH:MM:SS (12/24 hr)	Leap Year, NVSRAM, Square Wave Output	Active
DS1339U-3+	Analog Devices Inc./Maxim	I2C, 2-Wire Serial	2.7V ~ 5.5V	150µA @ 3.3V	8-TSSOP (0.118", 3.00mm)	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Active

Engineering Selection Recommendations

For Direct Functional Replacement (Minimal Design Changes):

DS1337U+T&R and 1337AGDVGI are the closest functional equivalents, both offering I2C 2-Wire Serial interface, full 1.8V ~ 5.5V supply voltage compatibility, alarm and leap year support, and ultra-low timekeeping current consumption (0.6µA and 0.3µA respectively). Both are Active status products with ROHS3 compliance. The primary trade-off is package format: DS1337U+T&R uses 8-TSSOP while 1337AGDVGI uses 8-TSSOP with different pitch specifications.

For Ultra-Low Power Applications:

1337AGDVGI delivers the lowest timekeeping current at 0.3µA @ 1.3V ~ 1.8V, making it optimal for battery-backed RTC applications where power consumption is critical. This part maintains full voltage range compatibility and Active product status.

For Extended Feature Set:

DS1338Z-33+ and DS1308U-33+T include 56B NVSRAM (Non-Volatile Static RAM) in addition to clock/calendar functionality, providing integrated memory for application data. Both maintain I2C interface and ROHS3 compliance, though supply voltage is limited to 3V ~ 5.5V.

For Through-Hole Assembly:

DS1337+ is the only substitute available in 8-DIP through-hole package format, suitable for breadboard prototyping or legacy PCB designs. It maintains 1.8V ~ 5.5V supply range, 0.6µA timekeeping current, and Active product status.

For Constrained Supply Voltage (1V ~ 4.4V):

AB-RTCMC-32.768KHZ-AIGZ-S7-T operates at the lowest minimum supply voltage (1V) and includes watchdog timer functionality. This part is suitable for ultra-low voltage applications but requires PCB layout accommodation for 8-WCDFN package.

Legacy Design Consideration:

BU9873FVT-GE2 is marked "Not For New Designs" and should be avoided for new product development. However, it remains available for legacy system maintenance and offers 1.8V ~ 5.5V compatibility with alarm and leap year features.

Frequently Asked Questions (FAQ)

Q: Can I substitute the RX-8564LC:B0 with any of these parts without PCB redesign?

A: Direct PCB substitution is not possible due to package differences. The RX-8564LC:B0 uses 12-TFSOJ packaging, while most substitutes use 8-pin packages (TSSOP, SOIC, DIP, or WCDFN). PCB layout modification is required. However, all substitutes maintain I2C 2-Wire Serial interface compatibility, so firmware integration remains unchanged.

Q: Which substitute offers the best power efficiency for battery-backed operation?

A: The 1337AGDVGI from Renesas Electronics provides the lowest timekeeping current at 0.3µA @ 1.3V ~ 1.8V, followed by DS1337+ and DS1337U+T&R at 0.6µA @ 1.3V ~ 1.8V. For applications requiring extended battery life, these three parts are preferred.

Q: Are all substitutes ROHS3 compliant?

A: Yes, all listed substitute parts are ROHS3 compliant and carry the same environmental compliance status as the RX-8564LC:B0.

Q: What is the difference between 12/24 hour and 24 hour time format support?

A: The RX-8564LC:B0 supports 24-hour format only. Substitutes offering 12/24 hour format (1337AGDVGI, BU9873FVT-GE2, DS1308 series, DS1337 series, DS1339U-3+) provide firmware-selectable time format, allowing configuration to 24-hour mode for compatibility. This does not affect I2C register protocol or application integration.

Q: Can I use DS1338Z-33+ or DS1308U-33+T if I need additional memory?

A: Yes. Both parts include 56B NVSRAM for application data storage beyond clock/calendar registers. However, supply voltage is limited to 3V ~ 5.5V (compared to RX-8564LC:B0 at 1.8V ~ 5.5V), and timekeeping current is higher at 125µA ~ 200µA. These trade-offs are acceptable only if the additional memory justifies the increased power consumption and narrower voltage range.

Q: What is the significance of "Square Wave Output" feature?

A: Square Wave Output provides a programmable frequency clock signal (typically 1Hz, 4kHz, 8kHz, or 32kHz) on a dedicated output pin. This feature is optional and not required for basic RTC clock/calendar operation. It is useful for synchronizing external circuits or generating timing signals. The RX-8564LC:B0 does not include this feature; substitutes offering it (1337AGDVGI, DS1308 series, DS1337 series, DS1338Z-33+, DS1339U-3+) provide this as an enhancement.

Q: Is the Trickle-Charger feature important for my application?

A: Trickle-Charger functionality (available in BQ32000DR and DS1339U-3+) allows slow charging of a rechargeable backup battery through an internal resistor network. This feature is optional and relevant only if your design uses a rechargeable battery for RTC backup power. The RX-8564LC:B0 does not include this feature; standard non-rechargeable backup batteries work with all listed substitutes.

Q: Why does BQ32000DR have higher timekeeping current (100µA) compared to other options?

A: BQ32000DR is optimized for 3V ~ 3.6V supply range and includes trickle-charger functionality, which increases quiescent current consumption. This part is suitable for fixed 3.3V systems where the higher current is acceptable. For variable supply voltage applications (1.8V ~ 5.5V), lower-current alternatives are preferred.

Q: Can I use AB-RTCMC-32.768KHZ-AIGZ-S7-T in a 5V system?

A: No. AB-RTCMC-32.768KHZ-AIGZ-S7-T operates at 1V ~ 4.4V maximum supply voltage. It cannot be used in systems requiring 5V operation. This part is suitable only for low-voltage applications (1V ~ 4.4V range).

Q: What does "Not For New Designs" mean for BU9873FVT-GE2?

A: "Not For New Designs" indicates the manufacturer has discontinued active development and recommends against using this part in new product designs. However, the part remains available for legacy system maintenance and repair. For new designs, select from Active status alternatives such as DS1337U+T&R, 1337AGDVGI, or DS1338Z-33+.

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