RA-4574SA:B3 Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The RA-4574SA:B3 is a Real Time Clock (RTC) IC manufactured by EPSON, designed for clock/calendar applications with 3-Wire Serial interface. This component provides timekeeping functionality with alarm and leap year support across a wide supply voltage range of 1.6V to 5.5V. The part is classified as Obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility through matching interface protocols, time/date format support, and operating temperature ranges while accommodating packaging and supply voltage variations.

Substiute Parts

RA-4574SA:B3 ROHS

EPSONIn Stock: 692RA-4574SA:B3 ROHS Datasheet

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DS1302SN+

Analog Devices Inc./Maxim IntegratedIn Stock: 1147DS1302SN+ Datasheet

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DS1306+

Analog Devices Inc./Maxim IntegratedIn Stock: 994DS1306+ Datasheet

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DS1343D-33+

Analog Devices Inc./Maxim IntegratedIn Stock: 2296DS1343D-33+ Datasheet

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S-35190A-J8T1U

ABLIC Inc.In Stock: 12112S-35190A-J8T1U Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the RA-4574SA:B3 is based on the following critical parameters:

Primary Compatibility Criteria:

• Interface Type: 3-Wire Serial protocol required for direct functional replacement
• Time/Date Format: HH:MM:SS and YY-MM-DD-dd support mandatory
• Operating Temperature Range: -40°C to 85°C minimum requirement
• Supply Voltage Overlap: Minimum 1.6V to 5.5V compatibility
• Mounting Type: Surface Mount preferred for PCB integration consistency
• Features: Alarm and Leap Year support required

Substitution Groups:

Group 1 - Direct 3-Wire Serial Interface Substitutes: DS1302SN+ and S-35190A-J8T1U maintain the 3-Wire Serial interface protocol, supporting identical time/date formats and operating temperature ranges. Both are Active products with current availability.

Group 2 - SPI Interface Substitutes (Protocol Change Required): DS1306+ and DS1343D-33+ use SPI interface instead of 3-Wire Serial, requiring circuit redesign and firmware modification. These are suitable only when system architecture permits interface protocol change.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (3-Wire Serial Interface):

DS1302SN+ is the preferred substitute when maintaining the 3-Wire Serial interface protocol. This part is Active with ROHS3 compliance and provides superior timekeeping current efficiency (0.3µA ~ 1µA) compared to the RA-4574SA:B3. Operating temperature range matches the original specification (-40°C to 85°C). Package change from 14-SOIC to 8-SOIC requires PCB layout modification. Supply voltage minimum increases from 1.6V to 2V, which is acceptable for most applications.

S-35190A-J8T1U offers an alternative 3-Wire Serial substitute with the lowest supply voltage minimum (1.3V ~ 5.5V), matching the original's low-voltage capability. This part is Active with ROHS3 compliance and maintains full operating temperature range compatibility. Package dimensions differ (8-SOIC 0.154" vs. 14-SOIC 0.209"), requiring PCB redesign. Timekeeping current is higher (8µA ~ 14µA) than DS1302SN+.

For SPI Interface Applications (Requires Circuit Redesign):

DS1306+ is suitable only when system architecture permits SPI protocol implementation. This part is Active with ROHS3 compliance but operates at reduced temperature range (0°C to 70°C), making it unsuitable for automotive or extended temperature applications. Through-hole mounting (16-DIP) differs from surface mount requirement. Timekeeping current consumption is significantly higher (25.3µA ~ 81µA).

DS1343D-33+ supports SPI interface with full automotive temperature range (-40°C to 85°C) and AEC-Q200 equivalent qualification. This part is Active with ROHS3 compliance and surface mount packaging. Supply voltage minimum of 3V is higher than the original 1.6V specification. Timekeeping current is substantially higher (120µA ~ 160µA), requiring power budget reassessment.

Frequently Asked Questions (FAQ)

Q: Can DS1302SN+ directly replace RA-4574SA:B3 without firmware changes?

A: DS1302SN+ maintains 3-Wire Serial protocol, time/date format support, and operating temperature range, enabling firmware compatibility. However, PCB layout modification is required due to package change from 14-SOIC to 8-SOIC. Pin-to-pin compatibility must be verified against specific application schematics.

Q: What is the primary difference between 3-Wire Serial and SPI interface substitutes?

A: 3-Wire Serial substitutes (DS1302SN+, S-35190A-J8T1U) maintain the original communication protocol, requiring only PCB layout changes. SPI substitutes (DS1306+, DS1343D-33+) require firmware modification and circuit redesign to implement the different protocol, making them suitable only for new designs or systems with flexible architecture.

Q: Why does DS1306+ have a reduced operating temperature range?

A: DS1306+ operates from 0°C to 70°C, which is narrower than the RA-4574SA:B3 specification of -40°C to 85°C. This limitation makes DS1306+ unsuitable for automotive, industrial, or extended temperature applications. Verify application temperature requirements before selection.

Q: How does supply voltage minimum affect part selection?

A: RA-4574SA:B3 operates from 1.6V minimum. DS1302SN+ requires 2V minimum, S-35190A-J8T1U operates from 1.3V, and DS1343D-33+ requires 3V minimum. Applications with supply voltages below 2V must use S-35190A-J8T1U or remain with the original part. Verify power supply specifications in your design.

Q: What packaging considerations apply to these substitutes?

A: RA-4574SA:B3 uses 14-SOIC (0.209", 5.30mm). DS1302SN+ uses 8-SOIC (0.209", 5.30mm) with identical width but fewer pins. S-35190A-J8T1U uses 8-SOIC (0.154", 3.90mm) with narrower width. DS1306+ uses 16-DIP through-hole package. DS1343D-33+ uses 14-WFDFN with exposed pad. All package changes require PCB redesign.

Q: Are all substitute parts RoHS compliant?

A: Yes. RA-4574SA:B3 is ROHS compliant. All substitute parts (DS1302SN+, DS1306+, DS1343D-33+, S-35190A-J8T1U) are ROHS3 compliant, meeting current environmental regulations.

Q: Which substitute offers the best timekeeping current efficiency?

A: DS1302SN+ provides the lowest timekeeping current (0.3µA ~ 1µA @ 2V ~ 5V), offering superior power efficiency compared to RA-4574SA:B3 (1µA ~ 2µA @ 3V ~ 5V). S-35190A-J8T1U consumes 8µA ~ 14µA, while SPI substitutes consume significantly higher current (25.3µA ~ 160µA).