DS1678S Real Time Clock (RTC) IC Equivalent & Substitute Parts

Part Overview

The DS1678S is a Real Time Clock (RTC) IC Time Event Recorder manufactured by Analog Devices Inc./Maxim Integrated. This component provides 32-byte non-volatile SRAM with I2C/2-Wire Serial interface, supporting 12/24-hour time format and YY-MM-DD-dd date format. The DS1678S is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across time-keeping, alarm, leap year, and Y2K features while accommodating potential package and memory differences.

Substiute Parts

DS1678S

Analog Devices Inc./Maxim IntegratedIn Stock: 3533DS1678S Datasheet

Current PartRFQ

DS1678S+

Analog Devices Inc./Maxim IntegratedIn Stock: 1276DS1678S+ Datasheet

DirectRFQ

ISL1209IU10Z-TK

Renesas Electronics CorporationIn Stock: 2296ISL1209IU10Z-TK Datasheet

MFR RecommendedRFQ

ISL1219IUZ-T

Renesas Electronics CorporationIn Stock: 6768ISL1219IUZ-T Datasheet

MFR RecommendedRFQ

RX-8035LC:AA3 PURE SN

EPSONIn Stock: 893RX-8035LC:AA3 PURE SN Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the DS1678S are grouped based on the following critical parameters that determine functional compatibility:

Primary Compatibility Criteria:

• Interface type: I2C, 2-Wire Serial
• Time format support: HH:MM:SS (12/24 hr)
• Date format support: YY-MM-DD-dd
• Operating temperature range: -40°C ~ 85°C
• Core features: Alarm, Leap Year functionality

Secondary Considerations:

• Memory size (32B primary, 2B acceptable for reduced storage)
• Package form factor (8-SOIC primary, 10-MSOP and 12-TFSOJ acceptable)
• Supply voltage ranges (4.5V ~ 5.5V primary, 2.7V ~ 5.5V acceptable)
• Product status (Active preferred over Obsolete)
• RoHS compliance (ROHS3 Compliant preferred)

Substitutes are classified into two categories: direct equivalents (DS1678S+) and functional alternatives (ISL1209IU10Z-TK, ISL1219IUZ-T, RX-8035LC:AA3 PURE SN) that maintain core RTC functionality with package and memory variations.

Parameter Comparison

Engineering Selection Recommendations

DS1678S+ (Direct Equivalent) Select DS1678S+ for designs requiring minimal modification. This part maintains identical electrical specifications, memory capacity (32B), package form factor (8-SOIC), and feature set (Alarm, Leap Year, NVSRAM, Y2K) as the original DS1678S. DS1678S+ is Active product status with ROHS3 compliance, eliminating obsolescence risk while preserving PCB layout and firmware compatibility.

ISL1209IU10Z-TK and ISL1219IUZ-T (Functional Alternatives) Select Renesas ISL1209IU10Z-TK or ISL1219IUZ-T for designs accommodating package and memory changes. Both parts provide I2C interface, 12/24-hour time format, YY-MM-DD-dd date format, and Alarm/Leap Year features. Memory is reduced to 2B SRAM (versus 32B NVSRAM). Package changes to 10-MSOP (0.118", 3.00mm Width). Supply voltage range expands to 2.7V ~ 5.5V with improved battery voltage support (1.8V ~ 5.5V). Both are Active with ROHS3 compliance. Timekeeping current is specified at 4µA ~ 6µA @ 3V ~ 5V.

RX-8035LC:AA3 PURE SN (Functional Alternative) Select EPSON RX-8035LC:AA3 PURE SN for designs requiring lowest timekeeping current consumption (2.5µA @ 3V) and widest battery voltage range (1V ~ 5.5V). This part provides I2C interface, 12/24-hour time format, YY-MM-DD-dd date format, and Alarm feature. Package is 12-TFSOJ (0.094", 2.40mm Width). Memory size is not specified. Supply voltage range is 2.4V ~ 5.5V. Product is Active with ROHS3 compliance. REACH status is Affected.

Frequently Asked Questions (FAQ)

Q: Can DS1678S+ be used as a direct replacement for DS1678S? A: Yes. DS1678S+ maintains identical electrical specifications, 32B memory capacity, 8-SOIC package, and feature set (Alarm, Leap Year, NVSRAM, Y2K). No PCB modifications are required. DS1678S+ is Active product status with ROHS3 compliance.

Q: What are the key differences between DS1678S and ISL1209IU10Z-TK? A: Memory is reduced from 32B NVSRAM to 2B SRAM. Package changes from 8-SOIC to 10-MSOP. Supply voltage range expands from 4.5V ~ 5.5V to 2.7V ~ 5.5V. Battery voltage support improves from 2.6V ~ 4.6V to 1.8V ~ 5.5V. Timekeeping current is specified at 4µA ~ 6µA @ 3V ~ 5V. Core RTC functionality (I2C interface, time/date format, Alarm, Leap Year) is maintained.

Q: What are the key differences between DS1678S and RX-8035LC:AA3 PURE SN? A: Package changes from 8-SOIC to 12-TFSOJ. Memory size is not specified. Supply voltage range expands from 4.5V ~ 5.5V to 2.4V ~ 5.5V. Battery voltage support expands from 2.6V ~ 4.6V to 1V ~ 5.5V. Timekeeping current is lower at 2.5µA @ 3V. Feature set is reduced to Alarm only (no Y2K or NVSRAM). Core RTC functionality (I2C interface, time/date format) is maintained.

Q: Which substitute part requires the least PCB redesign? A: DS1678S+ requires no PCB redesign. It maintains the 8-SOIC package and identical pinout. ISL1209IU10Z-TK and ISL1219IUZ-T require package redesign from 8-SOIC to 10-MSOP. RX-8035LC:AA3 PURE SN requires package redesign from 8-SOIC to 12-TFSOJ.

Q: Are all substitute parts RoHS compliant? A: DS1678S+ is ROHS3 Compliant. ISL1209IU10Z-TK is ROHS3 Compliant. ISL1219IUZ-T is ROHS3 Compliant. RX-8035LC:AA3 PURE SN is ROHS3 Compliant. The original DS1678S is RoHS non-compliant.

Q: What is the memory difference between substitute parts? A: DS1678S+ maintains 32B NVSRAM. ISL1209IU10Z-TK and ISL1219IUZ-T provide 2B SRAM. RX-8035LC:AA3 PURE SN memory size is not specified. Applications requiring large data storage should prioritize DS1678S+ or evaluate memory requirements against 2B capacity.

Q: Which substitute part has the lowest power consumption? A: RX-8035LC:AA3 PURE SN specifies 2.5µA @ 3V timekeeping current. ISL1209IU10Z-TK and ISL1219IUZ-T specify 4µA ~ 6µA @ 3V ~ 5V. DS1678S and DS1678S+ do not specify timekeeping current. Battery-powered applications should consider RX-8035LC:AA3 PURE SN for extended runtime.

Q: Can substitute parts operate at the same supply voltage as DS1678S? A: DS1678S operates at 4.5V ~ 5.5V. DS1678S+ maintains this range. ISL1209IU10Z-TK and ISL1219IUZ-T support 2.7V ~ 5.5V (compatible). RX-8035LC:AA3 PURE SN supports 2.4V ~ 5.5V (compatible). All substitute parts are compatible with 5V supply systems.