DS1337S Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The DS1337S is a Real Time Clock (RTC) IC with Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This component provides I2C/2-Wire Serial interface for timekeeping applications with alarm and leap year support. The DS1337S is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production support. Substitute components must maintain functional compatibility across core electrical parameters and interface specifications while meeting current RoHS compliance requirements.

Key Parameters

Parameter	DS1337S Specification
Manufacturer	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete
Package / Case	8-SOIC (0.154", 3.90mm Width)
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Voltage - Supply	1.8V ~ 5.5V
Current - Timekeeping (Max)	0.6µA @ 1.3V ~ 1.8V
Operating Temperature	-40°C ~ 85°C
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year, Square Wave Output
Mounting Type	Surface Mount
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict alignment with the following core parameters:

Primary Compatibility Criteria:

Interface: I2C, 2-Wire Serial (mandatory match)
Time Format: HH:MM:SS (12/24 hr) (mandatory match)
Date Format: YY-MM-DD-dd (mandatory match)
Operating Temperature: -40°C ~ 85°C (mandatory match)
Voltage Supply Range: 1.8V ~ 5.5V or compatible subset
Mounting Type: Surface Mount (mandatory match)
Features: Alarm and Leap Year support (mandatory match)

Secondary Compatibility Criteria:

Package compatibility (8-SOIC preferred for direct PCB replacement; alternative packages acceptable with board redesign)
Current consumption within acceptable operational limits
RoHS compliance status (preferred for new designs)
Product status (Active preferred; Obsolete acceptable for legacy support)

Substitute parts are grouped into two categories:

Category 1: Direct Package Compatibility (8-SOIC) Parts maintaining the 8-SOIC package enable direct PCB replacement without layout modifications.

Category 2: Alternative Package Compatibility Parts with different packages (8-MSOP, 8-TSSOP, 8-UFDFN, 8-WDFN) require PCB redesign but maintain full electrical and functional compatibility.

Parameter Comparison

Part Number	Manufacturer	Package	Interface	Voltage Supply	Current - Timekeeping (Max)	Operating Temp	Time Format	Date Format	Features	Product Status	RoHS Status
DS1337S	Analog Devices Inc./Maxim Integrated	8-SOIC	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	Obsolete	RoHS non-compliant
DS1337S+	Analog Devices Inc./Maxim Integrated	8-SOIC	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	Active	ROHS3 Compliant
1337GDVGI	Renesas Electronics Corporation	8-MSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	Active	ROHS3 Compliant
BU9873NUX-TTR	Rohm Semiconductor	8-UFDFN Exposed Pad	I2C, 2-Wire Serial	1.8V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year	Not For New Designs	ROHS3 Compliant
ISL12022IBZ-T	Renesas Electronics Corporation	8-SOIC	I2C, 2-Wire Serial	2.7V ~ 5.5V (Main) / 1.8V ~ 5.5V (Battery)	14µA ~ 15µA @ 3V ~ 5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Daylight Savings, Leap Year, SRAM	Active	ROHS3 Compliant
ISL12026IVZ	Renesas Electronics Corporation	8-TSSOP	I2C, 2-Wire Serial	2.7V ~ 5.5V (Main) / 1.8V ~ 5.5V (Battery)	10µA ~ 20µA @ 2.7V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year	Active	ROHS3 Compliant
ISL1208IRT8Z-TK	Renesas Electronics Corporation	8-WDFN Exposed Pad	I2C, 2-Wire Serial	2.7V ~ 5.5V (Main) / 1.8V ~ 5.5V (Battery)	4µA ~ 6µA @ 3V ~ 5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, SRAM	Obsolete	ROHS3 Compliant
ISL1208IU8Z-TK	Renesas Electronics Corporation	8-MSOP	I2C, 2-Wire Serial	2.7V ~ 5.5V (Main) / 1.8V ~ 5.5V (Battery)	4µA ~ 6µA @ 3V ~ 5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, SRAM	Active	ROHS3 Compliant
M41ST87WSS6F	STMicroelectronics	20-SSOP	I2C, 2-Wire Serial	2.7V ~ 3.6V	0.5mA @ 2.7V ~ 3.6V	-40°C ~ 85°C	HH:MM:SS:hh (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, NVSRAM, Square Wave Output, Supervisor, Watchdog Timer	Active	ROHS3 Compliant
MCP79400-I/MS	Microchip Technology	8-MSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	1.2µA (Typ) @ 3.3V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output, SRAM, Unique ID	Active	ROHS3 Compliant
MCP79400T-I/ST	Microchip Technology	8-TSSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	1.2µA (Typ) @ 3.3V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output, SRAM, Unique ID	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct PCB Replacement (No Layout Changes):

DS1337S+ is the primary substitute. It maintains identical electrical specifications, package geometry (8-SOIC), and functional features while offering Active product status and ROHS3 compliance. This part provides the most straightforward migration path from the obsolete DS1337S.

ISL12022IBZ-T is an alternative 8-SOIC option with Active status and ROHS3 compliance. It includes additional features (Daylight Savings, SRAM) and dual voltage supply support (main and battery). Higher timekeeping current consumption (14µA ~ 15µA) may impact battery-backed applications compared to DS1337S specifications.

For Designs Permitting Package Changes:

ISL1208IU8Z-TK (8-MSOP package) offers Active product status, ROHS3 compliance, and lower timekeeping current (4µA ~ 6µA). This part is suitable for space-constrained applications and provides superior power efficiency in battery-backed configurations.

MCP79400-I/MS and MCP79400T-I/ST (Microchip Technology) maintain the 1.8V ~ 5.5V supply range and provide Active status with ROHS3 compliance. Both include additional features (Unique ID, enhanced SRAM) and comparable timekeeping current specifications.

1337GDVGI (Renesas Electronics Corporation, 8-MSOP) provides Active status and ROHS3 compliance with identical electrical specifications to DS1337S. Package change from 8-SOIC to 8-MSOP requires PCB redesign.

Not Recommended for New Designs:

BU9873NUX-TTR carries "Not For New Designs" status despite ROHS3 compliance and active inventory. This designation indicates manufacturer discontinuation plans.

ISL1208IRT8Z-TK is classified as Obsolete and should not be selected for new production designs.

M41ST87WSS6F operates within a narrower voltage range (2.7V ~ 3.6V) and exhibits significantly higher timekeeping current (0.5mA), making it unsuitable for applications requiring the DS1337S's extended supply range and ultra-low power operation.

Frequently Asked Questions (FAQ)

Q: Can DS1337S+ be used as a direct replacement for DS1337S?

A: Yes. DS1337S+ maintains identical electrical specifications, package dimensions (8-SOIC), and functional features. The primary differences are Active product status and ROHS3 compliance. No PCB modifications are required.

Q: What is the impact of switching to an alternative package (8-MSOP, 8-TSSOP)?

A: Alternative packages require PCB layout redesign and footprint changes. Electrical and functional compatibility remains intact. Package selection should be based on available board space and manufacturing capabilities. Pin-to-pin compatibility must be verified against specific part datasheets.

Q: Are all substitute parts RoHS compliant?

A: All listed substitutes except DS1337S (the original part) are ROHS3 compliant. For applications requiring RoHS compliance, DS1337S+ is the recommended direct replacement.

Q: How do timekeeping current specifications affect battery-backed operation?

A: Lower timekeeping current extends battery life in backup power scenarios. DS1337S specifies 0.6µA @ 1.3V ~ 1.8V. ISL1208IU8Z-TK offers superior efficiency at 4µA ~ 6µA @ 3V ~ 5V. ISL12022IBZ-T consumes 14µA ~ 15µA, which may reduce battery backup duration in low-power applications.

Q: What is the significance of "Product Status: Not For New Designs"?

A: This designation indicates the manufacturer has announced discontinuation plans. While parts may remain available, they should not be selected for new product development. Active status parts are preferred for long-term production support.

Q: Can M41ST87WSS6F replace DS1337S in all applications?

A: No. M41ST87WSS6F operates within 2.7V ~ 3.6V supply range, excluding the DS1337S's lower voltage capability (1.8V ~ 2.7V). Timekeeping current is significantly higher (0.5mA vs. 0.6µA), making it unsuitable for ultra-low-power applications. Use only if supply voltage and power budget constraints are compatible.

Q: Are there functional differences between substitute parts?

A: Yes. Some substitutes include additional features (SRAM, Daylight Savings, Watchdog Timer, Unique ID) not present in DS1337S. These additions do not prevent substitution but may require firmware modifications to utilize. Core timekeeping, alarm, and leap year functions remain compatible across all listed parts.

Q: What packaging considerations apply to high-volume production?

A: Packaging format affects supply chain logistics and assembly processes. 8-SOIC and 8-MSOP packages are widely supported by contract manufacturers. Tape & Reel (TR) and Cut Tape (CT) formats are standard for automated assembly. Verify packaging availability with your supplier before design finalization.

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