DS1337U Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The DS1337U is a Real Time Clock (RTC) IC with Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This device operates via I2C 2-Wire Serial interface and is packaged in 8-TSSOP/8-MSOP format. The DS1337U is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain functional compatibility across I2C interface, time/date format support, alarm capabilities, and operating temperature range while accommodating packaging and supply voltage variations.

Key Parameters

Parameter	DS1337U
Manufacturer	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete
Package / Case	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Interface	I2C, 2-Wire Serial
Type	Clock/Calendar
Features	Alarm, Leap Year, Square Wave Output
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Voltage - Supply	1.8V ~ 5.5V
Current - Timekeeping (Max)	0.6µA @ 1.3V ~ 1.8V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
RoHS Status	RoHS non-compliant

Substitute Part Grouping Explanation

Substitution logic for the DS1337U is based on the following critical parameters:

Primary Compatibility Criteria:

I2C 2-Wire Serial interface (mandatory)
Clock/Calendar functionality with HH:MM:SS (12/24 hr) and YY-MM-DD-dd format support
Alarm and Leap Year features
Operating temperature range -40°C ~ 85°C
Supply voltage compatibility within 1.8V ~ 5.5V range
Surface mount technology

Secondary Considerations:

Package form factor (8-TSSOP/8-MSOP preferred for pin-compatible replacement; 8-SOIC acceptable for functional substitution)
RoHS compliance status
Current consumption during timekeeping operation
Additional features (Square Wave Output, SRAM, Watchdog Timer) as design requirements permit

Substitute parts are grouped into two categories:

Category A - Direct Pin-Compatible Substitutes (8-TSSOP/8-MSOP Package):

DS1337U+ (Analog Devices Inc./Maxim Integrated)
1337DVGI (Renesas Electronics Corporation)
1337DVGI8 (Renesas Electronics Corporation)
MCP79410-I/MS (Microchip Technology)

Category B - Functional Substitutes (Alternative Packages):

1338-31DCGI (Renesas Electronics Corporation) - 8-SOIC package
ISL12020MIRZ-T7A (Renesas Electronics Corporation) - 20-PowerLFDFN package
ISL12058IBZ-T (Renesas Electronics Corporation) - 8-SOIC package
M41T80M6F (STMicroelectronics) - 8-SOIC package
M41T82ZM6F (STMicroelectronics) - 8-SOIC package
MCP7940MT-I/MNY (Microchip Technology) - 8-WFDFN package

Parameter Comparison

Part Number	Manufacturer	Package	Interface	Supply Voltage	Time Format	Date Format	Features	Operating Temp	RoHS Status	Product Status
DS1337U	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	-40°C ~ 85°C	RoHS non-compliant	Obsolete
DS1337U+	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	-40°C ~ 85°C	ROHS3 Compliant	Active
1337DVGI	Renesas Electronics Corporation	8-TSSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	-40°C ~ 85°C	ROHS3 Compliant	Active
1337DVGI8	Renesas Electronics Corporation	8-TSSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	-40°C ~ 85°C	ROHS3 Compliant	Active
MCP79410-I/MS	Microchip Technology	8-TSSOP, 8-MSOP	I2C, 2-Wire Serial	1.8V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output, SRAM, Unique ID	-40°C ~ 85°C	ROHS3 Compliant	Active
1338-31DCGI	Renesas Electronics Corporation	8-SOIC	I2C, 2-Wire Serial	3.3V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Leap Year, NVSRAM, Square Wave Output	-40°C ~ 85°C	ROHS3 Compliant	Active
ISL12020MIRZ-T7A	Renesas Electronics Corporation	20-PowerLFDFN	I2C, 2-Wire Serial	2.7V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Daylight Savings, Leap Year, SRAM	-40°C ~ 85°C	ROHS3 Compliant	Active
ISL12058IBZ-T	Renesas Electronics Corporation	8-SOIC	I2C, 2-Wire Serial	1.8V ~ 3.6V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year	-40°C ~ 85°C	ROHS3 Compliant	Active
M41T80M6F	STMicroelectronics	8-SOIC	I2C, 2-Wire Serial	2V ~ 5.5V	HH:MM:SS:hh (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	-40°C ~ 85°C	ROHS3 Compliant	Active
M41T82ZM6F	STMicroelectronics	8-SOIC	I2C, 2-Wire Serial	2.38V ~ 5.5V	HH:MM:SS:hh (24 hr)	YY-MM-DD-dd	Alarm, Leap Year, SRAM, Watchdog Timer	-40°C ~ 85°C	ROHS3 Compliant	Active
MCP7940MT-I/MNY	Microchip Technology	8-WFDFN Exposed Pad	I2C, 2-Wire Serial	1.8V ~ 5.5V	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output, SRAM	-40°C ~ 85°C	ROHS3 Compliant	Active

Engineering Selection Recommendations

For Direct Replacement (Pin-Compatible, No PCB Redesign):

DS1337U+ is the primary recommended substitute. It maintains identical electrical specifications, package format, and feature set as the DS1337U while offering ROHS3 compliance and active product status. This part provides the lowest integration risk for existing designs.

1337DVGI and 1337DVGI8 (Renesas Electronics Corporation) are functionally equivalent alternatives in 8-TSSOP package. Both maintain full electrical compatibility and feature parity. Inventory availability differs between variants (657 Pcs and 960 Pcs respectively).

MCP79410-I/MS (Microchip Technology) provides pin-compatible substitution in 8-TSSOP/8-MSOP package with extended functionality including SRAM and Unique ID features. Supply voltage range and timekeeping current specifications remain compatible.

For Functional Substitution (PCB Layout Modification Required):

Parts in alternative packages (8-SOIC, 20-PowerLFDFN, 8-WFDFN) require PCB redesign but offer enhanced features or improved availability. Selection depends on specific design requirements:

1338-31DCGI: 56B NVSRAM, 8-SOIC package, minimum supply voltage 3.3V
ISL12020MIRZ-T7A: 128B SRAM, Daylight Savings feature, 20-PowerLFDFN package
ISL12058IBZ-T: Ultra-low supply voltage (1.8V ~ 3.6V), 8-SOIC package
M41T80M6F / M41T82ZM6F: STMicroelectronics alternatives with 24-hour format, 8-SOIC package
MCP7940MT-I/MNY: 64B SRAM, 8-WFDFN package, 1µA timekeeping current

All substitute parts listed maintain -40°C ~ 85°C operating temperature range and I2C 2-Wire Serial interface compatibility. All active-status substitutes carry ROHS3 compliance certification.

Frequently Asked Questions (FAQ)

Q: Can DS1337U+ be used as a direct replacement for DS1337U?

A: Yes. DS1337U+ is electrically and functionally identical to DS1337U, with identical package format (8-TSSOP/8-MSOP), supply voltage range (1.8V ~ 5.5V), and feature set (Alarm, Leap Year, Square Wave Output). The primary difference is product status (Active vs. Obsolete) and RoHS compliance (ROHS3 vs. non-compliant). No PCB modifications are required.

Q: What is the key difference between 8-TSSOP and 8-SOIC packages?

A: Both are 8-pin surface mount packages but differ in physical dimensions and pin pitch. 8-TSSOP (0.118" width, 3.00mm) is narrower than 8-SOIC (0.154" width, 3.90mm). Substituting between these packages requires PCB layout redesign. Pin assignments may differ; consult device datasheets for pinout verification.

Q: Are all substitute parts compatible with 1.8V supply voltage?

A: No. ISL12058IBZ-T supports 1.8V ~ 3.6V. M41T80M6F requires minimum 2V. M41T82ZM6F requires minimum 2.38V. 1338-31DCGI requires minimum 3.3V. Verify supply voltage compatibility with your design before selection.

Q: Which substitute offers the lowest timekeeping current consumption?

A: MCP7940MT-I/MNY operates at 1µA @ 5.5V. DS1337U and DS1337U+ consume 0.6µA @ 1.3V ~ 1.8V. ISL12058IBZ-T consumes 0.65µA @ 1.8V. Current consumption varies with supply voltage; compare specifications at your operating voltage.

Q: Do all substitutes support both 12-hour and 24-hour time formats?

A: DS1337U, DS1337U+, 1337DVGI, 1337DVGI8, MCP79410-I/MS, 1338-31DCGI, ISL12020MIRZ-T7A, and ISL12058IBZ-T support HH:MM:SS (12/24 hr) format. M41T80M6F and M41T82ZM6F support HH:MM:SS:hh (24 hr) format only. MCP7940MT-I/MNY supports HH:MM:SS (12/24 hr) format.

Q: Which substitutes include additional memory (SRAM/NVSRAM)?

A: MCP79410-I/MS includes 64B SRAM and 1Kb memory. 1338-31DCGI includes 56B NVSRAM. ISL12020MIRZ-T7A includes 128B SRAM. M41T82ZM6F includes 7B SRAM. MCP7940MT-I/MNY includes 64B SRAM. DS1337U and direct equivalents do not include additional memory.

Q: Are all substitute parts RoHS compliant?

A: All active-status substitutes listed (DS1337U+, 1337DVGI, 1337DVGI8, MCP79410-I/MS, 1338-31DCGI, ISL12020MIRZ-T7A, ISL12058IBZ-T, M41T80M6F, M41T82ZM6F, MCP7940MT-I/MNY) carry ROHS3 compliance certification. DS1337U is RoHS non-compliant.

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