DS1337U/T&R Real Time Clock (RTC) IC Equivalent & Substitute Parts

Part Overview

The DS1337U/T&R is a Real Time Clock (RTC) IC with Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This component operates via I2C 2-Wire Serial interface and is housed in an 8-TSSOP/8-MSOP package. The part is currently listed as obsolete, which necessitates identification of functionally equivalent alternatives for ongoing design requirements and production continuity.

Key Parameters

Parameter	DS1337U/T&R Specification
Manufacturer	Analog Devices Inc./Maxim Integrated
Product Status	Obsolete
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Package / Case	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
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 of the DS1337U/T&R is determined by the following critical parameters:

Primary Compatibility Criteria:

I2C 2-Wire Serial interface (mandatory for protocol compatibility)
Operating voltage range: 1.8V ~ 5.5V (ensures power supply compatibility)
Operating temperature range: -40°C ~ 85°C (environmental specification match)
Time format: HH:MM:SS (12/24 hr) and Date format: YY-MM-DD-dd (functional equivalence)
Surface mount technology with compatible package footprints

Secondary Considerations:

RoHS compliance status (regulatory requirement for new designs)
Product status (active vs. obsolete/not for new designs)
Timekeeping current consumption specifications
Presence of alarm, leap year, and square wave output features

Substitute parts are grouped into two categories: direct pin-compatible replacements in 8-TSSOP packaging (DS1337U+T&R, 1337DVGI, 1337DVGI8, BU9873FVT-GE2, ISL12026AIVZ) and functionally equivalent alternatives with different package formats (1338-31DCGI, ISL12057IBZ, ISL12058IBZ-T, M41ST85WMH6F, M41T62LC6F).

Parameter Comparison

Parameter	DS1337U/T&R	DS1337U+T&R	1337DVGI	1337DVGI8	BU9873FVT-GE2	ISL12026AIVZ	ISL12057IBZ	ISL12058IBZ-T	M41T62LC6F
Manufacturer	Analog Devices/Maxim	Analog Devices/Maxim	Renesas	Renesas	Rohm	Renesas	Renesas	Renesas	STMicroelectronics
Product Status	Obsolete	Active	Active	Active	Not For New Designs	Active	Active	Active	Active
Interface	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial	I2C, 2-Wire Serial
Voltage - Supply	1.8V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	2.7V ~ 5.5V	1.8V ~ 3.6V	1.8V ~ 3.6V	1.3V ~ 4.4V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Time Format	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS:hh (24 hr)
Date Format	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd	YY-MM-DD-dd
Package / Case	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	8-TSSOP	8-TSSOP	8-SOIC	8-SOIC	8-LCC
Current - Timekeeping (Max)	0.6µA @ 1.3V ~ 1.8V	0.6µA @ 1.3V ~ 1.8V	0.6µA @ 1.3V ~ 1.8V	0.6µA @ 1.3V ~ 1.8V	1µA ~ 1.35µA @ 3V ~ 5.5V	10µA ~ 20µA @ 2.7V ~ 5.5V	0.65µA @ 1.8V	0.65µA @ 1.8V	0.7µA ~ 0.95µA @ 1.3V ~ 4.4V
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Features	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year	Alarm, Leap Year	Alarm, Leap Year	Alarm, Leap Year	Alarm, Leap Year, Square Wave Output, Watchdog Timer

Engineering Selection Recommendations

For Direct Pin-Compatible Replacement (8-TSSOP/8-MSOP Package):

DS1337U+T&R is the primary direct substitute. It maintains identical electrical specifications and package format while offering active product status and ROHS3 compliance. This part is recommended for new designs requiring the same footprint and pinout as the obsolete DS1337U/T&R.

1337DVGI and 1337DVGI8 (Renesas Electronics) provide functionally equivalent alternatives with identical electrical parameters, I2C interface, and 8-TSSOP packaging. Both are active products with ROHS3 compliance. MSL rating differs (3 vs. 1), which may impact storage and handling requirements.

BU9873FVT-GE2 (Rohm Semiconductor) offers equivalent functionality in 8-TSSOP format with active product status designation as "Not For New Designs." This part is suitable for legacy system maintenance but not recommended for new design implementations.

ISL12026AIVZ (Renesas Electronics) provides 8-TSSOP packaging with active status and ROHS3 compliance. Voltage supply range is restricted to 2.7V ~ 5.5V, which may limit compatibility with designs requiring 1.8V operation.

For Alternative Package Formats:

ISL12057IBZ and ISL12058IBZ-T (Renesas Electronics) offer 8-SOIC packaging with active product status and ROHS3 compliance. Both feature restricted voltage supply range (1.8V ~ 3.6V) and lower timekeeping current consumption (0.65µA @ 1.8V). These are suitable for low-power applications where package footprint change is acceptable.

M41T62LC6F (STMicroelectronics) provides 8-LCC packaging with extended voltage range (1.3V ~ 4.4V) and includes watchdog timer functionality. Active product status and ROHS3 compliance support new design implementation.

Compliance Considerations:

All recommended substitutes except BU9873FVT-GE2 carry active product status. All substitutes are ROHS3 compliant, addressing regulatory requirements for new designs. The original DS1337U/T&R is RoHS non-compliant, making substitution necessary for applications subject to RoHS regulations.

Frequently Asked Questions (FAQ)

Q: Can DS1337U+T&R be used as a direct replacement for DS1337U/T&R?

A: Yes. DS1337U+T&R maintains identical electrical specifications, I2C interface, time/date format, operating temperature range, and 8-TSSOP/8-MSOP package format. The primary difference is product status (active vs. obsolete) and RoHS compliance (ROHS3 vs. non-compliant). Pinout and functionality are equivalent.

Q: What are the key differences between 8-TSSOP and 8-SOIC package options?

A: 8-TSSOP (0.118", 3.00mm width) and 8-SOIC (0.154", 3.90mm width) differ in physical dimensions and footprint. Both are surface mount packages with 8 pins. Selection depends on PCB layout constraints and available board space. ISL12057IBZ and ISL12058IBZ-T use 8-SOIC format and require PCB redesign if direct footprint replacement is required.

Q: Are there voltage supply compatibility concerns when substituting?

A: Yes. The original DS1337U/T&R operates across 1.8V ~ 5.5V. ISL12057IBZ and ISL12058IBZ-T are restricted to 1.8V ~ 3.6V, which may not support 5.5V supply designs. ISL12026AIVZ operates at 2.7V ~ 5.5V, excluding 1.8V operation. Verify supply voltage requirements before selection.

Q: Which substitute is recommended for new product designs?

A: DS1337U+T&R is the primary recommendation for new designs requiring direct footprint compatibility. For designs where package change is acceptable, ISL12058IBZ-T offers active product status, ROHS3 compliance, and low timekeeping current consumption (0.65µA @ 1.8V). Avoid BU9873FVT-GE2 for new designs due to "Not For New Designs" status.

Q: What is the significance of MSL (Moisture Sensitivity Level) ratings?

A: MSL ratings indicate moisture sensitivity during storage and handling. MSL 1 (unlimited shelf life) is preferred for inventory management. 1337DVGI and 1337DVGI8 carry MSL 3 (168 hours), requiring controlled storage conditions. DS1337U+T&R and most alternatives carry MSL 1, simplifying supply chain management.

Q: Do all substitutes support 12/24-hour time format?

A: All listed substitutes support HH:MM:SS (12/24 hr) time format except M41T62LC6F, which operates in 24-hour format only (HH:MM:SS:hh). If 12-hour format is required, M41T62LC6F is not suitable.

Q: Are there timekeeping current consumption differences that affect battery backup design?

A: Yes. DS1337U/T&R and direct equivalents consume 0.6µA @ 1.3V ~ 1.8V. ISL12026AIVZ consumes 10µA ~ 20µA, significantly higher. ISL12057IBZ and ISL12058IBZ-T consume 0.65µA @ 1.8V, comparable to the original. For battery-backed applications, lower consumption parts (0.6µA ~ 0.95µA range) are preferred for extended backup duration.

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