1337ACSRI Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The 1337ACSRI is a Real Time Clock (RTC) IC Clock/Calendar with I2C interface manufactured by Renesas Electronics Corporation in a 16-SOIC package. This component provides timekeeping functionality with alarm capability, leap year support, and square wave output. The product is currently obsolete, making identification of functionally equivalent substitute parts essential for ongoing system support, design updates, and component procurement.

Key Parameters

Parameter	1337ACSRI Specification
Manufacturer	Renesas Electronics Corporation
Category	Clock/Timing
Type	Clock/Calendar
Interface	I2C
Package / Case	16-SOIC (0.295", 7.50mm Width)
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
Voltage - Supply, Battery	1.3V ~ 3.7V
Current - Timekeeping (Max)	0.6µA @ 1.3V ~ 1.8V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Product Status	Obsolete
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the 1337ACSRI is determined by the following critical parameters:

Primary Compatibility Criteria:

I2C interface (2-Wire Serial protocol)
Clock/Calendar functionality with timekeeping capability
Operating temperature range: -40°C ~ 85°C
Supply voltage compatibility within 1.8V ~ 5.5V range
Time and date format support (HH:MM:SS and YY-MM-DD-dd)
Alarm and leap year features

Package Considerations: The original 1337ACSRI uses a 16-SOIC package. Substitute parts are grouped by package type, as this affects PCB layout and assembly compatibility. Substitutes include parts in 16-SOIC (direct package match), 8-SOIC, 8-TSSOP/8-MSOP, 8-WDFN, 8-UFDFN, and module-based packages. Package selection depends on available PCB footprint space and design constraints.

Functional Feature Alignment: All listed substitutes provide I2C Clock/Calendar functionality with alarm capability and leap year support. Some substitutes include additional features such as NVSRAM, EEPROM, trickle-charger, watchdog timer, or supervisor functions. These additional features do not prevent substitution but may provide enhanced system functionality.

Power Consumption: The 1337ACSRI operates at 0.6µA in timekeeping mode. Substitute parts range from 0.45µA to 200µA depending on package and feature set. Lower power consumption substitutes are preferred for battery-backed applications.

Parameter Comparison

Part Number	Manufacturer	Package / Case	Interface	Voltage - Supply	Voltage - Battery	Current - Timekeeping (Max)	Time Format	Features	Product Status
1337ACSRI	Renesas Electronics	16-SOIC (0.295", 7.50mm)	I2C	1.8V ~ 5.5V	1.3V ~ 3.7V	0.6µA @ 1.3V ~ 1.8V	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output	Obsolete
DS1339C-33#T&R	Analog Devices Inc./Maxim Integrated	16-SOIC (0.295", 7.50mm)	I2C, 2-Wire Serial	2.97V ~ 5.5V	1.3V ~ 3.7V	200µA @ 5.5V	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Active
DS1388Z-3+T&R	Analog Devices Inc./Maxim Integrated	8-SOIC (0.154", 3.90mm)	I2C, 2-Wire Serial	2.7V ~ 3.3V	1.3V ~ 5.5V	140µA @ 2.7V ~ 3.3V	HH:MM:SS:hh (12/24 hr)	EEPROM, Leap Year, Supervisor, Trickle-Charger, Watchdog Timer	Active
DS1341T+T&R	Analog Devices Inc./Maxim Integrated	8-WDFN Exposed Pad	I2C, 2-Wire Serial	1.8V ~ 5.5V	Not specified	0.5µA ~ 0.6µA @ 3V ~ 5V	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output	Active
DS1341U+T&R	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm)	I2C, 2-Wire Serial	1.8V ~ 5.5V	Not specified	0.5µA ~ 0.6µA @ 3V ~ 5V	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output	Active
DS1339U-3+	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm)	I2C, 2-Wire Serial	2.7V ~ 5.5V	1.3V ~ 3.7V	150µA @ 3.3V	HH:MM:SS (12/24 hr)	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Active
DS1308U-18+T	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm)	I2C, 2-Wire Serial	1.71V ~ 5.5V	1.3V ~ 5.5V	100µA @ 1.89V ~ 5.5V	HH:MM:SS (12/24 hr)	Leap Year, NVSRAM, Square Wave Output	Active
DS1338Z-18+T&R	Analog Devices Inc./Maxim Integrated	8-SOIC (0.154", 3.90mm)	I2C, 2-Wire Serial	1.71V ~ 5.5V	1.3V ~ 3.7V	100µA @ 1.89V	HH:MM:SS (12/24 hr)	Leap Year, NVSRAM, Square Wave Output	Active
BQ32000D	Texas Instruments	8-SOIC (0.154", 3.90mm)	I2C, 2-Wire Serial	3V ~ 3.6V	1.4V ~ 3.6V	100µA @ 3.3V	HH:MM:SS (24 hr)	Leap Year, Square Wave Output, Trickle-Charger	Active
BU9873NUX-TTR	Rohm Semiconductor	8-UFDFN Exposed Pad	I2C, 2-Wire Serial	1.8V ~ 5.5V	Not specified	1µA ~ 1.35µA @ 3V ~ 5.5V	HH:MM:SS (12/24 hr)	Alarm, Leap Year	Not For New Designs
AB-RTCMC-32.768KHZ-B5GA-S3-T	Abracon LLC	10-SMD Module	I2C, 2-Wire Serial	1.2V ~ 5.5V	Not specified	0.45µA ~ 0.55µA @ 2V ~ 5V	HH:MM:SS (24 hr)	Alarm, Leap Year, Square Wave Output	Active

Engineering Selection Recommendations

Direct Package Replacement (16-SOIC): DS1339C-33#T&R is the only substitute available in the original 16-SOIC package. This part is manufactured by Analog Devices Inc./Maxim Integrated and carries Active product status with RoHS3 compliance. It provides identical package footprint compatibility, eliminating PCB redesign requirements. The DS1339C-33#T&R includes trickle-charger functionality not present in the 1337ACSRI, offering enhanced system capability.

Low Power Alternatives: DS1341T+T&R and DS1341U+T&R both deliver 0.5µA ~ 0.6µA timekeeping current, matching the 1337ACSRI power profile. Both are Active status products with RoHS3 compliance. DS1341T+T&R uses 8-WDFN package; DS1341U+T&R uses 8-TSSOP/8-MSOP package. These options require PCB layout modification but provide superior power efficiency for battery-backed applications.

Module-Based Solution: AB-RTCMC-32.768KHZ-B5GA-S3-T from Abracon LLC offers the lowest timekeeping current at 0.45µA ~ 0.55µA and operates across the widest supply voltage range (1.2V ~ 5.5V). This 10-SMD module format is Active status and RoHS3 compliant. Module-based design simplifies integration but requires different PCB footprint.

Extended Feature Set: DS1388Z-3+T&R includes 512B EEPROM, supervisor, and watchdog timer functions alongside RTC capability. This part is Active status with RoHS3 compliance. The expanded feature set supports advanced system monitoring and data logging applications.

Avoid for New Designs: BU9873NUX-TTR carries "Not For New Designs" status and should not be selected for new development projects, despite meeting functional requirements.

Frequently Asked Questions (FAQ)

Q: Can I use an 8-SOIC package substitute in place of the original 16-SOIC 1337ACSRI?

A: No, not without PCB redesign. The 16-SOIC and 8-SOIC packages have different pin counts, pin spacing, and footprints. DS1339C-33#T&R is the only substitute maintaining the original 16-SOIC package. If PCB modification is acceptable, 8-SOIC alternatives like DS1338Z-18+T&R or BQ32000D are functionally compatible.

Q: What is the key difference between DS1341 variants (DS1341T+T&R vs. DS1341U+T&R)?

A: Both DS1341 variants provide identical electrical specifications and timekeeping current (0.5µA ~ 0.6µA). The difference is package type: DS1341T+T&R uses 8-WDFN Exposed Pad; DS1341U+T&R uses 8-TSSOP/8-MSOP. Selection depends on available PCB footprint space and assembly equipment compatibility.

Q: Why does BQ32000D specify only 24-hour time format while the 1337ACSRI supports 12/24 hour?

A: BQ32000D is designed for 24-hour operation only. If your application requires 12-hour format capability, select alternatives that explicitly support both formats: DS1339C-33#T&R, DS1341T+T&R, DS1341U+T&R, DS1339U-3+, DS1308U-18+T, DS1338Z-18+T&R, or BU9873NUX-TTR.

Q: Is the AB-RTCMC-32.768KHZ-B5GA-S3-T module format compatible with my existing PCB?

A: Module format compatibility depends on your PCB design. The AB-RTCMC module is a 10-SMD integrated assembly, not a discrete IC. It requires a different footprint than the original 16-SOIC package. Verify module dimensions and pin configuration against your PCB layout before selection.

Q: What does "Not For New Designs" status mean for BU9873NUX-TTR?

A: "Not For New Designs" indicates the manufacturer (Rohm Semiconductor) is not recommending this part for new product development. While functionally compatible, it may have limited long-term availability or support. For new designs, select Active status alternatives.

Q: Which substitute offers the best battery backup performance?

A: AB-RTCMC-32.768KHZ-B5GA-S3-T provides the lowest timekeeping current at 0.45µA ~ 0.55µA, extending battery life. DS1341T+T&R and DS1341U+T&R match the original 1337ACSRI at 0.5µA ~ 0.6µA. For battery-backed applications, these three options are preferred over higher-current alternatives.

Q: Are all substitutes RoHS3 compliant?

A: Yes, all listed substitutes carry RoHS3 compliance certification. The 1337ACSRI is obsolete and does not have current RoHS status. All Active status substitutes meet current environmental and regulatory requirements.

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