PT7C4337LEX Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The PT7C4337LEX is a Real Time Clock (RTC) IC with Clock/Calendar functionality, manufactured by Diodes Incorporated. This device features I2C/2-Wire Serial interface, alarm capability, leap year support, and square wave output in an 8-TSSOP package. The part is currently obsolete, making substitute components necessary for new designs and ongoing production requirements. Equivalent parts must maintain functional compatibility across interface protocol, time/date format support, operating voltage range, and package form factor.

Key Parameters

Parameter	PT7C4337LEX
Manufacturer	Diodes Incorporated
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year, Square Wave Output
Voltage Supply	1.8V ~ 5.5V
Current - Timekeeping (Max)	0.8µA @ 1.3V ~ 1.8V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-TSSOP (0.173", 4.40mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the PT7C4337LEX is determined by the following critical parameters:

Interface Compatibility: All substitute parts must support I2C/2-Wire Serial protocol to maintain firmware and circuit compatibility.

Time/Date Format: Substitutes must support HH:MM:SS (12/24 hour) time format and YY-MM-DD-dd date format.

Feature Set: Core features (Alarm, Leap Year, Square Wave Output) must be present in substitute parts.

Voltage Range: Operating supply voltage must encompass or be compatible with 1.8V ~ 5.5V range.

Operating Temperature: All substitutes must support -40°C ~ 85°C operating range.

Package Compatibility: Primary substitutes maintain 8-TSSOP or equivalent compact 8-pin packages. Secondary substitutes in 8-SOIC or 16-pin packages are available for applications with PCB layout flexibility.

Compliance: All substitutes maintain ROHS3 compliance and EAR99 classification.

Substitutes are grouped into two categories: Direct pin-compatible replacements in 8-TSSOP/8-MSOP packages, and functional equivalents in alternative 8-pin packages (8-SOIC) with identical electrical specifications.

Parameter Comparison

Part Number	Manufacturer	Interface	Time Format	Date Format	Features	Voltage Supply	Current - Timekeeping (Max)	Operating Temp	Package	Product Status
PT7C4337LEX	Diodes Incorporated	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	1.8V ~ 5.5V	0.8µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	8-TSSOP	Obsolete
DS1337U+T&R	Analog Devices Inc./Maxim Integrated	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	8-TSSOP, 8-MSOP	Active
DS1338U-18+	Analog Devices Inc./Maxim Integrated	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Leap Year, NVSRAM, Square Wave Output	1.71V ~ 5.5V	100µA @ 1.89V	-40°C ~ 85°C	8-TSSOP, 8-MSOP	Active
1337GDCGI8	Renesas Electronics Corporation	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output	1.8V ~ 5.5V	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	8-SOIC	Active
1338-31DCGI8	Renesas Electronics Corporation	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Leap Year, NVSRAM, Square Wave Output	3.3V ~ 5.5V	5µA @ 3.63V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Active
1339-31DCGI	Renesas Electronics Corporation	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year, Square Wave Output, Trickle-Charger	3.3V ~ 5.5V	200µA @ 3.63V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Active
DS1338Z-33+T&R	Analog Devices Inc./Maxim Integrated	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Leap Year, NVSRAM, Square Wave Output	3V ~ 5.5V	125µA ~ 200µA @ 3.63V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Active
DS1340Z-18+	Analog Devices Inc./Maxim Integrated	I2C, 2-Wire Serial	HH:MM:SS (24 hr)	YY-MM-DD-dd	Leap Year, Trickle-Charger	1.71V ~ 5.5V	100µA @ 1.89V	-40°C ~ 85°C	8-SOIC	Active
AB1805-T3	Abracon LLC	I2C, 2-Wire Serial	HH:MM:SS:hh	YY-MM-DD-dd	Alarm, Leap Year, SRAM, Trickle-Charger, Watchdog Timer	1.7V ~ 3.6V	0.17µA ~ 0.22µA @ 1.8V ~ 3V	-40°C ~ 85°C	16-VFQFN	Active
BU9873F-GTE2	Rohm Semiconductor	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Alarm, Leap Year	1.8V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	-40°C ~ 85°C	8-SOIC	Not For New Designs
DS1338C-18#	Analog Devices Inc./Maxim Integrated	I2C, 2-Wire Serial	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	Leap Year, NVSRAM, Square Wave Output	1.71V ~ 5.5V	100µA @ 1.89V	-40°C ~ 85°C	16-SOIC	Active

Engineering Selection Recommendations

Primary Substitutes (Direct Replacement):

DS1337U+T&R and DS1338U-18+ are the preferred direct replacements for PT7C4337LEX. Both maintain 8-TSSOP/8-MSOP package compatibility, support the full 1.8V ~ 5.5V supply voltage range, and provide identical time/date format support with I2C interface. DS1337U+T&R offers lower timekeeping current (0.6µA) compared to the original specification. DS1338U-18+ includes integrated NVSRAM (56B) for additional data storage. Both parts are in Active product status with full ROHS3 compliance.

Secondary Substitutes (8-SOIC Package):

1337GDCGI8 (Renesas) provides pin-compatible functionality in 8-SOIC form factor with identical electrical specifications to DS1337U+T&R. This option is suitable for applications where PCB layout accommodates the slightly larger 8-SOIC package (0.154" width vs. 0.173" for TSSOP).

1338-31DCGI8 (Renesas) offers NVSRAM integration with 56B memory but operates at 3.3V ~ 5.5V supply range, requiring verification of circuit compatibility if 1.8V operation is required.

DS1338Z-33+T&R (Analog Devices) provides 56B NVSRAM with 3V ~ 5.5V supply range and higher timekeeping current specification (125µA ~ 200µA).

Extended Feature Substitutes:

1339-31DCGI (Renesas) adds trickle-charger functionality at the cost of higher timekeeping current (200µA) and 3.3V ~ 5.5V supply range.

AB1805-T3 (Abracon) offers ultra-low timekeeping current (0.17µA ~ 0.22µA) with expanded feature set including watchdog timer and 256B SRAM, but operates at 1.7V ~ 3.6V range and requires 16-pin QFN package redesign.

Not Recommended for New Designs:

BU9873F-GTE2 (Rohm) carries "Not For New Designs" status and should be avoided despite electrical compatibility.

DS1340Z-18+ supports only 24-hour time format, limiting compatibility with applications requiring 12-hour format support.

Frequently Asked Questions (FAQ)

Q: Can DS1337U+T&R directly replace PT7C4337LEX without PCB modification?

A: Yes. DS1337U+T&R maintains identical 8-TSSOP/8-MSOP package pinout, supply voltage range (1.8V ~ 5.5V), and I2C interface protocol. No circuit redesign is required.

Q: What is the difference between DS1337U+T&R and DS1338U-18+?

A: Both support identical interface and voltage specifications. DS1338U-18+ includes 56B of integrated NVSRAM for non-volatile data storage, while DS1337U+T&R does not. DS1337U+T&R has lower timekeeping current (0.6µA vs. 100µA). Selection depends on whether additional non-volatile memory is required.

Q: Can 8-SOIC package substitutes be used instead of 8-TSSOP?

A: Yes, if PCB layout permits. 8-SOIC packages are slightly larger (0.154" width vs. 0.173" for TSSOP) but maintain identical electrical functionality. Pinout compatibility must be verified for each specific part number.

Q: Why does 1338-31DCGI8 have a higher minimum supply voltage (3.3V)?

A: 1338-31DCGI8 is optimized for 3.3V systems and includes integrated battery backup support (1.3V ~ 3.7V). Applications requiring 1.8V operation should use DS1337U+T&R or 1337GDCGI8 instead.

Q: Is AB1805-T3 compatible with existing PT7C4337LEX designs?

A: AB1805-T3 requires PCB redesign due to 16-pin QFN package and 1.7V ~ 3.6V supply range. It is suitable only for new designs where ultra-low power consumption (0.17µA ~ 0.22µA) justifies the layout changes.

Q: What compliance certifications apply to all substitute parts?

A: All listed substitutes maintain ROHS3 compliance, REACH Unaffected status, and EAR99 export classification, matching the original PT7C4337LEX specifications.

Q: Can BU9873F-GTE2 be used as a substitute?

A: BU9873F-GTE2 is electrically compatible but carries "Not For New Designs" product status. It should not be selected for new production or long-term availability requirements.

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