PT7C4339WEX Equivalent & Substitute Parts

Part Overview

The PT7C4339WEX is a Real Time Clock (RTC) IC with Clock/Calendar functionality manufactured by Diodes Incorporated. This device operates via I2C 2-Wire Serial interface and is housed in an 8-SOIC package. The part is currently obsolete, making equivalent and substitute components necessary for new designs, legacy system repairs, and production continuity. Substitute parts must maintain functional compatibility across timing, interface, power supply, and package considerations.

Key Parameters

Parameter	PT7C4339WEX
Manufacturer	Diodes Incorporated
Product Status	Obsolete
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Package / Case	8-SOIC (0.154", 3.90mm Width)
Voltage - Supply	3V ~ 5.5V
Voltage - Supply, Battery	1.3V ~ 3.7V
Current - Timekeeping (Max)	250µA @ 3V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD
Features	Alarm, Leap Year, Square Wave Output
RoHS Status	ROHS3 Compliant
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution logic for the PT7C4339WEX is based on the following critical parameters:

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

Power Supply Range: Substitute parts must operate within or encompass the 3V ~ 5.5V supply voltage range. Battery backup voltage range (1.3V ~ 3.7V) is required for continuous timekeeping during power loss.

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

Time and Date Format: Substitutes must support HH:MM:SS (12/24 hr) time format and YY-MM-DD date format as minimum requirements.

Package Compatibility: The 8-SOIC package is the primary form factor. Substitutes in alternative packages (8-TSSOP, 16-SOIC, 16-QFN) are acceptable if PCB layout can accommodate the different footprint dimensions.

Core Features: Alarm functionality, Leap Year support, and Square Wave Output are standard features across all qualified substitutes.

Compliance: All substitutes must maintain ROHS3 compliance and EAR99 export classification.

Parameter Comparison

Parameter	PT7C4339WEX	1339-31DVGI8	AB0805-T3	DS1338U-33+	DS1339U-2+T&R	DS1340Z-33+T&R	DS1341U+T&R	DS3231M+TRL	ISL12026IBZ
Manufacturer	Diodes Inc.	Renesas	Abracon	Analog Devices	Analog Devices	Analog Devices	Analog Devices	Analog Devices	Renesas
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active
Interface	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire
Package / Case	8-SOIC	8-TSSOP	16-QFN	8-TSSOP	8-TSSOP	8-SOIC	8-TSSOP	16-SOIC	8-SOIC
Voltage - Supply	3V ~ 5.5V	3.3V ~ 5.5V	1.7V ~ 3.6V	3V ~ 5.5V	1.8V ~ 5.5V	2.97V ~ 5.5V	1.8V ~ 5.5V	2.3V ~ 5.5V	2.7V ~ 5.5V
Voltage - Supply, Battery	1.3V ~ 3.7V	1.3V ~ 3.7V	1.5V ~ 3.6V	1.3V ~ 3.7V	1.3V ~ 3.7V	1.3V ~ 5.5V	Not specified	2.3V ~ 5.5V	1.8V ~ 5.5V
Current - Timekeeping (Max)	250µA @ 3V-5.5V	200µA @ 3.63V-5.5V	0.17µA ~ 0.22µA @ 1.8V-3V	125µA ~ 200µA @ 3.63V-5.5V	100µA @ 2.2V	150µA @ 5.5V	0.5µA ~ 0.6µA @ 3V-5V	130µA ~ 200µA @ 3.63V-5.5V	10µA ~ 20µA @ 2.7V-5.5V
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:hh	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)
Date Format	YY-MM-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
Features	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Alarm, Leap Year, SRAM, Trickle-Charger, Watchdog Timer	Leap Year, NVSRAM, Square Wave Output	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Leap Year, Trickle-Charger	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount

Engineering Selection Recommendations

Direct Package Match (8-SOIC): DS1340Z-33+T&R and ISL12026IBZ maintain the original 8-SOIC package footprint, enabling direct PCB substitution without layout modifications. Both are active products with ROHS3 compliance.

Alternative Package Options: Substitutes in 8-TSSOP (1339-31DVGI8, DS1338U-33+, DS1339U-2+T&R, DS1341U+T&R) require PCB footprint redesign but offer improved power efficiency. The 16-SOIC DS3231M+TRL and 16-QFN AB0805-T3 provide additional features (SRAM, Watchdog Timer) at the cost of larger package dimensions.

Power Efficiency Consideration: AB0805-T3 and DS1341U+T&R demonstrate significantly lower timekeeping current (0.17µA ~ 0.6µA) compared to the original PT7C4339WEX (250µA), beneficial for battery-backed applications.

Supply Voltage Compatibility: All substitutes operate within the 3V ~ 5.5V range. DS1340Z-33+T&R and ISL12026IBZ support extended battery voltage ranges (1.3V ~ 5.5V), providing superior backup power flexibility.

Active Product Status: All listed substitutes are active products with ongoing manufacturer support, ensuring long-term availability and supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with a different package than the original PT7C4339WEX?

A: Yes, if your PCB design allows footprint modification. DS1340Z-33+T&R and ISL12026IBZ maintain the 8-SOIC package for direct replacement. Alternative packages require PCB redesign but may offer performance advantages.

Q: Are all substitute parts I2C compatible with the original PT7C4339WEX firmware?

A: All listed substitutes use I2C 2-Wire Serial interface. However, register maps and command structures may differ between manufacturers. Firmware validation is required during integration.

Q: Which substitute offers the best power efficiency for battery-backed operation?

A: AB0805-T3 and DS1341U+T&R provide the lowest timekeeping current (0.17µA ~ 0.6µA), significantly reducing battery drain compared to the original 250µA specification.

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

A: Most substitutes support 12/24-hour format. DS1340Z-33+T&R operates in 24-hour format only. Verify firmware compatibility with your application requirements.

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

A: Both are 8-pin surface mount packages with different physical dimensions. 8-SOIC (0.154" width) matches the original PT7C4339WEX. 8-TSSOP (0.118" width) is narrower and requires PCB footprint redesign but offers improved thermal characteristics.

Q: Are all substitutes RoHS3 compliant?

A: Yes, all listed substitutes maintain ROHS3 compliance, meeting environmental and regulatory requirements equivalent to the original part.

Q: Which substitute provides additional memory for data storage?

A: AB0805-T3 includes 256B SRAM and ISL12020MIRZ-T includes 128B SRAM, enabling local data buffering beyond basic timekeeping functions.

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