PCF2129T/2,518 Equivalent & Substitute Parts

Part Overview

The PCF2129T/2,518 is a Real Time Clock (RTC) IC with Clock/Calendar functionality, manufactured by NXP USA Inc. This 16-SOIC surface mount device operates across a wide supply voltage range of 1.8V to 4.2V and features I2C/2-Wire Serial interface communication. The part is currently in Active product status with ROHS3 compliance and full inventory availability. Substitute parts are identified when design requirements necessitate alternative packaging formats, different supply voltage ranges, or specific feature sets while maintaining core RTC functionality and I2C interface compatibility.

Key Parameters

Parameter	PCF2129T/2,518
Manufacturer	NXP USA Inc.
Package / Case	16-SOIC (0.295", 7.50mm Width)
Interface	I2C, 2-Wire Serial
Voltage - Supply	1.8V ~ 4.2V
Voltage - Supply, Battery	1.8V ~ 4.2V
Current - Timekeeping (Max)	1.5µA @ 3.3V
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, TCXO/Crystal, Watchdog Timer
RoHS Status	ROHS3 Compliant
Product Status	Active

Substitute Part Grouping Explanation

Substitute parts for the PCF2129T/2,518 are grouped based on the following substitution criteria:

Primary Compatibility Parameters:

Interface: I2C, 2-Wire Serial (mandatory match)
Operating Temperature: -40°C ~ 85°C (mandatory match)
Date/Time Format: YY-MM-DD-dd and HH:MM:SS (12/24 hr) (mandatory match)
RoHS Status: ROHS3 Compliant (mandatory match)
Product Status: Active (mandatory match)

Secondary Compatibility Parameters (allowable variation):

Package / Case: Alternative surface mount packages acceptable (16-SOIC, 8-SOIC, 8-TSSOP)
Voltage - Supply: Range must encompass or overlap with 1.8V ~ 4.2V
Current - Timekeeping: Lower values preferred; higher values acceptable if within operational limits
Features: Core features (Alarm, Leap Year, Square Wave Output) required; additional features acceptable

Substitutes are organized by package type and voltage compatibility to facilitate design flexibility while maintaining functional equivalence.

Parameter Comparison

Part Number	Manufacturer	Package / Case	Interface	Voltage - Supply	Voltage - Supply, Battery	Current - Timekeeping (Max)	Operating Temperature	Time Format	Date Format	RoHS Status	Product Status
PCF2129T/2,518	NXP USA Inc.	16-SOIC (0.295", 7.50mm Width)	I2C, 2-Wire Serial	1.8V ~ 4.2V	1.8V ~ 4.2V	1.5µA @ 3.3V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS1338C-3#	Analog Devices Inc./Maxim Integrated	16-SOIC (0.295", 7.50mm Width)	I2C, 2-Wire Serial	2.7V ~ 5.5V	1.3V ~ 3.7V	200µA @ 3.3V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS1338U-18+T&R	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)	I2C, 2-Wire Serial	1.71V ~ 5.5V	1.3V ~ 3.7V	100µA @ 1.89V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS1307ZN+	Analog Devices Inc./Maxim Integrated	8-SOIC (0.154", 3.90mm Width)	I2C, 2-Wire Serial	4.5V ~ 5.5V	2V ~ 4.6V	200µA @ 5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS1308U-33+	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)	I2C, 2-Wire Serial	3V ~ 5.5V	1.3V ~ 5.5V	125µA ~ 200µA @ 3V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS1337U+T&R	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)	I2C, 2-Wire Serial	1.8V ~ 5.5V	Not specified	0.6µA @ 1.3V ~ 1.8V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS1339AU+T	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)	I2C, 2-Wire Serial	1.71V ~ 5.5V	1.3V ~ 3.7V	200µA @ 1.71V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
BQ32002DR	Texas Instruments	8-SOIC (0.154", 3.90mm Width)	I2C, 2-Wire Serial	3V ~ 3.6V	1.4V ~ 3.6V	65µA @ 3.3V	-40°C ~ 85°C	HH:MM:SS (24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
1339-31DVGI8	Renesas Electronics Corporation	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)	I2C, 2-Wire Serial	3.3V ~ 5.5V	1.3V ~ 3.7V	200µA @ 3.63V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active
DS3231MZ+	Analog Devices Inc./Maxim Integrated	8-SOIC (0.154", 3.90mm Width)	I2C, 2-Wire Serial	2.3V ~ 5.5V	2.3V ~ 5.5V	130µA ~ 200µA @ 3.63V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	YY-MM-DD-dd	ROHS3 Compliant	Active

Engineering Selection Recommendations

All listed substitute parts maintain Active product status and ROHS3 compliance, ensuring long-term availability and regulatory alignment with the PCF2129T/2,518.

For 16-SOIC Package Compatibility (Direct Footprint Match): DS1338C-3# is the primary substitute when 16-SOIC package retention is required. Supply voltage range extends to 5.5V, accommodating broader system designs. Current consumption increases to 200µA at 3.3V, which may impact battery-backed applications compared to the PCF2129T/2,518 at 1.5µA.

For Compact Packaging (8-TSSOP/8-MSOP): DS1338U-18+T&R, DS1308U-33+, DS1337U+T&R, DS1339AU+T, and 1339-31DVGI8 offer reduced footprint in 8-TSSOP/8-MSOP packages. DS1337U+T&R provides the lowest timekeeping current at 0.6µA within the 1.8V ~ 5.5V supply range, optimizing battery-backed operation. DS1338U-18+T&R operates from 1.71V, closely matching the PCF2129T/2,518 lower voltage threshold.

For 8-SOIC Package: DS1307ZN+, BQ32002DR, and DS3231MZ+ provide 8-SOIC alternatives. BQ32002DR operates within the narrowest supply range (3V ~ 3.6V) and delivers the lowest timekeeping current at 65µA. DS3231MZ+ extends supply voltage to 2.3V ~ 5.5V, providing maximum flexibility for diverse power architectures.

Voltage Compatibility Considerations: The PCF2129T/2,518 operates from 1.8V ~ 4.2V. DS1337U+T&R (1.8V ~ 5.5V) and DS1338U-18+T&R (1.71V ~ 5.5V) provide the closest voltage envelope overlap. BQ32002DR (3V ~ 3.6V) is suitable only for systems with fixed 3.3V supplies. DS1307ZN+ (4.5V ~ 5.5V) is incompatible with the PCF2129T/2,518 voltage range and should not be selected for direct substitution in low-voltage applications.

Frequently Asked Questions (FAQ)

Q: Can DS1338C-3# directly replace PCF2129T/2,518 without PCB modification?

A: Yes. Both devices use 16-SOIC (0.295", 7.50mm Width) packaging with identical footprints. I2C interface pinouts are compatible. However, verify that your system power supply accommodates the DS1338C-3# minimum voltage of 2.7V, as the PCF2129T/2,518 operates from 1.8V. Timekeeping current increases from 1.5µA to 200µA at 3.3V, which may reduce battery backup duration in low-power applications.

Q: Which substitute offers the lowest power consumption for battery-backed timekeeping?

A: DS1337U+T&R provides the lowest timekeeping current at 0.6µA within the 1.3V ~ 1.8V range, outperforming the PCF2129T/2,518 at 1.5µA. However, DS1337U+T&R uses 8-TSSOP packaging, requiring PCB redesign. For 16-SOIC retention, DS1338C-3# at 200µA represents a trade-off between footprint compatibility and power efficiency.

Q: Is BQ32002DR suitable for 1.8V operation like the PCF2129T/2,518?

A: No. BQ32002DR operates from 3V ~ 3.6V minimum, making it incompatible with the PCF2129T/2,518 voltage range of 1.8V ~ 4.2V. Select BQ32002DR only for systems with fixed 3.3V supplies where the narrower voltage range is acceptable.

Q: What is the key difference between DS1338U-18+T&R and DS1339AU+T?

A: Both use 8-TSSOP packaging and I2C interface. DS1338U-18+T&R operates from 1.71V ~ 5.5V with 100µA timekeeping current at 1.89V. DS1339AU+T operates from 1.71V ~ 5.5V with 200µA timekeeping current and includes a Trickle-Charger feature. Select DS1338U-18+T&R for lower power consumption; select DS1339AU+T if trickle-charging capability is required.

Q: Can I use DS1307ZN+ as a substitute for the PCF2129T/2,518?

A: No. DS1307ZN+ operates from 4.5V ~ 5.5V, which does not overlap with the PCF2129T/2,518 range of 1.8V ~ 4.2V. This part is incompatible for direct substitution in low-voltage applications. Use DS1307ZN+ only in systems with 5V power supplies where the PCF2129T/2,518 cannot be used.

Q: Does 1339-31DVGI8 support 12-hour time format like the PCF2129T/2,518?

A: Yes. 1339-31DVGI8 supports HH:MM:SS (12/24 hr) time format, matching the PCF2129T/2,518 functionality. It operates from 3.3V ~ 5.5V with 200µA timekeeping current and uses 8-TSSOP packaging, requiring PCB redesign if footprint change is acceptable.

Q: Which substitute parts maintain the same 16-SOIC package as the PCF2129T/2,518?

A: Only DS1338C-3# uses the 16-SOIC (0.295", 7.50mm Width) package. All other substitutes use either 8-SOIC or 8-TSSOP packages, requiring PCB layout modifications. If package retention is mandatory, DS1338C-3# is the only option.

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