PCF2127AT/1,518 Equivalent & Substitute Parts

Part Overview

The PCF2127AT/1,518 is a Real Time Clock (RTC) IC with Clock/Calendar functionality manufactured by NXP USA Inc. This device integrates a 512-byte I2C interface, 2-wire serial communication, and comprehensive timekeeping features including alarm, leap year support, square wave output, SRAM, TCXO/crystal oscillator, and watchdog timer capabilities. The part is currently classified as obsolete, which necessitates identification of active equivalent and substitute components for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across core electrical and mechanical parameters while meeting current product availability and compliance standards.

Key Parameters

Parameter	PCF2127AT/1,518
Manufacturer	NXP USA Inc.
Product Status	Obsolete
Type	Clock/Calendar
Memory Size	512B
Interface	I2C, 2-Wire Serial
Voltage Supply Range	1.8V ~ 4.2V
Voltage Supply Battery	1.8V ~ 4.2V
Current Timekeeping (Max)	1.5µA @ 3.3V
Operating Temperature	-40°C ~ 85°C
Package / Case	20-SOIC (0.295", 7.50mm Width)
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year, Square Wave Output, SRAM, TCXO/Crystal, Watchdog Timer
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	3 (168 Hours)

Substitute Part Grouping Explanation

Substitute parts for the PCF2127AT/1,518 are evaluated based on the following critical parameters that determine functional and mechanical compatibility:

Primary Substitution Criteria:

Interface type (I2C, 2-Wire Serial required)
Time and date format support (HH:MM:SS 12/24 hr; YY-MM-DD-dd)
Operating temperature range (-40°C ~ 85°C minimum)
Supply voltage compatibility (overlap with 1.8V ~ 4.2V range)
RTC functionality with clock/calendar capability
Surface mount technology
RoHS3 compliance

Secondary Considerations:

Memory size (512B preferred for feature parity)
Package form factor (20-SOIC preferred; smaller packages acceptable with functional equivalence)
Current consumption in timekeeping mode
Feature set (alarm, leap year, watchdog timer support)

Substitutes are grouped into two categories: direct NXP alternatives maintaining identical package and feature sets, and manufacturer-recommended alternatives from Renesas Electronics, Abracon LLC, and Analog Devices Inc./Maxim Integrated that meet core electrical and interface requirements while offering different package options and enhanced specifications.

Parameter Comparison

Parameter	PCF2127AT/1,518	PCF2127AT/2Y	1337GDCGI8	1337GDVGI	AB1805-T3	DS1308U-3+	DS1339AU+	DS1340Z-33+	DS1388Z-3+T&R	DS3231MZ+	DS3231SN#
Manufacturer	NXP USA Inc.	NXP USA Inc.	Renesas Electronics	Renesas Electronics	Abracon LLC	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active
Type	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar	Clock/Calendar
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	I2C, 2-Wire Serial	I2C, 2-Wire Serial
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:hh	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (24 hr)	HH:MM:SS:hh (12/24 hr)	HH:MM:SS (12/24 hr)	HH:MM:SS (12/24 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	YY-MM-DD-dd	YY-MM-DD-dd
Voltage Supply Range	1.8V ~ 4.2V	1.8V ~ 4.2V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.7V ~ 3.6V	2.7V ~ 5.5V	1.71V ~ 5.5V	2.97V ~ 5.5V	2.7V ~ 3.3V	2.3V ~ 5.5V	2.3V ~ 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	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	20-SOIC (0.295", 7.50mm)	20-SOIC (0.295", 7.50mm)	8-SOIC (0.154", 3.90mm)	8-TSSOP, 8-MSOP (0.118", 3.00mm)	16-VFQFN Exposed Pad	8-TSSOP, 8-MSOP (0.118", 3.00mm)	8-TSSOP, 8-MSOP (0.118", 3.00mm)	8-SOIC (0.154", 3.90mm)	8-SOIC (0.154", 3.90mm)	8-SOIC (0.154", 3.90mm)	16-SOIC (0.295", 7.50mm)
Memory Size	512B	512B	—	—	256B	56B	—	—	512B	—	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	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	Surface Mount	Surface Mount

Engineering Selection Recommendations

Direct NXP Replacement (Preferred for Pin-Compatible Migration):

PCF2127AT/2Y is the primary direct substitute for PCF2127AT/1,518. Both parts share identical electrical specifications, package form factor (20-SOIC), memory capacity (512B), and feature sets. The critical distinction is product status: PCF2127AT/2Y maintains active production status with significantly higher inventory availability (20,400 pcs vs. 1,002 pcs). This part requires no design modification and provides seamless functional equivalence. Packaging format differs (Cut Tape & Digi-Reel® vs. standard packaging), but electrical and mechanical characteristics remain unchanged.

Manufacturer-Recommended Alternatives (For Design Flexibility):

Renesas Electronics 1337GDCGI8 and 1337GDVGI offer active production status with enhanced supply voltage range (1.8V ~ 5.5V) and superior timekeeping current efficiency (0.6µA @ 1.3V ~ 1.8V). These parts require PCB layout modification due to package downsizing (8-SOIC and 8-MSOP respectively) but maintain full I2C interface compatibility and core RTC functionality. Both devices support 12/24-hour time format and YY-MM-DD-dd date format with alarm and leap year features.

Abracon LLC AB1805-T3 provides the lowest timekeeping current consumption (0.17µA ~ 0.22µA @ 1.8V ~ 3V) and includes integrated trickle-charger and watchdog timer functionality. The 16-VFQFN package requires significant PCB redesign but offers compact footprint and 256B SRAM capacity. Supply voltage range (1.7V ~ 3.6V) is narrower than the main part but overlaps the critical 1.8V ~ 3.3V operating window.

Analog Devices Inc./Maxim Integrated DS3231 series (DS3231MZ+ in 8-SOIC and DS3231SN# in 16-SOIC) deliver active production status with integrated temperature-compensated crystal oscillator (TCXO) and extended supply voltage range (2.3V ~ 5.5V). These devices support alarm functionality and square wave output with enhanced frequency stability. DS3231SN# maintains the 16-SOIC package footprint, enabling direct PCB substitution with minimal layout changes.

DS1388Z-3+T&R combines 512B memory capacity with supervisor and watchdog timer functionality in 8-SOIC package. Supply voltage range (2.7V ~ 3.3V) is narrower than the main part but suitable for 3.3V systems. EEPROM integration provides additional non-volatile storage beyond standard SRAM.

All recommended substitutes maintain ROHS3 compliance and -40°C ~ 85°C operating temperature range, ensuring regulatory and thermal compatibility with the original PCF2127AT/1,518 specification.

Frequently Asked Questions (FAQ)

Q: Can PCF2127AT/2Y be used as a direct drop-in replacement for PCF2127AT/1,518?

A: Yes. PCF2127AT/2Y is electrically and mechanically identical to PCF2127AT/1,518. Both devices feature 20-SOIC packaging, 512B memory, I2C interface, and identical supply voltage range (1.8V ~ 4.2V). The only difference is product status (active vs. obsolete) and packaging format (Cut Tape & Digi-Reel® vs. standard). No design changes are required.

Q: What are the key differences between the 20-SOIC package options and the smaller 8-SOIC/8-MSOP alternatives?

A: Package size directly impacts PCB footprint and layout complexity. The 20-SOIC package (0.295" width) accommodates more pins and typically includes additional features like integrated crystal oscillator support. The 8-SOIC (0.154" width) and 8-MSOP (0.118" width) packages reduce board space but require PCB redesign. Electrical functionality remains compatible across all packages for core RTC operations.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance, matching the original PCF2127AT/1,518 specification. This ensures regulatory compatibility for applications requiring RoHS certification.

Q: Which substitute offers the lowest power consumption in timekeeping mode?

A: The Abracon LLC AB1805-T3 delivers the lowest timekeeping current at 0.17µA ~ 0.22µA @ 1.8V ~ 3V. The Renesas Electronics 1337GDCGI8 and 1337GDVGI follow closely at 0.6µA @ 1.3V ~ 1.8V. The original PCF2127AT/1,518 consumes 1.5µA @ 3.3V, making these alternatives suitable for ultra-low-power applications.

Q: Can I use DS1340Z-33+ as a substitute if my design operates at 24-hour time format only?

A: Yes. DS1340Z-33+ supports 24-hour time format (HH:MM:SS) and YY-MM-DD-dd date format, matching the core timekeeping requirements. However, this device does not support 12-hour format. If your application requires 12/24-hour flexibility, select alternatives that explicitly support both formats (PCF2127AT/2Y, 1337GDCGI8, 1337GDVGI, DS3231 series).

Q: What is the supply voltage overlap between PCF2127AT/1,518 and the recommended substitutes?

A: The original part operates at 1.8V ~ 4.2V. All substitutes support at least the 1.8V ~ 3.3V range, ensuring compatibility with standard 3.3V systems. For 5V applications, select DS1340Z-33+, DS1339AU+, DS1308U-3+, or DS3231 series, which support extended voltage ranges up to 5.5V.

Q: Does package downsizing from 20-SOIC to 8-SOIC affect I2C communication?

A: No. I2C interface functionality is independent of package size. Both 20-SOIC and 8-SOIC packages implement identical I2C protocol and pin configuration for serial communication. Package selection affects only PCB layout and physical footprint, not electrical communication characteristics.

Q: Which substitute provides the best feature parity with PCF2127AT/1,518?

A: PCF2127AT/2Y offers complete feature parity, including 512B memory, alarm, leap year, square wave output, SRAM, TCXO/crystal support, and watchdog timer. DS1388Z-3+T&R also provides 512B memory with supervisor and watchdog timer functionality, though in a smaller 8-SOIC package. Both maintain identical time/date format support.

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