PT7C43390WEX Equivalent & Substitute Parts

Part Overview

The PT7C43390WEX 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 ongoing system support and new design alternatives.

The PT7C43390WEX provides timekeeping with alarm capability, leap year support, and square wave output functionality. Its low supply voltage range (1.3V to 5.5V) and minimal timekeeping current consumption (0.65µA to 0.7µA at 3V to 5V) make it suitable for battery-backed and low-power applications.

Key Parameters

Parameter	PT7C43390WEX
Manufacturer	Diodes Incorporated
Product Status	Obsolete
Package / Case	8-SOIC (0.154", 3.90mm Width)
Interface	I2C, 2-Wire Serial
Voltage - Supply	1.3V ~ 5.5V
Current - Timekeeping (Max)	0.65µA ~ 0.7µA @ 3V ~ 5V
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
RoHS Status	ROHS3 Compliant
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution for the PT7C43390WEX is determined by the following critical parameters:

Interface Compatibility: I2C 2-Wire Serial protocol
Package Compatibility: 8-SOIC (0.154", 3.90mm Width) or functionally equivalent surface-mount packages
Voltage Supply Range: Minimum 1.3V support for low-power applications
Timekeeping Current: Low-power operation (typically under 1µA for timekeeping mode)
Time/Date Format: HH:MM:SS (12/24 hr) and YY-MM-DD-dd support
Core Features: Alarm, Leap Year, Square Wave Output
Operating Temperature: -40°C ~ 85°C range
Compliance: ROHS3 Compliant

Substitute parts are grouped into two categories:

Category A - Direct Package Match (8-SOIC, 0.154" width): Parts maintaining identical or near-identical package dimensions, enabling direct PCB footprint compatibility.

Category B - Functional Equivalents (Alternative Packages): Parts providing equivalent functionality with different package types (8-TSSOP, 10-SMD Module) that require PCB layout modification but maintain full electrical compatibility.

Parameter Comparison

Part Number	Manufacturer	Package	Voltage Supply	Timekeeping Current (Max)	Interface	Features	Product Status
PT7C43390WEX	Diodes Incorporated	8-SOIC (0.154", 3.90mm)	1.3V ~ 5.5V	0.65µA ~ 0.7µA @ 3V ~ 5V	I2C, 2-Wire Serial	Alarm, Leap Year, Square Wave Output	Obsolete
1337AGDCGI8	Renesas Electronics Corporation	8-SOIC (0.154", 3.90mm)	1.8V ~ 5.5V	0.3µA @ 1.3V ~ 1.8V	I2C, 2-Wire Serial	Alarm, Leap Year, Square Wave Output	Active
DS3232MZ+TRL	Analog Devices Inc./Maxim Integrated	8-SOIC (0.154", 3.90mm)	2.3V ~ 4.5V	175µA @ 2.3V ~ 4.5V	I2C, 2-Wire Serial	Alarm, Leap Year, Square Wave Output, SRAM (236B)	Active
DS1338U-18+T&R	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm)	1.71V ~ 5.5V	100µA @ 1.89V	I2C, 2-Wire Serial	Leap Year, NVSRAM (56B), Square Wave Output	Active
DS1338U-3+	Analog Devices Inc./Maxim Integrated	8-TSSOP, 8-MSOP (0.118", 3.00mm)	2.7V ~ 5.5V	200µA @ 3.3V	I2C, 2-Wire Serial	Leap Year, NVSRAM (56B), Square Wave Output	Active
ISL12026IVZ-T	Renesas Electronics Corporation	8-TSSOP (0.173", 4.40mm)	2.7V ~ 5.5V	10µA ~ 20µA @ 2.7V ~ 5.5V	I2C, 2-Wire Serial	Alarm, Leap Year	Active
BU9873F-GTE2	Rohm Semiconductor	8-SOIC (0.173", 4.40mm)	1.8V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	I2C, 2-Wire Serial	Alarm, Leap Year	Not For New Designs
AB-RTCMC-32.768KHZ-B5ZE-S3-T	Abracon LLC	10-SMD Module	1.2V ~ 5.5V	0.5µA @ 2V ~ 5V	I2C, 2-Wire Serial	Alarm, Leap Year, Square Wave Output	Active
DS1338C-18#	Analog Devices Inc./Maxim Integrated	16-SOIC (0.295", 7.50mm)	1.71V ~ 5.5V	100µA @ 1.89V	I2C, 2-Wire Serial	Leap Year, NVSRAM (56B), Square Wave Output	Active
DS1339C-33#T&R	Analog Devices Inc./Maxim Integrated	16-SOIC (0.295", 7.50mm)	2.97V ~ 5.5V	200µA @ 5.5V	I2C, 2-Wire Serial	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Active
DS3231M+	Analog Devices Inc./Maxim Integrated	16-SOIC (0.295", 7.50mm)	2.3V ~ 5.5V	130µA ~ 200µA @ 3.63V ~ 5.5V	I2C, 2-Wire Serial	Alarm, Leap Year, Square Wave Output	Active

Engineering Selection Recommendations

Primary Recommendation - Direct Package Replacement:

The 1337AGDCGI8 (Renesas Electronics Corporation) is the optimal direct substitute for the PT7C43390WEX. Both devices share identical 8-SOIC (0.154", 3.90mm Width) packaging, enabling direct PCB footprint compatibility without layout modification. The 1337AGDCGI8 is in active production status, ensuring long-term availability. It maintains full I2C 2-Wire Serial interface compatibility, supports 12/24-hour time format and YY-MM-DD-dd date format, and includes alarm, leap year, and square wave output features. The voltage supply range (1.8V ~ 5.5V) overlaps substantially with the original part, though the minimum voltage is slightly higher at 1.8V versus 1.3V. The 1337AGDCGI8 demonstrates superior timekeeping current efficiency at 0.3µA, reducing power consumption in battery-backed applications. ROHS3 compliance and unlimited moisture sensitivity level (MSL 1) match the original specification.

Secondary Recommendation - Low-Power Module Alternative:

The AB-RTCMC-32.768KHZ-B5ZE-S3-T (Abracon LLC) provides a complete RTC module solution in a 10-SMD package format. This integrated module approach eliminates external component requirements and delivers exceptional timekeeping current performance at 0.5µA @ 2V ~ 5V. The extended voltage supply range (1.2V ~ 5.5V) with dedicated battery supply support (1.8V ~ 5.5V) makes it suitable for ultra-low-power and battery-backed applications. Module-based implementation requires PCB layout modification but offers superior reliability through integrated design. Active production status and ROHS3 compliance ensure regulatory compliance and supply continuity.

Alternative for Higher Pin-Count Applications:

The DS1338U-18+T&R (Analog Devices Inc./Maxim Integrated) offers expanded functionality with 56 bytes of NVSRAM and is available in active production. While the 8-TSSOP package differs from the original 8-SOIC footprint, the smaller package dimensions (0.118", 3.00mm Width) may provide space advantages in compact designs. This part includes non-volatile static RAM for data storage beyond timekeeping functions. Voltage supply compatibility (1.71V ~ 5.5V) and operating temperature range (-40°C ~ 85°C) align with the original specification.

Not Recommended for New Designs:

The BU9873F-GTE2 (Rohm Semiconductor) carries a "Not For New Designs" status, indicating manufacturer discontinuation trajectory. While functionally compatible, this part should not be selected for new product development due to uncertain long-term availability.

Frequently Asked Questions (FAQ)

Q: Can the 1337AGDCGI8 replace the PT7C43390WEX directly on the PCB?

A: Yes. Both parts use identical 8-SOIC (0.154", 3.90mm Width) packaging. The footprint, pin spacing, and mounting requirements are identical, allowing direct substitution without PCB layout modification. Pin-to-pin compatibility must be verified against the respective datasheets to confirm signal assignment alignment.

Q: What is the minimum voltage difference between the PT7C43390WEX and substitute parts?

A: The PT7C43390WEX operates from 1.3V minimum, while most active substitutes (1337AGDCGI8, BU9873F-GTE2) specify 1.8V minimum. The AB-RTCMC-32.768KHZ-B5ZE-S3-T module extends to 1.2V minimum. For applications requiring operation below 1.8V, the Abracon module or DS1338U-18+T&R (1.71V minimum) are appropriate selections.

Q: Why do some substitute parts have higher timekeeping current consumption?

A: Timekeeping current varies based on internal circuit design, manufacturing process technology, and feature integration. Parts like DS3232MZ+TRL (175µA) and DS1338U-3+ (200µA) include additional functionality such as SRAM or NVSRAM, which increases standby current. For battery-backed applications prioritizing minimal power draw, the 1337AGDCGI8 (0.3µA) or AB-RTCMC-32.768KHZ-B5ZE-S3-T (0.5µA) are preferred.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts carry ROHS3 Compliant certification, matching the original PT7C43390WEX specification. This ensures regulatory compliance for applications subject to RoHS directives.

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

A: Both are 8-pin surface-mount packages but differ in physical dimensions and lead configuration. The 8-SOIC (0.154", 3.90mm Width) features gull-wing leads with wider spacing, while 8-TSSOP (0.118", 3.00mm Width) uses shrink-lead configuration with tighter pitch. TSSOP packages occupy less PCB area but require more precise assembly equipment. Direct footprint substitution between these packages is not possible without PCB redesign.

Q: Can the DS3232MZ+TRL be used as a drop-in replacement?

A: The DS3232MZ+TRL maintains the same 8-SOIC (0.154", 3.90mm Width) package as the PT7C43390WEX, enabling direct PCB footprint compatibility. However, the voltage supply range (2.3V ~ 4.5V) is narrower than the original part, making it unsuitable for applications requiring operation below 2.3V. Pin-level compatibility must be verified before implementation.

Q: What advantages does the AB-RTCMC-32.768KHZ-B5ZE-S3-T module offer over discrete IC solutions?

A: The Abracon module integrates the RTC IC with the 32.768 kHz crystal oscillator in a single 10-SMD package, eliminating the need for external crystal components and associated PCB space. This integrated approach reduces component count, simplifies assembly, and improves reliability by eliminating crystal-related failure modes. The module's extended voltage range (1.2V ~ 5.5V) and low timekeeping current (0.5µA) make it ideal for battery-powered applications.

Q: Is the DS1338 series suitable for applications requiring non-volatile memory?

A: Yes. The DS1338U-18+T&R and DS1338U-3+ variants include 56 bytes of NVSRAM (Non-Volatile Static RAM), allowing data retention during power loss. The original PT7C43390WEX does not include this feature. If non-volatile data storage is required, DS1338 variants provide this capability while maintaining I2C interface compatibility.

Q: What is the operating temperature range for all substitute parts?

A: All listed substitute parts maintain the -40°C ~ 85°C operating temperature range specified for the PT7C43390WEX, ensuring compatibility with industrial and extended-temperature applications.

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