PT7C43390LEX Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The PT7C43390LEX is an active-status Real Time Clock (RTC) IC manufactured by Diodes Incorporated, designed for clock/calendar applications requiring I2C 2-Wire Serial interface. This 8-MSOP surface mount device operates across 1.3V to 5.5V supply range with ultra-low timekeeping current of 0.65µA to 0.7µA at 3V to 5V. The device includes alarm functionality, leap year support, and square wave output capability. Equivalent and substitute parts are identified based on matching functional parameters: I2C interface, clock/calendar operation, 12/24-hour time format, YY-MM-DD-dd date format, -40°C to 85°C operating temperature range, and surface mount packaging compatibility.

Key Parameters

Parameter	PT7C43390LEX
Manufacturer	Diodes Incorporated
Part Number	PT7C43390LEX
Product Status	Active
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Voltage Supply Range	1.3V ~ 5.5V
Current - Timekeeping (Max)	0.65µA ~ 0.7µA @ 3V ~ 5V
Operating Temperature	-40°C ~ 85°C
Package / Case	8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Mounting Type	Surface Mount
Features	Alarm, Leap Year, Square Wave Output
RoHS Status	ROHS3 Compliant
MSL Rating	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the PT7C43390LEX are grouped based on the following critical parameters that determine functional compatibility:

Primary Substitution Criteria:

Interface type: I2C, 2-Wire Serial
Device type: Clock/Calendar RTC IC
Time format support: HH:MM:SS (12/24 hr)
Date format support: YY-MM-DD-dd
Operating temperature range: -40°C to 85°C minimum
Supply voltage overlap: Minimum 1.3V to 5.5V range or compatible subset
Mounting type: Surface Mount
RoHS3 compliance

Secondary Compatibility Factors:

Package form factor (8-MSOP, 8-TSSOP, 8-SOIC, or module variants)
Timekeeping current consumption
Feature set (Alarm, Leap Year, Square Wave Output)
Product status (Active preferred; Not For New Designs acceptable with justification)

Substitutes are presented in two categories: direct pin-compatible alternatives and functional equivalents with different package footprints.

Parameter Comparison

Parameter	PT7C43390LEX	S-35390A-T8T1G	S-35390A-T8T1U	1337AGDVGI	1338-31DCGI	AB-RTCMC-32.768KHZ-B5GA-S3-T	BQ32000DR	BU9873NUX-TTR	DS1308U-3+	DS1338C-3#	DS1339U-3+
Manufacturer	Diodes Inc.	ABLIC Inc.	ABLIC Inc.	Renesas	Renesas	Abracon LLC	Texas Instruments	Rohm Semiconductor	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim
Product Status	Active	Active	Active	Active	Active	Active	Active	Not For New Designs	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	I2C, 2-Wire	I2C, 2-Wire
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 (12/24 hr)	HH:MM:SS (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)	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	1.3V ~ 5.5V	1.3V ~ 5.5V	1.3V ~ 5.5V	1.8V ~ 5.5V	3.3V ~ 5.5V	1.2V ~ 5.5V	3V ~ 3.6V	1.8V ~ 5.5V	2.7V ~ 5.5V	2.7V ~ 5.5V	2.7V ~ 5.5V
Current - Timekeeping (Max)	0.65µA ~ 0.7µA @ 3V ~ 5V	0.93µA ~ 1.1µA @ 3V ~ 5V	14µA ~ 30µA @ 3V ~ 5V	0.3µA @ 1.3V ~ 1.8V	5µA @ 3.63V ~ 5.5V	0.45µA ~ 0.55µA @ 2V ~ 5V	100µA @ 3.3V	1µA ~ 1.35µA @ 3V ~ 5.5V	Not specified	200µA @ 3.3V	150µA @ 3.3V
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	8-MSOP (0.118", 3.00mm)	8-TSSOP (0.173", 4.40mm)	8-TSSOP (0.173", 4.40mm)	8-MSOP (0.118", 3.00mm)	8-SOIC (0.154", 3.90mm)	10-SMD Module	8-SOIC (0.154", 3.90mm)	8-UFDFN Exposed Pad	8-MSOP (0.118", 3.00mm)	16-SOIC (0.295", 7.50mm)	8-MSOP (0.118", 3.00mm)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Features	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year	Alarm, Leap Year	Alarm, Leap Year, Square Wave Output	Leap Year, NVSRAM, Square Wave Output	Alarm, Leap Year, Square Wave Output	Leap Year, Square Wave Output, Trickle-Charger	Alarm, Leap Year	Leap Year, NVSRAM, Square Wave Output	Leap Year, NVSRAM, Square Wave Output	Alarm, Leap Year, Square Wave Output, Trickle-Charger
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Direct Pin-Compatible Substitutes (8-MSOP Package):

The 1337AGDVGI (Renesas) and DS1339U-3+ (Analog Devices/Maxim) maintain the same 8-MSOP footprint as the PT7C43390LEX. The 1337AGDVGI offers superior low-voltage performance with 0.3µA timekeeping current at 1.3V to 1.8V, though it requires minimum 1.8V supply. The DS1339U-3+ includes trickle-charger functionality and operates from 2.7V to 5.5V with 150µA timekeeping current. Both are active-status products with ROHS3 compliance and MSL-1 ratings.

Functional Equivalents with Package Variations:

The S-35390A-T8T1G and S-35390A-T8T1U (ABLIC Inc.) provide I2C clock/calendar functionality in 8-TSSOP package (0.173", 4.40mm width). The S-35390A-T8T1G maintains 0.93µA to 1.1µA timekeeping current comparable to the main part, while the S-35390A-T8T1U exhibits higher consumption at 14µA to 30µA. Both support 1.3V to 5.5V supply range and are active-status products.

The AB-RTCMC-32.768KHZ-B5GA-S3-T (Abracon LLC) is a 10-SMD module variant offering the lowest timekeeping current at 0.45µA to 0.55µA across 1.2V to 5.5V supply range. This module format provides integrated crystal oscillator functionality.

Alternative Packages for Layout Flexibility:

The BQ32000DR (Texas Instruments) and DS1338C-3# (Analog Devices/Maxim) use 8-SOIC and 16-SOIC packages respectively. The BQ32000DR operates within narrower 3V to 3.6V supply range with 100µA timekeeping current and includes trickle-charger support. The DS1338C-3# provides 56B NVSRAM with 200µA timekeeping current in a larger 16-SOIC footprint.

Legacy Consideration:

The BU9873NUX-TTR (Rohm Semiconductor) carries "Not For New Designs" status and should be used only for legacy system maintenance or replacement scenarios. It operates from 1.8V to 5.5V with 1µA to 1.35µA timekeeping current in 8-UFDFN package.

All substitute parts maintain ROHS3 compliance and -40°C to 85°C operating temperature range. Selection should prioritize active-status products (1337AGDVGI, S-35390A variants, AB-RTCMC module, BQ32000DR, DS1308U-3+, DS1338C-3#, DS1339U-3+) for new designs.

Frequently Asked Questions (FAQ)

Q: Can S-35390A-T8T1G replace PT7C43390LEX directly on the PCB?

A: The S-35390A-T8T1G maintains I2C interface, clock/calendar functionality, and -40°C to 85°C operating range. However, the package differs: S-35390A uses 8-TSSOP (0.173", 4.40mm width) versus PT7C43390LEX 8-MSOP (0.118", 3.00mm width). PCB footprint redesign is required. Electrical parameters are compatible within the 1.3V to 5.5V supply range.

Q: What is the difference between S-35390A-T8T1G and S-35390A-T8T1U?

A: Both use identical 8-TSSOP package and support 1.3V to 5.5V supply. The primary difference is timekeeping current: S-35390A-T8T1G consumes 0.93µA to 1.1µA at 3V to 5V, while S-35390A-T8T1U consumes 14µA to 30µA. For battery-backed applications requiring ultra-low power, S-35390A-T8T1G is preferred. Packaging differs: S-35390A-T8T1G is Cut Tape & Digi-Reel; S-35390A-T8T1U is Tape & Reel.

Q: Is the 1337AGDVGI suitable for 1.3V supply applications?

A: No. The 1337AGDVGI minimum supply voltage is 1.8V, not 1.3V. The PT7C43390LEX supports 1.3V to 5.5V. For applications requiring 1.3V operation, use PT7C43390LEX, S-35390A variants, or AB-RTCMC-32.768KHZ-B5GA-S3-T module.

Q: Does the AB-RTCMC-32.768KHZ-B5GA-S3-T module include the crystal oscillator?

A: Yes. The AB-RTCMC module is a 10-SMD integrated assembly including the RTC IC and 32.768 kHz crystal. This eliminates the need for external crystal component placement, reducing PCB area and component count compared to discrete IC solutions.

Q: Can DS1338C-3# be used as a drop-in replacement?

A: No. The DS1338C-3# uses 16-SOIC package (0.295", 7.50mm width) versus PT7C43390LEX 8-MSOP (0.118", 3.00mm). Significant PCB layout changes are required. However, it provides additional 56B NVSRAM storage and maintains I2C interface compatibility. Supply range is 2.7V to 5.5V, which does not cover the 1.3V to 1.8V window of the main part.

Q: Why is BU9873NUX-TTR marked "Not For New Designs"?

A: The BU9873NUX-TTR carries legacy status from Rohm Semiconductor. While functionally compatible with I2C clock/calendar operation and -40°C to 85°C range, it should be reserved for existing product maintenance or replacement of failed units in fielded systems. New designs should select from active-status alternatives.

Q: What is the MSL rating significance for these RTC ICs?

A: Moisture Sensitivity Level (MSL) indicates the maximum time a component can be exposed to ambient conditions (30°C, 85% relative humidity) before soldering. MSL-1 (Unlimited) components like PT7C43390LEX, S-35390A variants, and most substitutes have no time restriction. The 1337AGDVGI carries MSL-3 (168 hours), requiring controlled storage and handling within 168 hours of package opening before reflow soldering.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance, matching the PT7C43390LEX environmental certification status.

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