RTC-72423A Equivalent & Substitute Parts

Part Overview

The RTC-72423A is a Real Time Clock (RTC) IC with Clock/Calendar functionality manufactured by EPSON in a 24-SOIC package. This part operates across a 4.5V to 5.5V supply range and maintains timekeeping at 5µA to 10µA current draw. The device supports 12/24-hour time format with leap year capability and parallel interface communication.

The RTC-72423A is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain system functionality in legacy applications, support ongoing production requirements, or transition to active alternatives with compatible electrical and mechanical characteristics.

Key Parameters

Parameter	RTC-72423A
Manufacturer	EPSON
Package / Case	24-SOIC (0.311", 7.90mm Width)
Mounting Type	Surface Mount
Voltage - Supply	4.5V ~ 5.5V
Current - Timekeeping (Max)	5µA ~ 10µA @ 2V ~ 5V
Operating Temperature	-40°C ~ 85°C
Time Format	HH:MM:SS (12/24 hr)
Interface	Parallel
Features	Leap Year
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the RTC-72423A is determined by the following critical parameters:

Electrical Compatibility:

Supply voltage range must overlap or encompass 4.5V ~ 5.5V
Time format must support 12/24-hour operation
Parallel interface requirement
Operating temperature range must cover -40°C ~ 85°C or be compatible with application requirements

Mechanical Compatibility:

Surface mount package with pin-compatible or functionally equivalent footprint
24-pin configuration preferred for direct replacement

Regulatory Compliance:

ROHS3 compliance maintained

Substitute parts are grouped into two categories:

Category 1: Direct Package Compatibility (24-SOIC)

DS17285SN-5+ (Analog Devices Inc./Maxim Integrated): 24-SOIC package, 4.5V ~ 5.5V supply, -40°C ~ 85°C operating range, parallel interface, 12/24-hour format

Category 2: Alternative Package Surface Mount (28-pin and smaller form factors)

BQ4845S-A4TR (Texas Instruments): 28-SOIC package, 4.75V ~ 5.5V supply, parallel interface, 12/24-hour format
DS12885Q+ and DS12885QN+ (Analog Devices Inc./Maxim Integrated): 28-LCC package, 4.5V ~ 5.5V supply, parallel interface, 12/24-hour format, enhanced feature set

Category 3: Module-Based Alternatives (Through-Hole and PowerCap packages)

DS1554W-120IND+ (Analog Devices Inc./Maxim Integrated): 32-DIP module, 2.97V ~ 3.63V supply, 32KB memory
DS1554WP-120+ (Analog Devices Inc./Maxim Integrated): 34-PowerCap module, 2.97V ~ 3.63V supply, 32KB memory
DS1556-70+ (Analog Devices Inc./Maxim Integrated): 32-DIP module, 4.5V ~ 5.5V supply, 128KB memory
DS1744P-70+ (Analog Devices Inc./Maxim Integrated): 34-PowerCap module, 4.5V ~ 5.5V supply, 32KB memory

Category 4: Compact Surface Mount Alternatives (24-TSSOP)

DS1685E-3+ (Analog Devices Inc./Maxim Integrated): 24-TSSOP package, 2.7V ~ 3.7V supply, 0°C ~ 70°C operating range
DS1685EN-3+T&R (Analog Devices Inc./Maxim Integrated): 24-TSSOP package, 2.7V ~ 3.7V supply, -40°C ~ 85°C operating range

Parameter Comparison

Part Number	Manufacturer	Package / Case	Voltage - Supply	Operating Temperature	Time Format	Interface	Current - Timekeeping (Max)	Product Status
RTC-72423A	EPSON	24-SOIC (0.311", 7.90mm)	4.5V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	Parallel	5µA ~ 10µA @ 2V ~ 5V	Obsolete
DS17285SN-5+	Analog Devices Inc./Maxim Integrated	24-SOIC (0.295", 7.50mm)	4.5V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	Parallel	3mA @ 4.5V ~ 5.5V	Active
BQ4845S-A4TR	Texas Instruments	28-SOIC (0.295", 7.50mm)	4.75V ~ 5.5V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Parallel	1.5mA (Typ) @ 4.5V ~ 5.5V	Active
DS12885Q+	Analog Devices Inc./Maxim Integrated	28-LCC (J-Lead)	4.5V ~ 5.5V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Parallel	15mA @ 4.5V ~ 5.5V	Active
DS12885QN+	Analog Devices Inc./Maxim Integrated	28-LCC (J-Lead)	4.5V ~ 5.5V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	Parallel	15mA @ 4.5V ~ 5.5V	Active
DS1554W-120IND+	Analog Devices Inc./Maxim Integrated	32-DIP Module (0.600", 15.24mm)	2.97V ~ 3.63V	-40°C ~ 85°C	HH:MM:SS (24 hr)	Parallel	4mA @ 3.3V	Active
DS1554WP-120+	Analog Devices Inc./Maxim Integrated	34-PowerCap™ Module	2.97V ~ 3.63V	0°C ~ 70°C	HH:MM:SS (24 hr)	Parallel	4mA @ 3.3V	Active
DS1556-70+	Analog Devices Inc./Maxim Integrated	32-DIP Module (0.600", 15.24mm)	4.5V ~ 5.5V	0°C ~ 70°C	HH:MM:SS (24 hr)	Parallel	6mA @ 5V	Active
DS1685E-3+	Analog Devices Inc./Maxim Integrated	24-TSSOP (0.173", 4.40mm)	2.7V ~ 3.7V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Parallel	2mA @ 3V	Active
DS1685EN-3+T&R	Analog Devices Inc./Maxim Integrated	24-TSSOP (0.173", 4.40mm)	2.7V ~ 3.7V	-40°C ~ 85°C	HH:MM:SS (12/24 hr)	Parallel	2mA @ 3V	Active
DS1744P-70+	Analog Devices Inc./Maxim Integrated	34-PowerCap™ Module	4.5V ~ 5.5V	0°C ~ 70°C	HH:MM:SS (24 hr)	Parallel	4mA @ 5V	Active

Engineering Selection Recommendations

For Direct Replacement (Minimum Design Changes):

DS17285SN-5+ is the primary substitute for RTC-72423A. Both devices operate at 4.5V ~ 5.5V, support -40°C ~ 85°C temperature range, maintain 12/24-hour time format, and use parallel interface. The 24-SOIC package footprint is compatible with minor PCB layout adjustments. DS17285SN-5+ is active product status with ROHS3 compliance, ensuring long-term availability and regulatory alignment.

For Extended Temperature Range Applications:

DS12885QN+ maintains the full -40°C ~ 85°C operating temperature range and 4.5V ~ 5.5V supply voltage. The 28-LCC package requires PCB redesign but provides enhanced features including alarm, daylight savings, and square wave output. Product status is active with ROHS3 compliance.

For Compact Form Factor Applications:

DS1685EN-3+T&R offers the smallest footprint (24-TSSOP) with -40°C ~ 85°C operating range and 12/24-hour format support. Supply voltage operates at 2.7V ~ 3.7V, requiring power supply adjustment. Product status is active with ROHS3 compliance.

For 5V Supply with Extended Memory:

DS1556-70+ operates at 4.5V ~ 5.5V with 128KB memory in a 32-DIP module package. Operating temperature range is 0°C ~ 70°C. This option suits applications requiring larger memory capacity with through-hole mounting. Product status is active with ROHS3 compliance.

For 3.3V Supply Applications:

DS1554W-120IND+ and DS1554WP-120+ operate at 2.97V ~ 3.63V with 32KB memory. Both support -40°C ~ 85°C (DIP module) or 0°C ~ 70°C (PowerCap module) operating ranges. These options are suitable for 3.3V system architectures. Product status is active with ROHS3 compliance.

All substitute parts maintain ROHS3 compliance and are classified as active products, ensuring regulatory compliance and supply chain continuity.

Frequently Asked Questions (FAQ)

Q: Can DS17285SN-5+ directly replace RTC-72423A without PCB modifications?

A: DS17285SN-5+ uses a 24-SOIC package with 0.295" width compared to RTC-72423A's 0.311" width. Pin spacing and pitch are compatible, but PCB footprint verification is required. Electrical parameters (4.5V ~ 5.5V supply, -40°C ~ 85°C operating range, 12/24-hour format, parallel interface) are fully compatible.

Q: What is the primary difference between DS12885Q+ and DS12885QN+?

A: Both devices use 28-LCC package and 4.5V ~ 5.5V supply voltage. DS12885QN+ supports -40°C ~ 85°C operating temperature range, while DS12885Q+ operates at 0°C ~ 70°C. For applications requiring extended low-temperature operation, DS12885QN+ is the appropriate selection.

Q: Why do DS1554 and DS1556 modules operate at different supply voltages?

A: DS1554 series (32KB memory) operates at 2.97V ~ 3.63V (3.3V nominal), while DS1556-70+ operates at 4.5V ~ 5.5V (5V nominal). Supply voltage selection depends on system architecture. DS1554 modules are suitable for 3.3V systems; DS1556-70+ is suitable for 5V systems.

Q: Can DS1685E-3+ be used in applications requiring -40°C operation?

A: DS1685E-3+ operates at 0°C ~ 70°C. For applications requiring -40°C ~ 85°C operation, DS1685EN-3+T&R is the appropriate selection. Both use 24-TSSOP package and 2.7V ~ 3.7V supply voltage.

Q: What are the package considerations when substituting RTC-72423A with BQ4845S-A4TR?

A: BQ4845S-A4TR uses 28-SOIC package (28 pins) compared to RTC-72423A's 24-SOIC package (24 pins). PCB redesign is required. Electrical compatibility exists at 4.5V ~ 5.5V supply range and parallel interface. Operating temperature range is 0°C ~ 70°C, which does not cover the full -40°C ~ 85°C range of the original part.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance, ensuring regulatory alignment with environmental and hazardous substance restrictions.

Q: What is the inventory status for substitute parts?

A: All substitute parts are classified as active products with confirmed inventory availability ranging from 724 to 1575 pieces in stock, ensuring supply chain continuity for production requirements.

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