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RTC-72423B Equivalent & Substitute Parts
Part Overview
The RTC-72423B is a Real Time Clock (RTC) IC with Clock/Calendar functionality manufactured by EPSON in a 24-SOIC surface mount package. This device provides parallel interface timing and calendar operations with leap year support, operating across a 4.5V to 5.5V supply range and -40°C to 85°C temperature span. The product is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support, maintenance, and new design implementations where legacy compatibility is required.
Substiute Parts
Key Parameters
| Parameter | RTC-72423B |
|---|---|
| Manufacturer | EPSON |
| Category | Clock/Timing |
| Type | Clock/Calendar |
| Interface | Parallel |
| Package / Case | 24-SOIC (0.311", 7.90mm Width) |
| Mounting Type | Surface Mount |
| Voltage - Supply | 4.5V ~ 5.5V |
| Time Format | HH:MM:SS (12/24 hr) |
| Date Format | YY-MM-DD-dd |
| Features | Leap Year |
| Operating Temperature | -40°C ~ 85°C |
| Current - Timekeeping (Max) | 5µA ~ 10µA @ 2V ~ 5V |
| Product Status | Obsolete |
| RoHS Status | RoHS non-compliant |
Substitute Part Grouping Explanation
Substitution for the RTC-72423B is determined by the following critical parameters:
Primary Compatibility Criteria:
- Parallel interface operation
- Clock/Calendar functionality with time and date tracking
- Supply voltage range compatibility (4.5V ~ 5.5V primary consideration)
- Operating temperature range (-40°C ~ 85°C preferred for extended industrial applications)
- Surface mount packaging (preferred for direct PCB replacement)
Substitution Logic: Substitute parts are grouped into two categories based on package compatibility and electrical characteristics:
-
Direct Surface Mount Substitutes (24-SOIC / 24-TSSOP): Parts maintaining the same or compatible surface mount package footprint, enabling direct PCB replacement with minimal layout modification.
-
Functional Equivalents (Through-Hole / Alternative Packages): Parts providing identical clock/calendar functionality with parallel interface but in different package types, requiring PCB redesign or adapter solutions.
The RTC-72423B operates at 4.5V ~ 5.5V with -40°C ~ 85°C temperature range. Substitute parts meeting these exact specifications are preferred. Parts with overlapping but not identical voltage or temperature ranges are listed with engineering notes for application-specific evaluation.
Parameter Comparison
| Parameter | RTC-72423B | DS12885+ | DS12C887+ | DS1501YZ+T&R | DS1554-70+ | DS1685EN-3+ | DS1685EN-5+ | DS1685EN-5+T&R | DS1685QN-3+ | DS17285S-5+ | DS17285S-5+T&R |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Manufacturer | EPSON | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated | Analog Devices Inc./Maxim Integrated |
| Type | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar | Clock/Calendar |
| Interface | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel | Parallel |
| Package / Case | 24-SOIC (0.311", 7.90mm) | 24-DIP (0.600", 15.24mm) | 24-DIP Module (0.600", 15.24mm) | 28-SOIC (0.295", 7.50mm) | 32-DIP Module (0.600", 15.24mm) | 24-TSSOP (0.173", 4.40mm) | 24-TSSOP (0.173", 4.40mm) | 24-TSSOP (0.173", 4.40mm) | 28-LCC (J-Lead) | 24-SOIC (0.295", 7.50mm) | 24-SOIC (0.295", 7.50mm) |
| Mounting Type | Surface Mount | Through Hole | Through Hole | Surface Mount | Through Hole | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount | Surface Mount |
| Voltage - Supply | 4.5V ~ 5.5V | 4.5V ~ 5.5V | 4.5V ~ 5.5V | 4.5V ~ 5.5V | 4.5V ~ 5.5V | 2.7V ~ 3.7V | 4.5V ~ 5.5V | 4.5V ~ 5.5V | 2.7V ~ 3.7V | 4.5V ~ 5.5V | 4.5V ~ 5.5V |
| Time Format | 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) | 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 |
| Features | Leap Year | Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output | Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output | Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K | Alarm, Leap Year, NVSRAM, Watchdog Timer, Y2K | Alarm, NVSRAM, Square Wave Output, Y2K | Alarm, NVSRAM, Square Wave Output, Y2K | Alarm, NVSRAM, Square Wave Output, Y2K | Alarm, NVSRAM, Square Wave Output, Y2K | Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output | Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output |
| Operating Temperature | -40°C ~ 85°C | 0°C ~ 70°C | 0°C ~ 70°C | 0°C ~ 70°C | 0°C ~ 70°C | -40°C ~ 85°C | -40°C ~ 85°C | -40°C ~ 85°C | -40°C ~ 85°C | 0°C ~ 70°C | 0°C ~ 70°C |
| Product Status | Obsolete | Active | Active | Active | Active | Active | Active | Active | Active | Active | Active |
| RoHS Status | RoHS non-compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant |
Engineering Selection Recommendations
Direct Surface Mount Replacement (Preferred):
DS17285S-5+ and DS17285S-5+T&R are the closest functional equivalents to the RTC-72423B. Both maintain 24-SOIC surface mount packaging, 4.5V ~ 5.5V supply voltage, and parallel interface operation. These parts are active products with ROHS3 compliance, providing modern manufacturing support and regulatory alignment. The DS17285S series includes enhanced features (Alarm, Daylight Savings, NVSRAM, Square Wave Output) while maintaining backward compatibility with legacy clock/calendar applications.
Extended Temperature Range Compatibility:
DS1685EN-5+ and DS1685EN-5+T&R operate across the full -40°C ~ 85°C temperature range matching the RTC-72423B, with 4.5V ~ 5.5V supply voltage. These parts are available in 24-TSSOP surface mount packages and are ROHS3 compliant. The narrower package footprint (0.173" vs 0.311") requires PCB layout verification but offers space optimization benefits.
Functional Equivalents (Through-Hole Packages):
DS12885+ and DS12C887+ provide full clock/calendar functionality with parallel interface in 24-DIP through-hole packages. These parts operate at 4.5V ~ 5.5V but are limited to 0°C ~ 70°C operating temperature. Selection of these parts requires PCB redesign and is suitable only for applications not requiring extended low-temperature operation.
Compliance Consideration:
All substitute parts listed are ROHS3 compliant, addressing regulatory requirements absent in the obsolete RTC-72423B. Applications subject to RoHS directives must transition to compliant alternatives.
Frequently Asked Questions (FAQ)
Q: Can DS17285S-5+ directly replace RTC-72423B on existing PCBs?
A: Yes. DS17285S-5+ maintains identical 24-SOIC surface mount package dimensions (0.295" width vs 0.311" for RTC-72423B), 4.5V ~ 5.5V supply voltage, and parallel interface pinout compatibility. Pin-for-pin verification against original schematic is required before implementation.
Q: What is the key difference between DS1685EN-5+ and DS1685EN-5+T&R?
A: Both parts are electrically identical. The difference is packaging format: DS1685EN-5+ is supplied in tube packaging, while DS1685EN-5+T&R is supplied in tape and reel format. Selection depends on assembly process requirements and volume quantities.
Q: Why do some substitutes have narrower operating temperature ranges?
A: DS12885+, DS12C887+, DS1501YZ+T&R, DS1554-70+, DS17285S-5+, and DS17285S-5+T&R are rated 0°C ~ 70°C, limiting use in applications requiring -40°C ~ 85°C operation. DS1685EN-3+, DS1685EN-5+, DS1685EN-5+T&R, and DS1685QN-3+ maintain the full -40°C ~ 85°C range and are preferred for industrial and automotive applications.
Q: Are all substitute parts RoHS compliant?
A: Yes. All listed substitute parts are ROHS3 compliant. The original RTC-72423B is RoHS non-compliant. Regulatory requirements may mandate transition to compliant alternatives regardless of functional equivalence.
Q: What packaging options are available for surface mount replacement?
A: Surface mount options include 24-SOIC (DS17285S-5+, DS17285S-5+T&R), 24-TSSOP (DS1685EN-3+, DS1685EN-5+, DS1685EN-5+T&R), 28-SOIC (DS1501YZ+T&R), and 28-LCC (DS1685QN-3+). The 24-SOIC variants provide the closest footprint match to the original RTC-72423B.
Q: Can through-hole parts (DS12885+, DS12C887+, DS1554-70+) be used as substitutes?
A: Through-hole parts require PCB redesign and are not direct replacements. Selection is limited to applications where PCB modification is feasible and operating temperature does not exceed 70°C.
Q: What memory sizes are available in substitute parts?
A: Memory capacity varies: DS12885+ (114B), DS12C887+ (113B), DS1501YZ+T&R (256B), DS1554-70+ (32KB), DS1685 series (242B), and DS17285S series (2KB). Application firmware must accommodate the selected memory configuration.
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