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Equivalent & Substitute Parts for 1338-18DCGI
Part Overview
The 1338-18DCGI is a Real Time Clock (RTC) IC Clock/Calendar manufactured by Renesas Electronics Corporation, featuring I2C 2-Wire Serial interface in 8-SOIC surface mount packaging. This device provides 56 bytes of memory with leap year support, NVSRAM functionality, and square wave output capability. The part is currently obsolete, necessitating identification of active substitute components that maintain functional and electrical compatibility for new designs and production continuity.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Manufacturer Part Number | 1338-18DCGI |
| Manufacturer | Renesas Electronics Corporation |
| Category | Clock/Timing |
| Type | Clock/Calendar |
| Package / Case | 8-SOIC (0.154", 3.90mm Width) |
| Interface | I2C, 2-Wire Serial |
| Memory Size | 56B |
| Time Format | HH:MM:SS (12/24 hr) |
| Date Format | YY-MM-DD-dd |
| Voltage - Supply | 1.8V ~ 5.5V |
| Voltage - Supply, Battery | 1.3V ~ 3.7V |
| Current - Timekeeping (Max) | 2µA @ 3.3V |
| Operating Temperature | -40°C ~ 85°C |
| Mounting Type | Surface Mount |
| Features | Leap Year, NVSRAM, Square Wave Output |
| Product Status | Obsolete |
| RoHS Status | ROHS3 Compliant |
Substitute Part Grouping Explanation
Substitution eligibility for the 1338-18DCGI is determined by the following critical parameters:
Primary Compatibility Criteria:
- Interface type: I2C, 2-Wire Serial
- Time format: HH:MM:SS (12/24 hr)
- Date format: YY-MM-DD-dd
- Operating temperature range: -40°C ~ 85°C
- RoHS3 compliance
- Surface mount packaging (8-SOIC preferred for direct replacement)
Secondary Compatibility Criteria:
- Memory size: 56B (preferred) or equivalent
- Features: Leap year support, NVSRAM, square wave output
- Supply voltage range: Minimum 1.8V ~ 5.5V
- Battery supply voltage: Minimum 1.3V ~ 3.7V
- Timekeeping current: Low power operation
Substitute parts are grouped into two categories:
Category A - Direct Surface Mount Replacements (8-SOIC): Parts maintaining identical or superior electrical specifications with 8-SOIC packaging, enabling direct PCB substitution without layout modification.
Category B - Functional Equivalents with Package Variation: Parts meeting all electrical and interface requirements but with different packaging (8-DIP or module form factor), requiring PCB redesign or adapter solutions.
Parameter Comparison
| Parameter | 1338-18DCGI | ISL12008IB8Z | AB-RTCMC-32.768KHZ-EOZ9-S3-DBT | DS1307Z+ | DS1338Z-18+ |
|---|---|---|---|---|---|
| Manufacturer | Renesas | Renesas | Abracon LLC | Analog Devices/Maxim | Analog Devices/Maxim |
| Package / Case | 8-SOIC | 8-SOIC | 10-SMD Module | 8-SOIC | 8-SOIC |
| Interface | 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:hh (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 |
| Memory Size | 56B | - | 8B | 56B | 56B |
| Voltage - Supply | 1.8V ~ 5.5V | 2.7V ~ 5.5V | 1.4V ~ 5.5V | 4.5V ~ 5.5V | 1.71V ~ 5.5V |
| Voltage - Supply, Battery | 1.3V ~ 3.7V | 1.8V ~ 5.5V | 1.4V ~ 5.5V | 2V ~ 4.6V | 1.3V ~ 3.7V |
| Current - Timekeeping (Max) | 2µA @ 3.3V | 4µA ~ 6µA @ 3V ~ 5V | 1.5µA ~ 2.2µA @ 1.4V ~ 5V | 200µA @ 5V | 100µA @ 1.89V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C | -40°C ~ 85°C | 0°C ~ 70°C | -40°C ~ 85°C |
| Features | Leap Year, NVSRAM, Square Wave Output | Alarm, Leap Year | Alarm, EEPROM, Leap Year, Square Wave Output, SRAM, TCXO/Crystal, Trickle-Charger | Leap Year, NVSRAM, Square Wave Output | Leap Year, NVSRAM, Square Wave Output |
| Product Status | Obsolete | Active | Active | Active | Active |
| RoHS Status | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant |
Engineering Selection Recommendations
Category A - Direct Surface Mount Replacements (8-SOIC):
DS1338Z-18+ is the primary recommended substitute. This part maintains identical 8-SOIC packaging, matching memory size (56B), time/date formats, and feature set (leap year, NVSRAM, square wave output). Supply voltage range (1.71V ~ 5.5V) encompasses the original specification. Operating temperature range (-40°C ~ 85°C) is identical. Product status is active with established supply chain availability. RoHS3 compliance is confirmed.
DS1338Z-3+ provides equivalent functionality with 8-SOIC packaging and identical feature set. Supply voltage minimum (2.7V ~ 5.5V) is higher than the original, limiting low-voltage applications. Timekeeping current (200µA @ 3.3V) is higher than the original (2µA @ 3.3V), affecting battery life in low-power designs. Product status is active.
ISL12008IB8Z offers 8-SOIC packaging with active product status. Supply voltage range (2.7V ~ 5.5V) does not meet the original 1.8V minimum requirement. Time format is 24-hour only, eliminating 12-hour mode capability. Memory size is unspecified. Timekeeping current (4µA ~ 6µA) exceeds the original specification. This part is suitable only for designs not requiring 12-hour time format or extended low-voltage operation.
Category B - Functional Equivalents with Package Variation:
AB-RTCMC-32.768KHZ-EOZ9-S3-DBT is a 10-SMD module form factor providing enhanced features (alarm, EEPROM, SRAM, TCXO/Crystal, trickle-charger) with superior supply voltage range (1.4V ~ 5.5V) and lowest timekeeping current (1.5µA ~ 2.2µA). Product status is active. This part requires PCB redesign due to module packaging but offers superior performance for new designs.
DS1307Z+ and DS1307ZN+ provide 8-SOIC packaging with identical feature set (leap year, NVSRAM, square wave output) and 56B memory. Supply voltage range (4.5V ~ 5.5V) does not meet the original 1.8V minimum. Timekeeping current (200µA @ 5V) is significantly higher. Operating temperature for DS1307Z+ is limited to 0°C ~ 70°C. These parts are suitable only for designs operating within 4.5V ~ 5.5V supply range.
DS1307N+ is a through-hole 8-DIP package requiring significant PCB redesign. Supply voltage and current specifications are identical to DS1307Z+. This option is not recommended for surface mount applications.
DS1337+ is a through-hole 8-DIP package with alarm functionality and superior timekeeping current (0.6µA @ 1.3V ~ 1.8V). Supply voltage range (1.8V ~ 5.5V) matches the original. This part requires PCB redesign and is not recommended for direct replacement.
Frequently Asked Questions (FAQ)
Q: Can DS1338Z-18+ directly replace 1338-18DCGI without PCB modification?
A: Yes. Both parts use 8-SOIC packaging with identical pinout compatibility. Electrical specifications are compatible across the specified operating range. No PCB layout changes are required.
Q: What is the key difference between DS1338Z-18+ and DS1338Z-3+?
A: The primary difference is supply voltage range. DS1338Z-18+ operates from 1.71V minimum, supporting low-voltage applications. DS1338Z-3+ operates from 2.7V minimum. Timekeeping current also differs: DS1338Z-18+ draws 100µA @ 1.89V, while DS1338Z-3+ draws 200µA @ 3.3V. For battery-powered designs requiring extended runtime, DS1338Z-18+ is preferred.
Q: Why does ISL12008IB8Z show 24-hour time format only?
A: The ISL12008IB8Z is designed with 24-hour time format as a fixed feature. Applications requiring 12-hour format with AM/PM indication cannot use this part without firmware workarounds. The original 1338-18DCGI supports both 12-hour and 24-hour modes.
Q: Is AB-RTCMC-32.768KHZ-EOZ9-S3-DBT a drop-in replacement?
A: No. This part uses a 10-SMD module form factor instead of 8-SOIC DIP. PCB redesign is required. However, it offers superior features (integrated crystal, trickle-charger, EEPROM) and lower power consumption, making it suitable for new designs.
Q: What is the operating temperature limitation of DS1307Z+?
A: DS1307Z+ operates from 0°C to 70°C, which is narrower than the original 1338-18DCGI range of -40°C to 85°C. This part is not suitable for applications requiring full industrial temperature range.
Q: Can I use DS1307N+ as a substitute?
A: DS1307N+ is a through-hole 8-DIP package, not surface mount. It requires significant PCB redesign. Additionally, supply voltage range (4.5V ~ 5.5V) does not meet the original 1.8V minimum specification. This part is not recommended for direct replacement.
Q: Which substitute offers the lowest power consumption?
A: AB-RTCMC-32.768KHZ-EOZ9-S3-DBT provides the lowest timekeeping current at 1.5µA ~ 2.2µA across its operating range, compared to the original 2µA @ 3.3V. This module is optimal for battery-powered applications prioritizing extended runtime.
Q: Are all substitute parts RoHS3 compliant?
A: Yes. All listed substitute parts carry RoHS3 compliance certification, matching the original 1338-18DCGI specification.
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