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AB1804-T3 Equivalent & Substitute Parts
Part Overview
The AB1804-T3 is a Real Time Clock (RTC) IC with Clock/Calendar functionality manufactured by Abracon LLC. This 16-VFQFN surface mount device integrates 256B of memory, I2C/2-Wire Serial interface, and features including alarm, leap year compensation, SRAM, trickle-charger, and watchdog timer capabilities. The device operates across a 1.7V to 3.6V supply range with ultra-low timekeeping current of 0.17µA to 0.22µA at 1.8V to 3V.
The AB1804-T3 is classified as Obsolete. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications requiring RTC functionality with I2C interface compatibility.
Substiute Parts
Key Parameters
| Parameter | AB1804-T3 Specification |
|---|---|
| Manufacturer | Abracon LLC |
| Product Status | Obsolete |
| Type | Clock/Calendar |
| Interface | I2C, 2-Wire Serial |
| Package / Case | 16-VFQFN Exposed Pad (16-QFN 3x3) |
| Memory Size | 256B |
| Voltage - Supply | 1.7V ~ 3.6V |
| Voltage - Supply, Battery | 1.5V ~ 3.6V |
| Current - Timekeeping (Max) | 0.17µA ~ 0.22µA @ 1.8V ~ 3V |
| Operating Temperature | -40°C ~ 85°C |
| Features | Alarm, Leap Year, SRAM, Trickle-Charger, Watchdog Timer |
| Time Format | HH:MM:SS:hh |
| Date Format | YY-MM-DD-dd |
| RoHS Status | ROHS3 Compliant |
| Moisture Sensitivity Level (MSL) | 1 (Unlimited) |
Substitute Part Grouping Explanation
Substitution of the AB1804-T3 is determined by the following critical parameters:
Primary Compatibility Criteria:
- Interface type: I2C, 2-Wire Serial (mandatory match)
- Operating temperature range: -40°C ~ 85°C (mandatory match)
- RoHS compliance: ROHS3 Compliant (mandatory match)
- Mounting type: Surface Mount (mandatory match)
Secondary Compatibility Criteria:
- Voltage supply range: 1.7V ~ 3.6V (primary part specification)
- Memory capacity: 256B (primary part specification)
- Time/Date format support: HH:MM:SS:hh and YY-MM-DD-dd
- Features: Alarm, Leap Year, SRAM, Trickle-Charger, Watchdog Timer
Substitute parts are grouped into two categories:
Category 1 - Direct Package Equivalent (16-VFQFN): AB1805-T3 (Abracon LLC) - Active product status, identical package, electrical specifications, and feature set. This is the manufacturer-recommended direct replacement.
Category 2 - Functional Equivalents (Alternative Packages): Parts with I2C interface, -40°C ~ 85°C operating range, and ROHS3 compliance but in alternative packages (8-SOIC, 8-MSOP, 8-UFDFN). These require PCB layout redesign but maintain functional compatibility for RTC clock/calendar applications.
Parameter Comparison
| Parameter | AB1804-T3 | AB1805-T3 | 1337GDCGI8 | 1337GDVGI | BU9873NUX-TTR | DS1307ZN+ | DS1338C-33# | DS1340U-33+T&R | DS1388Z-33+ | ISL12022IBZ | ISL12058IUZ |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Manufacturer | Abracon LLC | Abracon LLC | Renesas | Renesas | Rohm | Analog Devices/Maxim | Analog Devices/Maxim | Analog Devices/Maxim | Analog Devices/Maxim | Renesas | Renesas |
| Product Status | Obsolete | Active | Active | Active | Not For New Designs | Active | Active | Active | Active | Active | Active |
| Interface | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial | I2C, 2-Wire Serial |
| Package / Case | 16-VFQFN Exposed Pad | 16-VFQFN Exposed Pad | 8-SOIC (0.154", 3.90mm) | 8-TSSOP, 8-MSOP (0.118", 3.00mm) | 8-UFDFN Exposed Pad | 8-SOIC (0.154", 3.90mm) | 16-SOIC (0.295", 7.50mm) | 8-TSSOP, 8-MSOP (0.118", 3.00mm) | 8-SOIC (0.154", 3.90mm) | 8-SOIC (0.154", 3.90mm) | 8-TSSOP, 8-MSOP (0.118", 3.00mm) |
| Voltage - Supply | 1.7V ~ 3.6V | 1.7V ~ 3.6V | 1.8V ~ 5.5V | 1.8V ~ 5.5V | 1.8V ~ 5.5V | 4.5V ~ 5.5V | 3V ~ 5.5V | 2.97V ~ 5.5V | 2.97V ~ 3.63V | 2.7V ~ 5.5V | 1.8V ~ 3.6V |
| 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 |
| RoHS Status | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant | ROHS3 Compliant |
| Moisture Sensitivity Level (MSL) | 1 (Unlimited) | 1 (Unlimited) | 1 (Unlimited) | 3 (168 Hours) | 1 (Unlimited) | 1 (Unlimited) | 1 (Unlimited) | 1 (Unlimited) | 1 (Unlimited) | 1 (Unlimited) | 1 (Unlimited) |
| Memory Size | 256B | 256B | — | — | — | 56B | 56B | — | 512B | 128B | — |
| Current - Timekeeping (Max) | 0.17µA ~ 0.22µA @ 1.8V ~ 3V | 0.17µA ~ 0.22µA @ 1.8V ~ 3V | 0.6µA @ 1.3V ~ 1.8V | 0.6µA @ 1.3V ~ 1.8V | 1µA ~ 1.35µA @ 3V ~ 5.5V | 200µA @ 5V | 125µA ~ 200µA @ 3.63V ~ 5.5V | 150µA @ 5.5V | 150µA @ 2.97V ~ 3.63V | 14µA ~ 15µA @ 3V ~ 5V | 0.65µA @ 1.8V |
Engineering Selection Recommendations
Primary Recommendation: AB1805-T3
The AB1805-T3 is the manufacturer-recommended equivalent for the obsolete AB1804-T3. Both devices are manufactured by Abracon LLC and share identical electrical specifications, feature sets, package configuration (16-VFQFN Exposed Pad), and operating parameters. The AB1805-T3 maintains Active product status with 5287 units in stock, ensuring long-term supply availability. No design modifications are required for direct substitution. Both parts are ROHS3 compliant with MSL 1 (Unlimited) rating.
Secondary Recommendations for Alternative Packages:
For applications where package redesign is acceptable, the following active parts provide functional RTC clock/calendar capability with I2C interface:
Renesas 1337GDCGI8 (8-SOIC) and 1337GDVGI (8-MSOP) - Both maintain -40°C ~ 85°C operating range and ROHS3 compliance. The 1337GDCGI8 offers MSL 1 (Unlimited) rating. These parts support 12/24-hour time format and YY-MM-DD-dd date format with alarm and leap year features. Note: 1337GDVGI has MSL 3 (168 Hours) rating.
Analog Devices DS1307ZN+ (8-SOIC) - Active status with 1528 units in stock. Supports 12/24-hour time format and includes NVSRAM and square wave output. Requires higher supply voltage (4.5V ~ 5.5V) compared to AB1804-T3 (1.7V ~ 3.6V). Suitable for 5V system designs only.
Analog Devices DS1338C-33# (16-SOIC) - Active status with 3200 units in stock. Maintains 16-pin package footprint with expanded supply range (3V ~ 5.5V). Includes NVSRAM and square wave output features. Requires PCB layout adjustment due to different pin configuration.
Analog Devices DS1340U-33+T&R (8-TSSOP/MSOP) - Active status with 4200 units in stock. Compact 8-pin package with trickle-charger feature. Supports 24-hour time format and YY-MM-DD-dd date format. Supply range 2.97V ~ 5.5V.
Analog Devices DS1388Z-33+ (8-SOIC) - Active status with 3420 units in stock. Offers 512B memory (larger than AB1804-T3), EEPROM, supervisor, trickle-charger, and watchdog timer. Supply range 2.97V ~ 3.63V with battery backup 1.3V ~ 5.5V.
Renesas ISL12022IBZ (8-SOIC) - Active status with 8506 units in stock. Provides 128B SRAM memory with daylight savings feature. Supply range 2.7V ~ 5.5V with battery backup 1.8V ~ 5.5V. Timekeeping current 14µA ~ 15µA @ 3V ~ 5V.
Renesas ISL12058IUZ (8-MSOP) - Active status with 2693 units in stock. Ultra-low timekeeping current 0.65µA @ 1.8V. Supply range 1.8V ~ 3.6V matches AB1804-T3 voltage specification. Compact 8-pin MSOP package.
Rohm BU9873NUX-TTR (8-UFDFN) - Classified as Not For New Designs. While 18520 units are in stock, this part is not recommended for new designs. Included for reference only for legacy system maintenance.
Frequently Asked Questions (FAQ)
Q: Can AB1805-T3 be used as a direct replacement for AB1804-T3 without PCB modifications?
A: Yes. The AB1805-T3 is the manufacturer-recommended equivalent with identical package (16-VFQFN Exposed Pad), pin configuration, electrical specifications, and feature set. No PCB layout changes are required. Both parts are ROHS3 compliant with MSL 1 (Unlimited) rating.
Q: What is the primary difference between AB1804-T3 and AB1805-T3?
A: The AB1804-T3 is classified as Obsolete, while AB1805-T3 maintains Active product status. Electrical and functional specifications are identical. The AB1805-T3 is recommended for new designs and ongoing production.
Q: Can I use an 8-pin RTC package as a substitute for the 16-pin AB1804-T3?
A: Functionally, yes, if your application requirements are met. However, this requires PCB redesign. The 8-pin alternatives (DS1307ZN+, 1337GDCGI8, 1337GDVGI, BU9873NUX-TTR, DS1340U-33+T&R, ISL12022IBZ, ISL12058IUZ) all provide I2C clock/calendar functionality with -40°C ~ 85°C operating range and ROHS3 compliance. Verify that memory size, feature set, and voltage requirements match your application before proceeding.
Q: Which substitute part has the lowest timekeeping current consumption?
A: The ISL12058IUZ offers 0.65µA @ 1.8V timekeeping current, which is comparable to the AB1804-T3 (0.17µA ~ 0.22µA @ 1.8V ~ 3V). The AB1805-T3 maintains the same ultra-low current specification as the original AB1804-T3.
Q: Are all substitute parts ROHS3 compliant?
A: Yes. All listed substitute parts are ROHS3 compliant. Moisture Sensitivity Level (MSL) varies: most parts are MSL 1 (Unlimited), with the exception of 1337GDVGI which is MSL 3 (168 Hours).
Q: What is the supply voltage compatibility range for substitute parts?
A: The AB1804-T3 operates at 1.7V ~ 3.6V. Direct equivalent AB1805-T3 maintains this range. Alternative packages vary: ISL12058IUZ matches at 1.8V ~ 3.6V; others support wider ranges (1.8V ~ 5.5V or 2.7V ~ 5.5V). Verify your system voltage before selection.
Q: Can DS1307ZN+ replace AB1804-T3 in a low-voltage application?
A: No. DS1307ZN+ requires 4.5V ~ 5.5V supply voltage, which is incompatible with the AB1804-T3 specification of 1.7V ~ 3.6V. This part is suitable only for 5V system designs.
Q: What memory capacity differences exist among substitute parts?
A: AB1804-T3 provides 256B memory. Alternatives vary: DS1307ZN+ and DS1338C-33# offer 56B; DS1388Z-33+ provides 512B; ISL12022IBZ provides 128B; others do not specify memory size. Select based on your application's data storage requirements.
Q: Is BU9873NUX-TTR recommended for new designs?
A: No. BU9873NUX-TTR is classified as Not For New Designs. While functionally compatible and in stock (18520 units), it should be used only for legacy system maintenance or repair. For new designs, select from Active status alternatives.
Q: What are the key parameters I must verify when selecting a substitute?
A: Verify: (1) I2C/2-Wire Serial interface compatibility, (2) Operating temperature range -40°C ~ 85°C, (3) ROHS3 compliance, (4) Supply voltage compatibility with your system, (5) Package footprint and pin configuration, (6) Memory size and feature requirements (alarm, leap year, trickle-charger, watchdog timer), (7) Timekeeping current specifications for battery-backed applications.
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