AB0803-T3 Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The AB0803-T3 is a Real Time Clock (RTC) IC manufactured by Abracon LLC, designed for clock/calendar applications with I2C serial interface. This 16-VFQFN package device provides 64B SRAM, alarm functionality, leap year support, and trickle-charger capability. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design alternatives.

Key Parameters

Parameter	AB0803-T3 Specification
Manufacturer	Abracon LLC
Product Status	Obsolete
Package / Case	16-VFQFN Exposed Pad (3x3)
Interface	I2C, 2-Wire Serial
Memory Size	64B
Time Format	HH:MM:SS:hh
Date Format	YY-MM-DD-dd
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
RoHS Status	ROHS3 Compliant
Mounting Type	Surface Mount

Substitute Part Grouping Explanation

Substitution for the AB0803-T3 is determined by the following critical parameters:

Primary Compatibility Criteria:

I2C/2-Wire Serial interface (mandatory)
Operating temperature range: -40°C ~ 85°C (mandatory)
Supply voltage overlap: minimum 1.7V ~ 3.6V range
Surface mount package type
ROHS3 compliance
Memory capacity: 64B or greater

Substitution Logic: Substitute parts are grouped into two categories based on package form factor and feature set:

Direct Package Equivalents (16-VFQFN): AB0805-T3 maintains identical package geometry and pinout, offering enhanced memory (256B) and watchdog timer functionality while preserving all core electrical specifications.
Functional Equivalents (Alternative Packages): Parts from Analog Devices (DS series), Texas Instruments (BQ series), and Rohm Semiconductor (BU series) provide I2C RTC functionality with different package options (8-SOIC, 8-MSOP, 8-TSSOP, 20-SOIC) and varying feature sets. These require PCB layout redesign but maintain electrical interface compatibility.

Parameter Comparison

Parameter	AB0803-T3	AB0805-T3	BQ32000D	BU9873FVM-GTTR	DS1308U-18+T	DS1338Z-33+T&R	DS1388Z-33+	DS3232SN#T&R
Manufacturer	Abracon LLC	Abracon LLC	Texas Instruments	Rohm Semiconductor	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim	Analog Devices Inc./Maxim
Product Status	Obsolete	Active	Active	Not For New Designs	Active	Active	Active	Active
Package / Case	16-VFQFN (3x3)	16-VFQFN (3x3)	8-SOIC (0.154", 3.90mm)	8-MSOP (0.110", 2.80mm)	8-TSSOP/MSOP (0.118", 3.00mm)	8-SOIC (0.154", 3.90mm)	8-SOIC (0.154", 3.90mm)	20-SOIC (0.295", 7.50mm)
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
Memory Size	64B	256B	—	—	56B	56B	512B	236B
Time Format	HH:MM:SS:hh	HH:MM:SS:hh	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:hh (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
Voltage - Supply	1.7V ~ 3.6V	1.7V ~ 3.6V	3V ~ 3.6V	1.8V ~ 5.5V	1.71V ~ 5.5V	3V ~ 5.5V	2.97V ~ 3.63V	2.3V ~ 5.5V
Voltage - Supply, Battery	1.5V ~ 3.6V	1.5V ~ 3.6V	1.4V ~ 3.6V	—	1.3V ~ 5.5V	1.3V ~ 3.7V	1.3V ~ 5.5V	2.3V ~ 5.5V
Current - Timekeeping (Max)	0.17µA ~ 0.22µA @ 1.8V ~ 3V	0.17µA ~ 0.22µA @ 1.8V ~ 3V	100µA @ 3.3V	1µA ~ 1.35µA @ 3V ~ 5.5V	100µA @ 200µA @ 1.89V ~ 5.5V	125µA ~ 200µA @ 3.63V ~ 5.5V	150µA @ 2.97V ~ 3.63V	120µA ~ 160µA @ 3.3V ~ 5.5V
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
Features	Alarm, Leap Year, SRAM, Trickle-Charger	Alarm, Leap Year, SRAM, Trickle-Charger, Watchdog Timer	Leap Year, Square Wave Output, Trickle-Charger	Alarm, Leap Year	Leap Year, NVSRAM, Square Wave Output	Leap Year, NVSRAM, Square Wave Output	EEPROM, Leap Year, Supervisor, Trickle-Charger, Watchdog Timer	Alarm, Leap Year, Square Wave Output, SRAM, TCXO/Crystal
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount

Engineering Selection Recommendations

Recommended Primary Substitute: AB0805-T3

The AB0805-T3 is the optimal direct replacement for AB0803-T3 applications. This part maintains identical package geometry (16-VFQFN Exposed Pad), pinout compatibility, and electrical specifications while offering increased memory capacity (256B vs. 64B) and additional watchdog timer functionality. Both parts are ROHS3 compliant, operate across -40°C to 85°C, and support identical I2C interface protocols. The AB0805-T3 is currently in active production with substantial inventory availability (21,300 units), ensuring long-term supply continuity.

Secondary Substitutes for Alternative Package Requirements:

When PCB redesign is acceptable, the following active parts provide functional RTC capability:

DS3232SN#T&R (Analog Devices): 20-SOIC package with 236B memory, integrated TCXO/Crystal, and comprehensive feature set (alarm, leap year, square wave output, SRAM). Supports -40°C to 85°C operation and ROHS3 compliance. Suitable for applications requiring enhanced frequency stability.
DS1338Z-33+T&R (Analog Devices): 8-SOIC package with 56B memory, NVSRAM, and square wave output. Operates 3V to 5.5V supply range with -40°C to 85°C temperature rating. Appropriate for space-constrained designs.
DS1388Z-33+ (Analog Devices): 8-SOIC package with 512B memory, EEPROM, supervisor, trickle-charger, and watchdog timer. Operates 2.97V to 3.63V supply with -40°C to 85°C rating. Suitable for applications requiring extended memory and supervisory functions.

Parts Not Recommended for New Designs:

BU9873FVM-GTTR (Rohm Semiconductor) carries "Not For New Designs" status and should be avoided for new development projects despite active inventory.

Frequently Asked Questions (FAQ)

Q: Can AB0805-T3 directly replace AB0803-T3 without PCB modification?

A: Yes. The AB0805-T3 maintains identical 16-VFQFN package geometry, pinout, and electrical interface specifications. No PCB layout changes are required. The primary difference is increased SRAM capacity (256B vs. 64B) and addition of watchdog timer functionality, both backward-compatible enhancements.

Q: What are the key differences between AB0803-T3 and DS3232SN#T&R?

A: Package form factor differs (16-VFQFN vs. 20-SOIC), requiring PCB redesign. DS3232SN#T&R offers larger memory (236B), integrated TCXO/Crystal for improved frequency stability, and operates across a wider supply voltage range (2.3V to 5.5V). Both maintain I2C interface, -40°C to 85°C operation, and ROHS3 compliance.

Q: Why is BU9873FVM-GTTR listed as "Not For New Designs"?

A: Rohm Semiconductor has designated this part as not recommended for new design implementations. While currently available in inventory, it should only be used for legacy system maintenance or repair applications. New projects should select from active-status alternatives.

Q: What supply voltage range is common across all substitutes?

A: No single voltage range encompasses all substitutes. AB0803-T3 and AB0805-T3 share 1.7V to 3.6V supply compatibility. DS series parts support broader ranges (1.71V to 5.5V or 2.3V to 5.5V). BQ32000D operates 3V to 3.6V minimum. Verify specific application voltage requirements against individual part specifications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts carry ROHS3 compliance certification, matching the AB0803-T3 environmental standard.

Q: Which substitute offers the lowest timekeeping current consumption?

A: AB0805-T3 matches AB0803-T3 at 0.17µA to 0.22µA @ 1.8V to 3V. BU9873FVM-GTTR provides 1µA to 1.35µA @ 3V to 5.5V. DS series parts consume 100µA to 200µA, significantly higher than Abracon offerings. For ultra-low-power battery-backed applications, AB0805-T3 remains optimal.

Q: Can DS1308U-18+T replace AB0803-T3 in existing designs?

A: Functional replacement is possible but requires PCB redesign due to different package (8-TSSOP/MSOP vs. 16-VFQFN). DS1308U-18+T provides 56B memory (less than AB0803-T3's 64B), operates 1.71V to 5.5V supply, and includes NVSRAM and square wave output features. I2C interface compatibility is maintained.

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