ISL12028IBZ Equivalent & Substitute Parts

Part Overview

The ISL12028IBZ is a Real Time Clock (RTC) IC with Clock/Calendar functionality, manufactured by Renesas Electronics Corporation. This device integrates I2C/2-Wire Serial interface with comprehensive timekeeping features including alarm, leap year compensation, supervisor, and watchdog timer capabilities. The ISL12028IBZ operates across a wide supply voltage range of 2.7V to 5.5V with battery backup support from 1.8V to 5.5V, housed in a 14-SOIC package.

The product status is listed as Obsolete, necessitating identification of functionally equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain compatibility across critical electrical parameters, interface protocols, and feature sets to ensure seamless integration into existing or new applications.

Key Parameters

Parameter	ISL12028IBZ
Manufacturer	Renesas Electronics Corporation
Category	Clock/Timing
Type	Clock/Calendar
Interface	I2C, 2-Wire Serial
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Leap Year, Supervisor, Watchdog Timer
Voltage - Supply	2.7V ~ 5.5V
Voltage - Supply, Battery	1.8V ~ 5.5V
Current - Timekeeping (Max)	10µA ~ 20µA @ 2.7V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	14-SOIC (0.154", 3.90mm Width)
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution logic for the ISL12028IBZ is based on the following critical parameters that must align across candidate parts:

Primary Compatibility Criteria:

Interface Protocol: I2C/2-Wire Serial (mandatory match)
Time Format: HH:MM:SS with 12/24 hour support
Date Format: YY-MM-DD-dd
Operating Temperature Range: -40°C to 85°C minimum
Supply Voltage: Overlap with 2.7V ~ 5.5V range
Battery Backup Support: Presence of backup voltage capability
Core Features: Alarm and Leap Year functionality (baseline requirements)
Mounting Type: Surface Mount preferred for PCB integration consistency
RoHS Compliance: ROHS3 Compliant

Secondary Considerations:

Package form factor (SOIC variants prioritized for mechanical compatibility)
Current consumption during timekeeping operation
Product status (Active status preferred over Obsolete or Not For New Designs)
Moisture Sensitivity Level and shelf life

Substitute parts are grouped by their adherence to these criteria, with preference given to parts maintaining the closest electrical and mechanical alignment to the original ISL12028IBZ specification.

Parameter Comparison

Parameter	ISL12028IBZ	BU9873NUX-TTR	DS1307N+	DS1307Z+T&R	DS1337+	DS1337S+	DS1338Z-18+T&R	DS1339U-3+	DS1339U-3+T&R	DS3231SN#T&R	M41T00AUDD1F
Manufacturer	Renesas	Rohm	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	Analog Devices/Maxim	STMicroelectronics
Interface	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire	I2C, 2-Wire
Time Format	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)	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 (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	Alarm, Leap Year, Supervisor, Watchdog Timer	Alarm, Leap Year	Leap Year, NVSRAM, Square Wave Output	Leap Year, NVSRAM, Square Wave Output	Alarm, Leap Year, Square Wave Output	Alarm, Leap Year, Square Wave Output	Leap Year, NVSRAM, Square Wave Output	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Alarm, Leap Year, Square Wave Output, Trickle-Charger	Alarm, Leap Year, Square Wave Output, TCXO/Crystal	Audio, Leap Year, Trickle-Charger
Voltage - Supply	2.7V ~ 5.5V	1.8V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	1.8V ~ 5.5V	1.8V ~ 5.5V	1.71V ~ 5.5V	2.7V ~ 5.5V	2.7V ~ 5.5V	2.3V ~ 5.5V	3V ~ 3.6V
Voltage - Supply, Battery	1.8V ~ 5.5V	—	2V ~ 4.6V	2V ~ 4.6V	—	—	1.3V ~ 3.7V	1.3V ~ 3.7V	1.3V ~ 3.7V	2.3V ~ 5.5V	1.7V ~ 3.6V
Current - Timekeeping (Max)	10µA ~ 20µA @ 2.7V ~ 5.5V	1µA ~ 1.35µA @ 3V ~ 5.5V	200µA @ 5V	200µA @ 5V	0.6µA @ 1.3V ~ 1.8V	0.6µA @ 1.3V ~ 1.8V	100µA @ 1.89V	150µA @ 3.3V	150µA @ 3.3V	110µA ~ 170µA @ 3.63V ~ 5.5V	14.3mA @ 3V ~ 3.6V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°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	0°C ~ 70°C
Mounting Type	Surface Mount	Surface Mount	Through Hole	Surface Mount	Through Hole	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	14-SOIC	8-UFDFN Exposed Pad	8-DIP	8-SOIC	8-DIP	8-SOIC	8-SOIC	8-TSSOP, 8-MSOP	8-TSSOP, 8-MSOP	16-SOIC	16-VFDFN Exposed Pad
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Not For New Designs	Active	Active	Active	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

Tier 1 - Preferred Substitutes (Active Status, Full Compatibility)

DS1337S+ and DS1337+ represent the most direct functional equivalents. Both maintain I2C/2-Wire Serial interface, support 12/24-hour time format with YY-MM-DD-dd date format, include alarm and leap year features, and operate across -40°C to 85°C. The DS1337S+ offers surface mount packaging (8-SOIC) matching the ISL12028IBZ mounting preference, while DS1337+ provides through-hole 8-DIP packaging. Both support supply voltage from 1.8V to 5.5V with ultra-low timekeeping current of 0.6µA at 1.3V to 1.8V. Active product status ensures long-term availability and manufacturing support.

DS1338Z-18+T&R provides extended battery backup capability (1.3V to 3.7V) with NVSRAM integration and operates in surface mount 8-SOIC format. Operating temperature range of -40°C to 85°C and supply voltage of 1.71V to 5.5V align with ISL12028IBZ requirements. Active status and ROHS3 compliance support production continuity.

Tier 2 - Compatible Substitutes (Active Status, Minor Parameter Variations)

DS1339U-3+ and DS1339U-3+T&R feature trickle-charger capability and square wave output in compact 8-TSSOP/8-MSOP surface mount packages. Supply voltage range of 2.7V to 5.5V with battery backup from 1.3V to 3.7V maintains compatibility. Timekeeping current of 150µA at 3.3V represents a moderate increase from ISL12028IBZ specifications. Active product status and ROHS3 compliance are confirmed.

DS3231SN#T&R integrates TCXO/Crystal oscillator in 16-SOIC surface mount package with alarm, leap year, and square wave output features. Supply voltage of 2.3V to 5.5V with battery backup from 2.3V to 5.5V provides extended operating range. Timekeeping current of 110µA to 170µA at 3.63V to 5.5V represents higher consumption. Active status and ROHS3 compliance support deployment.

Tier 3 - Limited Compatibility (Restricted Operating Conditions or Obsolete Status)

DS1307N+ and DS1307Z+T&R support I2C interface with leap year and NVSRAM features but operate at restricted supply voltage of 4.5V to 5.5V, narrower than ISL12028IBZ. DS1307N+ uses through-hole 8-DIP packaging; DS1307Z+T&R uses surface mount 8-SOIC. Timekeeping current of 200µA at 5V is significantly higher. DS1307Z+T&R operating temperature of 0°C to 70°C is narrower than required. Active status is confirmed.

BU9873NUX-TTR operates with supply voltage of 1.8V to 5.5V and ultra-low timekeeping current of 1µA to 1.35µA at 3V to 5.5V. However, product status is listed as Not For New Designs, limiting suitability for ongoing production. Battery backup voltage specification is not provided. Surface mount 8-UFDFN packaging differs from ISL12028IBZ form factor.

M41T00AUDD1F operates at restricted supply voltage of 3V to 3.6V with significantly elevated timekeeping current of 14.3mA at 3V to 3.6V. Operating temperature range of 0°C to 70°C is narrower than ISL12028IBZ. Time format supports 24-hour only, lacking 12-hour option. These restrictions limit compatibility for applications requiring extended temperature operation or lower power consumption.

Frequently Asked Questions (FAQ)

Q: Can DS1307 series parts directly replace ISL12028IBZ?

A: DS1307 series parts (DS1307N+, DS1307Z+T&R) maintain I2C interface and basic clock/calendar functionality but operate at restricted supply voltage of 4.5V to 5.5V, narrower than ISL12028IBZ specification of 2.7V to 5.5V. Timekeeping current consumption is significantly higher at 200µA versus 10µA to 20µA. These parts are suitable only for applications operating exclusively at 5V with higher power budgets.

Q: What is the primary advantage of DS1337 series substitutes?

A: DS1337 and DS1337S+ offer the closest electrical alignment to ISL12028IBZ. Both support supply voltage from 1.8V to 5.5V, include alarm and leap year features, maintain I2C/2-Wire Serial interface with 12/24-hour time format, and operate across -40°C to 85°C. Ultra-low timekeeping current of 0.6µA at 1.3V to 1.8V provides superior power efficiency. DS1337S+ surface mount 8-SOIC packaging matches ISL12028IBZ mounting preference. Active product status ensures long-term availability.

Q: Why is BU9873NUX-TTR listed despite "Not For New Designs" status?

A: BU9873NUX-TTR demonstrates exceptional timekeeping current performance of 1µA to 1.35µA at 3V to 5.5V and supports supply voltage from 1.8V to 5.5V. However, "Not For New Designs" status indicates Rohm Semiconductor is transitioning this product line. New designs should prioritize Active status alternatives such as DS1337 series or DS1338Z-18+T&R to ensure manufacturing continuity and long-term support.

Q: How does package form factor affect substitution?

A: ISL12028IBZ uses 14-SOIC surface mount packaging. Direct mechanical replacement requires surface mount packages. DS1337S+, DS1338Z-18+T&R, DS1339U-3+, DS1339U-3+T&R, and DS3231SN#T&R all provide surface mount options. Through-hole packages (DS1307N+, DS1337+) require PCB redesign. Compact packages like 8-UFDFN (BU9873NUX-TTR) and 8-TSSOP/8-MSOP (DS1339U series) may require layout modifications but offer space savings.

Q: What battery backup voltage considerations apply?

A: ISL12028IBZ supports battery backup from 1.8V to 5.5V. DS1337 and DS1337S+ do not specify battery backup voltage, limiting their suitability for applications requiring continuous timekeeping during main power loss. DS1338Z-18+T&R, DS1339U series, and DS3231SN#T&R all provide battery backup capability. DS1338Z-18+T&R and DS1339U series support 1.3V to 3.7V backup range; DS3231SN#T&R supports 2.3V to 5.5V, matching ISL12028IBZ extended range.

Q: Which substitute offers the lowest power consumption?

A: BU9873NUX-TTR provides the lowest timekeeping current at 1µA to 1.35µA at 3V to 5.5V. DS1337 and DS1337S+ follow closely at 0.6µA at 1.3V to 1.8V. For applications prioritizing ultra-low power operation, BU9873NUX-TTR is optimal despite "Not For New Designs" status. For new designs requiring Active status, DS1337 series represents the best power efficiency choice.

Q: Are all substitutes ROHS3 compliant?

A: All listed substitute parts are ROHS3 Compliant, matching ISL12028IBZ environmental compliance. All parts are also REACH Unaffected and classified under ECCN EAR99 and HTSUS 8542.39.0001, maintaining regulatory alignment with the original part.

Q: What is the significance of operating temperature range differences?

A: ISL12028IBZ operates across -40°C to 85°C. DS1307Z+T&R and M41T00AUDD1F restrict operation to 0°C to 70°C, unsuitable for industrial or automotive applications requiring extended temperature range. All other substitutes maintain -40°C to 85°C operation, ensuring compatibility with ISL12028IBZ temperature specifications.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message