BQ3285ESS Real Time Clock IC Equivalent & Substitute Parts

Part Overview

The BQ3285ESS is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Texas Instruments. This device features 242 bytes of parallel memory, alarm capability, daylight savings support, leap year compensation, non-volatile SRAM, and square wave output. The BQ3285ESS is packaged in a 24-SSOP surface mount configuration and operates across a 4.5V to 5.5V supply range with battery backup from 2.5V to 4V.

The BQ3285ESS has reached obsolete product status. Locating equivalent or substitute components is necessary to maintain design continuity, ensure supply chain reliability, and support ongoing production or maintenance requirements.

Substiute Parts

BQ3285ESS

Texas InstrumentsIn Stock: 1751BQ3285ESS Datasheet

Current PartRFQ

DS12885Q+T&R

Analog Devices Inc./Maxim IntegratedIn Stock: 2209DS12885Q+T&R Datasheet

MFR RecommendedRFQ

DS1501YZN+T&R

Analog Devices Inc./Maxim IntegratedIn Stock: 2679DS1501YZN+T&R Datasheet

MFR RecommendedRFQ

DS1558W+TRL

Analog Devices Inc./Maxim IntegratedIn Stock: 1128DS1558W+TRL Datasheet

MFR RecommendedRFQ

DS1685EN-3+

Analog Devices Inc./Maxim IntegratedIn Stock: 2562DS1685EN-3+ Datasheet

MFR RecommendedRFQ

DS1685Q-5+T&R

Analog Devices Inc./Maxim IntegratedIn Stock: 2043DS1685Q-5+T&R Datasheet

MFR RecommendedRFQ

DS1685SN-5+T&R

Analog Devices Inc./Maxim IntegratedIn Stock: 769DS1685SN-5+T&R Datasheet

MFR RecommendedRFQ

DS1687-3+

Analog Devices Inc./Maxim IntegratedIn Stock: 1723DS1687-3+ Datasheet

MFR RecommendedRFQ

DS1687-3IND+

Analog Devices Inc./Maxim IntegratedIn Stock: 2181DS1687-3IND+ Datasheet

MFR RecommendedRFQ

DS17287-3+

Analog Devices Inc./Maxim IntegratedIn Stock: 1884DS17287-3+ Datasheet

MFR RecommendedRFQ

DS1744WP-120+

Analog Devices Inc./Maxim IntegratedIn Stock: 2309DS1744WP-120+ Datasheet

MFR RecommendedRFQ

M48T08-150PC1

STMicroelectronicsIn Stock: 1658M48T08-150PC1 Datasheet

MFR RecommendedRFQ

M48T58Y-70PC1

STMicroelectronicsIn Stock: 1732M48T58Y-70PC1 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BQ3285ESS is determined by the following critical parameters:

Primary Substitution Criteria:

• Parallel interface architecture
• Clock/Calendar functionality with time and date tracking
• Non-volatile SRAM (NVSRAM) capability
• Alarm and square wave output features
• Supply voltage compatibility (primary and battery)
• Operating temperature range overlap
• RoHS3 compliance and regulatory alignment

Substitution Logic: Substitute parts must maintain parallel interface operation, support identical time/date formats (HH:MM:SS and YY-MM-DD-dd), and provide equivalent memory and feature sets. Package form factor may vary (24-SSOP, 24-SOIC, 24-TSSOP, 28-PLCC, 28-SOIC, 24-DIP, 48-LQFP, 34-PowerCap) provided the electrical interface remains compatible with the application circuit. Supply voltage ranges and battery backup specifications must overlap with the original design requirements.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes for 4.5V ~ 5.5V Supply Applications:

DS12885Q+T&R and DS1685Q-5+T&R are the closest functional equivalents for designs operating at 4.5V to 5.5V supply voltage. Both maintain the 12/24-hour time format, identical date format structure, and feature sets including alarm, NVSRAM, and square wave output. DS12885Q+T&R operates at 0°C to 70°C, matching the original temperature range. DS1685Q-5+T&R extends the operating range to 0°C to 70°C and provides improved MSL rating (1 vs. 2). Both are active products with ROHS3 compliance.

Alternative for Extended Temperature Range:

DS1685SN-5+T&R provides the same 4.5V to 5.5V supply compatibility with extended operating temperature (-40°C to 85°C) and maintains 242B memory, 12/24-hour format, and core features. This option suits applications requiring broader thermal performance.

For 2.7V ~ 3.7V Supply Designs:

DS1685EN-3+, DS1687-3+, DS1687-3IND+, and DS17287-3+ operate at 2.7V to 3.7V supply voltage. DS1685EN-3+ and DS1687-3+ maintain 242B memory with 12/24-hour time format. DS17287-3+ provides expanded 2KB memory with daylight savings and leap year support, matching the original feature set more closely. DS1687-3IND+ extends operating temperature to -40°C to 85°C.

For 3.3V Supply Designs:

DS1558W+TRL and DS1744WP-120+ operate at 2.97V to 3.63V (3.3V nominal). DS1558W+TRL uses 48-LQFP packaging with 24-hour time format. DS1744WP-120+ provides 32KB memory with expanded storage capacity and 34-PowerCap™ module packaging.

All substitute parts maintain parallel interface architecture, ROHS3 compliance, and regulatory alignment (REACH Unaffected, EAR99 classification). Product status is active for all listed substitutes, ensuring ongoing availability and supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can DS1685Q-5+T&R directly replace BQ3285ESS in a 5V circuit?

A: DS1685Q-5+T&R is electrically compatible for 4.5V to 5.5V supply applications. Both devices support 12/24-hour time format, identical date format (YY-MM-DD-dd), parallel interface, alarm functionality, NVSRAM, and square wave output. The primary difference is package form factor: DS1685Q-5+T&R uses 28-LCC (J-Lead) versus BQ3285ESS 24-SSOP. PCB layout modification is required to accommodate the different pin configuration and package dimensions.

Q: What is the memory difference between BQ3285ESS (242B) and DS17287-3+ (2KB)?

A: BQ3285ESS provides 242 bytes of non-volatile SRAM. DS17287-3+ provides 2048 bytes (2KB), offering approximately 8.4 times greater storage capacity. Both maintain identical time/date tracking and alarm functionality. The expanded memory in DS17287-3+ allows storage of additional application data beyond basic clock/calendar operations. This is a functional enhancement, not a limitation.

Q: Are there pin-compatible substitutes for the 24-SSOP package?

A: DS1685EN-3+ uses 24-TSSOP packaging, which differs from 24-SSOP in pitch and body dimensions. DS1685SN-5+T&R uses 24-SOIC packaging. Neither is pin-for-pin compatible with 24-SSOP. Through-hole alternatives DS1687-3+ and DS17287-3+ use 24-DIP Module packaging. Package conversion requires PCB redesign.

Q: Which substitute supports the widest operating temperature range?

A: DS1501YZN+T&R, DS1558W+TRL, DS1685SN-5+T&R, and DS1687-3IND+ all support -40°C to 85°C operating temperature, extending 70°C above the BQ3285ESS specification. This broader range suits industrial and automotive applications.

Q: What is the impact of lower timekeeping current in substitute parts?

A: BQ3285ESS draws 300µA at 5V during timekeeping. Most substitutes (DS1685EN-3+, DS1687-3+, DS1687-3IND+, DS17287-3+, DS1744WP-120+) draw 2mA at their respective supply voltages. Lower current consumption reduces battery drain during backup operation, extending battery life. This is a performance improvement for battery-backed applications.

Q: Can DS1744WP-120+ replace BQ3285ESS in a 5V design?

A: DS1744WP-120+ operates at 2.97V to 3.63V (3.3V nominal), not 5V. Direct substitution in a 5V circuit is not possible without voltage regulation. DS1744WP-120+ is suitable only for 3.3V supply designs. For 5V applications, use DS12885Q+T&R, DS1685Q-5+T&R, or DS1685SN-5+T&R.

Q: What does MSL (Moisture Sensitivity Level) mean for component selection?

A: MSL indicates moisture absorption limits during storage and handling. BQ3285ESS is MSL 2 (1 Year shelf life). Substitutes with MSL 1 (Unlimited) offer extended shelf life and reduced risk of moisture-related failures during storage. MSL 3 components (DS1558W+TRL, DS1744WP-120+) require more stringent moisture control and shorter storage windows.

Q: Are all substitutes ROHS3 compliant?

A: Yes. All listed substitute parts are ROHS3 compliant and REACH unaffected, matching the regulatory status of BQ3285ESS. All carry EAR99 export classification.