BQ3285EP Real Time Clock IC - Equivalent & Substitute Parts

Part Overview

The BQ3285EP is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Texas Instruments. This device provides 242 bytes of parallel interface memory with alarm, daylight savings, leap year, non-volatile SRAM, and square wave output capabilities. The BQ3285EP is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across time format, date format, parallel interface architecture, and core RTC features while accommodating differences in packaging, voltage specifications, and operating temperature ranges.

Substiute Parts

BQ3285EP

Texas InstrumentsIn Stock: 1352BQ3285EP Datasheet

Current PartRFQ

DS12885QN+

Analog Devices Inc./Maxim IntegratedIn Stock: 1177DS12885QN+ Datasheet

MFR RecommendedRFQ

DS12CR887-5+

Analog Devices Inc./Maxim IntegratedIn Stock: 1500DS12CR887-5+ Datasheet

MFR RecommendedRFQ

DS1501WZ+T&R

Analog Devices Inc./Maxim IntegratedIn Stock: 4814DS1501WZ+T&R Datasheet

MFR RecommendedRFQ

DS1501YZ+

Analog Devices Inc./Maxim IntegratedIn Stock: 713DS1501YZ+ Datasheet

MFR RecommendedRFQ

DS1511Y+

Analog Devices Inc./Maxim IntegratedIn Stock: 2153DS1511Y+ Datasheet

MFR RecommendedRFQ

DS1554-70+

Analog Devices Inc./Maxim IntegratedIn Stock: 1484DS1554-70+ Datasheet

MFR RecommendedRFQ

DS1554W-120IND+

Analog Devices Inc./Maxim IntegratedIn Stock: 1342DS1554W-120IND+ Datasheet

MFR RecommendedRFQ

DS1557WP-120+

Analog Devices Inc./Maxim IntegratedIn Stock: 1161DS1557WP-120+ Datasheet

MFR RecommendedRFQ

DS1685-5+

Analog Devices Inc./Maxim IntegratedIn Stock: 1293DS1685-5+ Datasheet

MFR RecommendedRFQ

DS1685S-3+

Analog Devices Inc./Maxim IntegratedIn Stock: 1114DS1685S-3+ Datasheet

MFR RecommendedRFQ

DS1685S-3+T&R

Analog Devices Inc./Maxim IntegratedIn Stock: 980DS1685S-3+T&R Datasheet

MFR RecommendedRFQ

DS1685SN-5+

Analog Devices Inc./Maxim IntegratedIn Stock: 979DS1685SN-5+ Datasheet

MFR RecommendedRFQ

DS17285SN-5+

Analog Devices Inc./Maxim IntegratedIn Stock: 1383DS17285SN-5+ Datasheet

MFR RecommendedRFQ

DS1746W-120IND+

Analog Devices Inc./Maxim IntegratedIn Stock: 1826DS1746W-120IND+ Datasheet

MFR RecommendedRFQ

DS1747-70IND+

Analog Devices Inc./Maxim IntegratedIn Stock: 3752DS1747-70IND+ Datasheet

MFR RecommendedRFQ

M48T58-70PC1

STMicroelectronicsIn Stock: 1546M48T58-70PC1 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the BQ3285EP are grouped based on the following critical parameters that determine functional compatibility:

Primary Compatibility Criteria:

• Parallel interface architecture (required for direct functional replacement)
• Time format support: HH:MM:SS with 12/24 hour capability
• Date format support: YY-MM-DD-dd
• Core RTC features: Alarm, NVSRAM, Square Wave Output
• Supply voltage compatibility: 4.5V ~ 5.5V primary supply
• Battery backup voltage range: 2.5V ~ 4V minimum overlap

Substitution Groups:

Group 1: Direct Package Equivalents (24-DIP Through Hole)

• DS12CR887-5+: 24-DIP Module, active status, enhanced feature set (trickle-charger)
• DS1685-5+: 24-DIP, active status, 242B memory (identical to BQ3285EP)

Group 2: Surface Mount Alternatives (24-SOIC)

• DS1685S-3+: 24-SOIC package, 242B memory, reduced voltage supply (2.7V ~ 3.7V)

Group 3: Extended Memory Variants (28-DIP/SOIC)

• DS1511Y+: 28-DIP Module, 256B memory, enhanced features (watchdog timer, Y2K)
• DS1501WZ+T&R: 28-SOIC, 256B memory, 3V ~ 3.6V supply
• DS1501YZ+: 28-SOIC, 256B memory, 4.5V ~ 5.5V supply

Group 4: High-Capacity Modules (32-DIP/34-PowerCap)

• DS1554-70+: 32-DIP Module, 32KB memory, enhanced features
• DS1554W-120IND+: 32-DIP Module, 32KB memory, 3.3V operation
• DS1557WP-120+: 34-PowerCap Module, 512KB memory, surface mount

Group 5: Alternative Package Formats

• DS12885QN+: 28-PLCC (J-Lead), surface mount, 114B memory

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Same Package, Same Memory): DS1685-5+ is the primary substitute for BQ3285EP. Both devices feature 242B memory, 24-DIP through-hole packaging, identical time and date formats, and parallel interface. DS1685-5+ is active status with ROHS3 compliance and extended operating temperature range (-40°C ~ 85°C vs. 0°C ~ 70°C). Supply voltage compatibility is maintained at 4.5V ~ 5.5V. Battery backup voltage differs slightly (2.5V ~ 3.7V vs. 2.5V ~ 4V), remaining within acceptable overlap for most applications.

For Through-Hole Mounting with Enhanced Features: DS12CR887-5+ maintains 24-DIP through-hole packaging with active status and ROHS3 compliance. This device provides trickle-charger functionality and extended temperature range (-40°C ~ 85°C). Memory capacity is reduced to 114B, and battery voltage range is narrower (2V ~ 3.05V). This option is suitable when enhanced temperature performance and trickle-charger capability are required.

For Surface Mount Implementation (Same Memory Capacity): DS1685S-3+ provides 242B memory in 24-SOIC surface mount package with active status and ROHS3 compliance. Supply voltage is reduced to 2.7V ~ 3.7V, requiring circuit redesign for lower voltage operation. This option is appropriate for new designs prioritizing surface mount assembly and lower power consumption.

For Extended Memory Requirements: DS1511Y+ (28-DIP Module) and DS1501 series (28-SOIC) offer 256B memory with watchdog timer and Y2K functionality. These devices maintain parallel interface and active status. DS1511Y+ preserves through-hole mounting; DS1501 variants provide surface mount options. Operating temperature extends to -40°C ~ 85°C. Time format is limited to 24-hour operation.

For High-Capacity Applications: DS1554 series (32KB memory) and DS1557WP-120+ (512KB memory) provide significantly expanded memory for applications requiring extended data logging. All maintain parallel interface and active status with ROHS3 compliance. DS1554 variants support through-hole mounting; DS1557WP-120+ is surface mount only. Operating temperature ranges extend to -40°C ~ 85°C for industrial variants.

Compliance Considerations: All substitute parts maintain ROHS3 compliance and REACH unaffected status, matching the BQ3285EP certification profile. All devices are classified as active products, ensuring long-term availability and supply chain stability compared to the obsolete BQ3285EP.

Frequently Asked Questions (FAQ)

Q: Can DS1685-5+ directly replace BQ3285EP without circuit modification? A: DS1685-5+ is functionally compatible as a direct replacement. Both devices feature identical 242B memory, 24-DIP through-hole packaging, HH:MM:SS (12/24 hr) time format, and YY-MM-DD-dd date format with parallel interface. Supply voltage (4.5V ~ 5.5V) and battery backup voltage ranges overlap sufficiently for most applications. Pin-to-pin compatibility should be verified against device datasheets before implementation.

Q: What is the primary difference between DS1685-5+ and DS12CR887-5+? A: Both are 24-DIP through-hole devices with active status. DS1685-5+ provides 242B memory matching BQ3285EP capacity, while DS12CR887-5+ offers 114B memory but includes trickle-charger functionality. DS12CR887-5+ has narrower battery voltage range (2V ~ 3.05V). Selection depends on whether trickle-charger capability is required and whether reduced memory capacity is acceptable.

Q: Why do some substitutes use 24-hour time format instead of 12/24 hour? A: DS1511Y+, DS1501 series, DS1554 series, and DS1557WP-120+ are designed for 24-hour time format operation only. These devices are suitable for applications that do not require 12-hour format support. Applications requiring 12/24 hour flexibility should select DS1685-5+, DS1685S-3+, or DS12CR887-5+.

Q: Can I use a surface mount substitute in a through-hole design? A: Surface mount devices (DS1685S-3+, DS1501 series, DS1557WP-120+) require different PCB footprints and assembly processes than through-hole designs. Direct substitution is not possible without PCB redesign and assembly process modification. Through-hole alternatives (DS1685-5+, DS12CR887-5+, DS1511Y+, DS1554 series) are recommended for existing through-hole designs.

Q: What memory capacity differences exist among substitutes? A: BQ3285EP and DS1685-5+ provide 242B. DS12CR887-5+ and DS12885QN+ offer 114B. DS1511Y+ and DS1501 series provide 256B. DS1554 series offers 32KB. DS1557WP-120+ provides 512KB. Memory selection depends on application data storage requirements. Reduced memory devices may require firmware modification; expanded memory devices provide additional capacity without functional changes.

Q: Are all substitutes ROHS3 compliant? A: All listed substitute parts maintain ROHS3 compliance and REACH unaffected status, matching BQ3285EP certification. This ensures environmental and regulatory compatibility across all substitute options.

Q: What operating temperature ranges are available? A: BQ3285EP operates 0°C ~ 70°C. Most active substitutes extend to -40°C ~ 85°C, providing wider industrial temperature range. DS1557WP-120+ operates 0°C ~ 70°C, matching BQ3285EP range. Temperature range selection depends on application environment requirements.

Q: Which substitute offers the best direct compatibility? A: DS1685-5+ provides the highest compatibility with BQ3285EP: identical 242B memory, 24-DIP through-hole package, matching time/date formats, parallel interface, and 4.5V ~ 5.5V supply voltage. Battery voltage range differs minimally (2.5V ~ 3.7V vs. 2.5V ~ 4V). This device is the recommended primary substitute for direct replacement applications.