BQ4285P-SB2 Equivalent & Substitute Parts

Part Overview

The BQ4285P-SB2 is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Texas Instruments. This device features 114 bytes of NVSRAM, parallel interface, and comprehensive timekeeping capabilities including alarm, daylight savings, leap year, and square wave output functions. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations.

Key Parameters

Parameter	Value
Manufacturer Part Number	BQ4285P-SB2
Manufacturer	Texas Instruments
Category	Clock/Timing
Type	Clock/Calendar
Memory Size	114B
Interface	Parallel
Package / Case	24-DIP (0.600", 15.24mm)
Voltage - Supply	4.5V ~ 5.5V
Voltage - Supply, Battery	2.5V ~ 4V
Operating Temperature	0°C ~ 70°C
Mounting Type	Through Hole
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the BQ4285P-SB2 is determined by the following critical parameters:

Primary Substitution Criteria:

Interface type (Parallel)
Memory size compatibility (114B minimum)
Time and date format support (HH:MM:SS and YY-MM-DD-dd)
Supply voltage range (4.5V ~ 5.5V primary operation)
Battery backup voltage support (2.5V ~ 4V range)
Operating temperature range (0°C ~ 70°C minimum)
Mounting type (Through Hole preferred for direct replacement)
Package form factor (24-DIP or compatible module)
Feature set (Alarm, Leap Year, NVSRAM, Square Wave Output)

Substitution Groups:

Group 1: Direct Pin-Compatible Replacements (24-DIP Through Hole)

DS12885+ (24-DIP, 114B memory, active status)
DS17287-3+ (24-DIP Module, 2KB memory, active status)

Group 2: Enhanced Memory Alternatives (Through Hole Modules)

DS1511W+ (28-DIP Module, 256B memory, 3V ~ 3.6V supply)
DS1744-70IND+ (28-DIP Module, 32KB memory, 4.5V ~ 5.5V supply)
DS1554-70IND+ (32-DIP Module, 32KB memory, 4.5V ~ 5.5V supply)

Group 3: Surface Mount Alternatives

DS1501YZN+ (28-SOIC, 256B memory, 4.5V ~ 5.5V supply)
DS1685E-5+T&R (24-TSSOP, 242B memory, 4.5V ~ 5.5V supply)
DS17285S-3+T&R (24-SOIC, 2KB memory, 2.7V ~ 3.7V supply)

Group 4: High-Capacity Modules (Surface Mount)

DS1556WP-120+ (34-PowerCap™ Module, 128KB memory, 2.97V ~ 3.63V supply)
DS1557WP-120IND+ (34-PowerCap™ Module, 512KB memory, 2.97V ~ 3.63V supply)

Parameter Comparison

Part Number	Manufacturer	Memory Size	Package / Case	Mounting Type	Voltage - Supply	Voltage - Battery	Operating Temp	Time Format	Features	Product Status
BQ4285P-SB2	Texas Instruments	114B	24-DIP (0.600", 15.24mm)	Through Hole	4.5V ~ 5.5V	2.5V ~ 4V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output	Obsolete
DS12885+	Analog Devices Inc./Maxim Integrated	114B	24-DIP (0.600", 15.24mm)	Through Hole	4.5V ~ 5.5V	2.5V ~ 4V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output	Active
DS17287-3+	Analog Devices Inc./Maxim Integrated	2KB	24-DIP Module (0.600", 15.24mm)	Through Hole	2.7V ~ 3.7V	2.5V ~ 3.7V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output	Active
DS1501YZN+	Analog Devices Inc./Maxim Integrated	256B	28-SOIC (0.295", 7.50mm Width)	Surface Mount	4.5V ~ 5.5V	2.5V ~ 3.7V	-40°C ~ 85°C	HH:MM:SS (24 hr)	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	Active
DS1511W+	Analog Devices Inc./Maxim Integrated	256B	28-DIP Module (0.600", 15.24mm)	Through Hole	3V ~ 3.6V	2.5V ~ 3.7V	0°C ~ 70°C	HH:MM:SS (24 hr)	Alarm, Leap Year, NVSRAM, Square Wave Output, Watchdog Timer, Y2K	Active
DS1554-70IND+	Analog Devices Inc./Maxim Integrated	32KB	32-DIP Module (0.600", 15.24mm)	Through Hole	4.5V ~ 5.5V	—	-40°C ~ 85°C	HH:MM:SS (24 hr)	Alarm, Leap Year, NVSRAM, Watchdog Timer, Y2K	Active
DS1556WP-120+	Analog Devices Inc./Maxim Integrated	128KB	34-PowerCap™ Module	Surface Mount	2.97V ~ 3.63V	3V	0°C ~ 70°C	HH:MM:SS (24 hr)	Alarm, Leap Year, NVSRAM, Watchdog Timer, Y2K	Active
DS1557WP-120IND+	Analog Devices Inc./Maxim Integrated	512KB	34-PowerCap™ Module	Surface Mount	2.97V ~ 3.63V	3V	-40°C ~ 85°C	HH:MM:SS (24 hr)	Alarm, Leap Year, NVSRAM, Watchdog Timer, Y2K	Active
DS1685E-5+T&R	Analog Devices Inc./Maxim Integrated	242B	24-TSSOP (0.173", 4.40mm Width)	Surface Mount	4.5V ~ 5.5V	2.5V ~ 3.7V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Alarm, NVSRAM, Square Wave Output, Y2K	Active
DS17285S-3+T&R	Analog Devices Inc./Maxim Integrated	2KB	24-SOIC (0.295", 7.50mm Width)	Surface Mount	2.7V ~ 3.7V	2.5V ~ 3.7V	0°C ~ 70°C	HH:MM:SS (12/24 hr)	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output	Active
DS1744-70IND+	Analog Devices Inc./Maxim Integrated	32KB	28-DIP Module (0.600", 15.24mm)	Through Hole	4.5V ~ 5.5V	—	-40°C ~ 85°C	HH:MM:SS (24 hr)	Leap Year, NVSRAM, Y2K	Active

Engineering Selection Recommendations

For Direct Replacement (Existing Through-Hole PCB Layout):

DS12885+ is the primary equivalent for the BQ4285P-SB2. Both devices share identical package geometry (24-DIP), memory size (114B), supply voltage range (4.5V ~ 5.5V), battery backup voltage (2.5V ~ 4V), operating temperature range (0°C ~ 70°C), and feature set (Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output). DS12885+ is manufactured by Analog Devices Inc./Maxim Integrated and maintains active product status with ROHS3 compliance.

For Through-Hole Designs Requiring Enhanced Memory:

DS17287-3+ provides 2KB memory in a 24-DIP module form factor with identical mounting type. Operating temperature and feature compatibility match the original specification. Supply voltage operates at 2.7V ~ 3.7V, which is compatible with the 4.5V ~ 5.5V primary supply range through appropriate voltage regulation.

DS1744-70IND+ and DS1554-70IND+ offer 32KB memory in through-hole module packages (28-DIP and 32-DIP respectively) with 4.5V ~ 5.5V supply compatibility. Both maintain ROHS3 compliance and active product status.

For Surface Mount Designs:

DS1685E-5+T&R provides the closest functional match in surface mount form (24-TSSOP), maintaining 4.5V ~ 5.5V supply voltage, 12/24-hour time format, and core features including alarm and square wave output. Memory size is 242B, exceeding the original 114B specification.

DS17285S-3+T&R offers 2KB memory in 24-SOIC package with full feature parity including daylight savings support. Supply voltage operates at 2.7V ~ 3.7V.

For High-Capacity Applications:

DS1556WP-120+ and DS1557WP-120IND+ provide 128KB and 512KB memory respectively in 34-PowerCap™ surface mount modules. Both maintain ROHS3 compliance and active status. Supply voltage is 2.97V ~ 3.63V with integrated 3V battery backup.

All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, matching the original part's regulatory classification.

Frequently Asked Questions (FAQ)

Q: Can DS12885+ be used as a direct drop-in replacement for BQ4285P-SB2?

A: Yes. DS12885+ matches the BQ4285P-SB2 in package geometry (24-DIP), memory size (114B), supply voltage (4.5V ~ 5.5V), battery backup voltage (2.5V ~ 4V), operating temperature range (0°C ~ 70°C), and feature set. Pin-level compatibility requires verification against device datasheets, but electrical and functional specifications are equivalent.

Q: What is the difference between 24-DIP and 24-DIP Module packages?

A: 24-DIP is a standard dual-in-line package with 24 pins. 24-DIP Module refers to an encapsulated module form factor that maintains the same 0.600" (15.24mm) pitch and pin count but may include integrated support circuitry. Both are through-hole mounting types suitable for PCB insertion.

Q: Can I use DS1501YZN+ (28-SOIC) in place of BQ4285P-SB2 (24-DIP)?

A: No direct substitution is possible due to package incompatibility. DS1501YZN+ is a surface mount device (28-SOIC) requiring different PCB layout and soldering process. However, it provides equivalent RTC functionality with enhanced memory (256B), extended operating temperature range (-40°C ~ 85°C), and additional features (Watchdog Timer, Y2K support).

Q: What are the supply voltage considerations when selecting a substitute?

A: The BQ4285P-SB2 operates at 4.5V ~ 5.5V primary supply with 2.5V ~ 4V battery backup. Substitutes with lower primary supply ranges (e.g., DS17287-3+ at 2.7V ~ 3.7V) require voltage regulation to interface with 5V systems. Substitutes with matching 4.5V ~ 5.5V ranges (DS12885+, DS1554-70IND+, DS1744-70IND+) integrate directly without additional conditioning.

Q: Does memory size affect substitution compatibility?

A: Memory size does not prevent substitution if the substitute provides equal or greater capacity. The BQ4285P-SB2 specifies 114B NVSRAM. Substitutes with 114B (DS12885+) provide exact equivalence. Substitutes with larger memory (2KB, 256B, 32KB) are compatible if the application does not depend on specific memory addressing or layout. Verify address bus width and memory organization against system requirements.

Q: Are all listed substitutes ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, matching the original BQ4285P-SB2 regulatory classification.

Q: What features are critical for RTC substitution?

A: Core features required for substitution are parallel interface, time format support (HH:MM:SS), date format support (YY-MM-DD-dd), NVSRAM, and alarm capability. The BQ4285P-SB2 includes daylight savings and square wave output; substitutes lacking these features (e.g., DS1744-70IND+) may require firmware or circuit modifications to maintain system functionality.

Q: Can I use a higher operating temperature range substitute in a 0°C ~ 70°C application?

A: Yes. A substitute rated for -40°C ~ 85°C (e.g., DS1501YZN+, DS1554-70IND+) exceeds the original 0°C ~ 70°C specification and is suitable for the same application. The wider temperature range provides additional design margin and environmental robustness.

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