BQ3285P-SB2 Equivalent & Substitute Parts

Part Overview

The BQ3285P-SB2 is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Texas Instruments. This device provides 114 bytes of NVSRAM with parallel interface in a 24-DIP through-hole package. The BQ3285P-SB2 is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing system support. Substitute parts maintain core RTC functionality while offering active product status and extended availability.

Key Parameters

Parameter	BQ3285P-SB2
Manufacturer	Texas Instruments
Product Status	Obsolete
Package / Case	24-DIP (0.600", 15.24mm)
Mounting Type	Through Hole
Memory Size	114B
Interface	Parallel
Voltage - Supply	4.5V ~ 5.5V
Voltage - Supply, Battery	2.5V ~ 4V
Operating Temperature	0°C ~ 70°C
Time Format	HH:MM:SS (12/24 hr)
Date Format	YY-MM-DD-dd
Features	Alarm, Daylight Savings, Leap Year, NVSRAM, Square Wave Output
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the BQ3285P-SB2 are grouped based on the following substitution criteria:

Primary Substitution Criteria (Mandatory Match):

Parallel interface
Clock/Calendar functionality with alarm capability
NVSRAM storage
ROHS3 compliance
EAR99 export classification

Secondary Grouping Factors:

Package type (24-DIP through-hole preferred for direct replacement; surface-mount and alternative packages listed separately)
Supply voltage compatibility (5V operation preferred; 3.3V variants noted)
Operating temperature range (0°C ~ 70°C matches original; extended range -40°C ~ 85°C noted)
Memory size (114B baseline; larger memory variants acceptable)

Substitution Groups:

Group 1: Direct 24-DIP Through-Hole Replacements (5V Operation)

DS12885N+ (24-DIP, 5V, extended temperature)
DS12885+ (24-DIP, 5V, matched temperature range)
DS1687-5+ (24-DIP Module, 5V, matched temperature range)

Group 2: Alternative Package Formats (5V Operation)

DS12885Q+ (28-PLCC surface mount, 5V)
DS1556-70IND+ (32-DIP Module, 5V, extended temperature)
DS1746-70+ (32-DIP Module, 5V, matched temperature range)
DS1746P-70+ (34-PowerCap Module, 5V, matched temperature range)

Group 3: Low-Voltage Surface-Mount Variants (3.3V Operation)

DS12R885S-33+T&R (24-SOIC, 3.3V, extended temperature)
DS17285S-3+T&R (24-SOIC, 3.3V, matched temperature range)
DS1501WZN+ (28-SOIC, 3.3V, extended temperature)

Parameter Comparison

Part Number	Manufacturer	Package / Case	Mounting Type	Memory Size	Voltage - Supply	Operating Temperature	Product Status	Time Format	Interface
BQ3285P-SB2	Texas Instruments	24-DIP (0.600", 15.24mm)	Through Hole	114B	4.5V ~ 5.5V	0°C ~ 70°C	Obsolete	HH:MM:SS (12/24 hr)	Parallel
DS12885N+	Analog Devices Inc./Maxim Integrated	24-DIP (0.600", 15.24mm)	Through Hole	114B	4.5V ~ 5.5V	-40°C ~ 85°C	Active	HH:MM:SS (12/24 hr)	Parallel
DS12885+	Analog Devices Inc./Maxim Integrated	24-DIP (0.600", 15.24mm)	Through Hole	114B	4.5V ~ 5.5V	0°C ~ 70°C	Active	HH:MM:SS (12/24 hr)	Parallel
DS12885Q+	Analog Devices Inc./Maxim Integrated	28-LCC (J-Lead)	Surface Mount	114B	4.5V ~ 5.5V	0°C ~ 70°C	Active	HH:MM:SS (12/24 hr)	Parallel
DS12R885S-33+T&R	Analog Devices Inc./Maxim Integrated	24-SOIC (0.295", 7.50mm Width)	Surface Mount	114B	2.97V ~ 3.63V	-40°C ~ 85°C	Active	HH:MM:SS (12/24 hr)	Parallel
DS1501WZN+	Analog Devices Inc./Maxim Integrated	28-SOIC (0.295", 7.50mm Width)	Surface Mount	256B	3V ~ 3.6V	-40°C ~ 85°C	Active	HH:MM:SS (24 hr)	Parallel
DS1556-70IND+	Analog Devices Inc./Maxim Integrated	32-DIP Module (0.600", 15.24mm)	Through Hole	128KB	4.5V ~ 5.5V	-40°C ~ 85°C	Active	HH:MM:SS (24 hr)	Parallel
DS1687-5+	Analog Devices Inc./Maxim Integrated	24-DIP Module (0.600", 15.24mm)	Through Hole	242B	4.5V ~ 5.5V	0°C ~ 70°C	Active	HH:MM:SS (12/24 hr)	Parallel
DS17285S-3+T&R	Analog Devices Inc./Maxim Integrated	24-SOIC (0.295", 7.50mm Width)	Surface Mount	2KB	2.7V ~ 3.7V	0°C ~ 70°C	Active	HH:MM:SS (12/24 hr)	Parallel
DS1746-70+	Analog Devices Inc./Maxim Integrated	32-DIP Module (0.600", 15.24mm)	Through Hole	128KB	4.5V ~ 5.5V	0°C ~ 70°C	Active	HH:MM:SS (24 hr)	Parallel
DS1746P-70+	Analog Devices Inc./Maxim Integrated	34-PowerCap™ Module	Surface Mount	128KB	4.5V ~ 5.5V	0°C ~ 70°C	Active	HH:MM:SS (24 hr)	Parallel

Engineering Selection Recommendations

For Direct Pin-Compatible Replacement (Preferred): Select DS12885+ for applications requiring matched operating temperature range (0°C ~ 70°C) and identical 24-DIP through-hole package. This part maintains full functional and electrical compatibility with the BQ3285P-SB2 while offering active product status and ROHS3 compliance.

Select DS12885N+ when extended operating temperature range (-40°C ~ 85°C) is required. This variant provides identical package and electrical specifications with enhanced temperature performance.

For Through-Hole Applications with Enhanced Memory: DS1687-5+ provides 242 bytes of NVSRAM in a 24-DIP module format, suitable for applications requiring additional non-volatile storage while maintaining 5V operation and matched temperature range.

DS1556-70IND+ and DS1746-70+ offer 128KB memory in 32-DIP module packages for applications requiring significantly larger storage capacity. Both maintain 5V operation; DS1556-70IND+ supports extended temperature range.

For Surface-Mount Designs: DS12885Q+ provides 28-PLCC package for surface-mount integration with 5V operation and matched temperature range.

DS12R885S-33+T&R and DS17285S-3+T&R are 24-SOIC surface-mount variants operating at 3.3V. DS12R885S-33+T&R supports extended temperature range; DS17285S-3+T&R matches the original temperature specification.

DS1501WZN+ offers 28-SOIC surface-mount package with 256 bytes memory and extended temperature range for 3.3V systems.

DS1746P-70+ provides 34-PowerCap module format for surface-mount applications requiring 128KB memory at 5V operation.

All substitute parts maintain ROHS3 compliance and EAR99 export classification consistent with the original BQ3285P-SB2.

Frequently Asked Questions (FAQ)

Q: Can DS12885+ directly replace BQ3285P-SB2 in existing PCB designs? A: Yes. DS12885+ matches the BQ3285P-SB2 in package type (24-DIP), pin count, supply voltage (4.5V ~ 5.5V), operating temperature range (0°C ~ 70°C), memory size (114B), and parallel interface. No PCB modifications are required.

Q: What is the difference between DS12885+ and DS12885N+? A: Both parts use identical 24-DIP packages and electrical specifications. DS12885N+ supports extended operating temperature range (-40°C ~ 85°C) compared to DS12885+ (0°C ~ 70°C). Select DS12885N+ for applications requiring operation below 0°C or above 70°C.

Q: Why are 3.3V variants (DS12R885S-33+T&R, DS17285S-3+T&R) listed as substitutes? A: These parts provide functional RTC equivalence with parallel interface and NVSRAM, but operate at 3.3V instead of 5V. They are suitable only for new designs or systems where 3.3V operation is acceptable. Existing 5V systems require 5V-rated substitutes.

Q: Can I use DS1556-70IND+ or DS1746-70+ as replacements? A: These 32-DIP module packages provide RTC functionality with significantly larger memory (128KB) and are physically larger than the original 24-DIP package. They are suitable for new designs where additional memory is beneficial, but require PCB redesign for existing applications.

Q: What does "Tape & Reel (TR)" packaging mean for DS12R885S-33+T&R and DS17285S-3+T&R? A: Tape & Reel packaging indicates components supplied on continuous tape for automated assembly. These parts are surface-mount devices in 24-SOIC packages, suitable for high-volume manufacturing. They are not compatible with through-hole PCB designs.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts maintain ROHS3 compliance and EAR99 export classification, consistent with the original BQ3285P-SB2.

Q: Which substitute offers the best compatibility for legacy system support? A: DS12885+ provides the closest functional and electrical match with active product status. It maintains identical package, voltage, temperature range, and memory specifications, requiring no design modifications.

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