DS1685Q-3 Equivalent & Substitute Parts

Part Overview

The DS1685Q-3 is a Real Time Clock (RTC) IC with integrated Clock/Calendar functionality, manufactured by Analog Devices Inc./Maxim Integrated. This device features 242 bytes of NVSRAM, parallel interface, alarm capability, and square wave output in a 28-LCC (J-Lead) surface mount package. The DS1685Q-3 is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across clock/calendar operations, time/date format support, and parallel interface architecture while accommodating different packaging options.

Substiute Parts

DS1685Q-3

Analog Devices Inc./Maxim IntegratedIn Stock: 2249DS1685Q-3 Datasheet

Current PartRFQ

BQ4802LYDWR

Texas InstrumentsIn Stock: 3828BQ4802LYDWR Datasheet

MFR RecommendedRFQ

BQ4802LYPWR

Texas InstrumentsIn Stock: 28912BQ4802LYPWR Datasheet

MFR RecommendedRFQ

M48T18-100PC1

STMicroelectronicsIn Stock: 1462M48T18-100PC1 Datasheet

MFR RecommendedRFQ

M48T58-70PC1

STMicroelectronicsIn Stock: 1546M48T58-70PC1 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the DS1685Q-3 is based on the following critical parameters:

Functional Compatibility Requirements:

• Clock/Calendar type with parallel interface
• Time format support: HH:MM:SS (12/24 hr)
• Date format support: YY-MM-DD-dd
• Operating temperature range: 0°C ~ 70°C
• Supply voltage compatibility within acceptable ranges

Acceptable Variations:

• Package/case type may differ (28-SOIC, 28-TSSOP, 28-DIP Module acceptable as alternatives to 28-LCC)
• Mounting type may change (Surface Mount or Through Hole)
• Supply voltage ranges may vary slightly (2.7V ~ 3.6V or 4.5V ~ 5.5V depending on substitute)
• Current consumption may differ
• Memory size and feature sets may vary
• RoHS compliance status may differ

Substitute Parts Identified:

1. BQ4802LYDWR (Texas Instruments, 28-SOIC, Active)
2. BQ4802LYPWR (Texas Instruments, 28-TSSOP, Active)
3. M48T18-100PC1 (STMicroelectronics, 28-DIP Module, Active)
4. M48T58-70PC1 (STMicroelectronics, 28-DIP Module, Active)

Parameter Comparison

Engineering Selection Recommendations

BQ4802LYDWR and BQ4802LYPWR (Texas Instruments): These parts are recommended for designs requiring surface mount packaging with low-voltage operation (2.7V ~ 3.6V). Both maintain 12/24-hour time format and YY-MM-DD-dd date format compatibility with the DS1685Q-3. BQ4802LYDWR uses 28-SOIC packaging; BQ4802LYPWR uses 28-TSSOP packaging. Both are Active products with ROHS3 compliance, providing long-term availability and regulatory compliance advantages over the obsolete DS1685Q-3.

M48T18-100PC1 and M48T58-70PC1 (STMicroelectronics): These parts are recommended for designs requiring through-hole packaging or legacy board compatibility. Both use 28-DIP Module packaging and operate at 4.5V ~ 5.5V (M48T18-100PC1) or 4.75V ~ 5.5V (M48T58-70PC1). Time format is limited to 24-hour operation. Both are Active products with ROHS3 compliance. These substitutes are suitable when PCB redesign for surface mount is not feasible.

Product Status Consideration: All substitute parts carry Active product status, ensuring continued manufacturing support, availability, and compliance with current regulatory requirements. The DS1685Q-3 obsolete status necessitates transition to one of these active alternatives.

Frequently Asked Questions (FAQ)

Q: Can BQ4802LYDWR or BQ4802LYPWR directly replace DS1685Q-3 without PCB modification?

A: No. While both Texas Instruments parts maintain functional compatibility (parallel interface, clock/calendar operation, 12/24-hour time format, YY-MM-DD-dd date format), they use different package types (28-SOIC and 28-TSSOP respectively) compared to the DS1685Q-3 (28-LCC). PCB layout and footprint changes are required.

Q: What is the key difference between BQ4802LYDWR and BQ4802LYPWR?

A: Both parts are functionally identical Texas Instruments BQ4802 clock/calendar ICs. The difference is packaging: BQ4802LYDWR uses 28-SOIC (0.295" width), while BQ4802LYPWR uses 28-TSSOP (0.173" width). BQ4802LYPWR offers smaller board footprint. Electrical specifications and feature sets are identical.

Q: Are M48T18-100PC1 and M48T58-70PC1 suitable for low-voltage applications?

A: No. Both STMicroelectronics parts require 4.5V ~ 5.5V (M48T18-100PC1) or 4.75V ~ 5.5V (M48T58-70PC1) supply voltage. The DS1685Q-3 operates at 2.7V ~ 3.7V. These substitutes are only suitable for designs with 5V supply rails. For low-voltage designs, use BQ4802LYDWR or BQ4802LYPWR.

Q: Does the DS1685Q-3 support 24-hour time format only?

A: No. The DS1685Q-3 supports both 12-hour and 24-hour time formats (HH:MM:SS 12/24 hr). BQ4802LYDWR and BQ4802LYPWR also support both formats. M48T18-100PC1 and M48T58-70PC1 support 24-hour format only.

Q: What is the inventory status of substitute parts?

A: BQ4802LYDWR: 3,770 pcs in stock. BQ4802LYPWR: 28,900 pcs in stock. M48T18-100PC1: 1,444 pcs in stock. M48T58-70PC1: 1,516 pcs in stock. All substitutes are available as new original stock.

Q: Are all substitute parts RoHS compliant?

A: Yes. All four substitute parts (BQ4802LYDWR, BQ4802LYPWR, M48T18-100PC1, M48T58-70PC1) are ROHS3 compliant. The original DS1685Q-3 is RoHS non-compliant. Compliance status should be verified against specific design requirements.

Q: Can I use M48T18-100PC1 in a surface mount assembly?

A: No. M48T18-100PC1 and M48T58-70PC1 are through-hole components (28-DIP Module packaging). They require through-hole PCB design and manual or selective wave soldering. For surface mount assembly, use BQ4802LYDWR (28-SOIC) or BQ4802LYPWR (28-TSSOP).