Maxim > Products > Real-time clocks (RTCs) > DS14285, DS14287

DS14285, DS14287
Real-Time Clock with NV RAM Control

Overview

Technical Documents

Ordering Info

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Status
Part Number	Status	Replacement	Explanation
DS14285	This product is No Longer Available. See Ordering Information for recommended replacements.	DS1685	There is no direct replacement. The DS1685 has 242 bytes of RAM.
DS14287	This product is No Longer Available. See Ordering Information for recommended replacements.	DS1687	There is no direct replacement.

Data Sheet

FULL DATA SHEET Download Rev 2 (PDF, 520kB) E-Mail

Description

FULL DATA SHEET Download Rev 2 (PDF, 520kB) E-Mail The DS14285/DS14287 real-time clock with NV RAM control provides the industry standard DS1287 clock function with the additional feature of providing nonvolatile control for an external SRAM. Functions include a nonvolatile time-of-day clock, alarm, 100-year calendar, programmable interrupt, square wave generator, and 114 bytes of nonvolatile static RAM. For the DS14287 a lithium energy source, quartz crystal, and write protection circuitry are contained within a 24-pin dual in-line package. The DS14285 requires an external quartz crystal connected to the X1 and X2 pins as well as an external energy source connected to the VBAT pin. A standard 32.768kHz quartz crystal can be directly connected to the DS14285 via pins 1 and 2 (X1, X2). The crystal selected for use should have a specified load capacitance (CL) of 6pF. For more information on crystal selection and crystal layout considerations, please consult Application Note 58, Crystal Considerations with Dallas Real-time Clocks. The DS14285/DS14287 uses its backup energy source and battery-backup controller to make a standard CMOS static RAM nonvolatile during power-fail conditions. During power fail, the DS14285/DS14287 automatically write-protects the external SRAM and provides a VCC output sourced from its internal battery. For the DS14287 the internal lithium cell is electrically isolated from the clock and memory when shipped from the factory. This isolation is removed after the first application of VCC, allowing the lithium cell to provide data retention to the clock, internal RAM, VCCO and active-low CEO on subsequent power-downs. Care must be taken after this isolation has been broken to avoid inadvertently discharging the lithium cell through the VCCO and active-low CEO pins.

This product contains lithium-metal batteries. See applicable regulations for transport requirements for batteries in equipment.

Key Features

Direct replacement for IBM AT computer clock/calendar Functionally compatible with the DS1285/DS1287 Available as chip (DS14285, DS14285S, or DS14285Q) or stand-alone module with embedded lithium battery and crystal (DS14287) Automatic backup supply and write protection to make external SRAM nonvolatile Counts seconds, minutes, hours, days, day of the week, date, month, and year with leap year compensation valid up to 2100 Binary or BCD representation of time, calendar, and alarm 12- or 24-hour clock with AM and PM in 12-hour mode Daylight savings time option Multiplex bus for pin efficiency Interfaced with software as 128 RAM locations 14 bytes of clock and control registers 114 bytes of general purpose RAM Programmable square wave output signal Bus-compatible interrupt signals (active-low IRQ) Three interrupts are separately software maskable and testable Time-of-day alarm once/second to once/day Periodic rates from 122µs to 500ms End of clock update cycle Optional industrial temperature version available DS14285 DIP, SO, and PLCC Underwriters Laboratories (UL) Recognized

Application Notes
Application Note 58	Crystal Considerations with Dallas Real-Time Clocks (RTCs)
Application Note 499	Using the Multiplex Bus RTC Extended Features
Application Note 504	Design considerations for Dallas Semiconductor real-time clocks
Application Note 505	Lithium Coin-Cell Batteries: Predicting an Application Lifetime
Application Note 701	Using the DS32kHz with Dallas Real-Time Clocks
Application Note 3778	Problems and Solutions for Adjusting to Changes in Daylight Saving Time
Application Note 3816	Selecting a Backup Source for Real-Time Clocks

Design Guides

Real-Time Clocks (PDF)

Reliability Reports
Reliability Report:	DS14285.pdf DS14287.pdf
Underwriters Laboratories (UL) Recognized

Software/Models

none

Ordering Information

Notes: Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day. Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt; -D = drypack; -U/+U on DS parts = cut tape. More: See Full Data Sheet or Maxim Product Naming Conventions. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.

Filters

Part Number: Package: Any -------- PLCC SOIC PDIP MOD Temperature: Any -------- -40°C to +85°C 0°C to +70°C Tape and Reel

DS14285	Free Sample	Buy	Status	Recommended Replacement	Package: TYPE PINS FOOTPRINT   DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS14285N		N/A	No Longer Available	DS1685-5IND+	PDIP(W);24 pin;520.4 mm² Outline Drawing:21-0044 (PDF) Land Pattern: Not Applicable Use pkgcode/variation: P24-3*	-40°C to +85°C	RoHS/Lead-Free: No Materials Analysis
DS14285+		N/A	No Longer Available	DS1685-5+	PDIP(W);24 pin;520.4 mm² Outline Drawing:21-0044 (PDF) Land Pattern: Not Applicable Use pkgcode/variation: P24+3*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285		N/A	No Longer Available	DS1685 There is no direct replacement. The DS1685 has 242 bytes of RAM.	PDIP(W);24 pin;520.4 mm² Outline Drawing:21-0044 (PDF) Land Pattern: Not Applicable Use pkgcode/variation: P24-3*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS14285N+		N/A	No Longer Available	DS1685-5IND+	PDIP(W);24 pin;520.4 mm² Outline Drawing:21-0044 (PDF) Land Pattern: Not Applicable Use pkgcode/variation: P24+3*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285Q+		N/A	No Longer Available	DS1685Q-5+	PLCC;28 pin;158 mm² Outline Drawing:21-0049 (PDF) Land Pattern: 90-0235 (PDF) Use pkgcode/variation: Q28+2*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285Q		N/A	No Longer Available	DS1685Q-5+	PLCC;28 pin;158 mm² Outline Drawing:21-0049 (PDF) Land Pattern: 90-0235 (PDF) Use pkgcode/variation: Q28-2*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS14285QN+		N/A	No Longer Available	DS1685QN-5+	PLCC;28 pin;158 mm² Outline Drawing:21-0049 (PDF) Land Pattern: 90-0235 (PDF) Use pkgcode/variation: Q28+2*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285QN		N/A	No Longer Available	DS1685QN-5+	PLCC;28 pin;158 mm² Outline Drawing:21-0049 (PDF) Land Pattern: 90-0235 (PDF) Use pkgcode/variation: Q28-2*	-40°C to +85°C	RoHS/Lead-Free: No Materials Analysis
DS14285S/T&R		N/A	No Longer Available	DS1685S-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24-7*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS14285S+T&R		N/A	No Longer Available	DS1685S-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24+7*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285S		N/A	No Longer Available	DS1685S-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24-7*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS14285S+		N/A	No Longer Available	DS1685S-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24+7*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285SN+		N/A	No Longer Available	DS1685SN-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24+7*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285SN+T&R		N/A	No Longer Available	DS1685SN-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24+7*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14285SN		N/A	No Longer Available	DS1685SN-5+	SOIC(W);24 pin;164.3 mm² Outline Drawing:21-0042 (PDF) Land Pattern: 90-0182 (PDF) Use pkgcode/variation: W24-7*	-40°C to +85°C	RoHS/Lead-Free: No Materials Analysis
DS14287	Free Sample	Buy	Status	Recommended Replacement	Package: TYPE PINS FOOTPRINT   DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS14287+		N/A	No Longer Available	DS1687-5+	EDIP;24 pin;544.6 mm² Outline Drawing:21-0241 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDP24+2*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS14287		N/A	No Longer Available	DS1687 There is no direct replacement.	EDIP;24 pin;544.6 mm² Outline Drawing:21-0241 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDP24-2*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis

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Rev 2; 2005-11-22
This page last modified: 2007-07-25