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Status
Part Number	Status
DS1742	Active: In Production. But some versions of the family are No Longer Available. See Ordering Information.

Data Sheet

FULL DATA SHEET (PDF, 280kB) Download   E-Mail

Description

The DS1742 is a full-function, year 2000-compliant (Y2KC), real-time clock/calendar (RTC) and 2k x 8 nonvolatile static RAM. User access to all registers within the DS1742 is accomplished with a bytewide interface as shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for the day of the month and leap year are made automatically. The RTC clock registers are double-buffered to avoid access of incorrect data that can occur during clock update cycles. The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by access to time register data. The DS1742 also contains its own power-fail circuitry, which deselects the device when the VCC supply is in an out-of-tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.

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

Key Features

Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit and Lithium Energy Source Clock Registers are Accessed Identically to the Static RAM; These Registers are Resident in the Eight Top RAM Locations Century Byte Register Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power BCD Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic Leap Year Compensation Valid Up to the year 2100 Battery Voltage Level Indicator Flag Power-Fail Write Protection Allows for ±10% VCC Power Supply Tolerance Lithium Energy Source is Electrically Disconnected to Retain Freshness until Power is Applied for the First Time Standard JEDEC Bytewide 2k x 8 Static RAM Pinout Quartz Accuracy ±1 Minute a Month at +25°C, Factory Calibrated Underwriters Laboratories (UL®) Recognized

Diagram

Block Diagram

Application Notes

Application Note 504: Design Considerations for Dallas Semiconductor Real-Time Clocks - DS1742 Application Note 519: Using a Nonvolatile Timekeeping RAM with a Microcontroller - DS1742

Design Guides

Real-Time Clocks (PDF)

Reliability Reports

Reliability Report: DS1742.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. More: SeeFull Data Sheet or Part 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.

Devices: 1-10 of 10

DS1742	Notes	Free Sample	Buy	Status	Recommended Replacement	Package: TYPE PINS FOOTPRINT   DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS1742-85+				Active		EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24+1*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1742-100			N/A	No Longer Available	DS1742-85+	EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24-1*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS1742-70			N/A	No Longer Available	DS1742-85+	Land Pattern: Not Available	0°C to +70°C	See data sheet
DS1742W-150			N/A	No Longer Available	DS1742W-120+	EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24-1*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS1742-100 IND			N/A	No Longer Available	DS1742-100IND+	EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24-1*	-40°C to +85°C	RoHS/Lead-Free: No Materials Analysis
DS1742W-120	3.3V, 120ns			Active		EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24-1*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS1742-100+				Active		EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24+1*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1742W-120+				Active		EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24+1*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1742W-150+				Active		EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24+1*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1742-100IND+				Active		EDIP;24 pin;610 mm² Outline Drawing: 21-0245 (PDF) Land Pattern: Not Available Use pkgcode/variation: MDF24+1*	-40°C to +85°C	RoHS/Lead-Free: Lead Free Materials Analysis

More Information

RTC Calculator

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