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Real Time Clock 4Meg, Nonvolatile, Y2K-Compliant Timekeeping RAM

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DS1557WP-120+ General Description

The DS1557 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and 512k x 8 nonvolatile static RAM. User access to all registers within the DS1557 is accomplished with a byte-wide interface as shown in Figure1. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for day of month and leap year are made automatically.

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Key Features

  • Integrated NV SRAM, Real-Time Clock (RTC), Crystal, Power-Fail Control Circuit, and Lithium Energy Source
  • Clock Registers are Accessed Identically to the Static RAM; These Registers Reside in the 16 Top RAM Locations
  • Century Byte Register (i.e., Y2K Compliant)
  • Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power
  • Precision Power-On Reset
  • Programmable Watchdog Timer and RTC Alarm
  • BCD-Coded 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
  • Also Available in Industrial Temperature Range: -40°C to +85°C


model DS1557WP-120+ package N/A
packingQty Tray,40 packingOption Tray
packageType X rohs roHN
lifeCycle production tempRange 0 to 70C
Manufacturer Analog Devices Inc. Product Category Real Time Clock
RoHS Details Mounting Style SMD/SMT
Package / Case PowerCap-34 RTC Bus Interface Parallel
Date Format YY-MM-DD-dd Time Format HH:MM:SS
Battery Backup Switching Backup Switching RTC Memory Size 512 kB
Supply Voltage - Max 3.63 V Supply Voltage - Min 2.97 V
Minimum Operating Temperature 0 C Maximum Operating Temperature + 70 C
Brand Analog Devices / Maxim Integrated Function Alarm, Calendar, Clock, NV Timekeeping RAM, Watchdog Timekeeper
Moisture Sensitive Yes Product Type Real Time Clocks
Series DS1557WP Factory Pack Quantity 40
Subcategory Clock & Timer ICs Part # Aliases DS1557WP 90-1557W+P12
DS1557: Block Diagram

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shipping Shipping And Packing
Shipping Method

Our products are mainly transported and delivered by DHL, FedEx, UPS and other logistics partners on site -- Available to 200+ countries.


AVAQ determines and packages all devices based on electrostatic discharge (ESD) and moisture sensitivity level (MSL) protection requirements.

warranty Warranty & Returns

Our policies and procedures are designed to ensure compliance with various quality specifications and to quickly resolve quality-related issues.

We promise to provide 365 days quality assurance service for all our products.

If you have any dissatisfaction with the quality of the product you received, you can contact us for a refund or exchange, as long as the product is kept in its original condition.


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Availability: 4715 PCS

Qty. Unit Price(USD) Ext. Price
1+ $38.387 $38.39
200+ $14.854 $2,970.80
500+ $14.334 $7,167.00
1000+ $14.076 $14,076.00

The prices below are for reference only.