DS1556, DS1556P 1M、非易失、Y2K兼容的时钟RAM

概述

The DS1556 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 128k x 8 nonvolatile static RAM. User access to all registers within the DS1556 is accomplished with a byte-wide interface as shown in Figure 1. 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.

The RTC registers are double-buffered into an internal and external set. The user has direct access to the external set. Clock/calendar updates to the external set of registers can be disabled and enabled to allow the user to access static data. Assuming the internal oscillator is turned on, the internal set of registers is continuously updated, which occurs regardless of external registers settings to guarantee that accurate RTC information is always maintained.

The DS1556 has interrupt (active-low IRQ/FT) and reset (active-low RST) outputs which can be used to control CPU activity. The active-low IRQ/FT interrupt output can be used to generate an external interrupt when the RTC register values match user programmed alarm values. The interrupt is always available while the device is powered from the system supply and can be programmed to occur when in the battery-backed state to serve as a system wake-up. Either the active-low IRQ/FT or active-low RST outputs can also be used as a CPU watchdog timer, CPU activity is monitored and an interrupt or reset output will be activated if the correct activity is not detected within programmed limits. The DS1556 power-on reset can be used to detect a system power down or failure and hold the CPU in a safe reset state until normal power returns and stabilizes; the active-low RST output is used for this function.

The DS1556 also contains its own power-fail circuitry, which automatically deselects the device when the V_CC supply enters an out of tolerance condition. This feature provides a high degree of data security during unpredictable system operation brought on by low V_CC levels.

关键特性

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% V_CC 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

Key Specifications: Timekeeping & Real-Time Clocks

Part Number

Functions

Time Format (hh = sec/100)

Date Format

Interface

Supply Voltage (V)

Memory Type

Memory Size (Bytes)

Number of Time of Day Alarms

Features

RoHS Available

Package

Operating Temp. Range (°C)

Price^**

DS1556

•	Watchdog Timekeeper

HH:MM:SS

YYYY-MM-DD

Bytewide

3.3
5

NV SRAM

128K

•

µP Reset

•	Battery + Crystal

•	Periodic Interrupt

•	PowerCap Package

Yes

MOD/32
PWRCP/34

-40 to +85

$15.75 @ 1k

See All Timekeeping & Real-Time Clocks (86)

Notes:
^**This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

定购信息

注：

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型号尾缀：T或T&R = 卷带; + = RoHS/无铅; # = RoHS/无铅豁免权。详细信息请参考：完整的数据资料或型号命名规则。
* “封装代码/变更”提供产品使用的变更信息。注意：型号尾缀中的“+”、“#”和“-”表示器件的RoHS状况，封装图上可能显示不同的尾缀字符。

器件： 1-16 of 16

DS1556

免费样品

采购

封装：	类型引脚占位面积
	封装图编码/变更 *

温度

RoHS/无铅？
材料分析

DS1556-70+

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32+1*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1556W-120

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32-1*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1556W-120+

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32+1*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1556-70

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32-1*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1556W-120IND+

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32+1*

-40°C至+85°C

RoHS/无铅：无铅
材料分析

DS1556-70IND

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32-1*

-40°C至+85°C

RoHS/无铅：否
材料分析

DS1556W-120IND

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32-1*

-40°C至+85°C

RoHS/无铅：否
材料分析

DS1556-70IND+

MOD；32引脚；
Dwg: 56-G0002-001
使用封装码/变更：MDF32+1*

-40°C至+85°C

RoHS/无铅：无铅
材料分析

DS1556WP-120

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2-6*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1556WP-120+

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2+6*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1556WP-120IND+

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2+6*

-40°C至+85°C

RoHS/无铅：无铅
材料分析

DS1556WP-120IND

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2-6*

-40°C至+85°C

RoHS/无铅：否
材料分析

DS1556P

免费样品

采购

封装：	类型引脚占位面积
	封装图编码/变更 *

温度

RoHS/无铅？
材料分析

DS1556P-70+

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2+6*

0°C至+70°C

RoHS/无铅：无铅
材料分析

DS1556P-70IND+

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2+6*

-40°C至+85°C

RoHS/无铅：无铅
材料分析

DS1556P-70

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2-6*

0°C至+70°C

RoHS/无铅：否
材料分析

DS1556P-70IND

PWRCP；34引脚；
Dwg: 56-G0003-001
使用封装码/变更：PC2-6*

-40°C至+85°C

RoHS/无铅：否
材料分析