DS1556WP-120IND【PDF 17/18 页】IC RTC RAM Y2K 3.3V 120NS 34PCM

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录1994

13页 14页 15页 16页 [17页]18页

DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM

8 of 18

USING THE CLOCK ALARM

The alarm settings and control for the DS1556 reside within Registers 1FFF2h to 1FFF5h. Register

1FFF6h contains two alarm enable bits: Alarm Enable (AE) and Alarm in Backup Enable (ABE). The AE

and ABE bits must be set as described below for the

IRQ/FT output to be activated for a matched alarm

condition.

The alarm can be programmed to activate on a specific day of the month or repeat every day, hour,

minute, or second. It can also be programmed to go off while the DS1556 is in the battery-backed state of

operation to serve as a system wake-up. Alarm mask bits AM1 to AM4 control the alarm mode. Table 3

shows the possible settings. Configurations not listed in the table default to the once per second mode to

notify the user of an incorrect alarm setting.

Table 3. Alarm Mask Bits

AM4

AM3

AM2

AM1

ALARM RATE

Once per second

When seconds match

When minutes and seconds match

When hours, minutes, and seconds match

When date, hours, minutes, and seconds match

When the RTC Register values match Alarm Register settings, the Alarm Flag bit (AF) is set to a 1. If

Alarm Flag Enable (AE) is also set to a 1, the alarm condition activates the

IRQ/FT pin. The IRQ/FT

signal is cleared by a read or write to the Flags Register (Address 1FFF0h) as shown in Figure 2 and 3.

When

CE is active, the IRQ/FT signal may be cleared by having the address stable for as short as 15 ns

and either

OE or WE active, but is not guaranteed to be cleared unless t

RC is fulfilled. The alarm flag is

also cleared by a read or write to the Flags Register but the flag will not change states until the end of the

read/write cycle and the

IRQ/FT signal has been cleared.

Figure 2. Clearing

IRQ Waveforms

CE,

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式