参数资料
型号: DS1556WP-120IND
厂商: Maxim Integrated Products
文件页数: 16/18页
文件大小: 0K
描述: IC RTC RAM Y2K 3.3V 120NS 34PCM
标准包装: 40
类型: 时钟/日历
特点: 警报器,闰年,NVSRAM,监视计时器,Y2K
存储容量: 128KB
时间格式: HH:MM:SS(24 小时)
数据格式: YY-MM-DD-dd
接口: 并联
电源电压: 2.97 V ~ 3.63 V
电压 - 电源,电池: 3V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 34-PowerCap? 模块
供应商设备封装: 34-PowerCap 模块
包装: 管件
DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM
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READING THE CLOCK
When reading the RTC data, it is recommended to halt updates to the external set of double-buffered RTC
Registers. This puts the external registers into a static state allowing data to be read without register
values changing during the read process. Normal updates to the internal registers continue while in this
state. External updates are halted when a 1 is written into the read bit, B6 of the Control Register
(1FFF8h). As long as a 1 remains in the Control Register read bit, updating is halted. After a halt is
issued, the registers reflect the RTC count (day, date, and time) that was current at the moment the halt
command was issued. Normal updates to the external set of registers will resume within 1 second after the
read bit is set to a 0 for a minimum of 500
s. The read bit must be a zero for a minimum of 500s to
ensure the external registers will be updated.
SETTING THE CLOCK
The MSB bit, B7, of the Control Register is the write bit. Setting the write bit to a 1, like the read bit,
halts updates to the DS1556 (1FFF8h to 1FFFFh) registers. After setting the write bit to a 1, RTC
Registers can be loaded with the desired RTC count (day, date, and time) in 24-hour BCD format. Setting
the write bit to a 0 then transfers the values written to the internal RTC Registers and allows normal
operation to resume.
CLOCK ACCURACY (DIP MODULE)
The DS1556 is guaranteed to keep time accuracy to within
1 minute per month at 25C. The RTC is
calibrated at the factory by Maxim using nonvolatile tuning elements, and does not require additional
calibration. For this reason, methods of field clock calibration are not available and not necessary. The
electrical environment also affects clock accuracy, and caution should be taken to place the RTC in the
lowest-level EMI section of the PC board layout. For additional information, refer to Application Note
58.
CLOCK ACCURACY (PowerCap MODULE)
The DS1556 and DS9034PCX are each individually tested for accuracy. Once mounted together, the
module will typically keep time accuracy to within
1.53 minutes per month (35 ppm) at 25°C. The
electrical environment also affects clock accuracy, and caution should be taken to place the RTC in the
lowest-level
EMI
section
of
the
PC
board
layout.
For
additional
information,
refer
to
Application Note 58.
FREQUENCY TEST MODE
The DS1556 frequency test mode uses the open drain
IRQ/FT output. With the oscillator running, the
IRQ/FT output will toggle at 512 Hz when the FT bit is a 1, the Alarm Flag Enable bit (AE) is a 0, and
the Watchdog Steering bit (WDS) is a 1 or the Watchdog Register is reset (Register 1FFF7h = 00h). The
IRQ/FT output and the frequency test mode can be used as a measure of the actual frequency of the
32.768 kHz RTC oscillator. The
IRQ/FT pin is an open-drain output that requires a pullup resistor for
proper operation. The FT bit is cleared to a 0 on power-up.
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