參數(shù)資料
型號(hào)： DS12885
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi)： Timer or RTC
英文描述： 1 TIMER(S), REAL TIME CLOCK, PDIP24
封裝： 0.600 INCH, PLASTIC, DIP-24
文件頁(yè)數(shù)： 3/22頁(yè)
文件大小： 356K
代理商： DS12885
DS12885/DS12887/DS12887A/DS12C887/DS12C887A
Real-Time Clock
____________________________________________________________________
11
Detailed Description
The DS12885 family of RTCs provide 14 bytes of real-
time clock/calendar, alarm, and control/status registers
and 114 bytes (113 bytes for DS12C887 and
DS12C887A) of nonvolatile, battery-backed static RAM.
A time-of-day alarm, three maskable interrupts with a
common interrupt output, and a programmable square-
wave output are available. The devices also operate in
either 24-hour or 12-hour format with an AM/PM indica-
tor. A precision temperature-compensated circuit moni-
tors the status of VCC. If a primary power-supply failure
is detected, the devices automatically switch to a back-
up supply. The backup supply input supports a primary
battery, such as lithium coin cell. The devices are
accessed through a multiplexed address/data bus that
supports Intel and Motorola modes.
Oscillator Circuit
The DS12885 uses an external 32.768kHz crystal. The
oscillator circuit does not require any external resistors
or capacitors to operate. Table 1 specifies several crys-
tal parameters for the external crystal. Figure 1 shows a
functional schematic of the oscillator circuit. An enable
bit in the control register controls the oscillator.
Oscillator startup times are highly dependent upon
crystal characteristics, PC board leakage, and layout.
High ESR and excessive capacitive loads are the major
contributors to long startup times. A circuit using a
crystal with the recommended characteristics and
proper layout usually starts within one second.
An external 32.768kHz oscillator can also drive the
DS12885. In this configuration, the X1 pin is connected
to the external oscillator signal and the X2 pin is floated.
COUNTDOWN
CHAIN
X1
X2
CRYSTAL
CL1CL2
RTC REGISTERS
DS12885
Figure 1. Oscillator Circuit Showing Internal Bias Network
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
Nominal
Frequency
fO
32.768
kHz
Series
Resistance
ESR
50
k
Ω
Load
Capacitance
CL
6pF
Table 1. Crystal Specifications*
*
The crystal, traces, and crystal input pins should be isolated
from RF generating signals. Refer to Application Note 58:
Crystal Considerations for Dallas Real-Time Clocks
for
additional specifications.
相關(guān)PDF資料
PDF描述
DS12885T 1 TIMER(S), REAL TIME CLOCK, PQFP32
DS12887A 1 TIMER(S), REAL TIME CLOCK, PDIP24
DS12C887A 1 TIMER(S), REAL TIME CLOCK, PDIP24
DS12885S 1 TIMER(S), REAL TIME CLOCK, PDSO24
DS12885QN 1 TIMER(S), REAL TIME CLOCK, PQCC28
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS12885+ 功能描述:實(shí)時(shí)時(shí)鐘 RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS12885N 功能描述:實(shí)時(shí)時(shí)鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS12885N+ 功能描述:實(shí)時(shí)時(shí)鐘 RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS12885Q 功能描述:實(shí)時(shí)時(shí)鐘 RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS12885Q/T&R 制造商:Rochester Electronics LLC 功能描述: 制造商:DSC 功能描述:
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