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参数资料
| 型号： | DS12885Q |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Timer or RTC |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PQCC28 |
| 封装： | PLASTIC, LCC-28 |
| 文件页数： | 2/6页 |
| 文件大小： | 127K |
| 代理商： | DS12885Q |
DS12885, DS12885Q, DS12885T
2 of 6
DESCRIPTION
The DS12885 Real Time Clock plus RAM is designed to be a direct replacement for the DS1285. The
DS12885 is identical in form, fit, and function to the DS1285, and has an additional 64 bytes of general
purpose RAM. Access to this additional RAM space is determined by the logic level presented on AD6
during the address portion of an access cycle. An external crystal and battery are the only components
required to maintain time–of–day and memory status in the absence of power. For a complete description
of operating conditions, electrical characteristics, bus timing, and pin descriptions other than X1, X2,
VBAT, and RCLR , see the DS12887 data sheet.
PIN DESCRIPTION
AD0–AD7
– Multiplexed Address/Data Bus
NC
– No Connection
MOT
– Bus Type Selection
CS
– Chip Select
AS
– Address Strobe
R/ W
– Read/Write Input
DS
– Data Strobe
RESET
– Reset Input
IRQ
– Interrupt Request Output
(open drain)
SQW
– Square Wave Output
VCC
– +5V Supply
GND
– Ground
X1,X2
– 32.768 kHz Crystal
Connections
VBAT
– +3V Battery Input
RCLR
– RAM Clear
PIN DESCRIPTION
X1, X2 – Connections for a standard 32.768 kHz quartz crystal. The internal oscillator circuitry is
designed for operation with a crystal having a specified load capacitance (CL) of 6 pF. The crystal is
connected directly to the X1 and X2 pins. There is no need for external capacitors or resistors. Note: X1
and X2 are very high impedance nodes. It is recommended that they and the crystal be guard–ringed with
ground and that high frequency signals be kept away from the crystal area. For more information on
crystal selection and crystal layout considerations, please consult Application Note 58, “Crystal
Considerations with Dallas Real Time Clocks.”
VBAT – Battery input for any standard 3-volt lithium cell or other energy source. Battery voltage must be
held between 2.5 and 4 volts for proper operation. A maximum load of 0.5
A at 25°C in the absence of
power should be used to size the external energy source.
The battery should be connected directly to the VBAT pin. A diode must not be placed in series with the
battery to the VBAT pin.
Furthermore, a diode is not necessary because reverse charging current
protection circuitry is provided internal to the device and has passed the requirements of Underwriters
Laboratories for UL listing.
RCLR
– The RCLR pin is used to clear (set to logic 1) all 114 bytes of general purpose RAM but does
not affect the RAM associated with the real time clock. In order to clear the RAM, RCLR must be forced
to an input logic “0” (–0.3 to +0.8 volts) during battery back–up mode when VCC is not applied. The
RCLR
function is designed to be used via human interface (shorting to ground manually or by switch)
and not to be driven with external buffers. This pin is internally pulled up. Do not use an external pull–
up resistor on this pin.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS12885Q/T&R | 制造商:Rochester Electronics LLC 功能描述: 制造商:DSC 功能描述: |
| DS12885Q/T&R | 功能描述:实时时钟 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS12885Q+ | 功能描述:实时时钟 RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS12885Q+T&R | 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK MULTIPLEXED 114BYTE 28PLCC - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC RTC W/RAM 128 BYTE 28-PLCC 制造商:Maxim Integrated Products 功能描述:Real Time Clock RTC |
| DS12885Q+T&R | 功能描述:实时时钟 RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
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