- 您现在的位置：买卖IC网 > PDF目录97860 > DS14285QN (DALLAS SEMICONDUCTOR) 1 TIMER(S), REAL TIME CLOCK, PQCC28 PDF资料下载
参数资料
| 型号： | DS14285QN |
| 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： | 23/25页 |
| 文件大小： | 303K |
| 代理商： | DS14285QN |
DS14285/DS14287
7 of 25
POWER-DOWN/POWER-UP CONSIDERATIONS
The real time clock function will continue to operate and all of the RAM, time, calendar, and alarm
memory locations remain nonvolatile regardless of the level of the VCC input. When VCC is applied to the
DS14285/DS14287 and reaches a level of greater than 4.25 volts (typical), the device becomes accessible
after 200 ms, provided that the oscillator is running and the oscillator countdown chain is not in reset (see
Register A). This time period allows the system to stabilize after power is applied. When VCC falls below
4.25 volts (typical), the chip select input is internally forced to an inactive level regardless of the value of
CS
at the input pin. The DS14285/DS14287 is, therefore, write-protected. When the DS14285/DS14287
is in a write-protected state, all inputs are ignored and all outputs are in a high impedance state. When
VCC falls below a level of approximately 3 volts, the external VCC supply is switched off and an internal
lithium energy source supplies power to the Real-time Clock and the RAM memory.
An external SRAM can be made nonvolatile by using the VCCO and SRAM chip enable pins (see Figure
1). Nonvolatile control of the external SRAM is analogous to that of the real time clock registers. When
VCC slews down during a power fail, CEO is driven to an inactive level regardless CEI . This write
protection occurs when VCC is less than 4.25 volts (typical).
During power up, when VCC reaches a level of greater than 4.25 volts (typical), CEO will reflect CEI
after 200 ms. During power-valid operation, the CEI input is passed to the CEO output with a
propagation delay of less than 10 ns.
When VCC is above a level of approximately 3V, the external SRAM will be powered by VCC through the
VCCO pin. When VCC is below a level of approximately 3V, the external SRAM will be powered by the
internal lithium cell through the VCCO pin. An internal comparator and switch determine whether VCCO is
powered by VCC or the internal lithium cell.
When the device is in battery backup mode, the energy source connected to the VBAT pin in the case of
the DS14285, or the internal lithium cell in the case of the DS14287 can power an external SRAM for an
extended period of time. The amount of time that the lithium cell can supply power to the external SRAM
is a function of the data retention current of the SRAM. The capacity of the lithium cell that is
encapsulated within the DS14287 module is 130 mAh. If an SRAM with a data retention current of less
than 1
A is used and the oscillator current is 300 nA (typical), the cumulative data retention time is
calculated at more than 11 years.
相关PDF资料 |
PDF描述 |
|---|---|
| DS14285S | 1 TIMER(S), REAL TIME CLOCK, PDSO24 |
| DS14285N | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
| DS14285SN | 1 TIMER(S), REAL TIME CLOCK, PDSO24 |
| DS14285Q | 1 TIMER(S), REAL TIME CLOCK, PQCC28 |
| DS14285 | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS14285QN+ | 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 |
| DS14285S | 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 |
| DS14285S/T&R | 制造商:Maxim Integrated Products 功能描述:IC RTC W/NV RAM CNTRL 24-SOIC |
| DS14285S/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 |
| DS14285S/TR | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Real-Time Clock with NV RAM |
发布紧急采购，3分钟左右您将得到回复。