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参数资料
| 型号： | MAX6917EO30 |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | REAL TIME CLOCK, PDSO20 |
| 封装： | 0.150 INCH, 0.025 INCH PITCH, MO-137AD, QSOP-20 |
| 文件页数： | 17/31页 |
| 文件大小： | 349K |
| 代理商： | MAX6917EO30 |
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MAX6917
I2C-Compatible RTC with Microprocessor
Supervisor, Alarm, and NV RAM Controller
24
______________________________________________________________________________________
Chip-Enable Gating
Internal gating of chip-enable (CE) signals prevents
erroneous data from corrupting external SRAM in the
event of an undervoltage condition. The MAX6917 uses
a transmission gate from CE_IN to CE_OUT (Figure 14).
During normal operation (RESET inactive), the transmis-
sion gate is enabled and passes all CE transitions.
When reset is asserted, this path becomes disabled,
preventing erroneous data from corrupting the external
SRAM. The short CE propagation delay from CE_IN to
CE_OUT enables the MAX6917 to be used with most
Ps. If CE_IN is low when reset asserts, CE_OUT
remains low for tRCE to permit completion of the current
write cycle.
Chip-Enable Input
The CE transmission gate is disabled and CE_IN is high
impedance (disabled mode) while RESET is active. During
a power-down sequence when VCC passes the reset
threshold, the CE transmission gate disables and CE_IN
immediately becomes high impedance if the voltage at
CE_IN is high. If CE_IN is low when RESET becomes
active, the CE transmission gate disables at the moment
CE_IN goes high or tRCE after RESET is active, whichever
occurs first (see the Chip-Enable Timing diagram). This
permits the current write cycle to complete during power-
down. The CE transmission gate remains disabled and
CE_IN remains high impedance (regardless of CE_IN
activity) for most of the reset-timeout period (tRST) any time
a RESET is generated. When the CE transmission gate is
enabled, the impedance of CE_IN appears as a 46
(typ)
load in series with the load at CE_OUT.
The propagation delay through the CE transmission
gate depends on VCC, the source impedance of the
driver connected to CE_IN, and the loading on
CE_OUT (see the Chip-Enable Propagation Delay vs.
CE_OUT Load Capacitance graph in the Typical
Operating Characteristics). For minimum propagation
delay, the capacitive load at CE_OUT should be mini-
mized, and a low-output-impedance driver should be
used on CE_IN (Figure 15).
START
SET WDI
HIGH
PROGRAM
CODE
SUBROUTINE OF
PROGRAM LOOP
SET WDI HIGH
RETURN
Figure 13. Watchdog Flow Diagram
MAX6917
CHIP-ENABLE
OUTPUT
CONTROL
RESET
GENERATOR
VOUT
CE_OUT
CE_IN
Figure 14. Chip-Enable Gating
MAX6917
25
EQUIVALENT
SOURCE IMPEDANCE
50
CABLE
50
3.6V
VCC
CL
10pF
GND
VCC
50
CE_IN
CE_OUT
BATT
CL INCLUDES LOAD CAPACITANCE AND SCOPE PROBE CAPACITANCE.
Figure 15. Propagation Delay Test Circuit
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX6917EO30+ | 功能描述:实时时钟 Integrated Circuits (ICs) 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 |
| MAX6917EO30+T | 功能描述:实时时钟 Integrated Circuits (ICs) 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 |
| MAX6917EO33+ | 功能描述:实时时钟 Integrated Circuits (ICs) 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 |
| MAX6917EO33+T | 功能描述:实时时钟 Integrated Circuits (ICs) 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 |
| MAX6917EO50 | 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 |
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