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参数资料
| 型号： | M41ST87WMX6 |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDSO28 |
| 封装： | 0.300 INCH, ROHS COMPLIANT, PLASTIC, SOX-28 |
| 文件页数： | 20/52页 |
| 文件大小： | 689K |
| 代理商： | M41ST87WMX6 |
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M41ST87Y, M41ST87W
Operating modes
Doc ID 9497 Rev 8
2.9
Internal tamper pull-up/down current
Depending on the capacitive and resistive loading of the tamper pin input (TPXIN), the user
may require more or less current from the internal pull-up/down used when monitoring the
normally closed switch mode. The state of the tamper current hi/tamper current low bit
(TCHI/TCLOX) determines the sizing of the internal pull-up/-down. TCHI/TCLOX = '1' uses a
1 M
Ω pull-up/-down resistor, while TCHI/TCLOX = '0' uses a 10 MΩ pull-up/-down resistor
2.10
Avoiding inadvertent tampers (normally closed
configuration)
In some applications it may be necessary to use a low pass filter to reduce electrical noise
on the tamper input pin when the TCMX bit = 0 (normally closed). This is especially true if
the tamper detect switch is located some distance (> 6”) from the tamper input pin. A low
pass filter can prevent unwanted, higher frequency noise from inadvertently being detected
as a tamper condition caused by the “antenna-effect” (produced by a longer signal wire or
mesh). This low pass filter can be constructed using a series resistor (R) in conjunction with
a capacitor (C) on the tamper input pin.
The cut-off frequency fc is determined according to the formula:
Figure 21.
Low-pass filter implementation for noise immunity
Table 6.
Calculated cut-off frequency for typical capacitance and resistance
values
R (
Ω)C (F)
fc
1/fc (s)
1000
1.00E-09
15.9 MHz
6.28 s
1000
1.00E-06
159.2 Hz
6.28 ms
5000
1.00E-09
31.8 kHz
31.4 s
5000
1.00E-06
31.8 Hz
31.4 ms
10000
1.00E-09
15.9 kHz
62.8 s
10000
1.00E-06
15.9 Hz
62.8 ms
f
c
12 Pi R C
()
=
TPIN
R
C
To Tamper Detect Switch
AI11185
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M41ST87WMX6F | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0 V and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM |
| M41ST87WMX6TR | 功能描述:实时时钟 Serial 1280 (160x8) 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 |
| M41ST87WSS6 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0 V and 3.3/3.0 V secure serial RTC and NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM |
| M41ST87WSS6F | 功能描述:实时时钟 128 NVRAM Serial RTC 3.0 to 3.6 Vcc 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 |
| M41ST87Y | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0, 3.3, or 3.0V, 1280 bit (160 x8) Secure Serial RTC and NVRAM Supervisor with Tamper Detection |
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