收藏本站
参数资料
型号： ST72C254G1M6
厂商： STMICROELECTRONICS
元件分类： 微控制器/微处理器
英文描述： 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PDSO28
封装： 0.300 INCH, PLASTIC, SOIC-28
文件页数： 50/136页
文件大小： 929K
代理商： ST72C254G1M6
ST72104G, ST72215G, ST72216G, ST72254G
20/136
7.4 CLOCK SECURITY SYSTEM (CSS)
The Clock Security System (CSS) protects the
ST7 against main clock problems. To allow the in-
tegration of the security features in the applica-
tions, it is based on a clock filter control and an In-
ternal safe oscillator. The CSS can be enabled or
disabled by option byte.
7.4.1 Clock Filter Control
The clock filter is based on a clock frequency limi-
tation function.
This filter function is able to detect and filter high
frequency spikes on the ST7 main clock.
If the oscillator is not working properly (e.g. work-
ing at a harmonic frequency of the resonator), the
current active oscillator clock can be totally fil-
tered, and then no clock signal is available for the
ST7 from this oscillator anymore. If the original
clock source recovers, the filtering is stopped au-
tomatically and the oscillator supplies the ST7
clock.
7.4.2 Safe Oscillator Control
The safe oscillator of the CSS block is a low fre-
quency back-up clock source (see Figure 13).
If the clock signal disappears (due to a broken or
disconnected resonator...) during a safe oscillator
period, the safe oscillator delivers a low frequency
clock signal which allows the ST7 to perform some
rescue operations.
Automatically, the ST7 clock source switches back
from the safe oscillator if the original clock source
recovers.
Limitation detection
The automatic safe oscillator selection is notified
by hardware setting the CSSD bit of the CRSR
register. An interrupt can be generated if the CS-
SIE bit has been previously set.
These two bits are described in the CRSR register
description.
7.4.3 Low Power Modes
7.4.4 Interrupts
The CSS interrupt event generates an interrupt if
the corresponding Enable Control Bit (CSSIE) is
set and the interrupt mask in the CC register is re-
set (RIM instruction).
Figure 13. Clock Filter Function and Safe Oscillator Function
Mode
Description
WAIT
No effect on CSS. CSS interrupt cause the
device to exit from Wait mode.
HALT
The CRSR register is frozen. The CSS (in-
cluding the safe oscillator) is disabled until
HALT mode is exited. The previous CSS
configuration resumes when the MCU is
woken up by an interrupt with “exit from
HALT mode” capability or from the counter
reset value when the MCU is woken up by a
RESET.
Interrupt Event
Event
Flag
Enable
Control
Bit
Exit
from
Wait
Exit
from
Halt
CSS event detection
(safe oscillator acti-
vated as main clock)
CSSD
CSSIE
Yes
No
fOSC/2
fCPU
fOSC/2
fCPU
fSFOSC
SAFE
OSCILLATOR
FUNCTION
CLOCK
FILTER
FUNCTION
相关PDF资料
PDF描述
ST72C254G2M3 8-BIT, FLASH, 6 MHz, MICROCONTROLLER, PDSO28
ST72C254G2M7 8-BIT, FLASH, 6 MHz, MICROCONTROLLER, PDSO28
ST72C254G2M1 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PDSO28
ST72C254G1B1 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PDIP32
ST72C254G1B7 8-BIT, FLASH, 6 MHz, MICROCONTROLLER, PDIP32
相关代理商/技术参数
参数描述
ST72C254G2B1 制造商:STMicroelectronics 功能描述:8-BIT MICROCONTROLLER - Bulk
ST72C254G2B6 功能描述:8位微控制器 -MCU Flash 8K SPI/I2C RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
ST72C254G2B6 制造商:STMicroelectronics 功能描述:8BIT MCU FLASH 8K 72C254 DIP32
ST72C254G2M3 功能描述:8位微控制器 -MCU ST72104G ST72215G ST72254G 8B MCU RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
ST72C254G2M3/TR 功能描述:8位微控制器 -MCU 8B MCU SINGLE VLTG FLASH MEMORY RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*