24
8024A–AVR–04/08
ATmega8HVA/16HVA
9.
System Clock and Clock Options
9.1
Clock Systems and their Distribution
Figure 9-1 presents the principal clock systems in the AVR and their distribution. All of the clocks
need not be active at a given time. In order to reduce power consumption, the clocks to modules
not being used can be halted by using different sleep modes, as described in ”Power Manage-
ment and Sleep Modes” on page 34. The clock systems are detailed below.
Figure 9-1.
Clock Distribution
9.1.1
CPU Clock – clk
CPU
The CPU clock is routed to parts of the system concerned with operation of the AVR core.
Examples of such modules are the General Purpose Register File, the Status Register and the
data memory holding the Stack Pointer. Halting the CPU clock inhibits the core from performing
general operations and calculations.
9.1.2
I/O Clock – clk
I/O
The I/O clock is used by the majority of the I/O modules. The I/O clock is also used by the Exter-
nal Interrupt module, but note that some external interrupts are detected by asynchronous logic,
allowing such interrupts to be detected even if the I/O clock is halted.
9.1.3
Flash Clock – clk
FLASH
The Flash clock controls operation of the Flash interface. The Flash clock is usually active simul-
taneously with the CPU clock.
9.1.4
Voltage ADC Clock – clk
VADC
The Voltage ADC is provided with a dedicated clock domain. The VADC clock is automatically
prescaled relative to the System Clock Prescalers setting by the VADC Prescaler, giving a fixed
VADC clock at 1 MHz.
Ultra Low Power
RC Oscillator
Watchdog Timer
Battery Protection
Reset Logic
CPU
CORE
RAM
FLASH and
EEPROM
Voltage
ADC
Other I/O
Modules
Coulomb Counter
ADC
AVR
Clock Control
Fast RC
Oscillator
clk
CPU
clk
FLASH
clk
VADC
clk
I/O
1/4
System Clock
Prescaler
VADC
Prescaler
Oscillator Sampling
Interface
Slow RC
Oscillator
clk
CCADC
相关PDF资料
ATSAM3N4AA-AU MCU FLASH 48-QFP
ATSAM3SD8CA-CU IC MCU 2X256KB CORTEX-M3 100-QFN
ATSAM3U1EB-CU IC MCU 64KB CORTEX-M3 144-TFBGA
ATSAM3X8EA-CU IC MCU 2X256KB CORTEX-M3 144-BGA
ATTINY12V-1SUR IC AVR MCU 1K FLASH 4MHZ 8-SOIC
ATTINY13-20SQR IC MCU AVR 1KB FLASH 20MHZ 8SOIC
ATTINY13A-MMUR MCU AVR 1KB FLASH 20MHZ 10DFN
ATTINY13V-10SUR MCU AVR 1KB FLASH 10MHZ 8SOIC
相关代理商/技术参数
ATMEGA8HVA-4CKUR 功能描述:8位微控制器 -MCU AVR 8KB FLSH 512B EE 1KB SRAM - 4 MHZ 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
ATMEGA8HVA-4TU 功能描述:8位微控制器 -MCU AVR 8KB, 512B EE 4MHz 1KB SRAM 1.8-9V 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
ATMEGA8HVA-4TUR 功能描述:8位微控制器 -MCU AVR 8KB FLSH 512B EE 1KB SRAM - 4 MHZ 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
ATMEGA8HVD-4MX 功能描述:8位微控制器 -MCU AVR 8KB, 512B EE 4MHz 1KB SRAM 2.1-8V 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
ATMEGA8L-8AC 功能描述:8位微控制器 -MCU AVR 8K FLASH 512B EE 1K SRAM ADC 3V 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
ATMEGA8L8AI 制造商:Atmel Corporation 功能描述:
ATMEGA8L-8AI 功能描述:8位微控制器 -MCU AVR 8K FLASH 512B EE 1K SRAM ADC 3V 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
ATMEGA8L-8AJ 功能描述:IC MCU AVR 8K 5V 8MHZ 32-TQFP RoHS:是 类别:集成电路 (IC) >> 嵌入式 - 微控制器, 系列:AVR® ATmega 标准包装:9 系列:87C 核心处理器:8051 芯体尺寸:8-位 速度:40/20MHz 连通性:UART/USART 外围设备:POR,WDT 输入/输出数:32 程序存储器容量:32KB(32K x 8) 程序存储器类型:OTP EEPROM 大小:- RAM 容量:256 x 8 电压 - 电源 (Vcc/Vdd):4.5 V ~ 5.5 V 数据转换器:- 振荡器型:内部 工作温度:0°C ~ 70°C 封装/外壳:40-DIP(0.600",15.24mm) 包装:管件