参数资料
| 型号： | AT90USB647-MU |
| 厂商： | Atmel |
| 文件页数： | 49/106页 |
| 文件大小： | 0K |
| 描述： | IC AVR MCU 64K 64QFN |
| 产品培训模块： | megaAVR Introduction |
| 标准包装： | 1,300 |
| 系列： | AVR® |
| 应用： | USB 微控制器 |
| 核心处理器： | AVR |
| 程序存储器类型： | 闪存（64 kB） |
| 控制器系列： | AT90 USB |
| RAM 容量： | 4K x 8 |
| 接口： | 2 线串行，SPI 串行，USART，USB |
| 输入/输出数： | 48 |
| 电源电压： | 2.7 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 64-VFQFN 裸露焊盘 |
| 包装： | 托盘 |
| 供应商设备封装： | 64-VQFN（9x9） |
| 配用： | ATSTK600-TQFP64-ND - STK600 SOCKET/ADAPTER 64-TQFP ATSTK525-ND - KIT STARTER FOR AT90USB AT90USBKEY2-ND - KIT DEMO FOR AT90USB |
| 其它名称： | AT90USB647-16MU AT90USB647-16MU-ND Q4939729A |
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47
7593L–AVR–09/12
AT90USB64/128
Note that the System Clock Prescaler can be used to implement run-time changes of the internal
clock frequency while still ensuring stable operation. Refer to “System clock prescaler” on page
47 for details.
7.7
Clock output buffer
The device can output the system clock on the CLKO pin. To enable the output, the CKOUT
Fuse has to be programmed. This mode is suitable when the chip clock is used to drive other cir-
cuits on the system. The clock also will be output during reset, and the normal operation of I/O
pin will be overridden when the fuse is programmed. Any clock source, including the internal RC
Oscillator, can be selected when the clock is output on CLKO. If the System Clock Prescaler is
used, it is the divided system clock that is output.
7.8
Timer/counter oscillator
The device can operate its Timer/Counter2 from an external 32.768kHz watch crystal or a exter-
nal clock source. See Figure 7-2 on page 43 for crystal connection.
Applying an external clock source to TOSC1 requires EXCLK in the ASSR Register written to
logic one. See “Asynchronous operation of the Timer/Counter” on page 161 for further descrip-
tion on selecting external clock as input instead of a 32kHz crystal.
7.9
System clock prescaler
The Atmel AT90USB64/128 has a system clock prescaler, and the system clock can be divided
by setting the “CLKPR – Clock Prescale Register” on page 48. This feature can be used to
decrease the system clock frequency and the power consumption when the requirement for pro-
cessing power is low. This can be used with all clock source options, and it will affect the clock
frequency of the CPU and all synchronous peripherals. clk
I/O, clkADC, clkCPU, and clkFLASH are
divided by a factor as shown in Table 7-10 on page 48.
When switching between prescaler settings, the System Clock Prescaler ensures that no
glitches occurs in the clock system. It also ensures that no intermediate frequency is higher than
neither the clock frequency corresponding to the previous setting, nor the clock frequency corre-
sponding to the new setting.
The ripple counter that implements the prescaler runs at the frequency of the undivided clock,
which may be faster than the CPU's clock frequency. Hence, it is not possible to determine the
state of the prescaler - even if it were readable, and the exact time it takes to switch from one
clock division to the other cannot be exactly predicted. From the time the CLKPS values are writ-
ten, it takes between T1 + T2 and T1 + 2 × T2 before the new clock frequency is active. In this
interval, two active clock edges are produced. Here, T1 is the previous clock period, and T2 is
the period corresponding to the new prescaler setting.
To avoid unintentional changes of clock frequency, a special write procedure must be followed
to change the CLKPS bits:
1.
Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in
CLKPR to zero.
2.
Within four cycles, write the desired value to CLKPS while writing a zero to CLKPCE.
Interrupts must be disabled when changing prescaler setting to make sure the write procedure is
not interrupted.
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| AT90USB647-MUR | 功能描述:8位微控制器 -MCU USB 64K FLASH 16 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 |
| AT90USB64X | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:USB DFU Bootloader |
| AT90USB82 | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-bit Microcontroller with 8/16K Bytes of ISP Flash and USB Controller |
| AT90USB82_0811 | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:8-bit Microcontroller with 8/16K Bytes of ISP Flash and USB Controller |
| AT90USB82-16MU | 功能描述:8位微控制器 -MCU AVR USB 8K FLASH 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 |
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