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ATTINY2313-20SUR 参数 Datasheet PDF下载

ATTINY2313-20SUR图片预览
型号: ATTINY2313-20SUR
PDF下载: 下载PDF文件 查看货源
内容描述: [RISC Microcontroller, 8-Bit, FLASH, AVR RISC CPU, 20MHz, CMOS, PDSO20, 0.300 INCH, GREEN, PLASTIC, MS-013AC, SOIC-20]
分类和应用: 闪存微控制器
文件页数/大小: 223 页 / 1792 K
品牌: ATMEL [ ATMEL ]
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Clock Sources  
The device has the following clock source options, selectable by Flash Fuse bits as  
shown below. The clock from the selected source is input to the AVR clock generator,  
and routed to the appropriate modules.  
Table 2. Device Clocking Select(1)  
Device Clocking Option  
External Clock  
CKSEL3..0  
0000  
Calibrated Internal RC Oscillator 4MHz  
Calibrated internal RC Oscillator 8MHz  
Watchdog Oscillator 128kHz  
External Crystal/Ceramic Resonator  
Reserved  
0010  
0100  
0110  
1000 - 1111  
0001/0011/0101/0111  
Note:  
1. For all fuses “1” means unprogrammed while “0” means programmed.  
The various choices for each clocking option is given in the following sections. When the  
CPU wakes up from Power-down, the selected clock source is used to time the start-up,  
ensuring stable Oscillator operation before instruction execution starts. When the CPU  
starts from reset, there is an additional delay allowing the power to reach a stable level  
before commencing normal operation. The Watchdog Oscillator is used for timing this  
real-time part of the start-up time. The number of WDT Oscillator cycles used for each  
time-out is shown in Table 3. The frequency of the Watchdog Oscillator is voltage  
dependent as shown in “ATtiny2313 Typical Characteristics” on page 179.  
Table 3. Number of Watchdog Oscillator Cycles  
Typ Time-out (VCC = 5.0V)  
Typ Time-out (VCC = 3.0V)  
Number of Cycles  
4K (4,096)  
4.1 ms  
65 ms  
4.3 ms  
69 ms  
64K (65,536)  
Default Clock Source  
Crystal Oscillator  
The device is shipped with CKSEL = “0010”, SUT = “10”, and CKDIV8 programmed.  
The default clock source setting is the Internal RC Oscillator with longest start-up time  
and an initial system clock prescaling of 8. This default setting ensures that all users can  
make their desired clock source setting using an In-System or Parallel programmer.  
XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can  
be configured for use as an On-chip Oscillator, as shown in Figure 12 on page 23. Either  
a quartz crystal or a ceramic resonator may be used.  
C1 and C2 should always be equal for both crystals and resonators. The optimal value  
of the capacitors depends on the crystal or resonator in use, the amount of stray capac-  
itance, and the electromagnetic noise of the environment. Some initial guidelines for  
choosing capacitors for use with crystals are given in Table 4 on page 23. For ceramic  
resonators, the capacitor values given by the manufacturer should be used.  
22  
ATtiny2313/V  
2543F–AVR–08/04  
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