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C8051F502-IM 参数 Datasheet PDF下载

C8051F502-IM图片预览
型号: C8051F502-IM
PDF下载: 下载PDF文件 查看货源
内容描述: 混合信号ISP功能的Flash MCU系列 [Mixed Signal ISP Flash MCU Family]
分类和应用: 微控制器和处理器外围集成电路PC时钟
文件页数/大小: 312 页 / 2813 K
品牌: SILICON [ SILICON ]
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C8051F50x-F51x  
XTAL1  
XTAL2  
10M  
32.768 kHz  
22pF*  
22pF*  
* Capacitor values depend on  
crystal specifications  
Figure 19.3. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram  
19.4.2. External RC Example  
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as  
shown in Figure 19.1, Option 2. The capacitor should be no greater than 100 pF; however for very small  
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-  
mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first  
select the RC network value to produce the desired frequency of oscillation, according to Equation , where  
f = the frequency of oscillation in MHz, C = the capacitor value in pF, and R = the pull-up resistor value in  
k.  
f = 1.23 103  R C  
Equation 19.1. RC Mode Oscillator Frequency  
For example: If the frequency desired is 100 kHz, let R = 246 kand C = 50 pF:  
f = 1.23(103)/RC = 1.23(103)/[246 x 50] = 0.1 MHz = 100 kHz  
Referring to the table in SFR Definition 19.6, the required XFCN setting is 010b.  
19.4.3. External Capacitor Example  
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in  
Figure 19.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,  
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the  
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-  
tor to be used and find the frequency of oscillation according to Equation 19.2, where f = the frequency of  
oscillation in MHz, C = the capacitor value in pF, and VDD = the MCU power supply in Volts.  
Rev. 1.1  
175