参数资料
型号: C8051F300-TB
厂商: Silicon Laboratories Inc
文件页数: 4/178页
文件大小: 0K
描述: BOARD PROTOTYPING W/C8051F300
标准包装: 1
类型: MCU
适用于相关产品: C8051F300
所含物品:
Rev. 2.9
101
C8051F300/1/2/3/4/5
11.4. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 11.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 11.3 (OSCXCN register). For
example, an 11.0592 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The rec-
ommended procedure is:
Step 1. Force the XTAL1 and XTAL2 pins low by writing 0’s to the port latch.
Step 2. Configure XTAL1 and XTAL2 as analog inputs.
Step 3. Enable the external oscillator.
Step 4. Wait at least 1 ms.
Step 5. Poll for XTLVLD => ‘1’.
Step 6. Switch the system clock to the external oscillator.
Note: Tuning-fork crystals may require additional settling time before XTLVLD returns a valid
result.
The capacitors shown in the external crystal configuration provide the load capacitance required by the
crystal for correct oscillation. These capacitors are “in series” as seen by the crystal and “in parallel” with
the stray capacitance of the XTAL1 and XTAL2 pins.
Note: The load capacitance depends upon the crystal and the manufacturer. Please refer to the
crystal data sheet when completing these calculations.
For example, a tuning-fork crystal of 32.768 kHz with a recommended load capacitance of 12.5 pF should
use the configuration shown in Figure 12.1, Option 1. The total value of the capacitors and the stray capac-
itance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF capacitors
yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 11.2.
Figure 11.2. 32.768 kHz External Crystal Example
22 pF
32.768 kHz
10 M
XTAL1
XTAL2
相关PDF资料
PDF描述
0210391037 CABLE JUMPER 1MM .102M 33POS
C8051F226-TB BOARD PROTOTYPING W/C8051F226
C8051F330-TB BOARD PROTOTYPING W/C8051F330
LGU2G101MELA CAP ALUM 100UF 400V 20% SNAP
SDR-Q SCOTCH CODE REFILL Q
相关代理商/技术参数
参数描述
C8051F300-TB-K 功能描述:BOARD PROTOTYPING W/C8051F300 制造商:silicon labs 系列:- 零件状态:在售 板类型:评估平台 类型:MCU 8-位 核心处理器:8051 操作系统:- 平台:- 配套使用产品/相关产品:C8051F30x 安装类型:固定 内容:板 标准包装:1
C8051F301 功能描述:8位微控制器 -MCU 8KB 2%osc 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
C8051F301-GM 功能描述:8位微控制器 -MCU 8KB 11P 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
C8051F301-GMR 功能描述:8位微控制器 -MCU 8KB 11P 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
C8051F301-GS 功能描述:8位微控制器 -MCU 8KB Flash 2%osc 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