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参数资料
型号： MC68HC705JJ7S
厂商： FREESCALE SEMICONDUCTOR INC
元件分类： 微控制器/微处理器
英文描述： 8-BIT, UVPROM, 2.1 MHz, MICROCONTROLLER, CDIP20
封装： WINDOWED, CERAMIC, DIP-20
文件页数： 155/164页
文件大小： 1165K
代理商： MC68HC705JJ7S
Analog Subsystem
MC68HC705JJ7 MC68HC705JP7 Advance Information Data Sheet, Rev. 4.1
90
Freescale Semiconductor
8.6.1 Absolute Voltage Readings
The absolute value of a voltage measurement can be calculated in software by first taking a reference
reading from a fixed source and then comparing subsequent unknown voltages to that reading as a
percentage of the reference voltage multiplied times the known reference value.
The accuracy of absolute readings will depend on the error sources taken into account using the features
of the analog subsystem and appropriate software as described in Table 8-6. As can be seen from this
table, most of the errors can be reduced by frequent comparisons to a known voltage, use of the inverted
comparator inputs, and averaging of multiple samples.
8.6.1.1 Internal Absolute Reference
If a stable source of VDD is provided, the reference measurement point can be internally selected. In this
case, the reference reading can be taken by setting the VREF bit and clearing the MUX1:4 bits in the
AMUX register. This connects the channel selection bus to the VDD pin. To stay within the VMAX range,
the DHOLD bit should be used to select the 1/2 divided input.
8.6.1.2 External Absolute Reference
If a stable external source is provided, the reference measurement point can be any one of the channel
selected pins from PB1–PB4. In this case the reference reading can be taken by setting the MUX bit in
the AMUX which connects channel selection bus to the pin connected to the external reference source.
If the external reference is greater than VDD –1.5 volts, then the DHOLD bit should be used to select the
1/2 divided input.
Table 8-6. Absolute Voltage Reading Errors
Error Source
Accuracy Improvements Possible
In Hardware
In Software
Change in reference voltage Provide closer tolerance reference
Calibration and storage of reference source over
temperature and supply voltage
Change in magnitude of
ramp current source
Not adjustable
Compare unknown with recent measurement
from reference
Non-linearity of ramp
current source vs. voltage
Not adjustable
Calibration and storage of voltages at 1/4, 1/2,
3/4, and FS
Frequency shift in internal
low-power oscillator
Use external oscillator with crystal
Compare unknown with recent measurement
from reference
Sampling capacitor leakage
Use faster conversion times
Compare unknown with recent measurement
from reference
Internal voltage divider ratio
Not adjustable
Compare unknown with recent measurement
from reference OR avoid use of divided input
Input offset voltage of
comparator 2
Not adjustable
Sum two readings on reference or unknown
using INV and INV control bit and divide by 2
(average of both)
Noise internal to MCU
Close decoupling at VDD and VSS pins and
reduce supply source impedance
Average multiple readings on both the reference
and the unknown voltage
相关PDF资料
PDF描述
MC68HC705K1DWR2 8-BIT, OTPROM, MICROCONTROLLER, PDSO16
MC68HC705K1CP 8-BIT, OTPROM, MICROCONTROLLER, PDIP16
MC68HC705K1P 8-BIT, OTPROM, 2 MHz, MICROCONTROLLER, PDIP16
MC68HC705K1DW 8-BIT, OTPROM, MICROCONTROLLER, PDSO16
MC68HC705KJ1CDW 8-BIT, OTPROM, 4 MHz, MICROCONTROLLER, PDSO16
相关代理商/技术参数
参数描述
MC68HC705JP7CDW 功能描述:IC MCU 8BIT 28-SOIC RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器， 系列:HC05 其它有关文件:STM32F101T8 View All Specifications 特色产品:STM32 32-bit Cortex MCUs 标准包装:490 系列:STM32 F1 核心处理器:ARM? Cortex?-M3 芯体尺寸:32-位 速度:36MHz 连通性:I²C，IrDA，LIN，SPI，UART/USART 外围设备:DMA，PDR，POR，PVD，PWM，温度传感器，WDT 输入/输出数:26 程序存储器容量:64KB（64K x 8） 程序存储器类型:闪存 EEPROM 大小:- RAM 容量:10K x 8 电压 - 电源 (Vcc/Vdd):2 V ~ 3.6 V 数据转换器:A/D 10x12b 振荡器型:内部 工作温度:-40°C ~ 85°C 封装/外壳:36-VFQFN，36-VFQFPN 包装:托盘 配用:497-10030-ND - STARTER KIT FOR STM32497-8853-ND - BOARD DEMO STM32 UNIV USB-UUSCIKSDKSTM32-PL-ND - KIT IAR KICKSTART STM32 CORTEXM3497-8512-ND - KIT STARTER FOR STM32F10XE MCU497-8505-ND - KIT STARTER FOR STM32F10XE MCU497-8304-ND - KIT STM32 MOTOR DRIVER BLDC497-6438-ND - BOARD EVALUTION FOR STM32 512K497-6289-ND - KIT PERFORMANCE STICK FOR STM32MCBSTM32UME-ND - BOARD EVAL MCBSTM32 + ULINK-MEMCBSTM32U-ND - BOARD EVAL MCBSTM32 + ULINK2更多... 其它名称:497-9032STM32F101T8U6-ND
MC68HC705JP7CP 制造商:Rochester Electronics LLC 功能描述: 制造商:Freescale Semiconductor 功能描述:
MC68HC705K1CDW 制造商:Motorola Inc 功能描述:
MC68HC705KJ1CDW 功能描述:8位微控制器 -MCU 8 Bit 4MHz 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
MC68HC705KJ1CP 功能描述:IC MCU 4MHZ 1.2K OTP 16-DIP RoHS:否 类别:集成电路 (IC) >> 嵌入式 - 微控制器， 系列:HC05 其它有关文件:STM32F101T8 View All Specifications 特色产品:STM32 32-bit Cortex MCUs 标准包装:490 系列:STM32 F1 核心处理器:ARM? Cortex?-M3 芯体尺寸:32-位 速度:36MHz 连通性:I²C，IrDA，LIN，SPI，UART/USART 外围设备:DMA，PDR，POR，PVD，PWM，温度传感器，WDT 输入/输出数:26 程序存储器容量:64KB（64K x 8） 程序存储器类型:闪存 EEPROM 大小:- RAM 容量:10K x 8 电压 - 电源 (Vcc/Vdd):2 V ~ 3.6 V 数据转换器:A/D 10x12b 振荡器型:内部 工作温度:-40°C ~ 85°C 封装/外壳:36-VFQFN，36-VFQFPN 包装:托盘 配用:497-10030-ND - STARTER KIT FOR STM32497-8853-ND - BOARD DEMO STM32 UNIV USB-UUSCIKSDKSTM32-PL-ND - KIT IAR KICKSTART STM32 CORTEXM3497-8512-ND - KIT STARTER FOR STM32F10XE MCU497-8505-ND - KIT STARTER FOR STM32F10XE MCU497-8304-ND - KIT STM32 MOTOR DRIVER BLDC497-6438-ND - BOARD EVALUTION FOR STM32 512K497-6289-ND - KIT PERFORMANCE STICK FOR STM32MCBSTM32UME-ND - BOARD EVAL MCBSTM32 + ULINK-MEMCBSTM32U-ND - BOARD EVAL MCBSTM32 + ULINK2更多... 其它名称:497-9032STM32F101T8U6-ND
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