参数资料
型号: MC9S08QD2CPC
厂商: FREESCALE SEMICONDUCTOR INC
元件分类: 微控制器/微处理器
英文描述: 8-BIT, FLASH, 16 MHz, MICROCONTROLLER, PDIP8
封装: ROHS COMPLIANT, PLASTIC, DIP-8
文件页数: 20/198页
文件大小: 2473K
代理商: MC9S08QD2CPC
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Analog-to-Digital Converter (S08ADC10V1)
MC9S08QD4 Series MCU Data Sheet, Rev. 6
116
Freescale Semiconductor
In cases where separate power supplies are used for analog and digital power, the ground connection
between these supplies must be at the VSSAD pin. This must be the only ground connection between these
supplies if possible. The VSSAD pin makes a good single point ground location.
8.6.1.2
Analog Reference Pins
In addition to the analog supplies, the ADC module has connections for two reference voltage inputs. The
high reference is VREFH, which may be shared on the same pin as VDDAD on some devices. The low
reference is VREFL, which may be shared on the same pin as VSSAD on some devices.
When available on a separate pin, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD). When available on a separate pin, VREFL must be connected to the same
voltage potential as VSSAD. Both VREFH and VREFL must be routed carefully for maximum noise
immunity and bypass capacitors placed as near as possible to the package.
AC current in the form of current spikes required to supply charge to the capacitor array at each successive
approximation step is drawn through the VREFH and VREFL loop. The best external component to meet this
current demand is a 0.1
μF capacitor with good high frequency characteristics. This capacitor is connected
between VREFH and VREFL and must be placed as near as possible to the package pins. Resistance in the
path is not recommended because the current will cause a voltage drop which could result in conversion
errors. Inductance in this path must be minimum (parasitic only).
8.6.1.3
Analog Input Pins
The external analog inputs are typically shared with digital I/O pins on MCU devices. The pin I/O control
is disabled by setting the appropriate control bit in one of the pin control registers. Conversions can be
performed on inputs without the associated pin control register bit set. It is recommended that the pin
control register bit always be set when using a pin as an analog input. This avoids problems with contention
because the output buffer will be in its high impedance state and the pullup is disabled. Also, the input
buffer draws dc current when its input is not at either VDD or VSS. Setting the pin control register bits for
all pins used as analog inputs must be done to achieve lowest operating current.
Empirical data shows that capacitors on the analog inputs improve performance in the presence of noise
or when the source impedance is high. Use of 0.01
μF capacitors with good high-frequency characteristics
is sufficient. These capacitors are not necessary in all cases, but when used they must be placed as near as
possible to the package pins and be referenced to VSSA.
For proper conversion, the input voltage must fall between VREFH and VREFL. If the input is equal to or
exceeds VREFH, the converter circuit converts the signal to $3FF (full scale 10-bit representation) or $FF
(full scale 8-bit representation). If the input is equal to or less than VREFL, the converter circuit converts it
to $000. Input voltages between VREFH and VREFL are straight-line linear conversions. There will be a
brief current associated with VREFL when the sampling capacitor is charging. The input is sampled for
3.5 cycles of the ADCK source when ADLSMP is low, or 23.5 cycles when ADLSMP is high.
For minimal loss of accuracy due to current injection, pins adjacent to the analog input pins must not be
transitioning during conversions.
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相关代理商/技术参数
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MC9S08QD2CPS 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:8-Bit HCS08 Central Processor Unit (CPU)
MC9S08QD2CSC 功能描述:8位微控制器 -MCU 9S08QD4 SERIES 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
MC9S08QD2CSCR 功能描述:8位微控制器 -MCU 9S08QD4 SERIES 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
MC9S08QD2MPC 功能描述:8位微控制器 -MCU 9S08QD4 SERIES 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
MC9S08QD2MPS 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:8-Bit HCS08 Central Processor Unit (CPU)