参数资料
型号: 20-101-1154
厂商: Rabbit Semiconductor
文件页数: 50/112页
文件大小: 0K
描述: MODULE RCM4120 RABBITCORE
标准包装: 1
系列: RabbitCore®
模块/板类型: MPU 核心模块
适用于相关产品: RCM4120
其它名称: 316-1122
38
RabbitCore RCM4100
4.4 A/D Converter (RCM4100 only)
The RCM4100 has an onboard ADS7870 A/D converter whose scaling and filtering are
done via the motherboard on which the RCM4100 module is mounted. The A/D converter
multiplexes converted signals from eight single-ended or four differential inputs to Serial
Port B on the Rabbit 4000.
The eight analog input pins, LN0–LN7, each have an input impedance of 6–7 M
,
depending on whether they are used as single-ended or differential inputs. The input signal
can range from -2 V to +2 V (differential mode) or from 0 V to +2 V (single-ended mode).
Use a resistor divider such as the one shown in Figure 9 to measure voltages above 2 V on
the analog inputs. See Appendix B.4.3 for information on how to measure negative voltages.
Figure 9. Resistor Divider Network for Analog Inputs
The R1 resistors are typically 20 k
to 100 k, with a lower resistance leading to more
accuracy, but at the expense of a higher current draw. The R0 resistors would then be
180 k
to 900 k for a 10:1 attenuator. The capacitor filters noise pulses on the A/D
converter input.
The actual voltage range for a signal going to the A/D converter input is also affected by
the 1, 2, 4, 5, 8, 10, 16, and 20 V/V software-programmable gains available on each channel
of the ADS7870 A/D converter. Thus, you must scale the analog signal with an attenuator
circuit and a software-programmable gain so that the actual input presented to the A/D
converter is within the range limits of the ADS7870 A/D converter chip (-2 V to + 2 V or
0 V to + 2 V).
The A/D converter chip can only accept positive voltages. With the R1 resistors connected
to ground, your analog circuit is well-suited to perform positive A/D conversions. When
the R1 resistors are tied to ground for differential measurements, both differential inputs
must be referenced to analog ground, and both inputs must be positive with respect to
analog ground.
R0
LN0
AGND
LN1
ADC
BVREF
R0
C
R1
C
ADC
(RCM4100)
1
3
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20-101-1183 功能描述:程序设计器配件 USB PROGRAM CABLE RoHS:否 制造商:Lattice 产品:ispDOWNLOAD Cables 用于:In-system Programming
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20-101-1185 功能描述:微处理器 - MPU IC CPU RABBIT 3000A (2 pack) RoHS:否 制造商:Atmel 处理器系列:SAMA5D31 核心:ARM Cortex A5 数据总线宽度:32 bit 最大时钟频率:536 MHz 程序存储器大小:32 KB 数据 RAM 大小:128 KB 接口类型:CAN, Ethernet, LIN, SPI,TWI, UART, USB 工作电源电压:1.8 V to 3.3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:FBGA-324