ADI ADuC7027 工业过程控制PLC开发方案

ADI 公司的ADuC7027是集成了12位模拟I/O, ARM7TDMI® MCU的精密模拟微控制器,采用ARM7TDMI核16位/32位RISC架构,片内振荡器精度±3%,外接时钟源高达44MHz, 41.78 MHz PLL具有可编程分频器. 模拟I/O具有多路12位1MSPS ADC和12位电压输出DAC.器件工作电压2.7V-3.3V,主要用在工业控制和自动化系统,智能传感器,精密仪表,基站系统,光网络等.本文介绍了ADuC702x 主要特性,方框图,典型应用电路,以及PLC评估系统主要特性, 系统总体框图,多种输入/输出电路,输入和输出与电源保护电路.

The ADuC7019/20/21/22/24/25/26/27/28/29 are fully integrated, 1 MSPS, 12-bit data acquisition systems incorporating high performance multichannel ADCs, 16-bit/32-bit MCUs, and Flash®/EE memory on a single chip.

The ADC consists of up to 12 single-ended inputs. An additional four inputs are available but are multiplexed with the four DAC output pins. The four DAC outputs are available only on certain models (ADuC7020, ADuC7026, ADuC7028, and ADuC7029). However, in many cases where the DAC outputs are not present, these pins can still be used as additional ADC inputs, giving a maximum of 16 ADC input channels. The ADC can operate in single-ended or differential input mode. The ADC input voltage is 0 V to VREF. A low drift band gap reference, temperature sensor, and voltage comparator complete the ADC peripheral set.

Depending on the part model, up to four buffered voltage output DACs are available on-chip. The DAC output range is programmable to one of three voltage ranges.

The devices operate from an on-chip oscillator and a PLL generating an internal high frequency clock of 41.78 MHz (UCLK). This clock is routed through a programmable clock divider from which the MCU core clock operating frequency is generated. The microcontroller core is an ARM7TDMI®, 16-bit/32-bit RISC machine, which offers up to 41 MIPS peak performance. Eight kilobytes of SRAM and 62 kilobytes of nonvolatile Flash/EE memory are provided on-chip. The ARM7TDMI core views all memory and registers as a single linear array.

On-chip factory firmware supports in-circuit serial download via the UART or I2C serial interface port; nonintrusive emulation is also supported via the JTAG interface. These features are incorporated into a low cost QuickStart™ development system supporting this MicroConverter® family.

The parts operate from 2.7 V to 3.6 V and are specified over an industrial temperature range of −40℃ to +125℃. When operating at 41.78 MHz, the power dissipation is typically 120 mW.

ADuC702x 主要特性:

Analog I/O

Multichannel, 12-bit, 1 MSPS ADC

Up to 16 ADC channels1

Fully differential and single-ended modes

0 V to VREF analog input range

12-bit voltage output DACs

Up to 4 DAC outputs available1

On-chip voltage reference

On-chip temperature sensor (±3°C)

Voltage comparator

Microcontroller

ARM7TDMI core, 16-bit/32-bit RISC architecture

JTAG port supports code download and debug

Clocking options

Trimmed on-chip oscillator (±3%)

External watch crystal

External clock source up to 44 MHz

41.78 MHz PLL with programmable divider

Memory

62 kB Flash/EE memory, 8 kB SRAM

In-circuit download, JTAG-based debug

Software-triggered in-circuit reprogrammability

On-chip peripherals

UART, 2× I2C® and SPI serial I/O

Up to 40-pin GPIO port1

4× general-purpose timers

Wake-up and watchdog timers (WDT)

Power supply monitor

3-phase, 16-bit PWM generator1

Programmable logic array (PLA)

External memory interface, up to 512 kB1

Power

Specified for 3 V operation

Active mode: 11 mA @ 5 MHz, 40 mA @ 41.78 MHz

Packages and temperature range

From 40-lead 6 mm × 6 mm LFCSP to 80-lead LQFP1

Fully specified for –40°C to +125°C operation

Tools

Low cost QuickStart™ development system

Full third-party support

ADuC702x 应用:

Industrial control and automation systems

Smart sensors, precision instrumentation

Base station systems, optical networking

图1.ADuC702x功能方框图

图2.ADuC702x典型应用电路图

PLC评估系统

The PLC demo system aims to demonstrate the complete PLC signal chain. It has four isolated input channels and four isolated output channels. The input channels have 24 bit resolution (using AD8220 IN-AMP + AD7793 Sigma Delta ADC) and each channel can be configured to accept a wide variety of input signals, from 4-20ma current loops to high voltage inputs 0-5, 0-10v, +/-5v, +/-10v. It can also accommodate RTD/TC inputs. The output channels have 16 bit resolution using the AD5422 which features an integrated output driver and built in fault detection and protection. The AD5422 has the following programmable output ranges, 4-20ma, 0-5v, 0-10v, +/-5v, +/-10v. Channel isolation is achieved using the ADuM5401 or ADuM1401. The complete design uses ADI converters, isolation technology, processors and power management products, allowing customers to evaluate the whole signal chain.

图3.PLC评估系统外形图

PLC评估系统主要特性:

Inputs Selectable: 0-20mA, 4-20mA, 0-5V, 0-10V, ±5V, ±10V, RTD, TC

Outputs Programmable: 0-20mA, 4-20mA, 0-5V, 0-10V, ±5V, ±10V

FOUR ISOLATED 24 BIT ANALOG INPUT CHANNELS

AD7793 24 Bit Sigma Delta ADC, 40nV Noise

ADR02 Wide Operating Range, Precision reference

ADR441 Ultralow Noise Voltage Reference

AD8220 Instrumentation Amplifier, >80db CMRR

ADUM5401 isoDigital Isolator with isoPower (up to 500mA)

ADUM1401 isoDigital Isolator

FOUR ISOLATED 16 BIT ANALOG OUTPUT CHANNELS

AD5422 Single Channel, 16-Bit, Serial Input, Current Source & Voltage Output DAC

0.01% Typical Total Unadjusted Error (TUE)

Single Chip Solution

Output Fault Detection and Protection

POWER/INTERFACE/CONTROL

ADI ARM7 ADUC7027

ADP3339 High Accuracy Ultralow Iq, LDO

ADM3251 Isolated Single Channel RS-232 Line Driver/Receiver


图4.PLC评估系统总体框图

图5.PLC评估系统输入通路1和通路2-电压和电流输入

图6.PLC评估系统输入通路3和通路4-电压和电流输入

图7.PLC评估系统热电耦输入电路

图8.PLC评估系统3线RTD输入电路

图9.PLC评估系统输出通路3和输出通路4-电压和电流输出

图10.PLC评估系统电源输出保护电路

图11.PLC评估系统模拟输入保护电路(1)


图12.PLC评估系统模拟输入保护电路(2)

图13.PLC评估系统模拟输出保护电路
详情请见:
52706和
52705以及
http://www.analog.com/en/digital-to-analog-converters/products/evaluation-boardstools/CU_eb_PLC_DEMO_SYSTEM/resources/fca.html