ADI 公司的ADuC7027是集成了12位模擬I/O, ARM7TDMI® MCU的精密模擬微控制器,采用ARM7TDMI核16位/32位RISC架構,片內振蕩器精度±3%,外接時鐘源高達44MHz, 41.78 MHz PLL具有可編程分頻器. 模擬I/O具有多路12位1MSPS ADC和12位電壓輸出DAC.器件工作電壓2.7V-3.3V,主要用在工業控制和自動化系統,智能傳感器,精密儀表,基站系統,光網絡等.本文介紹了ADuC702x 主要特性,方框圖,典型應用電路,以及PLC評估系統主要特性, 系統總體框圖,多種輸入/輸出電路,輸入和輸出與電源保護電路.

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 應用:

Industrial control and automation systems

Smart sensors, precision instrumentation

Base station systems, optical networking

 圖1.ADuC702x功能方框圖

圖2.ADuC702x典型應用電路圖

PLC評估系統

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.

圖3.PLC評估系統外形圖

PLC評估系統主要特性:

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


圖4.PLC評估系統總體框圖

圖5.PLC評估系統輸入通路1和通路2-電壓和電流輸入

圖6.PLC評估系統輸入通路3和通路4-電壓和電流輸入

圖7.PLC評估系統熱電耦輸入電路

圖8.PLC評估系統3線RTD輸入電路

圖9.PLC評估系統輸出通路3和輸出通路4-電壓和電流輸出

圖10.PLC評估系統電源輸出保護電路

圖11.PLC評估系統模擬輸入保護電路(1)


圖12.PLC評估系統模擬輸入保護電路(2)

圖13.PLC評估系統模擬輸出保護電路
詳情請見:
http://www.analog.com/static/imported-files/data_sheets/ADuC7019_20_21_22_24_25_26_27_28_29.pdf
和
http://www.analog.com/static/imported-files/user_guides/UG-181.pdf
以及
http://www.analog.com/en/digital-to-analog-converters/products/evaluation-boardstools/CU_eb_PLC_DEMO_SYSTEM/resources/fca.html