本文介绍了AD5421主要特性, 功能方框图,和HART调制解调器连接框图以及应用框图.
ADI公司的AD5421是完整的16位4mA-20mA转换器,包括用来给自身和发送器中其它器件供电的稳压器,输出电压从1.8V到12V,漂移为5ppm/℃.器件还包括精密的1.25V和2.5V基准电压源. AD5421采用标准的HART FSK协议通信,串口速率高达20Mbps,主要应用在工业过程控制,4-20mA回路供电发送器以及智能发送器.
16-Bit, Serial Input, Loop-Powered, 4mA to 20mA DAC
The AD5421 is a complete, loop powered, digital to 4mA-to-20mA converter, designed to meet the needs of smart transmitter manufacturers in the Industrial Control industry.It provides a high precision, fully integrated, low cost soluTIon in a compact TSSOP package.
The AD5421 includes a regulated voltage output that is used to power itself and other devices in the transmitter. This regulator provides a regulated 1.8V to 12V output voltage. The device also contains precision 1.25V and 2.5V references, The AD5421 thus eliminates the need for a discrete regulator and voltage reference.
The AD5421 can be used with standard HART FSK protocol communicaTIon circuitry without any degradaTIon in specified performance. The high speed serial interface is capable of operaTIng at 20 Mbps and allows for simple connection to commonly-used microprocessors and microcontrollers via a SPI compatible three-wire interface.
The AD5421 is guaranteed monotonic to 16-bits, offers 0.0015% integral nonlinearity, 0.03% offset error and 0.03 % gain error.
The AD5421 is available in a 28 lead TSSOP package and is specified over the extended industrial temperature range of –40℃ to +105℃.
AD5421主要特性:
16-Bit Resolution and Monotonicity
Pin selectable NAMUR Compliant Ranges
4mA to 20mA
3.8mA to 21mA
3.2mA to 24mA
NAMUR Compliant ALARM Currents
Downscale ALARM current = 3.2mA
Upscale ALARM Current = 22.8mA/24mA
0.05% maximum Total Unadjusted Error (TUE)
0.0015% maximum INL Error (15 Bits minimum)
5ppm/℃ typ Output Drift
350uA maximum Quiescent Current
Flexible SPI Compatible Serial Digital Interface
Schmitt Triggered Inputs
On-Chip Fault Alerts via FAULT pin or ALARM Current
Loss of SPI Interface Control
SPI Communication Error (Packet Error Check)
Programmed Loop Current out of Range
Insufficient Loop Voltage
Over Temperature
Automatic Readback of Fault Register on each write cycle
Slew Rate Control Function
Gain and Offset Adjust Registers
On-Chip Reference (10 ppm/℃ Max)
Selectable Regulated Voltage Output
Loop Voltage Range
5.5V to 52V
Temperature Range: -40℃ to +105℃
TSSOP Package
HART Compatible
AD5421应用:
Industrial Process Control
4-20mA Loop Powered Transmitter
Smart Transmitter
图1.AD5421功能方框图
图2.AD5421和HART调制解调器连接框图
图3.AD5421应用框图