Part Details for OP184 by Analog Devices Inc

Figure 1 shows the manner in which the AD5422 can be combined with the AD5700 HART modem and a UART interface to construct a HART-capable 4 mA to 20 mA current output, typical of PLC and DCS systems. The buffer connected to the +VSENSE pin is not necessary if the application does not require the IOUT and VOUT pins to be shorted. The HART_OUT signal from the AD5700 is attenuated and ac-coupled into the RSET pin of the AD5422. If the external RSET resistor is not being used, an alternative method of connecting the AD5422 and the AD5700 via the CAP2 pin can be found in Application Note AN-1065, as previously described. This method is only relevant to the 40-lead LFCSP package option of the AD5422 because the lower pin-count 24-lead TSSOP package does not contain a CAP2 pin.