|PGA 309XTR116 Smart Loop powered signal conditioner
The Texas Instruments/Burr Brown PGA309 offers low cost and minimal power consumption plus a highly accurate and versatile signal conditioner chip that can be rapidly adapted to multiple applications including intelligent sensors and data loggers. DASCOR has coupled the PGA309 with the XTR116, 4-20 mA current loop chip in a small stand-alone module that can be used to evaluate the PGA309 by itself, or in a current loop environment where all power is derived from the loop.
The board replicates many of the features, components and functions found on the larger PGA309DK evaluation board from Texas Instruments/Burr Brown. It connects directly to the PC interface board through a short ribbon cable and is fully programmable by the TI/BB software included in the Development Kit. Complete details, procedures and specifications for the PGA309 and XTR116 are included in their respective data sheets that can be downloaded from the Texas Instruments website. In addition, a White Paper authored by Art Kay is available that provides intricate detail of combining the PGA and XTR116. Copies of this paper are currently available by request from TI/BB or DASCOR at www.TI.com or www.dascor.com
The DASCOR evaluation module includes Euro-style terminal blocks for the current loop and sensor leads. Additional headers (25 mil posts on 100 mil centers) are provided in parallel with the loop and signal connections and for all signals common to the PGA309DK interface board that is part of the PGA309DK Development Kit from Texas Instruments/Burr Brown.
The DASCOR Evaluation Board is designed to mount into a Bud AN1301 die-cast aluminum box. A heavy ground plane helps to isolates the signal conditioning components from outside influences. Also, it serves as a heat sink to the box for the current loop pass transistor. All connections, including a fast-blow fuse, are accessible on the top surface.
Dual 33-Volt TUV’s further protect the circuit from transient over-voltage conditions on the loop. On the bottom of the board, multiple ferrite beads provide RF filtering on all signal lines. A full-wave bridge rectifier is in the loop to allow either polarity to be connected without damage to the circuit. Solder pads are provided for all anticipated components used for custom filtering and for setting up the external bridge to act as a temperature sensor for the PGA 309.