MTL5549 Analogue Output, 2ch 4-20mA smart isolating driver + LFD. The MTL5549 accepts 4/20mA floating signals from safe-area controllers to drive 2 current/pressure converters (or any other load up to 800Ω) in a hazardous area. For HART valve positioners, the module also permits bi directional transmission of digital communication signals. Process controllers with a readback facility can detect open or short circuits in the field wiring: if these occur, the current taken into the terminals drops to a preset level. The MTL4549C and MTL5549Y are very similar to the MTL5549 except that they provide open circuit detection only (i.e. no short-circuit detection).