Loop Conditions

Loop conditions

LD

ET

Loop connected, no gound key

High

High

Loop connected, ground key aktiv

High

Low

Loop disconnected, no ground key

Low

High

Loop Detection

Condition for switching of the logic output LD:

Status of the logic output LD depending on loop current:

LD = Low

LD = High

Loop Resistance

The useable loop resistance can be calculated as follows:

In accordance with the conditions menioned above a reliable loop detection will be guaranteed for a closed loop

resistance value lower than 815

Ω.

09/00

TFB3869T

12

(VBAT - 5V)

(VBAT - 5V)

120 * 23.3V

* RSET