The SCLT3-8BQ7 and CLT01-38SQ7 are 8-channel industrial protected current limiters and a serializers for interfacing automation digital inputs

The SCLT3-8BQ7 and CLT01-38SQ7 are 8-channel industrial protected current limiters and a serializers for interfacing automation digital inputs. They meet type 1, 2 and 3 input characteristics in accordance with the IEC 61131-2, programmable controller international standard. They integrate the SPI serializer, which is beneficial especially for applications with high channel counts. The serial communication allows the number of lines to be reduced, which in most applications, need to be galvanic isolated. Furthermore, their structure allows the transfer of the data and the additional information including thermal alarm, under-voltage indication and checksum bits. The devices optimize input VI characteristic shape to minimize power dissipation. This becomes critical when the application enclosure requires higher protection levels with closed cabinets. The power dissipated inside the module is very limited, no air circulation is present inside the box. Current limitation also reduces power losses on the sensor side. LED drivers, providing input states and using current from sensors, are energy-less (supplied directly from the input currents). 5 V regulator is included to drive opto-coupler (isolator) when galvanic isolation is needed. Another important parameter is the electrical protection and susceptibility of the application. ST xCLT products implement large protection diodes on each input and supply voltage line, therefore achieving excellent immunity levels with minimum external component count. Thanks to the compact QFN package (7 x 7 mm) and only few external components, the solution is becoming extremely small, especially in comparison with discrete solutions.