Part # Application Notes Industrial CLT3-4B AN2527 datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: CLT3-4 termination in industrial automation logic inputs STEVAL-IFP008V1


Part Details:

AN2527 Application note CLT3-4 termination in industrial automation logic inputs STEVAL-IFP008V1 Introduction The CLT3-4B (Current Limited Termination) is a quadruple logic input termination for sensor or mechanical switch interfaces. It is designed to work in 24 VDC applications such as Programmable Logic Controller PLC, Programmable Automation Controller PAC, and Distributed I/Os systems used in factory automation. The device optimizes the input VI characteristic to reduce power dissipation. This becomes critical when the application cabinet or housing requires higher protection levels such as IP65 and IP67. These closed cabinets are used in various automated lines including the food and chemical industry. The power dissipated inside the module is very limited as there is usually no air circulation inside the box. The current limitation reduces the power losses in the sensor as well. The most important challenge of CLT3-4 is the electrical protection and susceptibility it brings to the application. The CLT3-4B implements efficient protection diodes on each input and supply voltage lines. Associated serial resistors as described below ensure a higher level of susceptibility of the whole input module. Thanks to its compact device package, the complete CLT3-4BT6 application occupies little space on the PCB compared to an equivalent discrete solution. Features Termination for IEC61131-2 type 1 and 3 inputs 4 input channel topology Fully integrated internally fixed current limiter Optocoupler output drive Wide range supply voltage and temperature operation Benefits Low power dissipation vs. discrete solution Few external components Over-voltage protection ESD according to IEC61000-4-2, Class 3, 8 kV air discharge, 6 kV contact discharge Excellent EMC robustness: voltage surge, fast transient burst immunity (±2 kV, ±4 kV) Compact module TSSOP20 package General overview and device functionality can be found in document [1]. Document [2] describes typical applications and circuit behavior. This application note shows application modifications which improve the interface robustness and optimizes cost effectiveness. It also considers the connection of an indicator LED in series with the optocoupler. (According to IEC61131-2 each input high state should be indicated.) This connection reduces the number of components in the application bill of materials. September 2007 Rev 2 1/18 www.st.com Contents AN2527 Contents 1 CLT3-4BT6 description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Demo board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Thermal management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4 EMC requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1 Description of the procedure to evaluate the robustness of the CLT3-4BT6 . 10 4.2 ESD tests (according to the IEC61000-4-2) . . . . . . . . . . . . . . . . . . . . . . . 11 4.3 Burst tests (according to the IEC61000-4-4) . . . . . . . . . . . . . . . . . . . . . . 11 4.4 Surge test (according to the IEC61000-4-5) . . . . . . . . . . . . . . . . . . . . . . . 11 4.5 Conducted disturbance tests (according to the IEC61000-4-6) . . . . . . . . 11 4.6 Reverse analog input polarity tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5 EMC testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6 Operation in type 1 mode with LED connected to CLT3-4 output . . . 13


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Application Notes Industrial CLT3-4B AN2527.pdf Datasheet