CLT3-4B Current limited over-voltage protected quad digital termination Features ■ ■ ■ ■ ■ ■ 4 channel topology Wide range input dc Voltage: – VI= - 0.3 to 30 V with RI = 0 – VI = - 30 to 30 V with RI = 1.8 kΩ – Low side configuration with common ground Current limiter: – IGEN = 3 mA – Input current limiter activation voltage < 5 V – Temperature compensated operation Opto-coupler drive: – No coupler activation below 1.5 mA input current Input protection (RI = 1.2 kΩ): – IEC 61000-4-2 electrostatic discharge ESD, Class 3 In contact, ± 6 kV; in air, ± 8 kV Level B: temporary disruption; no change of opto-coupler state – IEC 61000-4-5 voltage surge, Class 3 ± 1000 V with 42 Ω serial resistor in differential mode Level B: temporary disruption – IEC 61000-4-4 transient burst immunity ± 4 kV peak voltage; 5 kHz repetitive rate Level A: fully functional Operating ambient temperature: - 25 to 85° C TSSOP20 Applications ■ Industrial automation ■ Programmable logic controller ■ Communication field bus nodes ■ Peripheral input / output modules ■ Machine tool interface Description The CLT3-4 is a quadruple input digital termination device designed for 24 V dc automation applications. It provides the front-end circuitry of a digital input module (I/O) in industrial automation, and drives an isolating opto-coupler. Figure 1. COM Pin configuration COM OUT1 OUT2 COM34 COM OUT3 OUT4 COM12 COM 20 19 18 17 16 15 14 13 12 11 1 2 3 4 5 6 7 8 9 10 Benefits ■ ■ ■ ■ ■ ■ ■ Reduced overall dissipation Compact with high integration Enables input to meet type 1 and 3 characteristic of IEC 61131-2 standard Compatible operation with 2 and 3 wires proximity sensor according EN60947-5-2 standard Insensitive to the on state sensor impedance Surface mount package for highly automated assembly Enhanced functional reliability November 2007 IN COM IN2 ESD12 ESDC VC ESD34 IN3 COM IN4 The pins ESD, COMIJ, COM (pins # 1, 3, 6, 8, 10, 11, 13, 15, 16, 18, 20) must be connected together externally. This common pad COM is enlarged to reduce the thermal resistance and improve the device cooling. The COM and IN pins are designed to minimize the EMI effects on the circuit. Rev 5 1/13 www.st.com Characteristics 1 CLT3-4B Characteristics Figure 2. Functional block diagram OPTO COUPLER DRIVER OUT1 IN1 I1 0.75xILIM ESD OVER VOLTAGE PROTECTION I1 0.25xILIM CURRENT LIMITER ILIM 1.5mA ESD12 COM12 ESD OVER VOLTAGE PROTECTION CURRENT LIMITER ILIM 1.5mA 0.25xILIM I2 0.75xILIM I2 IN2 OUT2 OPTO COUPLER DRIVER Vc BIASING CIRCUIT ESD Volt Prot TO COMPARATORS COM ESDC OPTO COUPLER DRIVER IN3 OUT3 I3 0.75xILIM I3 0.25xILIM ESD OVER VOLTAGE PROTECTION CURRENT LIMITER ILIM 1.5mA ESD34 COM34 ESD OVER VOLTAGE PROTECTION CURRENT LIMITER ILIM I4 OPTO COUPLER DRIVER VI (1) IIN Parameter VC IN IN Value Unit Supply steady state voltage, RC = 0 kΩ - 0.3 to 30 V Supply steady state voltage, RC = 4.7 kΩ - 30 to 30 V Input steady state voltage, RI = 0 kΩ - 0.3 to 30 V Input steady state voltage, RI = 1.2 kΩ - 0.3 to 32 V Input repetitive pulse voltage, RI = 1.2 kΩ - 0.3 to 35 V Input repetitive pulse voltage, RI = 1.8 kΩ, RC = 4.7 kΩ (2) - 30 to 30 V Input maximum forward current, RI = 1.2 kΩ, RC = 4.7 kΩ 5 mA Input maximum reverse current, RI = 1.8 kΩ, RC = 4.7 kΩ (2) 20 mA 2.5 V - 4 to 4 mA Operating ambient temperature - 25 to 85 °C Operating and storage junction temperature - 25 to 150 °C VOM OUT Maximum output steady state voltage IOM OUT Output current TAMB TJ AII 1. VI = VIN + RI x IIN; VIN = voltage at the input pin itself 2. According to test diagram and design recommendations described in Section 2.2. 2/13 OUT4 Absolute ratings (limiting values) Symbol VCC I4 0.75xILIM IN4 Table 1. 1.5mA 0.25xILIM CLT3-4B Characteristics Table 2. Thermal resistance Symbol Rth(j-a) Table 3. Symbol Parameter Value Unit 90 °C/W TSSOP20 thermal resistance junction to ambient Board copper surface = 2 cm2, copper thickness = 35 µm Electrical characteristics (TJ = 25 °C, VCC = 24 V and COM pin voltage referred unless otherwise specified) Pin Name Conditions Min. Typ Max. Unit 2.1 3 3.7 mA Current limitation ILIM IN Input limiting current VOUT = 0.9 to 2.0 V VIN = 5 to 27 V TAMB = - 25 to 85° C VLOW IN Maximum off state voltage IIN = 100 µA 1.5 VTH IN Activation threshold IIN = 2.1 mA 3.4 5 V 31 38 - V VI = 5 V, (1) - 10 40 µA IIN = 1.5 mA, (2) - 10 40 µA 0.15 0.5 V V Input and Supply Protection VCL IN Clamping voltage IIN = 7 mA; tP = 1 ms Opto-coupler driver operation IOFF OUT VOFF OUT Off state output voltage ION OUT On state output current Off state output current IIN = 1.5 mA VIN = 5 V 1.5 2 - mA VIN = 4.2 V, VC = 10 V 1.5 2 - mA Supply and biasing circuit VC VC Supply voltage TAMB = - 25 to 85° C IC VC Supply current VIN = VC = 30 V 10 V 550 800 µA 1. According to Figure 9: Robust application diagram on page 8 with use of a RI = 1.8 kΩ resistor, and an opto-coupler (RLED (0 V) = 15 kΩ) 2. According to Figure 9: Robust application diagram on page 8 with use of a RI = 0 kΩ resistor, and an opto-coupler (RLED (0 V) = 15 kΩ) Table 4. Symbol Switching electrical characteristics (TJ = 25 °C, VCC = 24V and COM pin voltage referred unless otherwise specified) Pin Name FMAX IN-OUT Input to output running frequency tPLH IN-OUT Input activation propagation time tPHL IN-OUT Input de-activation propagation time Conditions Min. Typ Max. Unit 5 kHz COUT = 22 nF 6 µs COUT = 22 nF 10 µs 3/13 Characteristics Table 5. Symbol VPP CLT3-4B CLT3 System electromagnetic compatibility ratings, RI = 1.8 kΩ, RC = 4.7 kΩ (unless otherwise specified) Node IN Parameter name and conditions Value Unit ESD protection, IEC 61000-4-2, per input, in air ±8 kV ESD protection, IEC 61000-4-2, per input, in contact ±6 kV ESD protection, IEC 61000-4-2, per input, in air, RI = 0 Ω ±3 kV ESD protection, IEC 61000-4-2, per input, in contact, RI = 0 Ω ±3 kV ±4 kV ±1 kV ±1 kV VPPB VI Total Peak Pulse Voltage Burst, IEC 61000-4-4 CIN = 100 pF, COUT = 22 nF, F = 5 kHz (1) VPP VI Peak Pulse Voltage Surge, IEC 61000-4-5, R = 42 Ω (2) VPP VCC Peak Pulse Voltage Surge, IEC 61000-4-5, R = 2 Ω (2) 1. Refer to Application note AN2527 for test conditions. 2. See test circuit in Figure 12. Figure 3. Typical junction to ambient thermal resistance versus copper surface under common pad (FR4 epoxy, copper thickness is 35 µm) Rth(j-a)(° C/W) 160 140 120 100 80 60 40 20 0 0.0 1.1 S(cm²) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Functional description The CLT3-4 is a quadruple input digital termination device designed for 24 V DC automation applications. It provides the front-end circuitry of a digital input module (I/O) in industrial automation, and drives an isolating opto-coupler. Available in a four channels configuration, it offers a high-density termination by minimizing the external components count. It is housed in a TSSOP20 surface mount package to reduce the printed board size. Made of an input voltage protection, a serial current limiting circuit and an opto-coupler driver, each channel circuit terminates the connection between the logic input and the associated high side sensor or switch. The CLT3-4 is a 3 mA quad channel device compatible the type 1 and 3 characteristics of the IEC 61131-2 standard. Each input voltage clamping block protects the module input against electromagnetic interferences such as those described in the IEC 61131-2 standard and IEC 61000-4-2 (ESD), 4-4 (transient burst), 4-5 (voltage surge) standards. The supply input is also designed with such a protection structure. 4/13 CLT3-4B Characteristics The current limiting circuit connected between the input and the output pins is compensated all over the temperature range. Thanks to its low tolerance, the current limitation allows reducing drastically the dissipation of the input compared to a resistive input: the overall module requires less cooling capability and becomes smaller. The output block of each termination channel controls the operation of an opto-coupler that is enabled by a Light Emitting Diode. When the input current is less than 1.5 mA, this output circuit derivates the input current to maintain the opto-coupler off. The original structure of the CLT limiter allows its activation threshold to be low and insensitive to the output voltage up to a maximum value of 2.0 V. When the CLT input voltage VIN is higher than 5 V, or the module input voltage Vi higher than 11 V and a series resistor RI = 1.2 kΩ, the output current that is a share of the input current (3/4) is higher than 1.5 mA. The whole termination channel including the optocoupler is on. Depending on the input type operation that is described by the IEC 61131-2 standard, the input resistance RI can be adjusted because of the different on-state threshold VON MIN. This document describes operation and characteristics for type 3 operation with VON MIN = 11 V and RI = 1.2 kΩ. In type 1 operation the on state threshold VON MIN is 12.34 V instead, and the input resistor RI is set 2.2 kΩ. 1.2 Input characteristics of CLT3-4 Figure 4. Typical input characteristics of each CLT3-4 channel VIN(V) 30 30 25 3.7 20 15 10 On-state 5 5 Off-state 0 0 0.5 1 1.5 2 2.5 3 3.5 4 IIN(mA) 5/13 Characteristics Figure 5. CLT3-4B Typical current limiter variation versus junction temperature 0.9 V < VOUT < 2 V Figure 6. IIim / IIim (25° C) 3.6 102% Typical limiter threshold voltage variation versus junction temperature for IIN = 2.1 mA VTH (V) 100% VIN = 27 V 98% 3.5 96% 94% 3.4 92% VIN = 5 V 90% 3.3 88% 86% Tj (° C) Tj (°C) 3.2 84% -25 0 25 50 75 100 125 -25 0 25 50 75 100 125 1.3 CLT3-4 Input / output transfer characteristics (with respect to common pin COM) Figure 7. Current tranfer characteristic Figure 8. IOUT (mA) 4 3 Forbidden 2.5 IOUT (mA) 4 ISOLATOR ON Transition zone 3.5 ISOLATOR ON 3.5 3.7 3 2.1 2.5 2 2 1.5 1.5 1 1 Transition zone 0.04 0.5 0.5 0 0 0.5 1 ISOLATOR OFF 6/13 Transconductance characteristic 1.5 2 IIN (mA) 2.5 3 3.5 4 0 0 5 10 15 VI (V) 20 25 30 CLT3-4B Application information 2 Application information 2.1 Application description The CLT device is used between the input module and the opto-coupler of an I/O module. To secure the coupler off state and the non-conduction of its diode, the maximum CLT output current is 40 µA with R opto = 15 kΩ. When the CLT input voltage VIN is higher than 5 V, a minimum CLT output current of 1.5 mA will secure the opto-coupler on state. The CLT limiter is insensitive to the output voltage up to 2.0V. Therefore, its output is able to drive any state of the art opto-coupler. Some additional device can be added in series with the opto-coupler if the output voltage remains within its functional limits. A stand-alone sensor is normally connected on the CLT input. For a good off state control, its quiescent current has to be less than 1.5 mA (EN60947-5-2 standard compatible) keeping then the opto-coupler off thanks to the CLT device (IOUT < 40 µA). And its maximum ON state voltage VS-ON will be lower than 8 V (EN60947-5-2 standard compatible) corresponding to the difference between the minimum supply voltage (VCC MIN = 19.2 V) and the maximum current limitation activation voltage: VCC MIN = VS-ON + VI VI = VIN + RI x IIN MAX (VI = 11 V when VIN = 5 V, RI = 1.2 kΩ, IIN < 3.7 mA). 2.2 Input reverse polarity robustness Each input of the CLT device may be biased to a reverse polarity. This case corresponds to a connection mistake or a reverse biasing that is generated by the demagnetization of a monitored inductive solenoid. The involved input can withstand the reverse current up to 20 mA (in the configuration shown in Figure 10) through its input protection diode while its opto-coupler remains OFF. Such a case is not critical for the CLT3-4 itself, as it represents less than 15 mW per disturbed input. But the input resistors should be designed with care regardless of their thermal characteristics (refer to Application note AN2527). When the reverse polarity operation is required in types 3 input mode, it is recommended to increase the input resistance RI to 1.8 kΩ in order to reduce its dissipation and keep the input current below its maximum allowed level (20 mA). The surge and transient immunity robustness of the CLT3 is then also increased. A 1.8 kΩ value allows the reverse input current to be reduced to 16.2 mA and the resistor dissipation to be reduced to 0.47 W, for 30 V VCC and a - 30 V VI voltages. The CLT3 normal operation in type 3 is fully compatible with this recommended resistance since its internal state threshold is monitored at VIN = 4.2 V and VC = 10V - corresponding to VI = 11 V and VCC = 19 V. In type 1 input operation where RI = 2.2 kΩ the dissipation of this resistor is less than 0.39 W. The other inputs remain operational, as long as the power supply is working properly (VCC >19 V). Refer to Application note AN 2527 for representative application design case. 7/13 Application information CLT3-4B The CLT3-4 and the 24 V bus power supply have the same ground COM = GND. The reverse polarity of the power supply will shutdown the device. And the power supply resistor RC will limit the default current protecting the power supply pin VC. Its dissipation will be less than 0.2 W. Then, the whole module supply voltage rating is extended to from 0 to 30 V to -30 to +30 V. 2.3 EMC considerations Figure 9 gives a typical application diagram where output capacitors are used to increase CLT device immunity against fast transient bursts. Figure 11 gives the printed circuit board layout associated with this schematic. Refer to AN2527 for EMC considerations. Figure 9. Robust application diagram VI 1 COM COM IN1 OUT1 VIN 2 wires sensor RI ESD12 24V SUPPLY 3 wires sensor COM12 RI VC VCC IN2 OUT2 VC COM ESDC COM IN3 OUT3 RC RI Contact switch ESD34 COM34 RI 2 wires sensor 8/13 IN4 OUT4 COM COM CLT3-4B Application information Figure 10. Current sharing in the CLT device when IN4 is biased at - 30 V and the others at + 30 V, RI = 1.8 kΩ 0.8 mA Vcc = + 30 V 4.7 k Ω INN VCL= 38 V 3.7 mA I1 = + 30 V VC IREG N OUT1 1.8 kΩ OPTO N GND (0 V) COM OPTO 4 1.8 kΩ I2 = -30 - V 16.2 mA IN4 IREG4 OUT2 CLT3 - 4 Figure 11. TSSOP20 printed circuit board example COMMON PAD MODULE CONNECTOR COM COM IN1 OUT1 ESD12 COM12 IN2 OUT2 VC COM ESDC COM IN3 OUT3 ESD34 GND COM34 IN4 OUT4 COM COM COOLING PAD The input and supply pins are designed to withstand electromagnetic interferences. As shown on the device block diagram, each channel input is protected by a clamping diode that is connected to the common pin COM. Combined with a serial input resistance RI = 1.2 kΩ, this clamping diode implements an effective protection against transient voltage burst (± 4 kV, IEC 61000-4-4) and voltage surge (± 1 kV, IEC 61000-4-5). 9/13 Application information CLT3-4B Depending on the input type operation the input resistance RI can be adjusted because of the different on-state threshold VON MIN. So the surge voltage is also increased from the minimum level of the type 3 to the type as shown in Table 6. Table 6. Setting the input resistor RI according to the input type operation Type VON MIN (V) RI (kΩ) VPP surge (kV) 1 15 2.2 2 3 11 1.2 to 1.8 1 This combination allows the surge voltage to be applied from each input to other inputs, the ground and the supply contacts in differential or common modes (see Figure 12). Thanks to its high resistance RC = 4.7 kΩ, the supply pin VC withstands IEC 61000-4-5 with ±1000 V surge voltage (see Figure 12). Finally, an external output capacitor may be placed in parallel with the opto-coupler diode to filter the transient disturbances injected in the inputs of the module and secure the immunity of the opto-coupler itself. Figure 12. Input pin IN and supply pin VC voltage surge test circuit VPPS = ± 1 kV with 2 Ω VCC RC VC RI VPPI IN1 I VPPS VPP RI VPPI = ± 1 kV with 42 Ω IN2 RI CLT3 -4 VPPI GND COMP 5 nF PE/FE 10/13 CLT3-4B 3 Package information Package information ● Epoxy meets UL94,V0 In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. Table 7. TSSOP20 dimensions Dimensions Ref. Millimeters Min. E1 D A A2 aaa A A1 b C C PIN 1 INDENTIFICATION 20 11 Seating plane 0.25 mm Gage plane C E k L 1 10 Typ. L1 0.05 A2 0.8 b c D 6.4 E 6.2 E1 Min. Typ. 4.3 Max. 0.047 0.15 0.002 1.05 0.031 0.039 0.041 0.19 0.3 0.007 0.012 0.09 0.2 0.003 0.007 6.5 6.6 0.252 0.256 0.259 6.4 6.6 0.244 0.252 0.256 4.4 4.5 0.169 0.173 0.177 e 1.0 0.65 0.45 L1 k Max. 1.2 A1 L e Inches 0.6 0.026 0.75 0.017 0.023 0.029 1.0 0° 0.039 8° aaa 0.006 0.1 0° 8° 0.004 Figure 13. TSSOP20 footprint (dimensions in mm) 7.26 4.93 0.36 6.21 0.65 11/13 Ordering information 4 Ordering information Table 8. 5 CLT3-4B Ordering information Order code Marking Package Weight Base qty Delivery mode CLT3-4BT6 CLT3-4B TSSOP20 0.074 g 74 Tube CLT3-4BT6-TR CLT3-4B TSSOP20 0.074 g 2500 Tape and reel Revision history Table 9. Document revision history Date Revision August-2002 4A 27-Nov-2007 12/13 5 Changes Previous release. Reformatted and restructured to current standard. Updated Figure 2, Figure 9, Figure 10, Figure 11, and deleted Figure 12. Added paragraphs to Functional description and Application information. Extended application field with a new diagram (Figure 11) for reverse polarity test. Updated Package information. CLT3-4B Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. 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