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| IC-NT LIGHT CHAIN PULSE DRIVER FEATURES Adjustable LED pulse operation, set range of 0.4..1A Controlled current slew rate enables short light pulses down to 1s LED efficiency degradation compensated by positive current temperature coefficient Low standby current; circuit activation by input data Low power requirement for external set resistor Control logic with 3-step shift register Compatible to CMOS levels Data output buffer with built-in 120 wave impedance adaption Single 5V supply Thermal shutdown and power-down reset ESD protection Small outline package SO8 Suited for high-risk applications according to IEC 1496-1 Option: Extended temperature range of -20C..85C APPLICATIONS Electro-sensitive protective equipment (ESPE) Light curtain LED driver Light barrier LED driver PACKAGES SO8 BLOCK DIAGRAM +5V 2 VDD CONTROL INPUTS IC-NT LOGIC OUTPUT BUFFER 1 DIN 6A DOUT FF1 D C R 6A Q Q1 6 FF2 D C R Q Q2 FF3 3 CLK & D C R Q Q3 LED CURRENT SINK VDD +5V 4 SHEN SEND 6A S Dis 500 LED 8 1 1 VDD ENABLE A 1:1200 VTREF PDR TR POWER DOWN RESET REFERENCE AND THERMAL SHUTDOWN + 50 ISET 5 RSET GND 7 (c)1997 iC-Haus GmbH Integrierte Schaltkreise Am Kuemmerling 18, 55294 Bodenheim Rev A0 1.8k Tel (+49)6135-9292-0 Fax (+49)6135-9292-192 http://www.ichaus.com IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 2/8 DESCRIPTION The IC-NT device is an LED pulse driver for light barrier applications, especially light chain circuitries. The device, which is controlled by a shift register logic, features an adjustable LED current sink with a set range of 0.4..1A (at room temperature). For chain circuitries with several transmitters in operation, the internal set of three flipflops enables a secure beam and data shift control, free of race conditions. The decrease in LED efficiency with a rise in temperature is almost compensated by a positive temperature coefficient of the current sink. In order to generate steep light pulses, the LED switch off is actively supported by the discharge of its junction capacitance. The duration of this LED short-circuiting is controlled by a monoflop. In the event of a quick follow-up light pulse, a monoflop reset is performed automatically to protect against cross currents. The driver stage for the LED output prepares for a light pulse when DIN reads a high signal; synchronized with the CLK leading edge, the first flipflop transfers the DIN data to Q1 and powers up the LED sink. Since the chain is loaded with just one single high bit and DIN is given by the output DOUT of the previous device, input DIN now reads low at the falling edge of CLK. The LED current sink stops the power, at the same time as an internal data shift from Q1 to Q2 occurs. The LED pulse is well-defined by the time difference between two leading edges of the clock signal CLK. The second falling edge of CLK triggers the third flipflop and activates the next device in the chain via DOUT if enabled by SHEN. Since only one device is activated at a time, several IC-NT drivers may share one resistor, RSET, to define the LED current value. The shift register is reset and the LED current sink is turned off in the event of excessive temperature or undervoltage. Protective diodes to prevent destruction through ESD are also included. The IC-NT device fulfills safety requirements according to IEC 1496-1. An extended temperature range of -20C..85C is also available as an option. PACKAGE SO8 to JEDEC Standard PIN CONFIGURATION SO8 (top view) PIN FUNCTIONS No. Name Function 1 2 3 4 5 6 7 8 DIN VDD CLK SHEN ISET DOUT GND LED Data Input Supply Voltage 5V Clock Shift Enable Current Adjust, attachement RSET Data Output Ground Pulse Output, LED Cathode IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 3/8 ABSOLUTE MAXIMUM RATINGS Values beyond which damage may occur; device operation is not guaranteed. Item Symbol Parameter Conditions Fig. Min. G001 VDD G002 V() G003 V() E001 Vd() E002 Vd(LED) TG1 Tj TG2 Ts Supply Voltage Voltage at Inputs DIN, CLK, SHEN Voltage at DOUT, ISET, LED ESD Susceptibility at VDD, ISET and digital inputs/outputs ESD Susceptibility at LED Junction Temperature Storage Temperature MIL-STD-883, HBM 100pF discharged through 1.5k with standard circuitry, HBM 100pF discharged through 1.5k 5 -40 -40 -0.5 -0.5 -0.5 Max. 7 VDD+0.5 VDD+0.5 2 2 150 150 V V V kV kV C C Unit THERMAL DATA Operating Conditions: VDD= 4.75..5.5V Item Symbol Parameter Conditions Fig. Min. T1 Ta Operating Ambient Temperature Range (Extended temperature range of -20..85C on request) Thermal Resistance Junction to Ambient surface mounted without special cooling areas 0 Typ. Max. 70 C Unit T2 Rthja 170 K/W All voltages are referenced to ground unless otherwise noted. All currents into the device pins are positive; all currents out of the device pins are negative. IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 4/8 ELECTRICAL CHARACTERISTICS Operating Conditions: VDD= 4.75..5.5V, RSET= 1.8..4.5k, Tj= -20..125C, unless otherwise noted Item Symbol Parameter Conditions Tj C Total Device 001 VDD 002 I(VDD) Permissible Supply Voltage Range Supply Current in VDD (Standby) Analog section disabled; DIN= lo, CLK,SHEN= hi or lo, logic levels: lo= 0..0.45V, hi= VDD-0.45V..VDD Analog section disabled; DIN= lo CLK, SHEN hi or lo, logic levels: lo= 22%VDD, hi= 78%VDD Analog section enabled; RSET 1.8k, LED current sink off Analog section enabled; RSET 1.8k, LED current sink on -20 27 85 Toff -20 27 85 Toff 4.75 5.5 60 V A Fig. Min. Typ. Max. Unit 003 I(VDD) Supply Current in VDD 1 mA 004 I(VDD) Supply Current in VDD 7.5 7.5 8.5 1.0 25 25 26 1.0 4.3 mA mA mA mA mA mA mA mA V V mV 005 I(VDD) Supply Current in VDD 006 VDDon 007 VDDoff 008 VDDhys 009 Vc()hi 010 Vc()lo 011 Toff Turn-on Threshold VDD (Power-on Release) Undervoltage Threshold at VDD (Power-down Reset) Hysteresis Clamp Voltage hi at DIN, CLK, SHEN, DOUT, ISET, LED Clamp Voltage lo at DIN, CLK, SHEN, DOUT, ISET, LED Shutdown Temperature decreasing voltage VDD VDDhys= VDDon-VDDoff Vc()hi= V()-VDD, I()= 10mA I()= -10mA, VDD= 0V other pins open 2.7 100 0.4 -1.25 110 1.25 -0.4 150 V V C LED Current Sink 101 V(ISET) Reference Voltage at ISET -20 27 85 Toff 27 0.30 1.27 1.50 1.79 0 0.33 1200 duty cycle I(LED) 1%, RSET= 1.8k, V(LED)= 1.0V..VDD duty cycle I(LED) 1%, RSET= 4.5k, V(LED)= 0.85V..VDD -20 27 85 Toff -20 27 85 Toff 3 3 LED shutdown, switch Sdis closed 0.65 0.82 0.93 0.26 0.33 0.37 0.85 1.00 1.2 0 0.34 0.40 0.48 0 1.06 1.18 1.48 0.44 0.48 0.61 150 150 400 A A A A A A A A ns ns ns 0.36 V V V V %/K 102 TC(ISET) Temperature Coefficient of Reference Voltage at ISET 103 CR() 104 I(LED) Current Ratio I(LED) / -I(ISET) LED Pulse Current 105 I(LED) LED Pulse Current 106 tr(LED) 107 tf(LED) LED Current Rise Time LED Current Fall Time 108 tdis(LED) LED Discharge Duration IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 5/8 ELECTRICAL CHARACTERISTICS Operating Conditions: VDD= 4.75..5.5V, RSET= 1.8..4.5k, Tj= -20..125C, unless otherwise noted Item Symbol Parameter Conditions Tj C LED Current Sink (continued) 109 Ir(LED) LED Discharge Current V(VDD/LED)= 1.5V 300 200 500 850 mA Fig. Min. Typ. Max. Unit 110 Rpu(LED) Pull-up Resistor at LED Control Inputs DIN, SHEN, CLK 201 Vt()hi 202 Vt()lo 203 Vhys() 204 Ipd() Threshold Voltage hi Threshold Voltage lo Schmitt-Trigger Input Hysteresis Pull-Down Current V()= 5.0V 78 22 400 3 6 12 %VDD %VDD mV A Output Buffer DOUT 301 Vs()hi 302 Vs()lo 303 Isc()hi 304 Isc()lo 305 Rout() 306 tr() 307 tf() Saturation Voltage hi Saturation Voltage lo Short-Circuit Current hi Short-Circuit Current lo Output Resistance Rise Time Fall Time Vs(DOUT)hi= VDD-V(DOUT), I(DOUT)= -4mA I(DOUT)= 4mA V(DOUT)= 0V V(DOUT)= VDD VDD= 5.0V, V(DOUT)= 2.5V CL(DOUT) 50pF CL(DOUT) 50pF -100 20 80 -40 40 120 20 20 0.4 0.4 -20 100 190 60 60 V V mA mA ns ns Switching Characteristics 401 tphl(CLK LED Pulse Turn-on Delay -LED) 402 tplh(CLK LED Pulse Turn-off Delay -LED) 403 tplh(CLK- DOUT Switch Delay hi DOUT) 404 tphl(CLK- DOUT Switch Delay lo DOUT) DIN= hi, CLK lohi until I(LED)= 10% set value DIN= lo, CLK lohi until I(LED)= 90% set value CL(DOUT) 50pF, CLK hilo CL(DOUT) 50pF, CLK hilo 4 4 2 2 25 25 100 80 60 60 ns ns ns ns IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 6/8 OPERATING REQUIREMENTS: Logic Operating Conditions: VDD= 4.75..5.5V, Ta= 0..70C, CL()= 50pF, input levels lo= 0..0.45V, hi= VDD-0.45V..VDD, see Fig. 1 for reference levels and waveforms Item Symbol Parameter Conditions Fig. Min. I1 I2 I3 I4 I5 I6 ten tset1 thold1 tset2 thold2 tw Activation Time (standby to operation): DIN lohi before CLK lohi Setup time: DIN stable before CLK lohi Hold time: DIN stable after CLK lohi Setup time: SHEN stable before CLK hilo Hold time: SHEN stable after CLK hilo LED Pulse time: 1st to 2nd CLK lohi 4 2 2 2 2 4 5 50 50 50 50 1.0 Max. s ns ns ns ns s Unit Fig. 1: Reference levels Fig. 2: Timing characteristics Fig. 3: LED Current Pulse Fig. 4: Chain configuration (SHEN= hi), LED pulse definition by clock signal IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 7/8 APPLICATIONS INFORMATION Light curtain The circuit in Figure 5 shows IC-NT chained to a light curtain where consecutive LEDs emit clock-driven light pulses. When discussing the function of IC-NT, it is assumed that all flipflops in IC1..ICn have been reset, for example after the operating voltage has been switched on. The signal DIN1= hi activates the IC1 current sink which is switched to LED1 with the CLK rising edge. With DIN1= lo, the next CLK rising edge resets FF1, turns off the LED and deactivates the current sink in IC1. Simultaneously, FF1 sends the stored information to FF2. FF3 also accepts this information via the CLK trailing edge (provided that SHEN= hi) and activates the current sink in the next component, IC2, via the output driver. The pulse diagram in Figure 6 is also valid for the subsequent components in the chain, i.e. the ICs switched as a light curtain make up a clock-driven shift register which passes on the input information. The typical timing of a CLK signal, shown in Figure 6, is characterized by two successive pulses which determine the length of a light pulse tw from 1..3s, followed by a longer activation time of ten 5s. In general, the CLK pulse interval is determined and lengthened by the activation time required by the receiver or by more extensive, system-set default options. Because of the high LED pulse currents, the PCB layout of the light curtain sender must be designed to avoid large voltage drops on the supply lines. The high, short-term pulse current is provided by back-up capacitors C1..Cn at the pulse driver ICs; these should have a low inductance due to the high current increase rate. The leads to the LED anode and to IC-NT's GND pin should be as short as possible. The capacitors selected should ensure that the voltage drop caused by the light pulse is less than 1V, i.e. that C1..Cn= 1F for a light pulse of 1A x 1s, for example. In practice, the voltage at the IC drops much less during a light pulse, as charge from the back-up capacitors of neighboring ICs also flows into the chip. A low-inductance capacitance distribution can be achieved more economically by placing further smaller capacitors in parallel. Since only one device is activated at a time within one section of a light curtain, several IC-NTs may share the external resistor RSET, needed to set the pulse current. This parallel chain circuit should be limited to ca. 5 ICs due to the increasing capacitive loading at pin ISET. Fig. 5: Schematic of a Chain Configuration IC-NT LIGHT CHAIN PULSE DRIVER Rev A0, Page 8/8 Fig. 6: Signals of the Chain Configuration of Figure 5 ORDERING INFORMATION Type IC-NT Package SO8 Order designation IC-NT-SO8 For information about prices, terms of delivery, options for other case types, etc., please contact: iC-Haus GmbH Am Kuemmerling 18 D-55294 Bodenheim GERMANY Tel (+49)6135-9292-0 Fax (+49)6135-9292-192 http://www.ichaus.com This specification is for a newly developed product. iC-Haus therefore reserves the right to modify data without further notice. Please contact us to ascertain the current data. The data specified is intended solely for the purpose of product description and is not to be deemed guaranteed in a legal sense. Any claims for damage against us - regardless of the legal basis - are excluded unless we are guilty of premeditation or gross negligence. We do not assume any guarantee that the specified circuits or procedures are free of copyrights of third parties. Copying - even as an excerpt - is only permitted with the approval of the publisher and precise reference to source. |
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