LED Driver for High Power LEDs ILD4071 700mA High Integration - DC/DC Step-Down Converter Datasheet Rev. 1.0, 2011-11-16 ILD4071 Table of Contents Table of Contents 1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 3.1 3.2 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pin Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Pin Definitions and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 4.1 4.2 4.3 General Product Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Functional Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermal Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1 5.2 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 General Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Power Supply Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6 6.1 6.2 6.2.1 6.2.2 6.3 Enable, Dimming Function and Thermal Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical Characteristics Enable, Bias, Dimming Function and Thermal Protection . . . . . . . . . . . . . PWM Dimming with µC connected to ILD4071 PWMI pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internal PWM dimming Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overtemperature Protection of the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 12 13 14 15 16 7 7.1 7.2 7.3 Open Load Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical Characteristics: Open Load Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Open Load Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 17 17 18 8 8.1 8.2 8.3 Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Output Peak Current Adjustment via RSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Switching Frequency Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ILD4071 in LED Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 19 20 22 9 Package Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 10 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Datasheet 2 8 8 9 9 Rev. 1.0, 2011-11-16 700mA High Integration - DC/DC Step-Down Converter 1 • • • • • • • • • • • • • • • • • ILD4071 Overview Constant Current Generation Wide Input Voltage Range from 5V to 40V Peak Current Regulation Very low current consumption (<2uA) in Sleep Mode Integrated power transistor with low saturation voltage Integrated fast freewheeling diode Integrated load current sense resistor Integrated status pull down transistor Overtemperature Protection Switching frequency (typ. 200kHz) adjustable via external RC network PG-DSO-8 EP External PWM Dimming Input Integrated PWM Dimming Engine Analog Dimming (output current adjustable via external low power resistor and possibility to connect PTC resistor for LED protection during overtemperature conditions) Stable switching frequency due to fix OFF-time concept with VREC (supply voltage) feedforward Under- and Overvoltage shutdown with hysteresis Small thermally enhanced exposed heatslug SMD package Green Product (RoHS) Compliant Description The ILD4071 is a highly integrated smart LED buck controller with built in protection functions. The main function of this device is to drive single or multiple series connected LEDs efficiently from a voltage source higher than the LED forward voltage by regulating a constant LED current. The constant current regulation is especially beneficial for LED color accuracy and long LED lifetime. The built in freewheeling diode and switching transistor with current sense requires less external components and saves system costs. High flexibility is achieved by placing low power resistors to adjust output currents up to 700mA and the regulator switching frequency (typ. 200kHz). An integrated PWM dimming engine provides a LED dimming function by placing a simple RC network to GND. This feature is dedicated for simple decentralized light modules without micro controller involvement. Type Package Marking ILD4071 PG-DSO-8 EP ILD4071 Datasheet 3 Rev. 1.0, 2011-11-16 ILD4071 Overview Applications • • • • • LED Controller for Industrial Applications Universal Constant Current and Voltage Source General Illumination e.g. Halogen Replacement Residential Architectural and Industrial Commercial Lighting for in- and outdoor Signal and Marker Lights for Orientation or Navigation (e.g. steps, exit ways, etc.) For automotive and transportation applications, please refer to the Infineon® Auto LED products. Datasheet 4 Rev. 1.0, 2011-11-16 ILD4071 Block Diagram 2 Block Diagram The ILD4071 regulates the LED current by monitoring the load current (Peak Current Measurement) through the internal switch cycle by cycle. When the current through the switch reaches the threshold Ipeak the switch is shutOFF and it is kept OFF for a time equal to tOFF. Both Ipeak and tOFF can be fixed through few external components. The peak current Ipeak is fixed by a resistor connected to the SET pin while the tOFF is fixed by RC network. As tOFF is fixed and the duty cycle depends on VREC, the frequency depends on VREC as well. Refer to Chapter 8.2 for the evaluation of the switching frequency. PWMI FREQ EN VREC 6 3 1 ON/OFF Logic 5 Internal Supply UV+OV Lockout OFF-Time Control 8 internal PWM Generation PowerSwitch Driver Logic SW Power Switch Thermal Protection ST Peak Current Measurement 2 Open Load Detection Figure 1 Datasheet Peak Current Adjustment 4 7 SET GND Block Diagram ILD4071 5 Rev. 1.0, 2011-11-16 ILD4071 Pin Configuration 3 Pin Configuration 3.1 Pin Assignment VREC 1 8 SW ST 2 7 GND EN 3 6 FREQ SET 4 5 PWMI EP Figure 2 Pin Configuration ILD4071 3.2 Pin Definitions and Functions Pin Symbol Function 1 VREC Voltage Recirculation Output and Internal Supply Input; This pin is the supply pin of the IC (see block diagram). Furthermore the cathode of the integrated fast freewheeling diode is connected to this pin as well. 2 ST Status Output; Open collector diagnostic output to indicate an open load failure. Refer to Chapter 7 for more details. 3 EN Enable; Apply logic HIGH signal to enable the device 4 SET SET Input; Connect a low power resistor to adjust the output current. 5 PWMI PWM Input; PWM signal for dimming LEDs. Connect external R and C combination to achieve an auto PWM-dimming function with defined frequency and duty cycle. 1) internal PWM dimming function (external RC connected to GND) 2) external PWM dimming function (µC is controlling this pin) Refer to Chapter 6 for more details. 6 FREQ FREQuency Select Input; Connect external Resistor and Capacitor to GND to set the OFF-time of the switching frequency. 7 GND Ground; Connect to system ground. Datasheet 6 Rev. 1.0, 2011-11-16 ILD4071 Pin Configuration Pin Symbol Function 8 SW Integrated Power-Switch Output; Collector of the integrated NPN-power transistor. EP Datasheet Exposed Pad; Connect to external heatspreading copper area with electrically GND (e.g. inner GND layer of the PCB via thermal vias) 7 Rev. 1.0, 2011-11-16 ILD4071 General Product Characteristics 4 General Product Characteristics 4.1 Absolute Maximum Ratings Absolute Maximum Ratings1) Tj = -40 °C to +125 °C; all voltages with respect to ground (unless otherwise specified) Pos. Parameter Symbol Limit Values Min. Max. Unit Conditions Voltages 4.1.1 VREC (Pin 1) Recirculation and Supply Input VREC -0.3 45 V – 4.1.2 ST (Pin 2) Diagnostic Status Output Voltage VST -0.3 45 V – 4.1.3 ST (Pin 2) Diagnostic Status Current IST – 150 mA – 4.1.4 EN (Pin 3) Enable Input Voltage VEN -0.3 45 V – 4.1.5 SET (Pin 4) Peak Current Adjust Input Voltage VSET -0.3 6 V – 4.1.6 PWMI (Pin 5) PWM Input Voltage VPWMI -0.3 6 V – 4.1.7 FREQ (Pin 6) OFF-time Adjustment Input VFREQ -0.3 6 V – 4.1.8 SW (Pin 8) Switch Output VSW -0.3 45 V – Tj Tstg -40 150 °C – -55 150 °C – 2 kV HBM 2) Temperatures 4.1.9 Junction Temperature 4.1.10 Storage Temperature ESD Susceptibility 4.1.11 ESD Resistivity all Pins to GND VESD,HBM -2 1) Not subject to production test, specified by design. 2) ESD susceptibility HBM according to EIA/JESD 22-A 114B Note: Stresses above the ones listed here may cause permanent damage to the device. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note: Integrated protection functions are designed to prevent IC destruction under fault conditions described in the data sheet. Fault conditions are considered as “outside” normal operating range. Protection functions are not designed for continuous repetitive operation. Datasheet 8 Rev. 1.0, 2011-11-16 ILD4071 General Product Characteristics 4.2 Functional Range Pos. Parameter Symbol 4.2.1 Supply Voltage Range 4.2.2 Output current range VREC IOUT fSW Tj 4.2.3 Switching Frequency 4.2.4 Junction Temperature Limit Values Min. Max. 5 401) 100 700 300 -40 125 Conditions – 1) 50 Unit mA – kHz Tj = 25°C to 150°C °C – 1) Not subject to production test, specified by design. Note: Within the functional range the IC operates as described in the circuit description. The electrical characteristics are specified within the conditions given in the related electrical characteristics table. 4.3 Thermal Resistance Note: This thermal data was generated in accordance with JEDEC JESD51 standards. For more information, go to www.jedec.org. Pos. Parameter 4.3.1 Junction to Case 4.3.2 Junction to Ambient (2s2p) Symbol RthJ-case RthJA Limit Values Unit Conditions – K/W 1) 2) – K/W 1) 3) Min. Typ. Max. – 10 – 40 1) Not subject to production test, specified by design. 2) Specified RthJ-case value is simulated at natural convection on a cold plate setup (all pins and the exposed Pad are fixed to ambient temperature). Ta=25°C, Power Switch and freewheeling diode are dissipating 1W. 3) Specified RthJA value is according to Jedec JESD51-2,-7 at natural convection on FR4 2s2p board; The Product (Chip+Package) was simulated on a 76.2 x 114.3 x 1.5 mm board with 2 inner copper layers (2 x 70µm Cu, 2 x 35µm Cu). According to JESD51-5 a thermal via array under the exposed pad contacted the first inner copper layer. Ta=25°C, Power Switch and freewheeling diode are dissipating 1W. Datasheet 9 Rev. 1.0, 2011-11-16 ILD4071 Electrical Characteristics 5 Electrical Characteristics All parameters have been tested at 25°C, unless otherwise specified. 5.1 General Parameters Electrical Characteristics: Buck Regulator VREC = 24 V, Tj = -40 °C to +125 °C, all voltages with respect to ground (unless otherwise specified) Pos. Parameter Symbol Limit Values Min. Typ. Max. Unit Conditions 5.1.1 Voltage Drop over Power Transistor VDrop,100 – 0.8 – V Ipeak=100mA 5.1.2 Voltage Drop over Power Transistor VDrop,700 – 1.4 – V Ipeak=700mA 5.1.3 Freewheeling diode forward voltage Vfw,100 – 0.8 – V Ipeak=100mA 5.1.4 Freewheeling diode forward voltage Vfw,700 – 1.4 – V Ipeak=700mA 5.1.5 Peak over current limit – 1.4 – A – 5.1.6 Peak current accuracy Ipeak_lim Ipeak_acc 450 500 550 mA 5.1.7 Input under voltage shutdown threshold – 5 V VREC = 12V VEN = 5V VLED = 7.2V RSET = 14kΩ LSW = 220µH fSW = 200kHz VEN = 5V VREC decreasing; see VREC,UVOFF – Figure 3 5.1.8 Input voltage startup threshold VREC,UVON – – 6 V 5.1.9 Input over voltage shutdown threshold VREC,OVOFF 40.5 – – V VEN = 5V VREC increasing; see Figure 3 VEN = 5V VREC increasing; see Figure 3 5.1.10 Input over voltage startup threshold VREC,OV 40 – – V VEN = 5V VREC decreasing; see Figure 3 5.1.11 Switch ON delay 5.1.12 Switch OFF delay 5.1.13 Reference Voltage at SET pin 5.1.14 Pull up current for FREQ pin 5.1.15 Oscillator switch off threshold 5.1.16 Oscillator switch on threshold tdON tdOFF VSET IFREQ VFREQ,HIGH VFREQ,LOW – 400 600 ns 1) – – – 500 ns 1) 1.16 1.225 1.29 V – 5 – – mA VFREQ=0V – 3.2 – V – – 1.2 – V – 850 1) The minimum switching ON time tON must be greater than tdON + tdOFF Datasheet 10 Rev. 1.0, 2011-11-16 ILD4071 5.2 Power Supply Monitoring Over- and Undervoltage shutdown If the supply voltage VREC drops below the Input under voltage threshold voltage VREC,UVOFF, the power stage is switched OFF and the device is in normal consumption mode (Iq,ON). If VREC rises again and reaches the Input under voltage startup threshold VREC,UVON the power stage is restarted and the device is back to normal operation mode. Same behavior applies to overvoltage. The internal status transistor is switching off during an overvoltage or undervoltage event on VREC. A detailed description of the under- and overvoltage behavior is displayed in Figure 3 below. VREC VREC,OVhyst VR EC,OVoff VREC,OVon VREC,UVhyst VREC,U Von VREC,UVoff t VSW t I LED Iset t ST t ST pulldown ON Figure 3 Datasheet ST pull-down transistor OFF ST pulldown ON ST pull-down transistor OFF ST pulldown ON Over- and Undervoltage Protection 11 Rev. 1.0, 2011-11-16 ILD4071 Enable, Dimming Function and Thermal Protection 6 Enable, Dimming Function and Thermal Protection 6.1 Description Enable function: A logic high signal on the EN pin turns the device on. A logic low signal on enable pin EN brings the device in sleep mode. The current consumption is typ. 0.1µA in this case. The EN pin has an internal pull down resistor which ensures that the IC is in sleep mode and the power stage is switched off in case the pin EN is externally not connected. Dimming function: The PWMI pin combines two functions: 1) PWM dimmming via a µC (3.3Vand 5V µC) 2) Integrated PWM dimming engine for standalone solutions in decentralized light module (frequency and duty cycle adjustable via external R,C network) A detailed description of the PWMI pin is displayed in Figure 4 below. VPWMI PWMI OFF Æ DC=0% VPWMI,OFF Internal PWM VPWMI,ON PWMI ON Æ DC=100% SWON Figure 4 Datasheet SW - OFF SWON SW - OFF SWON SW - OFF SWON SW - OFF t PWMI Pin description 12 Rev. 1.0, 2011-11-16 ILD4071 Enable, Dimming Function and Thermal Protection 6.2 Electrical Characteristics Enable, Bias, Dimming Function and Thermal Protection All parameters have been tested at 25°C, unless otherwise specified. Electrical Characteristics: Enable, Bias, Dimming Function and Thermal Protection VREC = 24 V, Tj = -40 °C to +125 °C, all voltages with respect to ground (unless otherwise specified) Pos. Parameter Symbol Limit Values Min. Typ. Max. Unit Conditions 6.2.1 Current Consumption, sleep mode Iq,OFF – 0.1 2 µA VEN = 0V; 6.2.2 Current Consumption, active mode (Open Load) Iq,ON – – 5 mA 6.2.3 Current Consumption, active mode Iq,ON – – 10 mA VEN = 5.0V; Ipeak = 0mA (open load); VEN = 5.0V; Ipeak = 700mA 6.2.4 EN Turn On Threshold VEN,ON 2.8 – – V – 6.2.5 EN Turn Off Threshold VEN,OFF – – 0.8 V – 6.2.6 EN high input current IEN,hi – 100 – µA VEN = 5V 6.2.7 EN low input current IEN,lo 0 – 20 µA VEN = 0.5V 6.2.8 PWMI Turn On Threshold VPWMI,ON – 1 – V see Figure 4 6.2.9 PWMI Turn Off Threshold VPWMI,OFF – 2 – V see Figure 4 6.2.10 PWMI source current IPWMI – 250 – µA Rset = 10kΩ VPWMI = 0.5V; 6.2.11 Over temperature shutdown Tj,sd 150 175 – °C 1) 6.2.12 Over temperature shutdown Tj,sd_hyst hysteresis – 15 – K 1) 1) Specified by design. Not subject to production test. Datasheet 13 Rev. 1.0, 2011-11-16 ILD4071 Enable, Dimming Function and Thermal Protection 6.2.1 PWM Dimming with µC connected to ILD4071 PWMI pin The PWMI pin can be used for PWM dimming. It is a commonly practiced dimming method to prevent color shift in LED light applications. TPWMI VPWMI VPWMI,OFF VPWMI,ON t tOFF Ipeak t SW - OFF Figure 5 Datasheet SW - ON SW - OFF SW - ON SW - OFF Timing Diagram for LED Dimming with µC 14 Rev. 1.0, 2011-11-16 ILD4071 Enable, Dimming Function and Thermal Protection 6.2.2 Internal PWM dimming Function The ILD4071 has an integrated PWM dimming engine. Via an external RPWM and CPWM network it is possible to achieve a PWM LED current waveform. The duty cycle and dimming frequency is depending on the size of the external components (see formula in Figure 7). This feature is specially designed to achieve a stand alone PWM dimming function without the usage of micro controllers or external logic. This allows a flexible and cost effective usage of the device in a decentralized light module application. The advantage of a PWM dimming (to reduce the LED load current) is the change of light intensity only, at constant light color. With an external RC network a PWM programming between 100Hz and 1200Hz and Duty Cycles between 4% and max. 20%. is possible. Figure 6 displays the external components corresponding to the desired PWM frequency and duty cycle. The following setup applies for the table displayed in Figure 6: VREC=12V, VLED=7.2V, LSW=220µH, RSET=14kΩ. PWMI GND 7 Figure 6 Datasheet 5 RPWMI CPWMI RPWMI CPWMI fPWMI 216k Ω 216k Ω 216k Ω 216k Ω 87k Ω 87k Ω 87k Ω 87k Ω 44k Ω 44k Ω 44k Ω 44k Ω 64nF 32nF 21nF 16nF 150nF 75nF 50nF 37nF 265nF 132nF 88nF 66nF 100Hz 200Hz 300Hz 400Hz 100Hz 200Hz 300Hz 400Hz 100Hz 200Hz 300Hz 400Hz DC 4% 4% 4% 4% 10% 10% 10% 10% 20% 20% 20% 20% RPWMI and CPWMI versus fPWMI and DC 15 Rev. 1.0, 2011-11-16 ILD4071 Enable, Dimming Function and Thermal Protection 6.3 Overtemperature Protection of the Device A temperature sensor at the power stage causes the overheated device to switch OFF to prevent destruction. During over temperature condition the internal ST transistor is switched OFF. Due to the autorestart function of the device the status signal will toggle accordingly. The timing of this pattern is dependant on the thermal capability of the application and can be used to distinguish between open load error and overtemperature condition. More details on the overtemperature behavior is displayed in Figure 7 below. VEN H L t Tj TjSD ΔΤ TjSO t Ta VSW t ILED I peak t ST t ST pulldown OFF Figure 7 Datasheet ST pull-down transistor ON ST OFF ST ON ST OFF ST ON ST OFF ST ON ST OFF Overtemperature Behavior 16 Rev. 1.0, 2011-11-16 ILD4071 Open Load Diagnosis 7 Open Load Diagnosis 7.1 Description The ILD4071 has an integrated open load during ON diagnosis. During normal operation the ST pin (open collector output) is pulled to GND (internal transistor is ON). The open load detection is realized by monitoring the switching behavior at the SW pin. During an open load event the integrated power stage at the SW pin will be statically turned ON. If the output stage is turned ON for more than the open load diagnosis delay time (tOL) an open load condition is detected. An open load event will switch OFF the internal transistor. If a µC is connected to the ST pin an external pull up resistor should be placed to achieve a logic HIGH level for the proper open load error signalling reporting. For a timing diagram on the functionality of the open load diagnosis please refer to Figure 8. 7.2 Electrical Characteristics: Open Load Diagnosis All parameters have been tested at 25°C, unless otherwise specified. Electrical Characteristics: Open Load Diagnosis VREC = 24 V, Tj = -40 °C to +125 °C, all voltages with respect to ground (unless otherwise specified) Pos. Parameter Symbol Min. Typ. Max. 7.2.1 Open Load diagnosis DelayTime tOL 20 – 7.2.2 Voltage Drop over internal ST transistor VDrop,ST – 0.3 Datasheet Limit Values 17 Unit Conditions – µs – – V IST=150mA Rev. 1.0, 2011-11-16 ILD4071 Open Load Diagnosis 7.3 Open Load Diagnosis The ST pin can be connected directly to a µC input. During an open load condition the ST transistor is OFF. An external pull up resistor connected to VDD is required to signal a logic high signal on the ST pin during an open load error. Please consider that this diagnosis functionality is only active if the device is in active mode (HIGH potential at the EN pin). Refer to application drawing Figure 13. VEN High Low VPWMI t TPWMI VPWMI,OFF VPWMI,ON SW - OFF SW - ON SW - OFF SW - ON SW - OFF t VSW High - z t Open Load Event Open Load t t OL ST ST pull-down transistor ON Figure 8 Datasheet ST pull-down transistor OFF t Open Load diagnosis via µC connected to ST pin 18 Rev. 1.0, 2011-11-16 ILD4071 Application Information 8 Application Information Note: The following information is given as a hint for the implementation of the device only and shall not be regarded as a description or warranty of a certain functionality, condition or quality of the device. 8.1 Output Peak Current Adjustment via RSET The external resistor RSET is used to adjust the peak current of the regulator. Maximum achievable peak current is 700mA and minimum achievable peak current is 100mA. The SET pin provides an internally fixed voltage level at typ.: 1.225V. Out of this considerations the equation is: Ipeak = (1.225V / RSET) * 5710 The factor 5710 is derived from following considerations: • • Ipeak, max = 700mA (RSET = 10kΩ) Ipeak,min = 100mA (RSET = 70kΩ) Internal comperator voltage at SET pin = 1.225V. The circuitry behind the SET pin is adjusting higher peak currents with lower RSET values. The RSET value should be in the range from 10kΩ to 70kΩ to achieve the requested peak current range. The following setup applies for the table displayed in Figure 9: VREC=12V, VLED=7.2V, LSW=220µH. Figure 9 Datasheet IPEAK [mA] RSET [kΩ] 100 70 200 35 300 23 400 18 500 14 600 12 700 10 RSET Resistor Selection 19 Rev. 1.0, 2011-11-16 ILD4071 Application Information 8.2 Switching Frequency Determination The switching concept of the ILD4071 is based on peak current regulation with constant OFF time (tOFF). Thus the switching frequency fSW is dependent on Input voltage (VREC) variations. With the external RFREQ, CFREQ, RCOMP RCLAMP and ZCLAMP network, it is possible to adjust and stabilize the switching frequency of the regulator and achieve a. 1) no compensation, fSW increases accordingly to the VREC increase 2) switching frequency stabilized in a defined VREC range via compensation resistor RCOMP 3) switching frequency stabilized over the whole VREC range via RCOMP and additional clamping circuit ZCLAMP and RCLAMP (=1kΩ) 1 2 3 RCLAMP 1 1 VREC VREC FREQ 6 FREQ CFREQ RFREQ GND CFREQ fSW ‐ Compensation via RCOMP 600000 600000 500000 500000 500000 fSW [Hz] 600000 400000 300000 400000 300000 200000 200000 200000 100000 100000 100000 0 0 5 10 15 20 25 0 5 VREC [V] Figure 10 CFREQ fSW ‐ Compensation via RCOMP + V REC Clamp 700000 300000 ZCLAMP 7 700000 400000 6 RFREQ GND 700000 fSW [Hz] fSW [Hz] FREQ 7 fSW ‐ Without Compensation RCOMP VREC 6 RFREQ GND 7 1 RCOMP 10 15 20 25 5 10 VREC [V] 15 20 25 VREC [V] Setting tOFF Time of Regulator with External RFREQ, CFREQ Network, stabilize fSW via RCOMP, RCLAMP and ZCLAMP Setup 2 applies for the table displayed in Figure 11: VREC=12V, VLED=7.2V, LSW=220µH, RSET=14kΩ. Figure 11 Datasheet Rcomp Rfreq Cfreq fsw toff 255.8k Ω 115.8k Ω 69.7k Ω 46.8k Ω 72.8k Ω 52.7k Ω 17.1k Ω 7.7k Ω 4.6k Ω 3.1k Ω 4.9k Ω 3.5k Ω 220pF 220pF 220pF 220pF 100pF 100pF 50kHz 100kHz 150kHz 200kHz 250kHz 300kHz 6.47μs 3.19μs 2.12μs 1.59μs 1.27μs 1.06μs RFREQ, CFREQ versus fSW Table 20 Rev. 1.0, 2011-11-16 ILD4071 Application Information VEN High Low t VFREQ VFREQ,high VFREQ,low t ILED I set=I peak Imin VSW I ripple ton tup toff tdown t VREC+Vfw Vdrop Transistor Figure 12 Datasheet Diode T Diode T Diode T Diode T Diode t Theoretical Operating Waveforms 21 Rev. 1.0, 2011-11-16 ILD4071 Application Information 8.3 ILD4071 in LED Application Figure 13 provides a simplified application with two high brightness LEDs in series. A µC is controlling the EN pin to put the device into sleep/active mode. Also the PWMI pin can be directly controlled via a µC port if PWM dimming of the LED current is required. The open load ST pin monitors the load condition of the application and gives feedback to the µC. An external pull up resistor is recommended to achieve a logic HIGH signal during an open load error (internal status transistor is switched OFF and the ST pin is high ohmic). The external low power resistor RSET is used to set the required peak current for the LED load (refer to Figure 9 for more details). To set the desired switching frequency of the buck regulator the external RFREQ and CFREQ network must be connected to GND (reference values are given in Figure 11). ILED Vs = 5V to 40V LSW 1 CREC VREC SW COUT 8 VREC VDD open load status connected to µC SW Driver RST 2 RCLAMP ST connect to µC pin 3 FREQ RFREQ SET RSET Figure 13 6 EN GND 4 DCLAMP RCOMP Open Load PWMI CFREQ 7 5 PWM dimming via µC Simplified Application Diagram ILD4071 Note: This is a very simplified example of an application circuit. The function must be verified in the real application Datasheet 22 Rev. 1.0, 2011-11-16 ILD4071 Package Outlines 9 Package Outlines 0.35 x 45˚ 1.27 0.41±0.09 2) 0.2 M 0.19 +0.06 0.08 C Seating Plane C A-B D 8x 0.64 ±0.25 D 0.2 6 ±0.2 8˚ MAX. C 0.1 C D 2x 1.7 MAX. Stand Off (1.45) 0.1+0 -0.1 3.9 ±0.11) M D 8x Bottom View 8 1 5 1 4 8 4 5 2.65 ±0.2 3 ±0.2 A B 4.9 ±0.11) 0.1 C A-B 2x Index Marking 1) Does not include plastic or metal protrusion of 0.15 max. per side 2) Dambar protrusion shall be maximum 0.1 mm total in excess of lead width 3) JEDEC reference MS-012 variation BA Figure 14 PG-DSO-8-27-PO V01 Outline PG-DSO-8 EP Green Product (RoHS compliant) To meet the world-wide customer requirements for environmentally friendly products and to be compliant with government regulations the device is available as a green product. Green products are RoHS-Compliant (i.e Pb-free finish on leads and suitable for Pb-free soldering according to IPC/JEDEC J-STD-020). For further package information, please visit our website: http://www.infineon.com/packages. Datasheet 23 Dimensions in mm Rev. 1.0, 2011-11-16 ILD4071 Revision History 10 Revision History Version Date Rev. 1.0 2011-11-16 Initial Data sheet for ILD4071 Datasheet Changes 24 Rev. 1.0, 2011-11-16 Edition 2011-11-16 Published by Infineon Technologies AG 81726 Munich, Germany © 2012 Infineon Technologies AG All Rights Reserved. Legal Disclaimer The information given in this document shall in no event be regarded as a guarantee of conditions or characteristics. With respect to any examples or hints given herein, any typical values stated herein and/or any information regarding the application of the device, Infineon Technologies hereby disclaims any and all warranties and liabilities of any kind, including without limitation, warranties of non-infringement of intellectual property rights of any third party. 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