Adjustable Linear Low Dropout LED Driver TLE4309 Features • • • • • • • • • • • • Adjustable constant current up to 500 mA Operating supply voltage range 4.5 V to 24 V Maximum supply voltage up to 45 V Low dropout voltage PWM / ENABLE input << 1 µA quiescent current when disabled Overtemperature protection Short circuit proof Reverse polarity protection Operating junction temperature range: -40 °C to 150 °C Suitable for applications up to 85 °C ambient temperature. Green Product (RoHS compliant) PG-TO263-7 Functional Description The TLE4309 is an integrated adjustable constant current source for driving loads up to 500 mA. The output current level can be adjusted with an external shunt resistor. Supplying high power LEDs with the TLE4309 ensures constant brightness independent from supply voltage or LED forward voltage spread. Therefore, LED lifetime is extended by protecting from overcurrent and overtemperature The PWM/EN input permits LED brightness regulation by pulse width modulation. Setting the pin to “low” switches off the IC entirely. Due to the high impedance of the PWM/EN input, the TLE4309 can be used as a protected high side switch. Protection circuits prevent from damage to the IC in case of overload, short circuit, and reverse polarity. A chip temperature monitoring circuit shuts off the power stage and prevents the IC from destruction under fault conditions. In case of negative input voltage, a leakage current is flowing only from the output to the input, hence the LED are protected against reverse supply. Input voltage peaks up to 45 V are absorbed by the IC, preventing the LEDs from overcurrent. The TLE4309G is provided in the surface mounted PG-TO-263 package with excellent thermal resistance. Type Package Marking TLE4309G PG-TO263-7-1 TLE4309 Datasheet 1 Rev. 1.0, 2007-03-20 TLE4309 Circuit Description An external shunt resistor in the ground path of the connected LEDs senses the LED current. A regulation loop maintains the voltage drop across the shunt resistor at a constant level. Selecting the shunt resistance permits to adjust the appropriate constant current . The output current calculates V REF I Q, typ = -----------R REF (1) where VREF is the reference voltage. (see “Electrical Characteristics” table). The equation applies in a range of 0.39 Ω ≤ RREF ≤ 1.8 Ω. On Page 7, the output current is shown as a function of the reference resistance. TLE 4309 I PWM / EN +12V optional 100nF 7 Q 5 REF 1 2 Bias Supply Temp. Shutdown Bandgap Reference Logic 4 GND Figure 1 T L E 4 3 0 9 _ B L OCK DI A GRA M+ A P P CI RCUIT .V S D RRE F Block Diagram and Typical Application Circuit During operation, the LED brightness is modifiable by adjusting the duty cycle at the PWM/EN input. This allows to dim the LEDs during operation or adapt the output current to different LED luminosity classes. A low signal at the PWM/EN input sets the IC into sleep mode consuming less than 1 µA. Due to its high input impedance, the PWM/EN pin can be used as an enable input. Connect the pin directly to the supply line, if its function is not needed. The minimum supply voltage calculates as the sum of the LED forward voltages, the TLE4309 dropout voltage and the maximum voltage drop across the reference resistor RREF . Datasheet 2 Rev. 1.0, 2007-03-20 TLE4309 P-TO-263 1 TL E4 30 9_ PINO UT.VSD TAB 7 I n.c REF Q PWM GND n.c. / EN Figure 2 Pin Configuration (top view) Table 1 Pin Definitions and Functions Pin No. Symbol Function 1 I Input. 2 PWM / EN Pulse Width Modulation Input / ENABLE input. If not needed connect to I (pin 1). 3 n. c. Internally not connected. Leave open. 4 GND Ground reference; connect to heatsink area and to TAB. 5 REF Reference Input; connect to shunt resistor. 6 n. c. Internally not connected. Leave open. 7 Q Output. TAB Datasheet Connect to heatsink area and to GND pin. 3 Rev. 1.0, 2007-03-20 TLE4309 Table 2 Absolute Maximum Ratings Parameter Symbol Limit Values Unit Remarks Min. Max. VI II -42 45 V – – – mA internally limited VQ IQ -1 40 V – – – mA internally limited VREF IREF -1 16 V – -2 2 mA – Input Voltage Current Output Voltage Current Reference Input Voltage Current Pulse Width Modulation / Enable Input Voltage Current VPWM IPWM -40 40 V – -1 1 mA – Tj Tstg -40 150 °C – -50 150 °C – 2 kV Human Body Model1) Temperatures Junction temperature Storage temperature ESD Susceptibility ESD Resistivity VESD,HBM -2 1) ESD susceptibility, HBM according to EIA/JESD 22-A114B 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 4 Rev. 1.0, 2007-03-20 TLE4309 Table 3 Operating Range Parameter Symbol VI PWM / ENABLE voltage VPWM Tj Junction temperature Reference resistor RREF Input voltage Limit Values Unit Remarks Min. Max. 4.5 24 V – 0 24 V – -40 150 °C – 0 1.8 Ω – 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 . Table 4 Thermal Resistance Parameter Symbol Typical Unit Limit Values Remarks Junction ambient Rthja 78 K/W Footprint only1) 52 K/W 300mm2 heat sink area1) 39 K/W 600mm2 heat sink area1) 3 K/W – Junction case Rthjc 1) Worst case regarding peak temperature; mounted on PCB FR4, 80 × 80 × 1.5 mm3, 35 µm Cu, horizontal position, zero airflow. Datasheet 5 Rev. 1.0, 2007-03-20 TLE4309 Table 5 Electrical Characteristics VI = 13.5 V; VPWM ≥ VPWM,H; -25 °C < Tj < 125 °C; all voltages with respect to ground; unless otherwise specified Parameter Symbol Limit Values Unit Test Condition Min. Typ. Max. 171 178 185 mA (VQ-VREF)1) = 6.6 V; RREF = 1.0 Ω 438 456 474 mA (VQ-VREF)1) = 6.6 V; RREF = 0.39 Ω IQmax Vdr – 600 – mA – 0.35 0.7 V RREF = 0 Ω IQ = 300 mA Reference Voltage VREF 172 178 184 mV 0.39 < RREF < 1.0 Ω Tj = 25 °C Reference Voltage VREF IREF 171 178 185 mV 0.39 < RREF < 1.0 Ω -1 0.1 1 µA VREF = 180 mV Current consumption Iq,OFF off mode – 0.1 2 µA PWM/EN = L, Tj < 85 °C Current consumption Iq – 12 22 mA VQ = 6.6 V; RREF = 0.47 Ω 2.6 – – V – VPWM,L IPWM,H – – 0.7 V – – 220 500 µA VPWM = 5.0 V PWM input current low level IPWM,L -1 – 1 µA VPWM = 0.0 V Turn on delay time tPWM,ON 0 tPWM,OFF 0 15 40 µs 70% of IQnom 15 40 µs 30% of IQnom Output Output current Output current limit Dropout voltage IQ Reference Reference Input Current Current Consumption PWM / ENABLE PWM high level valid VPWM,H PWM low level valid PWM input current high level Turn off delay time 1) (VQ - VREF) equals the forward voltage sum of the connected LEDs, see figure 1. Datasheet 6 Rev. 1.0, 2007-03-20 TLE4309 Typical Performance Characteristics Output Current versus Reference Resistor IQ 0.39 0.47 600 mA Reference Voltage versus Junction Temperature A E D03503.V S D VQ = 6.6 V VREF 500 AED03506.VSD 185 mV 180 400 175 300 170 200 165 100 0 0.2 0.5 1.0 160 -40 Ω 2.0 RREF IQ 40 80 °C 160 Tj Output Current versus Supply Voltage PWM/EN Pin Input Current versus Voltage applied AED03504.VSD 600 mA 0 AED03505.VSD 1.0 VQ = 6.6 V RREF = 0.47 Ω I P WM 500 mA 400 0.5 300 200 100 0 0 5 10 15 20 25 30 0 V 40 5 10 15 20 25 30 V 40 VP WM VI Datasheet 0 7 Rev. 1.0, 2007-03-20 TLE4309 Package Outline 10 ±0.2 4.4 9.8 ±0.15 1.27 ±0.1 B 0.1 0.05 2.4 2.7 ±0.3 4.7 ±0.5 8 1) 8.5 9.25 ±0.2 (15) 1±0.3 A 1) 0...0.15 7x0.6 ±0.1 0.5 ±0.1 6x1.27 8˚ max. 0.25 1) M A B 0.1 Typical All metal surfaces tin plated, except area of cut. GPT09114 Figure 3 PG-TO263-7-1 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). find all packages, sorts of packing and others on the Infineon Internet Page “Packages”: http://www.infineon.com/packages. Dimensions in mm SMD = Surface Mounted Device Datasheet 8 Rev. 1.0, 2007-03-20 TLE4309 Application Note: Thermal Considerations 1) By describing an example, this section shows how the power dissipation and the needed thermal resistance can be estimated. For a typical application circuit as shown in Figure 1, the following parameters shall apply: • • • • • • • Number of LEDs in series: 3 LED current desired: IF = 260 mA LED minimum forward voltage: VF,MIN = 3.0 V LED maximum forward voltage: VF,MAX = 3.4 V Supply minimum DC voltage: VI,MIN = 11.0 V Supply maximum DC voltage: VI,MAX = 13.0 V Maximum ambient temperature: Ta,max = 85 °C 1. Selecting the reference resistor: The reference resistor RREF can be selected by using the formular on page 2 or by taking the value from the typical performance graph “Output Current versus Reference Resistor” on Page 7. In order to obtain a LED forward current of IF = 260 mA, the graph shows an reference resistor of RREF = 0.68 Ω. 2. Verifying the minimum supply voltage: In order to be able to drive the LEDs with a constant current, the minimum supply voltage needed is: VI,MIN = VF,MAX,total + Vdr + VREF whereas VF,MAX,total is the maximum forward voltage sum of the LEDs connected in series, Vdr the dropout voltage and VREF the reference voltage. Since the power dissipation is low at a small voltage drop accross the regulator, Vdr = 0.35 V is assumed. The maximum reference voltags is VREF = 185mV. Therefore, a minimum supply voltage of 11 V is sufficient for the example given above. 3. Determining the minimum and maximum LED forward current: The TLE4309 has an accuracy of < 4 %. With a reference resistor of RREF = 0.68 Ω, the output current IQ will be between 251 mA and 272 mA. 1) This 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. Datasheet 9 Rev. 1.0, 2007-03-20 TLE4309 4. Calculating the maximum power dissipation: For calculating the maximum power dissipation, the minimum forward voltage sum of the LEDs connected in series VF,MIN,total (= No. of LEDs * VF,MIN) , the maximum supply voltage VI,MAX , the IC current consumption Iq,MAX , as well as the the maximum output current IQ,MAX needs to be considered. Hence, the maximum power dissipation PD,MAX calculates: PD,MAX = (VI,MAX - VF,MIN,total) * IQ,MAX + VI,MAX * Iq,MAX With assuming a maximum current consumption of 15 mA @ IQ = 260 mA, the maximum power dissipation for the example is 1.28 W. 5. Thermal Resistance needed: The thermal resistance from junction to ambient Rth,j-a calculates: Rth,j-a = (Tj,max - Ta,max) / PD,MAX With allowing a junction temperature of 150 °C, the Rth,j-a needed in our example would be 50 K/W. In case some copper area on the PCB is used as a heat sink, the area needed is approximately 6 cm2 (board in horizontal position, no airflow). If the area is not available, several via holes to the GND-layer or to a heatsink area on the PCB backside help to distribute the heat. For additional information on the thermal resistance see Infineon’ s special subject book “Thermal Resistance - Theory and Practice” including extended package information. Datasheet 10 Rev. 1.0, 2007-03-20 TLE4309 Revision History Version Date Rev. 1.0 2007-03-20 Final Datasheet and initial version of RoHS-compliant derivate of TLE4309G Page 1 and Page 8: RoHS compliance statement and green product feature added Page 1 and Page 8: Package changed to RoHS compliant version Legal Disclaimer updated Datasheet Changes 11 Rev. 1.0, 2007-03-20 Edition 2007-03-20 Published by Infineon Technologies AG 81726 Munich, Germany © 2007 Infineon Technologies AG All Rights Reserved. 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