LED Driver with Adjustable Current TLE 4241 GM

1 TypeOrdering CodePackageTLE 4241 GMQ67006-A9644P-DSO-8-9 LED Driver with Adjustable Current TLE 4241 GM P-DSO-8-3, -6, -7, -8, -9 Data Sheet1 Rev. , 2004-04-13 Features Adjustable constant output Current Wide input voltage range Low drop voltage Open load detection Overtemperature protection Short circuit proof Reverse polarity proof Wide temperature range: -40 C < Tj < 150 C Very small SMD-PackageFunctional DescriptionThe TLE 4241 GM is an integrated Adjustable constant Current source. It provides anoutput Current Adjustable via different means (SET, PWM, reference resistor) which iskept nearly independent from load and supply voltage changes.

2 The IC is designed tosupply LEDs under the severe conditions of automotive applications resulting in constantbrightness and extended LED lifetime. It is provided in the very small P-DSO-8-9(Micro 8) package. Protection circuits prevent damage to the device in case of overload,short circuit, reverse polarity and overtemperature. The connected LEDs are protectedagainst reverse polarity as well as excess voltages up to 45 V. A status output allowshandling of open load and short circuit at the main PWM input offers the possibility to adjust the LED brightness by pulse an implemented high/low Current switch the output Current level can be reduced brake/tail light implemented features such as Adjustable output Current , the high/low Current switchand the provided PWM input make the device well suited for a broad range of LED andother applications.

3 Data Sheet2 Rev. , 2004-04-13 TLE 4241 GMCircuit DescriptionFigure 1 Block DiagramAn internal reference voltage of typ. supplies the REF pin which is connected toGND via an external resistor. In the SET = H mode the reference Current flowing on theREF pin is mirrored with an amplification to form the desired output Current . The Current in the SET = H mode calculates:(1)The output Current is shown as a function of the reference resistance on Page 10 for thehigh as well as for the low Current the PWM input the LED brightness can be regulated via duty cycle.

4 Also PWM = Lsets the TLE 4241 in sleep mode resulting in a very low Current consumption of << 1 Atyp. Due to the high impedance of the PWM input (see timing diagram IPWM versus VPWMon Page 12) the PWM pin can thus also be used as an Enable ConverterQREFSETPWMSTIGNDIQtyp, ----------------------487 + =TLE 4241 GM Data Sheet3 Rev. , 2004-04-13 Figure 2 Pin Configuration (top view)Table 1 Pin Definitions and FunctionsPin ; internally connected to pin 52 STStatus Output; open collector output, connect to external pull-up resistor (10 k or higher)3 PWMP ulse Width Modulation Input; if not needed connect to VI4 SETHigh/Low Current Input; choice of Current level5 GNDG round; internally connected to pin 16 REFR eference Input; connect to GND via an external resistor to adjust the output current7 QOutput8 IInput.

5 Block to GND directly at the IC with a 100 nF ceramic capacitorAEP0300281 GNDIST27 PWM36 SET45 QREFGND Data Sheet4 Rev. , 2004-04-13 TLE 4241 GMApplication InformationFigure 3 Application CircuitFigure 3 shows a typical application with the TLE 4241 GM LED Driver . The 3 LEDs aredriven with an adequate supply Current adjusted by the resistor RREF. Thus brightnessvariations due to forward voltage spread of the LEDs are prevented. The luminosityspread arising from the LED production process can be compensated via software by anappropriate duty cycle applied to the PWM pin.

6 Hence selection of the LEDs to forwardvoltage as well as to luminosity classes can be spared. The slightly negative temperaturecoefficient of the TLE 4241 GM output Current protects the LEDs against over-temperature stress if the IC is placed nearby the LEDs. The voltage drop (VI - VQ) across the TLE 4241 GM is monitored in order to detect anopen load condition indicated at the status output pin ST. In case of open load, thevoltage drop will decrease below the lower status switching threshold Vdr,L. Hence, thestatus output ST will be driven low.

7 In normal operation, the voltage drop is above theupper status threshold Vdr,H, thus the open collector output ST is in high-ohmic state (seealso section Status Output at the Electrical Characteristics).The function of ST, SET and PWM as well as their timings are shown in Figure 4241 GREFR CSETPWMSTTLE 4271 WDRQVIQBattVLA E67 BOSRAMWRO22 F100 nF10 k TLE 4241 GM Data Sheet5 Rev. , 2004-04-13 Figure 4 Function and Timing DiagramOpen , HtVPWM, LVSETVSET, HtVSET, L4710mAIQtVSTtVSTLtSET, HtSET, LtPWM, ONtPWM, OFF Data Sheet6 Rev.

8 , 2004-04-13 TLE 4241 GMNote: Maximum ratings are absolute ratings; exceeding any one of these values maycause irreversible damage to the integrated 2 Absolute Maximum Ratings-40 C < Tj < 150 CParameterSymbolLimit Values CurrentII mAinternally limitedOutputVoltageVQ-140V CurrentIQ mAinternally limitedStatus CurrentIST 55mAinternally limitedReference CurrentIREF-22mA Pulse Width Modulation InputVoltageVPWM-4040V Current -11mA High/Low Current InputVoltageVSET-4040V CurrentISET-11mA TemperaturesJunction temperatureTj-40150 C Storage temperatureTstg-50150 C Thermal

9 ResistancesJunction ambientRthja 105K/W1)1) Worst case regarding peak temperature; mounted on PCB 80 80 mm3, 35 m Cu, 300 mm2 heat 4241 GM Data Sheet7 Rev. , 2004-04-13 Table 3 Operating RangeParameterSymbolLimit voltageVI445V Status output voltageVST 16V SET voltageVSET040V PWM voltageVPWM040V Junction temperatureTj-40150 C Reference ResistorRREF7100k SET = SET = L Data Sheet8 Rev. , 2004-04-13 TLE 4241 GMTable 4 Electrical Characteristics9V VI 16 V; RREF = 10 k ; VPWM VPWM,H; -40 C < Tj < 150 C; all voltages withrespect to ground; positive Current defined flowing into pin; unless otherwise specifiedParameterSymbolLimit ValuesUnit Test consumption off modeIqOFF APWM = L, TJ < 85 C;VI VCurrent consumptionIqL 510mASET = L; VQ = 6 VCurrent consumptionIqH 610mASET = H; VQ = 6 VCurrent consumption open loadIqL,O 10mASET = L; VQ openCurrent consumption open loadIqH,O 10mASET = H.

10 VQ openOutputOutput = L, VQ = 6 V mASET = L, VQ = 4 VOutput = H, VQ = 6 V mASET = H, VQ = 4 VCurrent RatioIQH/IQL678 Output Current limitIQmax 83 mASET = L; RREF = 0 Output Current limitIQmax 83 mASET = H; RREF = 0 Drop voltageVdr = L;IQ = 80% of IQ,nom,LDrop voltageVdr = H;IQ = 80% of IQ,nom,HPWM InputPWM high levelVPWM, V PWM low levelVPWM,L PWM input currenthigh levelIPWM,H 220500 AVPWM = VPWM input currentlow levelIPWM,L-10 10 AVPWM = VTurn on delay timetPWM,ON0530 s20%/80% IQ, see Figure 4 TLE 4241 GM Data Sheet9 Rev.