19-4746; Rev 1; 5/10 TION KIT EVALUA BLE AVAILA High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect The MAX16839 programmable current regulator operates from a 5V to 40V input voltage range and features an open-drain, constant-current sink output capable of sinking up to 100mA. The MAX16839 is well suited for automotive applications and other applications that require a general-purpose linear LED driver. The device directly withstands automotive load dump events of up to 45V. An onboard pass element minimizes external component count while providing Q5% output current accuracy. The MAX16839 includes a dimming input that controls the duty cycle of the output current, allowing a wide LED dimming range. In addition, the dimming input functions as an on/off control of the output current. In multiple LED string applications, the dimming input synchronizes the LED current-sink turn-on, ensuring simultaneous brightness in LED strings. Additional features include thermal and open-LED protection and an open-LED fault-detection output. In multiple LED string applications where all FLTS pins are connected together, an open-LED detection in one LED string turns off all the strings simultaneously. Open-LED protection also features fault memory, to avoid LED flashing during subsequent power-up cycles. The MAX16839 is available in thermally enhanced, 6–pin TDFN-EP and 8-pin SO-EP packages and is specified over the -40NC to +125NC automotive temperature range. Features S 5V to 40V Operating Range S Integrated 2I Open-Drain Pass Transistor S 15mA to 100mA Programmable LED Current S PWM Dimming S Open-LED Fault Detection S Open-LED Fault Event Status Memory S LED Open-Fault Detect Latches Off Multiple LED Strings S Multichip Synchronized LED Current Sink S ±5% LED Current Accuracy S -40NC to +125NC Operating Temperature Range S Thermal Protection S Undervoltage Lockout S 6-Pin TDFN-EP and 8-Pin SO-EP Packages Ordering Information PART TEMP RANGE MAX16839ATT+ -40NC to +125NC 6 TDFN-EP* MAX16839ASA+ -40NC to +125NC 8 SO-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Typical Application Circuit Applications Automotive Exterior: Turn Signal Light, Brake Light, Tail and Marker Lights VBAT VIN = 5V TO 40V Automotive Interior: Cluster and Warning Lights, Dome and Map Lights Truck, Train, Airplane, and Emergency Car LED Lighting General Lighting: Signage, LED Lamps PIN-PACKAGE REVERSE PROTECTION DIODE ILED = 100mA CIN = 0.01FF LEDs IN DIM Pin Configurations appear at end of data sheet. SINK MAX16839 FLTS CFLTS = 0.1FF CS GND RCS = 2I ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX16839 General Description MAX16839 High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect ABSOLUTE MAXIMUM RATINGS (Voltages are specified with respect to GND.) IN, SINK..................................................................-0.3V to +45V FLTS.......................................................................-0.3V to +18V DIM...........................................................................-0.3V to +6V CS..........................................................................-0.3V to +0.5V Continuous Current into SINK and CS..............................120mA Continuous Power Dissipation (TA = +70NC) 6-Pin TDFN (derate 23.8mW/NC above +70NC)......1904.8mW Junction-to-Case Thermal Resistance (BJC) (Note 1)....9NC/W Junction-to-Ambient Thermal Resistance (BJA) (Note 1)... 42NC/W 8-Pin SO (derate 18.9mW/NC above +70NC)...........1509.4mW Junction-to-Case Thermal Resistance (BJC) (Note 1)....5NC/W Junction-to-Ambient Thermal Resistance (BJA) (Note 1).............................................53NC/W Operating Temperature Range......................... -40NC to +125NC Junction Temperature......................................................+150NC Storage Temperature Range............................. -65NC to +150NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to http://www.maxim-ic.com/thermal-tutorial. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 12V, VFLTS = 0V, RCS = 4.07I, VGND = 0V, DIM = unconnected, CIN = 0.1FF (Note 2), TJ = TA = -40NC to +125NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3) PARAMETER SYMBOL Supply Voltage Range VIN Quiescent Current IIN Undervoltage Lockout VUVLO CONDITIONS MIN TYP 5 0.25 VIN rising UVLO Hysteresis MAX UNITS 40 V 0.6 mA 3.6 V 0.3 V CS REGULATOR TA = +25NC CS Voltage Accuracy VCS CS Load Regulation Internal Switch On-Resistance RDS_ON -40NC P TA P +125NC, 0.9V P VSINK P 5.5V (Note 4) 195.5 203 193 210.5 213 mV 20mA P ISINK P 100mA 40 (Note 5) 2 4 I 30% of VIN rising edge to 50% of ISINK, VDIM = 2.1V (Notes 6, 7) 4 9 Fs VDIM rising edge to 50% of ISINK 2.3 5.5 Fs VDIM falling edge to 50% of ISINK 1.3 3.5 Fs FV/mA LED CURRENT TRANSIENT RESPONSE LED Current Turn-On Delay tDIN LED Current Turn-On Delay Relative to DIM tDDIN LED Current Turn-Off Delay Relative to DIM LED Current Rise Time tr 10% of ISINK to 90% of ISINK 2.5 5.5 Fs LED Current Fall Time tf 90% of ISINK to 10% of ISINK 2.5 6 Fs 7.38 7.75 FAULT EVENT STATUS MEMORY FLTS Activation Threshold VINTH VIN rising, VCS = 0V 7 FLTS Activation Hysteresis 20 V mV LED Open Threshold VCSO 25 30 35 mV LED Open Blanking TB 14 25 50 Fs 12 15 18 V Fault Voltage VFLTS VIN = 40V, VCS = 0V, CFLTS = 0.1FF 2 _______________________________________________________________________________________ High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect (VIN = 12V, VFLTS = 0V, RCS = 4.07I, VGND = 0V, DIM = unconnected, CIN = 0.1FF (Note 2), TJ = TA = -40NC to +125NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3) PARAMETER FLTS Charge Current SYMBOL MIN TYP VCS P 25mV 0.65 VFLTS = 0.5V 2.25 VFLTH 0.95 VIH 2.1 ICFLTS FLTS Discharge Current FLTS Threshold To Turn Off LED Current Sink DIM LOGIC Input High Voltage Input Low Voltage CONDITIONS MAX UNITS 2.8 4.8 mA 5 7.25 FA 1.3 1.65 V V VIL DIM Voltage Logic Hysteresis 0.8 V 0.15 VDIM_HYS DIM Pullup Current VDIM = 0V DIM Pulldown Current VDIM = 0.8V, VIN = 2.4V DIM Pulse Width V 10 30 60 FA 0.385 1 1.5 mA 10 kHz 70 DIM Frequency Fs fDIM LEAKAGE CURRENTS SINK Leakage Current VSINK = 40V, VDIM = 0V 1 FA FLTS Leakage Current VFLTS = 8V, VIN = 0V 1 FA THERMAL SHUTDOWN Thermal Shutdown Temperature Thermal Shutdown Hysteresis Temperature rising 160 NC 15 NC A 51I resistor is connected between SINK and a 6.5V supply to reduce power dissipation during the factory test. All devices are 100% production tested at TA = +25NC. Limits over temperature are guaranteed by design. Guaranteed by design and not production tested. Internal switch resistance is measured with ISINK = 0.95 x ISINK0 (ISINK0 is ISINK at VSINK = 0.9V). Supply turn-on delay will be measured by rising supply in 6Fs from GND to 12V, and measurement starts when VIN = 4V (typical UVLO). Note 7: DIM is kept high to avoid delay due to high capacitance from test setup. In applications, a 30FA pullup current charges parasitic capacitance at DIM with negligible delay. Ensure that unnecessary capacitance is not added at DIM during the PCB layout. Note Note Note Note Note 2: 3: 4: 5: 6: _______________________________________________________________________________________ 3 MAX16839 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VIN = 12V, RCS = 4.07I from CS to GND, CFLTS = 0.1FF, CIN = 0.1FF, DIM input unconnected, TA = +25NC, unless otherwise noted. Typical values are at TA = +25NC.) OUTPUT CURRENT vs. TEMPERATURE 16.6 16.5 16.4 16.3 49.7 98.6 49.6 49.5 49.4 49.3 MAX16839 toc01c 49.8 ILOAD = 100mA 98.8 98.4 98.2 98.0 97.8 97.6 16.2 49.2 97.4 16.1 49.1 97.2 16.0 49.0 97.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC) TEMPERATURE (NC) TEMPERATURE (NC) 100 203.0 202.5 202.0 201.5 201.0 2.8 VIN = 12V 2.6 2.4 80 RDS(ON) (I) 203.5 RDS(ON) VS. TEMPERATURE 3.0 MAX16839 toc03 IILED = 100mA OUTPUT CURRENT (mA) 204.0 MAX16839 toc02 VIN = 12V 204.5 120 MAX16839 toc04 OUTPUT CURRENT vs. INPUT VOLTAGE VCS vs. OUTPUT CURRENT 205.0 VCS (mV) OUTPUT CURRENT vs. TEMPERATURE 99.0 OUTPUT CURRENT (mA) 16.7 ILOAD = 50mA 49.9 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 16.8 MAX16839 toc01a ILOAD = 16mA 16.9 50.0 MAX16839 toc01b OUTPUT CURRENT vs. TEMPERATURE 17.0 IILED = 50mA 60 40 2.2 2.0 1.8 1.6 1.4 IILED = 15mA 20 1.2 200.5 1.0 0 200.0 20 30 40 50 60 70 80 90 100 5 10 15 20 25 30 35 VIN (V) QUIESCENT CURRENT vs. TEMPERATURE LED CURRENT RISE TIME 400 VIN = 12V 375 350 -40 -25 -10 5 20 35 50 65 80 95 110 125 40 TEMPERATURE (NC) OUTPUT CURRENT (mA) LED CURRENT FALL TIME MAX16839 toc06 MAX16839 toc05 10 QUIESCENT CURRENT (FA) MAX16839 High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect 325 MAX16839 toc07 VDIM 2V/div VDIM 2V/div 0V 0V 300 275 LED CURRENT 250 50mA/div 225 0 LED CURRENT 50mA/div 0 200 -40 -25 -10 5 20 35 50 65 80 95 110 125 2Fs/div 2Fs/div TEMPERATURE (NC) 4 _______________________________________________________________________________________ High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect FLTS DISCHARGE LEAKAGE CURRENT vs. TEMPERATURE MAX16839 toc09 VIN IS TURNED OFF VDIM 2V/div 50 VIN 5V/div 0V 0V ILED 50mA/div VFLTS 5V/div 0 0V 1s/div 20Fs/div 40 LEAKAGE CURRENT (nA) MAX16839 toc08 MAX16839 toc10 LED CURRENT RISE/FALL TIMES VIN = 0V VFLTS = 8V 30 20 10 0 -10 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC) FAULT ACTIVATION THRESHOLD vs. TEMPERATURE MAX16839 toc11 FAULT ACTIVATION THRESHOLD (V) ILED RESPONSE TO SUPPLY CHOPPING MAX16839 toc12 7.40 7.39 7.38 VIN 5V/div 7.37 7.36 7.35 7.34 ILED 20mA/div 7.33 7.32 0 7.31 7.30 -40 -25 -10 5 20 35 50 65 80 95 110 125 4ms/div TEMPERATURE (NC) LED RISE TIME DELAY (SUPPLY CHOPPING) FAULT ACTIVATION THRESHOLD AND OPEN-LED BLANKING MAX16839 toc13 MAX16839 toc14 VIN 2V/div VIN 5V/div 0V ILED 20mA/div VFLTS 2V/div 0 1Fs/div 0V 20Fs/div _______________________________________________________________________________________ 5 MAX16839 Typical Operating Characteristics (continued) (VIN = 12V, RCS = 4.07I from CS to GND, CFLTS = 0.1FF, CIN = 0.1FF, DIM input unconnected, TA = +25NC, unless otherwise noted. Typical values are at TA = +25NC.) MAX16839 High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect Typical Operating Characteristics (continued) (VIN = 12V, RCS = 4.07I from CS to GND, CFLTS = 0.1FF, CIN = 0.1FF, DIM input unconnected, TA = +25NC, unless otherwise noted. Typical values are at TA = +25NC.) FAULT INTEGRATION ON OPEN LED (100Hz, 75% DUTY CYCLE AT DIM) FAULT INTEGRATION ON OPEN LED (100Hz, 50% DUTY CYCLE AT DIM) FAULT INTEGRATION ON OPEN LED WITH SUPPLY CHOPPING MAX16839 toc15b MAX16839 toc15a MAX16839 toc16 100Hz AT DIM VFLT 5V/div VDIM 2V/div VFLT VCS 200mV/div 5V/div VDIM VIN 5V/div 2V/div VFLTS 5V/div 500mA/div ILED 500mA/div ILED 100µs/div 4ms/div 200Fs/div Pin Description PIN NAME FUNCTION TDFN SO 1 1 IN 2 2 DIM Dimming Input. Drive DIM high or leave unconnected to turn on the LED current-sink driver. Drive DIM low to turn off the LED current-sink driver. In multiple LED-string applications, connect all DIM inputs together to synchronize the LED current-sink turn-on. 3 3 FLTS LED Fault Memory. Connect a 0.1FF to 10FF capacitor from FLTS to ground. In multiple LEDstring applications, connect all FLTS pins together to have all strings latch off if one of them opens (see Figure 2). Connect FLTS to ground to disable fault protection. 4 6 GND Ground 5 7 CS 6 8 SINK LED Driver Current-Sink Output — 4, 5 N.C. No Connection. Not internally connected. — — EP Positive Input Supply. Bypass with a 10nF (typ) capacitor to GND. Current-Sense Input. Connect a current-sense resistor between CS and GND to program the output current level. Exposed Pad. Connect EP to a large-area contiguous copper ground plane for effective power dissipation. Do not use as the only IC ground connection. EP must be connected to GND. 6 _______________________________________________________________________________________ High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect The MAX16839 programmable current regulator operates from a 5V to 40V input voltage range and features an open-drain, constant current-sink output capable of sinking up to 100mA. The MAX16839 directly withstands automotive load-dump events of up to 45V. A single resistor-programmable output current and onboard pass element minimize the number of external components while providing Q5% output current accuracy. The MAX16839 includes a dimming input that controls the duty cycle of the output current, allowing a wide LED dimming range to be implemented. In addition, the dimming input functions as an on/off control of the output current. In multiple LED-string applications, the dimming input synchronizes the LED current-sink turn-on, ensuring simultaneous brightness in LED strings. IN Additional features include thermal protection and an open-LED detection output that can turn off multiple LED strings simultaneously. See Figure 1. Open-LED Detection and Fault Event Status Memory The MAX16839 has an integrated open-LED detection that reduces external components required to implement this function. The following conditions enable the open-LED detection feature: U FLTS not connected to ground U VIN > VINTH (7.38V) (typ) U Thermal Shutdown Inactive U VDIM = High 5V REG SINK 5V IREG REFERENCE GENERATOR 30µA CS DIM IN 1mA ENABLE 15V CLAMP MAX16839 2.8mA FAULT THERMAL SHDN OPEN-LED DETECT FLTS GND Figure 1. Internal Block Diagram _______________________________________________________________________________________ 7 MAX16839 Detailed Description MAX16839 High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect The MAX16839 detects an open-LED event when VCS drops below 30mV for 25µs. When the fault condition is detected, the LED driver is turned off, and a 2.8mA current source charges the capacitor between FLTS and ground, up to 15V or to VIN if VIN is less than 15V. During subsequent power cycles, if the voltage on FLTS is greater than 1.65V due to the charge retained in the FLTS capacitor, the LED driver is turned off. This provides an open-LED fault-protection feature that can be disabled by connecting FLTS to ground. In a multistring application (Figure 2), where all FLTS pins are connected together, a fault detected on one channel causes other channels to turn off as well. The retention capability on 12V the FLTS is dependent on the leakage current and the value of the capacitor used. If the retention capability is high, the fault condition could be retained or memorized for a long period after the supply is turned off. Thermal Protection The MAX16839 enters thermal-shutdown mode in the event of overheating. When the junction temperature exceeds TJ = +160NC, the internal thermal-protection circuit turns off the series pass element. The MAX16839 recovers from thermal-shutdown mode when the junction temperature drops to TJ = +145NC. FLTS does not assert during an overheating event. t 50mA VIN 12V VIN UVLO ILED t t LEDGOOD (INTERNAL) ILED 50mA t 12V FLTS t t 2.5Fs 4Fs VIN = 5V TO 40V CIN = 0.01FF LEDS ILED IN FLTS CS GND CIN = 0.01FF LEDS IN DIM SIGNAL DIM SINK MAX16839 RCS CONNECT TO 5V SUPPLY OR LEAVE UNCONNECTED DIM FLTS SIGNAL CFLTS = 0.1FF SINK ILED MAX16839 FLTS CS GND RCS Figure 2. Multistring Application 8 _______________________________________________________________________________________ High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect FLTS Capacitor If a fault condition is detected, a 2.8mA current source charges CFLTS to memorize the fault condition and avoid flashing during the subsequent power-up cycles. The choice of the CFLTS is based on the following conditions: U Fault hold time dropout voltage of the regulator. If the device is operated below VIN(MIN), the output current may not meet the full regulation specification (see the Typical Operating Characteristics). For applications that require more than 3 LEDs per string and have slow supply rise time (> 14Fs), FLTS should, in general, be connected to ground to avoid false triggering of the open-LED protection. U Board leakage and FLTS leakage U Input supply voltage as this affects the maximum FLTS voltage U The number of ICs connected together in case of a multistring application Use the following equation to calculate the FLTS capacitor (CFLTS): I ×t ×N C FLTS = FLTS FLTS (VFLTS − VFLTH ) where IFLTS is the maximum leakage current through FLTS, tFLTS is the desired fault retention period, VFLTS is the typical voltage (minimum of 15V or the supply voltage) to which CFLTS is charged during a fault event, VFLTH is the minimum threshold to detect the fault memory as logic-high, and N is the number of devices in a multistring application. Programming the LED Current The MAX16839 uses a sense resistor to program the output current sink. To program the LED current, connect a sense resistor from the current-sense input (CS) to GND with short traces. The value of the sense resistor for a given desired current is calculated with the following equation: PWM Dimming The MAX16839 includes a PWM dimming input (DIM) to control the LED brightness. An application of up to a 10kHz signal is recommended at DIM for proper operation. DIM also functions as an active-high enable input. Driving DIM low turns off the output. Driving DIM high or leaving DIM unconnected turns on the output. For VIN > undervoltage-lockout threshold, the MAX16839 activates a 30FA (typ) pullup current at DIM. When VIN < undervoltage-lockout threshold, the MAX16839 activates a 1mA pulldown current. Supply Chopped Dimming The MAX16839 can do efficient supply chopped dimming, as it is specially designed for very low startup delay. The LED current is turned on in 4Fs (typ) after the supply comes up. The LED current pulse-width modulates in phase with the supply voltage. Minimize the input filter capacitor after the chopper circuit for fast rise and fall times of the input supply. Power Dissipation The power dissipation (PD) of the MAX16839 is determined from the following equation: PD = (VIN × IIN ) + (VIN − ∑VLED − VCS ) × (ILED × DUTY) where: V (V) R CS (Ω) = CS ILED (A) VIN = supply voltage IIN = supply current where VCS is 203mV (typ) (see the Electrical Characteristics table). Input Voltage For proper operation, the minimum input voltage must always be: VIN(MIN) = VCS(MAX) + VFT(MAX) + ∆VDO where VCS(MAX) is the maximum voltage drop across the sense resistor RCS, VFT(MAX) is the total forward voltage of all series connected LEDs, and DVDO is the maximum CVLED = total forward voltage for the LED string ILED = LED current VCS = 203mV drop across RCS DUTY = PWM duty cycle The MAX16839 thermal specifications are given according to the JEDEC-51 guidelines. Good mechanical/thermal design practices must be applied to help maintain the device junction temperature below the absolute maximum ratings at all times. _______________________________________________________________________________________ 9 MAX16839 Applications Information MAX16839 High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect Pin Configurations TOP VIEW + IN 1 DIM 2 FLTS 3 MAX16839 EP 6 SINK 5 CS 4 GND IN 1 DIM 2 FLTS 3 N.C. 4 TDFN MAX16839 EP 8 SINK 7 CS 6 GND 5 N.C. SO Chip Information PROCESS: BiCMOS DMOS + Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE Document No. 6 TDFN-EP T633+2 21-0137 8 SO-EP S8E+12 21-0111 10 ������������������������������������������������������������������������������������� High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect REVISION NUMBER REVISION DATE 0 7/9 Initial release 1 5/10 Changed one feature of IC; replaced TOC 15 with two TOCs DESCRIPTION PAGES CHANGED — 1,2, 3, 5–11 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2010 Maxim Integrated Products 11 Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX16839 Revision History