19-0733; Rev 1; 3/07 KIT ATION EVALU E L B A AVAIL High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection The MAX16823 three-channel LED driver operates from a 5.5V to 40V input voltage range and delivers up to 70mA per channel to one or more strings of high-brightness LEDs (HBLEDs). Each channel’s current is programmable using an external current-sense resistor in series with the LEDs. Three DIM inputs allow a wide range of independent pulsed dimming in addition to providing the on and off control of the outputs. Wave-shaping circuitry reduces EMI while providing fast turn-on and turn-off times. The MAX16823 is well suited for automotive applications requiring a high-voltage input and is able to withstand load-dump events up to 45V. On-board pass elements minimize external components while providing ±5% LED current accuracy. Additional features include an activehigh, open-drain LEDGOOD output for open LED detection, a +3.4V (±5%) regulated output with 4mA output current capability, short-circuit and thermal protections. The MAX16823 is available in thermally enhanced 5mm x 5mm, 16-pin TQFN-EP and 16–pin TSSOP-EP packages and is specified over the -40°C to +125°C automotive temperature range. Features o 5.5V to 40V Operating Range o Adjustable Constant Output Current (5mA to 70mA and Up to 2A with External BJT) o ±5% Output Current Accuracy o Open LED Detection o Three Independent High-Voltage DIM Inputs o Three Integrated Pass Elements with Low Dropout Voltage (0.7V max) o Undervoltage Lockout o Output Short-Circuit Protection o 3.4V Voltage Regulator with 4mA Capability o Accurate, Low 203mV Current Sense o Overtemperature Shutdown o -40°C to +125°C Operating Temperature Range Ordering Information Applications Automotive Exterior: Rear Combination Lights (RCLs), CHMSL Automotive Interior: RGB Ambient Lighting, Cluster Lighting, and LCD Backlighting Emergency Vehicle Warning Lights Navigation and Marine Indicators Architectural and Industrial Lighting PART TEMP RANGE MAX16823ATE+ -40°C to +125°C MAX16823AUE+ -40°C to +125°C PINPACKAGE 16 TQFN-EP* PKG CODE T1655-3 16 TSSOP-EP* U16E-3 +Denotes a lead-free package. *EP = Exposed pad. Pin Configurations appear at end of data sheet. Typical Operating Circuit VIN IN CIN IN OUT1 MAX16823 IN OUT2 OUT3 DIM1 DIM2 DIM3 REG RLEDGOOD CS1 LEDGOOD CLGC CREG LGC CS2 REG CS3 GND CS1 CS2 CS3 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX16823 General Description MAX16823 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +45V OUT1, OUT2, OUT3, DIM1, DIM2, DIM3 to GND ...........................................-0.3V to (VIN + 0.3V) REG, LGC, LEDGOOD to GND ................................-0.3V to +6V CS1, CS2, CS3 to GND .........................................-0.3V to +0.5V OUT1, OUT2, OUT3 Short Circuited to GND Duration (VIN + 16V) ..........................................60min Maximum Current into Any Pin (except IN, OUT1, OUT2, OUT3)..................................±20mA Continuous Power Dissipation (TA = +70°C) 16-Pin TQFN 5mm x 5mm (derate 33.3mW/°C above +70°C) .........................2666mW 16-Pin TSSOP (derate 26.1mW/°C above +70°C) ....2088.8mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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, CREG = 0.1µF, IREG = 0, CLGC = 15nF, VDIM1 = VDIM2 = VDIM3 = 3.4V, RCS_ = 2.85Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Supply Voltage Range Undervoltage Lockout Ground Current Guaranteed Output Current UVLO IG MIN TYP 5.5 V 4.9 5.4 VIN falling 4.0 4.6 5.2 1.5 3 IOUT1 = IOUT2 = IOUT3 = 70mA 70 V mA mA 5 % IOUT_ = 70mA, 6.5V ≤ VIN ≤ 40V 0.3 0.7 IOUT_ = 70mA, 5.5V ≤ VIN ≤ 6.5V 0.3 0.8 8 mA/µs VOUT_ = 0V 180 mA Output Current Slew Rate Short-Circuit Current UNITS 40 4.4 5mA ≤ IOUT_ ≤ 70mA ΔVDO MAX VIN rising IOUT LED Current-Sense Accuracy Dropout Voltage (Note 2) CONDITIONS VIN V LEDGOOD LEDGOOD Output Logic Low VOL ISINK = 2mA LGC Pullup Resistor 65 100 0.4 V 135 kΩ LGC Input Upper Threshold VUTH 2.53 LGC Input Lower Threshold VLTH 0.8 V 20 mA LGC Pulldown Current VLGC > VUTH LGC Clock Period CLGC = 15nF 0.77 1.5 V 2.3 ms -0.1 +0.1 µA 2.4 VIN V DIMMING INPUT (DIM1, DIM2, DIM3) DIM_ Logic-Input Bias Current IDIM_ DIM_ Input-Voltage High DIM_ Input-Voltage Low DIM_ Frequency 0 0.6 V 3 kHz OUTPUTS (OUT1, OUT2, AND OUT3) (Note 3) Turn-On Time DIM_ rising edge to 90% of OUT_ current 12 28 µs Turn-Off Time DIM_ falling edge to 10% of OUT_ current 8 18 µs Output Current Rise Time 10% to 90% 7 18 µs Output Current Fall Time 90% to 10% 6 15 µs 2 _______________________________________________________________________________________ High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection (VIN = 12V, CREG = 0.1µF, IREG = 0, CLGC = 15nF, VDIM1 = VDIM2 = VDIM3 = 3.4V, RCS_ = 2.85Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 193 203 213 mV +1.2 µA CURRENT SENSE Regulated CS_ Voltage VCS_ 5mA ≤ IOUT_ ≤ 70mA Input Current (CS1, CS2, CS3) Current out of CS_ OVERTEMPERATURE PROTECTION (Note 4) Thermal Shutdown Temperature 155 °C Thermal Shutdown Hysteresis 23 °C 3.4V REGULATOR (REG) Output Voltage VREG REG Short-Circuit Current 0 ≤ IREG ≤ 4mA 3.275 3.41 3.547 3.221 3.38 3.547 VREG = 0V 13 V mA Note 1: All devices 100% production tested at TJ = +25°C. Limits over the operating temperature range are guaranteed by design. Note 2: Dropout is measured as follows: Connect a resistor from OUT_ to CS_. Connect RCS_ = 2.85Ω from CS_ to GND. Set VIN = VOUT + 3V (record VOUT as VOUTA). Reduce VIN until VOUT = 0.97 x VOUTA (record as VINB and VOUTB). VDO = VINB - VOUTB. Note 3: Output current rise and fall times are measured with a 62Ω series resistor from OUT_ to CS_. Note 4: Overtemperature protection does not function if the output of the 3.4V reference (REG) is shorted to ground. Typical Operating Characteristics (VIN = 12V, CREG = 0.1µF, IREG = 0, VLGC = unconnected, connect RCS_ = 2.85Ω from CS_ to GND. Connect OUT_ to CS_ through a resistor, TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) VCS_ vs. OUTPUT CURRENT 50 ILOAD = 35mA 90 80 OUTPUT CURRENT (mA) 0.208 ILOAD = 70mA 60 40 0.209 0.207 VCS_ (V) OUTPUT CURRENT (mA) 80 OUTPUT CURRENT vs. INPUT VOLTAGE 100 MAX16823 toc02 MAX16823 toc01 90 70 0.210 0.206 0.205 0.204 60 50 40 0.203 20 0.202 20 0.201 10 0.200 0 ILOAD = 5mA 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C ) 0 10 20 30 40 50 OUTPUT CURRENT (mA) 60 70 IOUT = 70mA 70 30 10 MAX16823 toc03 OUTPUT CURRENT vs. TEMPERATURE 100 30 IOUT = 5mA 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 _______________________________________________________________________________________ 40 3 MAX16823 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = 12V, CREG = 0.1µF, IREG = 0, VLGC = unconnected, connect RCS_ = 2.85Ω from CS_ to GND. Connect OUT_ to CS_ through a resistor, TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) 0.7 0.6 0.5 0.4 ILOAD = 70mA 0.3 0.2 VIN = 40V VIN = 20V 1.1 1.0 0.9 0.8 VIN = 12V 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) VREG vs. VIN 330Hz DIMMED OPERATION MAX16823 toc09 MAX16823 toc08 3.44 3.43 ILOAD = 70mA VIN = 12V, DIM PULSED AT 33Hz (1% DUTY CYCLE) VREG (V) 3.42 ILOAD = 70mA ILOAD = 1mA 3.0 3.45 MAX16823 toc07 ILOAD = 4mA 3.2 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) VCS_ vs. IREG 0.210 0.209 0.208 0.207 0.206 0.205 0.204 0.203 0.202 0.201 0.200 0.199 0.198 0.197 0.196 0.195 3.3 3.1 VIN = 5.5V 0.6 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) VDIM 2V/div IREG = 0 3.41 0V ILED 50mA/div 3.40 3.39 IREG = 1mA 3.38 0A IREG = 4mA 3.37 3.36 3.35 0 1 2 3 4 5 6 IREG (mA) 7 8 9 10 0 5 10 15 20 25 VIN (V) 35 20μs/div 40 LEDGOOD RESPONSE TIMES MAX16823 toc11 MAX16823 toc10 VDIM 2V/div MAX16823 toc12 VIN = 12V CLGC = 15nF ILOAD = 70mA VIN = 12V, DIM PULSED AT 200Hz (50% DUTY CYCLE) VDIM 2V/div ILOAD = 70mA 0A VIN = 12V, DIM PULSED AT 200Hz (50% DUTY CYCLE) VLGC 5V/div 0V 0A 10μs/div VDIM 5V/div 0V VLEDGOOD 5V/div 0V 0V ILOAD 50mA/div 0V ILOAD 50mA/div 10μs/div 30 200Hz DIMMED OPERATION (EXPANDED) 200Hz DIMMED OPERATION (EXPANDED) 4 3.4 1.2 0.7 0.1 ILOAD = 0 VREG (V) SUPPLY CURRENT (mA) DROPOUT VOLTAGE (mV) 0.8 VDIM1 = VDIM2 = VDIM3 = 0V 1.3 3.5 MAX16823 toc05 MAX16823 toc04 0.9 VREG vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE 1.4 MAX16823 toc06 DROPOUT VOLTAGE vs. TEMPERATURE 1.0 VCS_ (V) MAX16823 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection 2ms/div _______________________________________________________________________________________ High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection PIN NAME FUNCTION TQFN TSSOP 1 3 DIM1 Dimming Input 1. DIM1 is a low-frequency dimming input for channel 1. A logic-low turns off OUT1 and a logic-high turns on OUT1. 2 4 DIM2 Dimming Input 2. DIM2 is a low-frequency dimming input for channel 2. A logic-low turns off OUT2 and a logic-high turns on OUT2. 3 5 DIM3 Dimming Input 3. DIM3 is a low-frequency dimming input for channel 3. A logic-low turns off OUT3 and a logic-high turns on OUT3. 4 6 LEDGOOD 5, 6, 7 7, 8, 9 IN 8 10 LGC LED Detection-Timing Setting. Connect a capacitor from LGC to ground to set the delay time for LEDGOOD. 9 11 REG 3.4V Voltage Regulator. Connect a 0.1µF capacitor from REG to GND. 10 12 GND Ground Open LED Output. LEDGOOD is an open-drain output. A logic-high indicates the LED connection is good in all three channels. A logic-low indicates an open LED connection. See the LEDGOOD section. Positive Input Supply. Bypass with a 0.1µF (min) capacitor to GND. Connect all IN pins together. 11 13 CS3 Channel 3 Sense Amplifier Positive Input. Connect the current-sense resistor between CS3 and GND to program the output current level for channel 3. 12 14 CS2 Channel 2 Sense Amplifier Positive Input. Connect the current-sense resistor between CS2 and GND to program the output current level for channel 2. 13 15 CS1 Channel 1 Sense Amplifier Positive Input. Connect the current-sense resistor between CS1 and GND to program the output current level for channel 1. 14 16 OUT3 Current Regulator Output 3 15 1 OUT2 Current Regulator Output 2 16 2 OUT1 EP EP EP Current Regulator Output 1 Exposed Pad. Connect EP to a large-area ground plane for effective power dissipation. Do not use as the IC ground connection. _______________________________________________________________________________________ 5 MAX16823 Pin Description MAX16823 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection Detailed Description The MAX16823 three-channel current regulator operates from a 5.5V to 40V input voltage range and delivers up to 70mA per channel to one or more strings of HBLEDs. The output currents are programmable using external current-sense resistors in series with the LEDs. Three DIM inputs allow a wide range of independent pulsed dimming in addition to providing the on and off control of the outputs. The MAX16823 offers an LEDGOOD output that indicates an open-circuit condition when one or more LED channels are open. Integrated pass elements minimize external components while providing ±5% output current accuracy. Additional features include a 3.4V (±5%) voltage regulator with 4mA output current capability, short-circuit and thermal protection. The MAX16823 uses a feedback loop to linearly control the current from each output. The voltage across each sense resistor is compared to a fixed reference voltage and the error is amplified to drive the internal power pass device for a particular channel. See the Block Diagram. The regulation point is factory-set at 203mV. The regulated current is adjusted by the value of RCS__. The MAX16823 is a constant-current LED driver internally optimized for driving the impedance range expected from one or more HBLEDs. 3.4V Regulator (REG) The MAX16823 includes a fixed 3.4V voltage regulator that delivers up to 4mA of load current for auxiliary applications throughout the 5.5V to 40V input voltage range. Connect a 0.1µF compensation capacitor from REG to ground. Shorting REG to ground disables the thermal shutdown. Thermal Protection The MAX16823 enters a thermal-shutdown mode in the event of overheating. This typically occurs in overload or output short-circuit conditions. When the junction temperature exceeds TJ = +155°C, the internal thermal protection circuitry turns off the series pass elements. The MAX16823 recovers from thermal-shutdown mode once the junction temperature drops by 23°C. The part will therefore protect itself by low-frequency thermal cycling in the event of a short-circuit or overload condition. 6 Applications Information Programming the LED Current The MAX16823 uses sense resistors to set the output current for each channel. To set the LED current for a particular channel, connect a sense resistor across the corresponding current-sense input (CS_) and GND. For optimal accuracy, connect the low-side of the currentsense resistors to the IC’s ground pin with short traces. The value needed for the sense resistor for a given current can be calculated with the equation below: RCS _ (Ω) = VCS _ (V) IOUT _ (A) where VCS_ is 203mV and IOUT_ is the desired LED current (ILED). Input-Voltage Considerations For proper operation, the minimum input voltage must always be: VIN(MIN) ≥ VCS _(MAX) + VFT(MAX) + VDO(MAX) where VFT(MAX) is the total forward voltage of all seriesconnected LEDs. The minimum operating voltage of the device is 5.5V. LEDGOOD The MAX16823 features an active-low, open-drain LEDGOOD output that goes low either when one or more LED channels are open or when a signal at any of the dimming inputs remains low for a period greater than the programmed LEDGOOD delay time tDELAY. Program tDELAY with a capacitor connected between LGC and ground. The LEDGOOD output goes low after the programmed delay period tDELAY has elapsed. Use the following formula to set the delay period: tDELAY = 257,900(Ω) × CLGC (F) where CLGC is the capacitor connected between LGC and ground. The LEDGOOD output goes low during the thermal shutdown. _______________________________________________________________________________________ High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection REG UVLO IN IN I_REG IN IN OUT1 BANDGAP CS1 GND DIM1 IN MAX16823 THERMAL SHUTDOWN I_REG OUT2 DIM2 CS2 IN I_REG OUT3 DIM3 CS3 LEDGGOOD LGC LEDGOOD DETECTOR Pulse-Dimming Inputs (DIM_) The MAX16823 features pulsed or chopped-current dimming inputs (DIM_) to chop the LED current and to adjust the brightness. DIM_ also serves as an activehigh enable input. A logic-low at DIM_ turns off OUT_ and a logic-high turns on OUT_. If the signal at DIM stays low more than the programmed LEDGOOD delay time, LEDGOOD goes low (Figure 1). Two Brightness Levels for TAIL/STOP Lights Figure 2 shows the PWM dimming operation for the MAX16823 with an ICM7555 timer. The ICM7555 provides an adjustable duty cycle using two external resistors and a capacitor. In TAIL operation, the output of the ICM7555 feeds into DIM and lights up the LEDs. The LED’s brightness depends on the duty cycle of the _______________________________________________________________________________________ 7 MAX16823 Block Diagram MAX16823 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection ICM7555. When VSTOP is present, DIM is pulled up to VSTOP. The PWM dimming operation is disabled and the LEDs light up to full brightness. See the ICM7555 data sheet for formulas to calculate the dimming frequency and the duty cycle. Outputs Latch-Off Figure 3 shows a circuit with DIM1, DIM2, DIM3, and LEDGOOD connected through a resistor to VREG. This circuit is useful for applications that require all outputs to latch off when one of the LEDs opens. The MAX16823 resumes current regulation again through power cycling, once the fault condition is removed. Other Applications The application circuit in Figure 4 implements a twolevel brightness current for TAIL/STOP lights. In TAIL operation, Q1 is off and RCS1 sets the output current. In STOP operation, Q1 turns on and the output current is set by a parallel combination of RCS1 and R2. Figure 5 shows an application circuit with the MAX16823 using a single BJT to provide high output current. For proper operation: VIN(MIN) > VBE(MAX) + VFT(MAX) + VCS _ + VDO(MAX) For minimized dropout, the LEDs can be placed in the collector. tON DIM tOFF LEDGOOD GOES LOW WHEN tOFF > tDELAY LEDGOOD Figure 1. LEDGOOD Timing Delay STOP D1 TAIL OUT3 OUT2 IN D4 OUT1 C1 R1 REG 0.1μF R2 D2 DIM1 CS1 IN DIS RCS1 DIM2 OUT R3 D3 TH TRG GND LEDs MAX16823 CS2 100kΩ DIM3 RCS2 C2 ICM7555 CS3 GND Figure 2. PWM Dimming Operation with ICM7555 8 _______________________________________________________________________________________ RCS3 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823 VIN OUT3 OUT2 IN CIN VREG OUT1 R1 LEDs MAX16823 DIM1 LEDs CS1 DIM2 LEDs RCS1 DIM3 CS2 LEDGOOD RCS2 REG CS3 GND CREG RCS3 Figure 3. Output_ Latch-Off STOP D1 OUT3 OUT2 D2 IN TAIL TAIL STOP/TAIL OUT1 TAIL LEDs MAX16823 DIM1 CS1 LEDs DIM2 R2 DIM3 CIN LEDs R3 RCS1 Q1 R1* CS2 REG CREG RCS2 GND CS3 RCS3 *R1 = 100kΩ Figure 4. Two-Brightness Level with Current Level Switch for TAIL/STOP Lights _______________________________________________________________________________________ 9 MAX16823 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection Preload Current Figure 6 shows the MAX16823 with a preload circuit. In the circuit, the BJT, RPRELOAD, and REG generate a preset load current. The preset load current IPRESET is determined with the following formula: VIN Q1 OUT_ IN CIN V − 0.7V IPRESET = REG RPRELOAD REG C2 LEDs MAX16823 PWM DIMMING This circuit is used with older body controllers that monitor minimum RCL current to detect failures. DIM_ CS_ RCS_ GND Figure 5. Increased LED Current (Amper Range) with a Single BJT STOP TAIL CIN TAIL IN OUT1 IN OUT2 IN OUT3 DIM1 DIM2 TAIL STOP MAX16823 100kΩ DIM3 CS1 100kΩ LGC CS2 REG CLGC RPRELOAD CS3 CREG GND RCS1 RCS2 Figure 6. Preload Current Setting 10 ______________________________________________________________________________________ RCS3 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection CS2 CS3 GND REG TOP VIEW 12 11 10 9 TOP VIEW OUT2 1 8 CS1 13 LGC + 16 OUT3 15 CS1 OUT1 2 14 CS2 DIM1 3 7 OUT3 14 MAX16823 OUT2 15 *EP + 5 IN IN DIM2 4 1 2 3 4 DIM2 DIM3 LEDGOOD 13 CS3 DIM3 5 12 GND LEDGOOD 6 11 REG IN 7 10 LGC *EP IN 8 DIM1 OUT1 16 6 IN MAX16823 9 IN TSSOP *EP = EXPOSED PAD. TQFN Chip Information PROCESS: BiCMOS-DMOS ______________________________________________________________________________________ 11 MAX16823 Pin Configurations Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) QFN THIN.EPS MAX16823 High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection 12 ______________________________________________________________________________________ High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection TSSOP 4.4mm BODY.EPS XX XX PACKAGE OUTLINE, TSSOP, 4.40 MM BODY, EXPOSED PAD 21-0108 E 1 1 Revision History Pages changed at Rev 1: 1, 13 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 ____________________ 13 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX16823 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)