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19-0733; Rev 3; 9/09
KIT ATION EVALU E AILABL AV
High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection
General Description
The MAX16823 three-channel LED driver operates from a 5.5V to 40V input voltage range and delivers up to 100mA 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 -40C to +125C automotive temperature range.
Features
o 5.5V to 40V Operating Range o Adjustable Constant Output Current (5mA to 100mA 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 -40C to +125C Operating Temperature Range
MAX16823
Ordering Information
PART MAX16823ATE+ MAX16823ATE/V+ MAX16823AUE+ TEMP RANGE -40C to +125C -40C to +125C -40C to +125C PIN-PACKAGE 16 TQFN-EP* 16 TQFN-EP* 16 TSSOP-EP*
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
MAX16823AUE/V+ -40C to +125C 16 TSSOP-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. /V Denotes an automotive qualified part.
Pin Configurations appear at end of data sheet.
Typical Operating Circuit
VIN
IN CIN IN IN DIM1 DIM2 REG RLEDGOOD LEDGOOD LGC REG CLGC CREG GND DIM3
OUT1
MAX16823
OUT2 OUT3
CS1 CS2 CS3
CS1
CS2
CS3
________________________________________________________________ Maxim Integrated Products
1
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
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 = +70C) 16-Pin TQFN 5mm x 5mm (derate 33.3mW/C above +70C) .........................2666mW 16-Pin TSSOP (derate 26.1mW/C above +70C) ....2088.8mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = 0.1F, IREG = 0, CLGC = 15nF, VDIM1 = VDIM2 = VDIM3 = 3.4V, RCS_ = 2.85 from CS_ to GND, TJ = TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Supply Voltage Range Undervoltage Lockout Ground Current Guaranteed Output Current LED Current-Sense Accuracy Dropout Voltage (Note 2) Output Current Slew Rate Short-Circuit Current LEDGOOD LEDGOOD Output Logic Low LGC Pullup Resistor LGC Input Upper Threshold LGC Input Lower Threshold LGC Pulldown Current LGC Clock Period DIMMING INPUT (DIM1, DIM2, DIM3) DIM_ Logic-Input Bias Current DIM_ Input-Voltage High DIM_ Input-Voltage Low DIM_ Frequency OUTPUTS (OUT1, OUT2, AND OUT3) (Note 3) Turn-On Time Turn-Off Time Output Current Rise Time Output Current Fall Time DIM_ rising edge to 90% of OUT_ current DIM_ falling edge to 10% of OUT_ current 10% to 90% 90% to 10% 12 8 7 6 28 18 18 15 s s s s 0 IDIM_ -0.1 2.4 +0.1 VIN 0.6 3 A V V kHz VUTH VLTH VLGC > VUTH CLGC = 15nF 0.77 VOL ISINK = 2mA 65 100 2.53 0.8 20 1.5 2.3 0.4 135 V k V V mA ms VOUT_ = 0V VDO SYMBOL VIN UVLO IG IOUT 5mA IOUT_ 70mA IOUT_ = 70mA, 6.5V VIN 40V IOUT_ = 70mA, 5.5V VIN 6.5V 0.3 0.3 8 180 VIN rising VIN falling IOUT1 = IOUT2 = IOUT3 = 70mA 100 5 0.7 0.8 CONDITIONS MIN 5.5 4.4 4.0 4.9 4.6 1.5 TYP MAX 40 5.4 5.2 3 UNITS V V mA mA % V mA/s mA
2
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 12V, CREG = 0.1F, IREG = 0, CLGC = 15nF, VDIM1 = VDIM2 = VDIM3 = 3.4V, RCS_ = 2.85 from CS_ to GND, TJ = TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER CURRENT SENSE Regulated CS_ Voltage Input Current (CS1, CS2, CS3) OVERTEMPERATURE PROTECTION (Note 4) Thermal Shutdown Temperature Thermal Shutdown Hysteresis 3.4V REGULATOR (REG) Output Voltage REG Short-Circuit Current VREG 3.275 0 IREG 4mA VREG = 0V 3.221 3.41 3.38 13 3.547 3.547 V mA 155 23 C C VCS_ 5mA IOUT_ 70mA Current out of CS_ 193 203 213 +1.2 mV A SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX16823
Note 1: All devices 100% production tested at TJ = +25C. 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_ = 2.85 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 62 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 = 0.1F, IREG = 0, VLGC = unconnected, connect RCS_ = 2.85 from CS_ to GND. Connect OUT_ to CS_ through a resistor, TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.)
OUTPUT CURRENT vs. TEMPERATURE
MAX16823 toc01
VCS_ vs. OUTPUT CURRENT
MAX16823 toc02
OUTPUT CURRENT vs. INPUT VOLTAGE
90 80 OUTPUT CURRENT (mA) 70 60 50 40 30 20 10 0 IOUT = 5mA 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 40 IOUT = 70mA
MAX16823 toc03
100 90 80 OUTPUT CURRENT (mA) 70 60 50 40 30 20 10 0 ILOAD = 5mA ILOAD = 35mA ILOAD = 70mA
0.210 0.209 0.208 0.207 VCS_ (V) 0.206 0.205 0.204 0.203 0.202 0.201 0.200 0 10 20 30 40 50 OUTPUT CURRENT (mA) 60
100
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C )
70
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
Typical Operating Characteristics (continued)
(VIN = 12V, CREG = 0.1F, IREG = 0, VLGC = unconnected, connect RCS_ = 2.85 from CS_ to GND. Connect OUT_ to CS_ through a resistor, TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.)
DROPOUT VOLTAGE vs. TEMPERATURE
MAX16823 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX16823 toc05
VREG vs. TEMPERATURE
ILOAD = 0 3.4
MAX16823 toc06 MAX16823 toc09 MAX16823 toc08
1.0 0.9 0.8 DROPOUT VOLTAGE (mV) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 ILOAD = 70mA
1.4 1.3 SUPPLY CURRENT (mA) 1.2 1.1 1.0 0.9 0.8 VIN = 12V 0.7 0.6 VIN = 5.5V VIN = 20V VIN = 40V VDIM1 = VDIM2 = VDIM3 = 0V
3.5
VREG (V)
3.3 ILOAD = 4mA 3.2 ILOAD = 1mA
3.1
3.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
-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 0 1 2 3
MAX16823 toc07
VREG vs. VIN
3.45 3.44 3.43 3.42 VREG (V) 3.41 3.40 3.39 3.38 3.37 3.36 3.35 IREG = 1mA IREG = 4mA IREG = 0
330Hz DIMMED OPERATION
ILOAD = 70mA VIN = 12V, DIM PULSED AT 33Hz (1% DUTY CYCLE)
VDIM 2V/div 0V ILED 50mA/div 0A
VCS_ (V)
ILOAD = 70mA
456 IREG (mA)
7
8
9
10
0
5
10
15
20 25 VIN (V)
30
35
40
20s/div
200Hz DIMMED OPERATION (EXPANDED)
MAX16823 toc10
200Hz DIMMED OPERATION (EXPANDED)
MAX16823 toc11
LEDGOOD RESPONSE TIMES
MAX16823 toc12
VDIM 2V/div 0V ILOAD 50mA/div ILOAD = 70mA 0A VIN = 12V, DIM PULSED AT 200Hz (50% DUTY CYCLE) 10s/div
ILOAD = 70mA VIN = 12V, DIM PULSED AT 200Hz (50% DUTY CYCLE) VDIM 2V/div 0V ILOAD 50mA/div 0A
VIN = 12V CLGC = 15nF
VDIM 5V/div 0V VLEDGOOD 5V/div 0V VLGC 5V/div 0V
10s/div
2ms/div
4
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection
Pin Description
PIN TQFN 1 2 3 TSSOP 3 4 5 NAME DIM1 DIM2 DIM3 FUNCTION 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. 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. 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. 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 0.1F (min) capacitor to GND. Connect all IN pins together. LED Detection-Timing Setting. Connect a capacitor from LGC to ground to set the delay time for LEDGOOD. 3.4V Voltage Regulator. Connect a 0.1F capacitor from REG to GND. Ground Channel 3 Sense Amplifier Positive Input. Connect the current-sense resistor between CS3 and GND to program the output current level for channel 3. Channel 2 Sense Amplifier Positive Input. Connect the current-sense resistor between CS2 and GND to program the output current level for channel 2. Channel 1 Sense Amplifier Positive Input. Connect the current-sense resistor between CS1 and GND to program the output current level for channel 1. Current Regulator Output 3 Current Regulator Output 2 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.
MAX16823
4
6
LEDGOOD
5, 6, 7 8 9 10 11 12 13 14 15 16 --
7, 8, 9 10 11 12 13 14 15 16 1 2 --
IN LGC REG GND CS3 CS2 CS1 OUT3 OUT2 OUT1 EP
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
Detailed Description
The MAX16823 three-channel current regulator operates from a 5.5V to 40V input voltage range and delivers up to 100mA 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.
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 _ () = 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() x CLGC (F) where CLGC is the capacitor connected between LGC and ground. The LEDGOOD output goes low during the thermal shutdown.
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 0.1F 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 = +155C, the internal thermal protection circuitry turns off the series pass elements. The MAX16823 recovers from thermal-shutdown mode once the junction temperature drops by 23C. The part will therefore protect itself by low-frequency thermal cycling in the event of a short-circuit or overload condition.
6
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection
Block Diagram
REG
MAX16823
UVLO IN IN IN IN BANDGAP
I_REG OUT1
CS1
GND
DIM1
IN THERMAL SHUTDOWN I_REG OUT2
MAX16823
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
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
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.
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.
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.
tON
DIM tOFF
LEDGOOD LEDGOOD GOES LOW WHEN tOFF > tDELAY
Figure 1. LEDGOOD Timing Delay
STOP D1 TAIL D4 R1 C1 IN OUT3 OUT2 OUT1 REG 0.1F R2 D2 DIS R3 TH TRG C2 ICM7555 GND GND IN OUT D3 100k DIM3 CS3 RCS3 RCS2 DIM2 CS2 DIM1 LEDs
MAX16823
CS1 RCS1
Figure 2. PWM Dimming Operation with ICM7555
8 _______________________________________________________________________________________
High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
VIN IN CIN VREG OUT3 OUT2 OUT1
R1 LEDs
MAX16823
DIM1 DIM2 DIM3 CS2 LEDGOOD RCS2 REG CREG GND CS3 CS1 RCS1
LEDs LEDs
RCS3
Figure 3. Output_ Latch-Off
STOP
D1 D2 TAIL IN OUT3 OUT2 OUT1 STOP/TAIL TAIL TAIL
LEDs
MAX16823
DIM1 DIM2 R2 CIN R1* DIM3 RCS1 Q1 R3 CS1 LEDs LEDs
REG CREG GND
CS2 RCS2 CS3 RCS3
*R1 = 100k
Figure 4. Two-Brightness Level with Current Level Switch for TAIL/STOP Lights
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
Preload Current
VIN IN CIN OUT_ Q1
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: V - 0.7V IPRESET = REG RPRELOAD
LEDs
REG C2
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
IN IN CIN IN DIM1 DIM2 100k
TAIL OUT1 OUT2 OUT3 TAIL STOP
MAX16823
DIM3 100k LGC REG CLGC RPRELOAD CREG GND
CS1
CS2 CS3
RCS1
RCS2
RCS3
Figure 6. Preload Current Setting
10 ______________________________________________________________________________________
High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection
Pin Configurations
CS2 CS3 REG
MAX16823
TOP VIEW
GND
12
11
10
9
TOP VIEW
OUT2 1 8 7 LGC IN IN IN OUT1 2 DIM1 3
+
16 OUT3 15 CS1 14 CS2
CS1 13 OUT3 14 OUT2 15 OUT1 16
DIM2 4 DIM3 5 LEDGOOD 6
MAX16823
13 CS3 12 GND 11 REG 10 LGC
MAX16823
*EP
6 5
+
1 DIM1 2 DIM2 3 DIM3
IN 7 IN 8 *EP
9 IN
4 LEDGOOD
TSSOP *EP = EXPOSED PAD.
TQFN
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 16 TQFN-EP 16 TSSOP PACKAGE CODE T1655+3 U16E+3 DOCUMENT NO. 21-0140 21-0108
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High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection MAX16823
Revision History
REVISION NUMBER 0 1 2 3 REVISION DATE 1/07 3/07 10/08 9/09 Initial release Released TQFN package. Updated General Description, Features, EC table, and Detailed Description. Added automotive packages. DESCRIPTION PAGES CHANGED -- 1 1, 2, 6 1
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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