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19-4746; Rev 1; 5/10
TION KIT EVALUA BLE AVAILA
High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect
General Description
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.
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
Features
MAX16839
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 MAX16839ATT+ MAX16839ASA+ *EP = Exposed pad. TEMP RANGE -40NC to +125NC -40NC to +125NC PIN-PACKAGE 6 TDFN-EP* 8 SO-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
Applications
Automotive Exterior: Turn Signal Light, Brake Light, Tail and Marker Lights Automotive Interior: Cluster and Warning Lights, Dome and Map Lights Truck, Train, Airplane, and Emergency Car LED Lighting General Lighting: Signage, LED Lamps
VBAT
Typical Application Circuit
VIN = 5V TO 40V
REVERSE PROTECTION DIODE ILED = 100mA CIN = 0.01FF LEDs
IN DIM SINK MAX16839 FLTS CFLTS = 0.1FF GND CS RCS = 2I
Pin Configurations appear at end of data sheet.
_______________________________________________________________ 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.
High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect MAX16839
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 Supply Voltage Range Quiescent Current Undervoltage Lockout UVLO Hysteresis CS REGULATOR TA = +25NC CS Voltage Accuracy CS Load Regulation Internal Switch On-Resistance RDS_ON LED CURRENT TRANSIENT RESPONSE LED Current Turn-On Delay LED Current Turn-On Delay Relative to DIM LED Current Turn-Off Delay Relative to DIM LED Current Rise Time LED Current Fall Time FAULT EVENT STATUS MEMORY FLTS Activation Threshold FLTS Activation Hysteresis LED Open Threshold LED Open Blanking Fault Voltage 2 VCSO TB VFLTS VIN = 40V, VCS = 0V, CFLTS = 0.1FF 25 14 12 VINTH VIN rising, VCS = 0V 7 7.38 20 30 25 15 35 50 18 7.75 V mV mV Fs V tr tf tDIN tDDIN 30% of VIN rising edge to 50% of ISINK, VDIM = 2.1V (Notes 6, 7) VDIM rising edge to 50% of ISINK VDIM falling edge to 50% of ISINK 10% of ISINK to 90% of ISINK 90% of ISINK to 10% of ISINK 4 2.3 1.3 2.5 2.5 9 5.5 3.5 5.5 6 Fs Fs Fs Fs Fs VCS -40NC P TA P +125NC, 0.9V P VSINK P 5.5V (Note 4) 20mA P ISINK P 100mA (Note 5) 195.5 193 40 2 4 203 210.5 213 mV FV/mA I SYMBOL VIN IIN VUVLO VIN rising CONDITIONS MIN 5 0.25 3.6 0.3 TYP MAX 40 0.6 UNITS V mA V V
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High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect
ELECTRICAL CHARACTERISTICS (continued)
(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 FLTS Discharge Current FLTS Threshold To Turn Off LED Current Sink DIM LOGIC Input High Voltage Input Low Voltage DIM Voltage Logic Hysteresis DIM Pullup Current DIM Pulldown Current DIM Pulse Width DIM Frequency LEAKAGE CURRENTS SINK Leakage Current FLTS Leakage Current THERMAL SHUTDOWN Thermal Shutdown Temperature Thermal Shutdown Hysteresis Note Note Note Note Note 2: 3: 4: 5: 6: Temperature rising 160 15 NC NC VSINK = 40V, VDIM = 0V VFLTS = 8V, VIN = 0V 1 1 FA FA fDIM VFLTH VIH VIL VDIM_HYS VDIM = 0V VDIM = 0.8V, VIN = 2.4V 10 0.385 70 10 0.15 30 1 60 1.5 SYMBOL ICFLTS VCS P 25mV VFLTS = 0.5V CONDITIONS MIN 0.65 2.25 0.95 2.1 0.8 TYP 2.8 5 1.3 MAX 4.8 7.25 1.65 UNITS mA FA V V V V FA mA Fs kHz
MAX16839
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.
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High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect MAX16839
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
MAX16839 toc01a
OUTPUT CURRENT vs. TEMPERATURE
MAX16839 toc01b
OUTPUT CURRENT vs. TEMPERATURE
98.8 98.6 OUTPUT CURRENT (mA) 98.4 98.2 98.0 97.8 97.6 97.4 97.2 97.0 ILOAD = 100mA
MAX16839 toc01c MAX16839 toc04
17.0 16.9 16.8 OUTPUT CURRENT (mA) 16.7 16.6 16.5 16.4 16.3 16.2 16.1 16.0
ILOAD = 16mA
50.0 49.9 49.8 OUTPUT CURRENT (mA) 49.7 49.6 49.5 49.4 49.3 49.2 49.1 49.0
ILOAD = 50mA
99.0
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC)
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC)
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC)
VCS vs. OUTPUT CURRENT
MAX16839 toc02
OUTPUT CURRENT vs. INPUT VOLTAGE
MAX16839 toc03
RDS(ON) VS. TEMPERATURE
3.0 2.8 2.6 2.4 RDS(ON) (I) 2.2 2.0 1.8 1.6 1.4 1.2 1.0 VIN = 12V
205.0 204.5 204.0 203.5 VCS (mV) 203.0 202.5 202.0 201.5 201.0 200.5 200.0 10 20 30 40 50 60 70
VIN = 12V
120 IILED = 100mA 100 OUTPUT CURRENT (mA) 80 60 40 20 0 IILED = 15mA IILED = 50mA
80
90 100
5
10
15
20
25
30
35
40
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC)
OUTPUT CURRENT (mA)
VIN (V)
QUIESCENT CURRENT vs. TEMPERATURE
375 QUIESCENT CURRENT (FA) 350 325 300 275 250 225 200 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC) VIN = 12V
MAX16839 toc05
LED CURRENT RISE TIME
MAX16839 toc06
LED CURRENT FALL TIME
MAX16839 toc07
400
VDIM 2V/div 0V
VDIM 2V/div 0V
LED CURRENT 50mA/div 0 2Fs/div 2Fs/div
LED CURRENT 50mA/div 0
4
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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.)
LED CURRENT RISE/FALL TIMES
MAX16839 toc08
MAX16839
FLTS DISCHARGE
MAX16839 toc09
LEAKAGE CURRENT vs. TEMPERATURE
VIN 5V/div LEAKAGE CURRENT (nA) 0V VIN = 0V VFLTS = 8V
MAX16839 toc10
50 40 30 20 10 0 -10
VDIM 2V/div 0V
VIN IS TURNED OFF
ILED 50mA/div 0 20Fs/div 1s/div
VFLTS 5V/div 0V
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC)
FAULT ACTIVATION THRESHOLD vs. TEMPERATURE
FAULT ACTIVATION THRESHOLD (V)
ILED RESPONSE TO SUPPLY CHOPPING
MAX16839 toc11
7.40 7.39 7.38 7.37 7.36 7.35 7.34 7.33 7.32 7.31 7.30
MAX16839 toc12
VIN 5V/div
ILED 20mA/div 0
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (NC)
4ms/div
LED RISE TIME DELAY (SUPPLY CHOPPING)
MAX16839 toc13
FAULT ACTIVATION THRESHOLD AND OPEN-LED BLANKING
MAX16839 toc14
VIN 5V/div 0V ILED 20mA/div 0 1Fs/div 20Fs/div
VIN 2V/div
VFLTS 2V/div 0V
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5
High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect 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.)
FAULT INTEGRATION ON OPEN LED (100Hz, 50% DUTY CYCLE AT DIM)
MAX16839 toc15a
FAULT INTEGRATION ON OPEN LED (100Hz, 75% DUTY CYCLE AT DIM)
MAX16839 toc15b
FAULT INTEGRATION ON OPEN LED WITH SUPPLY CHOPPING
MAX16839 toc16
100Hz AT DIM VFLT VFLT VCS 200mV/div
5V/div
5V/div
VDIM
2V/div
VDIM
2V/div
VIN 5V/div VFLTS 5V/div
ILED
500mA/div
ILED
500mA/div
4ms/div
100s/div
200Fs/div
Pin Description
PIN TDFN 1 2 SO 1 2 NAME IN DIM FUNCTION Positive Input Supply. Bypass with a 10nF (typ) capacitor to GND. 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. 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. Ground Current-Sense Input. Connect a current-sense resistor between CS and GND to program the output current level. LED Driver Current-Sink Output No Connection. Not internally connected. 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.
3 4 5 6 -- --
3 6 7 8 4, 5 --
FLTS GND CS SINK N.C. EP
6
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High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect
Detailed Description
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. Additional features include thermal protection and an open-LED detection output that can turn off multiple LED strings simultaneously. See Figure 1.
MAX16839
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
Open-LED Detection and Fault Event Status Memory
IN
5V REG SINK 5V 30A REFERENCE GENERATOR CS IN 1mA ENABLE 15V CLAMP IREG
DIM
MAX16839
2.8mA OPEN-LED DETECT
FAULT THERMAL SHDN
FLTS
GND
Figure 1. Internal Block Diagram
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7
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 25s. 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
MAX16839
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. 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.
Thermal Protection
12V
VIN t
12V UVLO
VIN
50mA
ILED t LEDGOOD (INTERNAL) t 50mA ILED
t
12V FLTS t 4Fs 2.5Fs
t
VIN = 5V TO 40V
LEDS
CIN = 0.01FF
CONNECT TO 5V SUPPLY OR LEAVE UNCONNECTED DIM SIGNAL
CIN = 0.01FF
LEDS
ILED
IN SINK DIM
IN DIM SINK
ILED
MAX16839
CS GND RCS FLTS
FLTS SIGNAL CFLTS = 0.1FF
MAX16839
FLTS GND RCS CS
Figure 2. Multistring Application
8
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High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect
Applications Information
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 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 xt xN C FLTS = FLTS FLTS (VFLTS - VFLTH )
FLTS Capacitor
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. 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. 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. The power dissipation (PD) of the MAX16839 is determined from the following equation: PD = (VIN x IIN ) + (VIN - VLED - VCS ) x (ILED x DUTY) where: VIN = supply voltage IIN = supply current 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.
MAX16839
PWM Dimming
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. 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: V (V) R CS () = CS ILED (A) where VCS is 203mV (typ) (see the Electrical Characteristics table). 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
Supply Chopped Dimming
Programming the LED Current
Power Dissipation
Input Voltage
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9
High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect MAX16839
Pin Configurations
TOP VIEW
+ IN DIM FLTS 1 2 3 6 5 EP 4 SINK CS GND
IN DIM FLTS N.C.
1 2 3 4
+
8 7
MAX16839
SINK CS GND N.C.
MAX16839
EP
6 5
TDFN
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 6 TDFN-EP 8 SO-EP PACKAGE CODE T633+2 S8E+12 DOCUMENT NO. 21-0137 21-0111
10
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High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect
Revision History
REVISION NUMBER
0 1
MAX16839
REVISION DATE
7/9 5/10 Initial release
DESCRIPTION
PAGES CHANGED
-- 1,2, 3, 5-11
Changed one feature of IC; replaced TOC 15 with two TOCs
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
(c)
11
2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.

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