19-0656; Rev 2; 8/09 KIT ATION EVALU E L B A AVAIL Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller Features The MAX16809 is an integrated, high-efficiency white or RGB LED driver. It is designed for LCD backlighting and other LED lighting applications with multiple strings of LEDs. The MAX16809's current-mode PWM controller regulates the necessary voltage to the LED array. Depending on the input voltage and LED voltage range, this device can be used with boost or buckboost (SEPIC) topologies. The MAX16809 LED driver includes 16 open-drain, constant-current-sinking LED driver outputs rated for 36V continuous operation. The LED current-control circuitry achieves 3% current matching among strings and enables paralleling of outputs for LED string currents higher than 55mA. The output-enable pin is used for simultaneous PWM dimming of all output channels. Dimming frequency range is 50Hz to 30kHz and dimming ratio is up to 5000:1. The constant-current outputs are single resistor programmable and the LED current can be adjusted up to 55mA per output channel. The MAX16809 operates either in stand-alone mode or with a microcontroller (C) using an industry-standard, 4wire serial interface. The MAX16809 includes overtemperature protection, operates over the full -40C to +125C temperature range, and is available in a 5mm x 7mm thermally enhanced, 38-pin TQFN exposed paddle package. 16 Constant-Current Output Channels (Up to 55mA Each) 3% Current Matching Among Outputs Paralleling Channels Allows Higher Current per LED String Outputs Rated for 36V Continuous Voltage Output-Enable Pin for PWM Dimming (Up to 30kHz) One Resistor Sets LED Current for All Channels Wide Dimming Ratio Up to 5000:1 Low Current-Sense Reference (300mV) for High Efficiency 8V to 26.5V Input Voltage or Higher with External Biasing Devices 4-Wire Serial Interface to Control Individual Output Channels Applications LCD White or RGB LED Backlighting: LCD TVs, Desktop, and Notebook Panels Automotive Navigation, Heads-Up, and Infotainment Displays Industrial and Medical Displays Ambient, Mood, and Accent Lighting Ordering Information PART MAX16809ATU+ TEMP RANGE PIN-PACKAGE -40C to +125C 38 TQFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Pin Configuration appears at end of data sheet. Typical Operating Circuits VIN VOUT L COUT Q1 CC2 RCS CC1 OUT CS AGND LEDs R1 RC1 R2 COMP VCC FB CIN 3V TO 5.5V OUT0 V+ OUT1 CBYP OUT2 PGND OUT3 OUT4 MAX16809 LE DIN OUT5 OUT6 CLK OUT7 OUT8 DOUT OE OUT9 OUT10 SET OUT11 OUT12 OUT13 OUT14 RSET OUT15 RTCT REF STAND-ALONE OPERATION RT CREF CT Typical Operating Circuits continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX16809 General Description MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller ABSOLUTE MAXIMUM RATINGS VCC to AGND..........................................................-0.3V to +30V Current into VCC (VCC > 24V) .............................................30mA V+ to PGND..............................................................-0.3V to +6V OUT to AGND.............................................-0.3V to (VCC + 0.3V) OUT Current (10s duration) .................................................1A FB, COMP, CS, RTCT, REF to AGND.......................-0.3V to +6V COMP Sink Current.............................................................10mA OUT0-OUT15 to PGND..........................................-0.3V to +40V DIN, CLK, LE, OE, SET to PGND..................-0.3V to (V+ + 0.3V) DOUT Current...................................................................10mA OUT0-OUT15 Sink Current.................................................60mA Total PGND Current (1s pulse time) .................................960mA Continuous Power Dissipation (TA = +70C) 38-Pin TQFN (derate 35.7mW/C* above +70C) ......2857mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C *Per JEDEC51 Standard (Multilayer Board). 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 (PWM CONTROLLER) (VCC = +15V, V+ = +3V to +5.5V referenced to PGND, RT = 10k, CT = 3.3nF, REF = open, COMP = open, CREF = 0.1F, VFB = 2V, CS = AGND, AGND = PGND = 0V; all voltages are measured with respect to AGND, unless otherwise noted. TJ = TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5 5.05 V 0.4 4 mV 50 mV REFERENCE Output Voltage VREF Line Regulation VLINE IREF = 1mA, TJ = +25C 12V< VCC < 25V, IREF = 1mA Load Regulation VLOAD 1mA < IREF < 20mA 4.95 6 Total Output-Voltage Variation VREFT (Note 2) 4.875 Output Noise Voltage VNOISE 10Hz < f < 10kHz Output Short-Circuit Current ISHORT VREF = 0V 30 Initial Accuracy TJ = +25C 51 Voltage Stability 12V < VCC < 25V 5.125 50 V V 180 mA 54 57 kHz 0.2 0.5 % OSCILLATOR Temperature Stability RTCT Ramp Peak-to-Peak RTCT Ramp Valley 1 % 1.7 V 1.1 Discharge Current IDIS Frequency Range fOSC V VRTCT = 2V, TJ = +25C 7.9 8.3 8.7 VRTCT = 2V, -40oC TJ +125C 7.5 8.3 9.0 20 mA 1000 kHz 2.5 2.55 V -0.01 -0.1 ERROR AMPLIFIER FB Input Voltage VFB FB shorted to COMP 2.45 Input Bias Current IB(FB) Open-Loop Gain AVOL Unity-Gain Bandwidth fGBW Power-Supply Rejection Ratio PSRR 12V VCC 25V 60 80 dB COMP Sink Current ISINK VFB = 2.7V, VCOMP = 1.1V 2 6 mA 0.5 1.2 COMP Source Current ISOURCE 2V VCOMP 4V VFB = 2.3V, VCOMP = 5V COMP Output-Voltage High VOH VFB = 2.3V, RCOMP = 15k to AGND COMP Output-Voltage Low VOL VFB = 2.7V, RCOMP = 15k to VREF 2 5 A 100 dB 1 MHz 1.8 mA 1.1 V 5.8 0.1 _______________________________________________________________________________________ V Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller (VCC = +15V, V+ = +3V to +5.5V referenced to PGND, RT = 10k, CT = 3.3nF, REF = open, COMP = open, CREF = 0.1F, VFB = 2V, CS = AGND, AGND = PGND = 0V; all voltages are measured with respect to AGND, unless otherwise noted. TJ = TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CURRENT-SENSE AMPLIFIER Current-Sense Gain ACS Maximum Current-Sense Signal VCS_MAX (Notes 3, 4) 2.85 3 3.40 V/V (Note 3) 0.275 0.300 0.325 V 12V VCC 25V 70 VCOMP = 0V -1 tPWM 50mV overdrive 60 OUT Low-Side On-Resistance VRDS_ONL ISINK = 200mA OUT High-Side On-Resistance VRDS_ONH ISOURCE = 100mA Power-Supply Rejection Ratio PSRR Current-Sense Input Bias Current ICS Current Sense to OUT Delay dB -2.5 A ns MOSFET DRIVER Source Current (Peak) ISOURCE CLOAD = 10nF Sink Current (Peak) TJ = -40C to +85C (Note 2) 4.5 10 TJ = -40C to +125C 4.5 12 TJ = -40C to +85C (Note 2) 3.5 7.5 TJ = -40C to +125C 3.5 10 2 A ISINK CLOAD = 10nF 1 A Rise Time tR CLOAD = 1nF 15 ns Fall Time tF CLOAD = 1nF 22 ns UNDERVOLTAGE LOCKOUT/STARTUP Startup Voltage Threshold VCC_START 7.98 8.4 8.82 V Minimum Operating Voltage After Turn-On VCC_MIN 7.1 7.6 8.0 V Undervoltage-Lockout Hysteresis UVLOHYST 0.8 V PULSE-WIDTH MODULATION (PWM) Maximum Duty Cycle DMAX Minimum Duty Cycle DMIN 94.5 96 97.5 % 0 % SUPPLY CURRENT Startup Supply Current VCC = 7.5V 32 65 A Operating Supply Current ISTART ICC VFB = VCS = 0V 3 5 mA VCC Zener Voltage VZ ICC = 25mA 24 26.5 V _______________________________________________________________________________________ 3 MAX16809 ELECTRICAL CHARACTERISTICS (PWM CONTROLLER) (continued) MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller ELECTRICAL CHARACTERISTICS (LED DRIVER) (V+ = +3V to +5.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SYMBOL Operating Supply Voltage Output Voltage CONDITIONS V+ MIN TYP 3.0 VOUT_ _ MAX UNITS 5.5 V 36 V Standby Current (Interface Idle, All Output Ports High Impedance) RSET = 360, DIN, LE, CLK = PGND or V+, OE = V+, DOUT unconnected 3.6 4.5 mA Standby Current (Interface Active, All Output Ports High Impedance) RSET = 360, fCLK = 5MHz, OE = V+, DIN, LE = PGND or V+, DOUT unconnected 3.8 4.8 mA RSET = 360, OE = PGND, DIN, LE = V+, DOUT unconnected 30 52.5 mA Supply Current (Interface Idle, All Output Ports Active Low) I+ INTERFACE (DIN, CLK, DOUT, LE, OE) Input-Voltage High (DIN, CLK, LE, OE) VIH Input-Voltage Low (DIN, CLK, LE, OE) VIL Hysteresis Voltage (DIN, CLK, LE, OE) VHYST Input Leakage Current (DIN, CLK) ILEAK 0.7 x V+ V 0.3 x V+ 0.8 -1 V V +1 A OE Pullup Current to V+ IOE V+ = 5.5V, OE = PGND 0.25 1.5 25 A LE Pulldown Current to PGND ILE V+ = 5.5V, LE = V+ 0.25 1.5 25 A Output-Voltage High (DOUT) VOH Output-Voltage Low (DOUT) VOL OUT_ _ Output Current OUT_ _ Leakage Current 4 IOUT_ _ ISOURCE = 4mA V+ - 0.5V V ISINK = 4mA 0C TA +125C, VOUT = 1V to 2.5V, RSET = 360 TA = -40C, VOUT = 1V to 2.5V, RSET = 360 0.5 43.25 47.5 V 51.75 mA 40 OE = V+ _______________________________________________________________________________________ 55 1 A Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller (V+ = +4.5V to +5.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 5) PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS INTERFACE TIMING CHARACTERISTICS CLK Clock Period tCP 40 ns CLK Pulse-Width High tCH 19 ns CLK Pulse-Width Low tCL 19 ns DIN Setup Time tDS 4 ns DIN Hold Time tDH 8 ns DOUT Propagation Delay tDO 50 ns DOUT Rise Time tDR CDOUT = 10pF, 20% to 80% 10 ns DOUT Fall Time tDF CDOUT = 10pF, 80% to 20% 10 ns LE Pulse-Width High tLW 20 LE Setup Time tLS 15 10 ns ns LE Rising to OUT_ _ Rising Delay tLRR (Note 6) 110 ns LE Rising to OUT_ _ Falling Delay tLRF (Note 6) 340 ns CLK Rising to OUT_ _ Rising Delay tCRR (Note 6) 110 ns CLK Rising to OUT_ _ Falling Delay tCRF (Note 6) 340 ns OE Rising to OUT_ _ Rising Delay tOER (Note 6) 110 ns OE Falling to OUT_ _ Falling Delay tOEF (Note 6) 340 ns OUT_ _ Turn-On Fall Time tF 80% to 20% (Note 6) 210 ns OUT_ _ Turn-Off Rise Time tR 20% to 80% (Note 6) 130 ns _______________________________________________________________________________________ 5 MAX16809 5V TIMING CHARACTERISTICS MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller 3.3V TIMING CHARACTERISTICS (V+ = +3V to < +4.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA = TJ = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 5) PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS INTERFACE TIMING CHARACTERISTICS CLK Clock Period tCP 52 ns CLK Pulse-Width High tCH 24 ns CLK Pulse-Width Low tCL 24 ns DIN Setup Time tDS 4 ns DIN Hold Time tDH 8 ns DOUT Propagation Delay tDO DOUT Rise Time tDR CDOUT = 10pF, 20% to 80% DOUT Fall Time tDF CDOUT = 10pF, 80% to 20% LE Pulse-Width High tLW 20 ns LE Setup Time tLS 15 ns 12 70 ns 12 ns 12 ns LE Rising to OUT_ _ Rising Delay tLRR (Note 6) 140 ns LE Rising to OUT_ _ Falling Delay tLRF (Note 6) 400 ns CLK Rising to OUT_ _ Rising Delay tCRR (Note 6) 140 ns CLK Rising to OUT_ _ Falling Delay tCRF (Note 6) 400 ns OE Rising to OUT_ _ Rising Delay tOER (Note 6) 140 ns OE Falling to OUT_ _ Falling Delay tOEF (Note 6) 400 ns OUT_ _ Turn-On Fall Time tF 80% to 20% (Note 6) 275 ns OUT_ _ Turn-Off Rise Time tR 20% to 80% (Note 6) 150 ns Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: 6 This device is 100% production tested at TJ = +25C and +125C. Limits to -40C are guaranteed by design. Guaranteed by design, not production tested. Parameter is measured at trip point of latch with VFB = 0V. Gain is defined as A = VCOMP/VCS, 0.05V VCS 0.25V. See Figures 3 and 4. A 65 pullup resistor is connected from OUT_ _ to 5.5V. Rising refers to VOUT_ _ when current through OUT_ _ is turned off and falling refers to VOUT_ _ when current through OUT_ _ is turned on. _______________________________________________________________________________________ Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller VCC FALLING 6 ICC (A) VCC (V) 7 VCC = 7.5V 39 5 4 5.1 CT = 560pF 4.9 37 4.7 35 4.5 ICC (mA) 8 41 MAX16809 toc02 VCC RISING MAX16809 toc01 9 33 MAX16809 toc03 BOOTSTRAP UVLO vs. TEMPERATURE 10 OPERATING SUPPLY CURRENT vs. TEMPERATURE AFTER STARTUP (fOSC = fSW = 300kHz) STARTUP CURRENT vs. TEMPERATURE 4.3 31 4.1 29 3.9 27 3.7 3 2 HYSTERESIS 1 0 25 -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 (C) TEMPERATURE (C) TEMPERATURE (C) REFERENCE VOLTAGE vs. TEMPERATURE REFERENCE VOLTAGE vs. REFERENCE LOAD CURRENT REFERENCE VOLTAGE vs. SUPPLY VOLTAGE 5.04 5.00 4.996 IREF = 20mA 4.96 4.994 4.90 VREF (V) 4.98 VREF (V) IREF = 1mA 5.00 IREF = 1mA 4.998 4.95 5.02 MAX16809 toc06 5.06 5.000 MAX16809 toc05 5.05 MAX16809 toc04 5.08 4.85 4.992 4.990 4.988 4.80 4.986 4.94 4.75 4.92 4.70 4.90 4.65 -40 -25 -10 5 20 35 50 65 80 95 110 125 4.984 4.982 4.980 0 10 TEMPERATURE (C) 20 30 40 50 60 12 14 530 18 20 22 24 26 520 510 500 490 480 470 8.04 MAX16809 toc08 RT = 3.65k CT = 560pF 16 VCC (V) VRT/CT = 2V RT/CT DISCHARGE CURRENT (mA) 540 10 OSCILLATOR RT/CT DISCHARGE CURRENT vs. TEMPERATURE MAX16809 toc07 550 70 IREF (mA) OSCILLATOR FREQUENCY (fOSC) vs. TEMPERATURE OSCILLATOR FREQUENCY (kHz) VREF (V) 3.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 8.02 8.00 7.98 7.96 7.94 7.92 7.90 460 7.88 450 -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 (C) TEMPERATURE (C) _______________________________________________________________________________________ 7 MAX16809 Typical Operating Characteristics (VCC = +15V, V+ = 3V to 5.5V, RT = 10k, CT = 3.3nF, VREF = COMP = open, CREF = 0.1F, VFB = 2V, CS = AGND = PGND = 0V. Typical values are at TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +15V, V+ = 3V to 5.5V, RT = 10k, CT = 3.3nF, VREF = COMP = open, CREF = 0.1F, VFB = 2V, CS = AGND = PGND = 0V. Typical values are at TA = +25C, unless otherwise noted.) CT = 1nF 100 CT = 560pF 0.34 CT = 100pF 10 0.28 0.26 1 0.24 0.22 0.20 0.1 -40 -25 -10 5 20 35 50 65 80 95 110 125 10M FREQUENCY (Hz) TEMPERATURE (C) OUT IMPEDANCE vs. TEMPERATURE (RDS_ON NMOS DRIVER) PROPAGATION DELAY FROM CURRENT-LIMIT COMPARATOR TO OUT vs. TEMPERATURE ERROR-AMPLIFIER OPEN-LOOP GAIN AND PHASE vs. FREQUENCY 5 4 3 MAX16809 toc13 80 140 10 120 -15 100 70 60 50 40 30 -115 -140 -165 20 1 10 0 0 0 -20 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) TEMPERATURE (C) COMP VOLTAGE LEVEL TO TURN OFF DEVICE vs. TEMPERATURE SUPPLY CURRENT vs. OSCILLATOR FREQUENCY CT = 100pF 6.0 2.1 ICC (mA) 1.9 5.0 4.5 4.0 1.8 TA = +125C TA = -40C 3.5 1.7 -190 10k 100k 1M 10M 100M SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 720) 5.5 2.0 10 100 1k FREQUENCY (Hz) 2.00 TA = +125C SUPPLY CURRENT (mA) 6.5 0.01 1 MAX16809 toc16 2.2 7.0 MAX16809 toc15 VCC = 15V -90 40 2 2.3 -65 PHASE 60 20 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 GAIN 80 MAX16809 toc17 6 90 GAIN (dB) 7 MAX16809 toc14 100 PROPAGATION DELAY (ns) ISINK = 200mA 8 RDS_ON () 1M TEMPERATURE (C) MAX16809 toc12 9 100k 10k -40 -25 -10 5 20 35 50 65 80 95 110 125 10 CT = 10nF CT = 4.7nF CT = 3.3nF CT = 2.2nF ISOURCE = 100mA TA = +85C 1.95 TA = +25C 1.90 TA = -40C 1.85 3.0 1.6 2.5 1.5 8 1.80 2.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 20 120 220 320 420 520 620 720 820 920 1020 TEMPERATURE (C) FREQUENCY (kHz) 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.0 5.5 PHASE (DEGREES) RT (k) 0.30 RDS_ON () CT = 220pF 0.32 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 MAX16809 toc11 0.36 MAX16809 toc10 0.38 CS THRESHOLD (V) 1000 MAX16809 toc09 0.40 OUT IMPEDANCE vs. TEMPERATURE (RDS_ON PMOS DRIVER) TIMING RESISTANCE vs. OSCILLATOR FREQUENCY CURRENT-SENSE TRIP THRESHOLD vs. TEMPERATURE VCOMP (V) MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller MAX16809 toc18 45 TA = +125C 3.65 TA = +85C 3.60 TA = +25C TA = -40C 3.55 40 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 3.70 SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS ON, RSET = 720) MAX16809 toc19 SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 360) TA = +85C TA = +125C 35 30 25 TA = +25C 20 TA = -40C 15 3.50 3.5 4.0 4.5 5.0 3.0 5.5 3.5 4.0 TA = -40C 25 OUT_ _ CURRENT (mA) 30 25 TA = +25C 20 TA = +25C TA = +85C 15 TA = +125C 10 5 TA = -40C 0 15 3.0 3.5 4.0 4.5 5.0 0 5.5 0.5 1.0 1.5 2.0 2.5 OUT_ _ CURRENT vs. OUT_ _ VOLTAGE (RSET = 720, V+ = 5.0V) 60 30 MAX16809 toc22 OUT_ _ CURRENT vs. OUT_ _ VOLTAGE (RSET = 360, V+ = 3.3V) TA = -40C TA = +25C TA = +85C 30 TA = +125C 20 TA = -40C 25 OUT_ _ CURRENT (mA) 50 40 3.0 OUT_ _ VOLTAGE (V) SUPPLY VOLTAGE (V) OUT_ _ CURRENT (mA) 5.5 MAX16809 toc23 SUPPLY CURRENT (mA) TA = +85C 35 20 30 MAX16809 toc20 45 TA = +125C 5.0 OUT_ _ CURRENT vs. OUT_ _ VOLTAGE (RSET = 720, V+ = 3.3V) SUPPLY CURRENT vs. SUPPLY VOLTAGE (INTERFACE IDLE, ALL OUTPUTS ON, RSET = 360) 40 4.5 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) MAX16809 toc21 3.0 20 TA = +25C TA = +85C 15 TA = +125C 10 5 10 0 0 0 0.5 1.0 1.5 2.0 OUT_ _ VOLTAGE (V) 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 OUT_ _ VOLTAGE (V) _______________________________________________________________________________________ 9 MAX16809 Typical Operating Characteristics (continued) (VCC = +15V, V+ = 3V to 5.5V, RT = 10k, CT = 3.3nF, VREF = COMP = open, CREF = 0.1F, VFB = 2V, CS = AGND = PGND = 0V. Typical values are at TA = +25C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +15V, V+ = 3V to 5.5V, RT = 10k, CT = 3.3nF, VREF = COMP = open, CREF = 0.1F, VFB = 2V, CS = AGND = PGND = 0V. Typical values are at TA = +25C, unless otherwise noted.) OUT_ _ CURRENT vs. V+ (RSET = 720, VOUT = 2V) OUT_ _ CURRENT vs. OUT_ _ VOLTAGE (RSET = 360, V+ = 5.0V) OUT_ _ CURRENT (mA) 40 OUT_ _ CURRENT (mA) TA = +25C TA = +85C 30 TA = +125C 20 MAX16809 toc25 TA = -40C 50 25.0 MAX16809 toc24 60 24.5 TA = +85C TA = +125C 24.0 TA = +25C TA = -40C 23.5 10 0 23.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.0 3.5 OUT_ _ VOLTAGE (V) TA = +85C 5.5 MAX16809 toc27 40 30 20 10 TA = +125C 46 0 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 10 5.0 50 OUT_ _ CURRENT (mA) TA = +25C TA = -40C 47 4.5 OUT_ _ CURRENT vs. SET RESISTANCE (V+ = 5.0V) MAX16809 toc26 49 48 4.0 SUPPLY VOLTAGE (V) OUT_ _ CURRENT vs. V+ (RSET = 360, VOUT = 2V) OUT_ _ CURRENT (mA) MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller 5.0 5.5 0 1 2 3 SET RESISTANCE (k) ______________________________________________________________________________________ 4 5 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller PIN NAME 1, 31, 32, 36, 38 N.C. 2 FB 3 COMP 4-11 FUNCTION No Connection. Not internally connected. Leave unconnected. Error-Amplifier Inverting Input Error-Amplifier Output OUT8-OUT15 LED Driver Outputs. OUT8-OUT15 are open-drain, constant-current-sinking outputs rated for 36V. Active-Low, Output Enable Input. Drive OE low to PGND to enable the OUT0-OUT15. Drive OE high to disable OUT0-OUT15. 12 OE 13 DOUT 14 SET LED Current Setting. Connect RSET from SET to PGND to set the LED current. LED Driver Positive Supply Voltage. Bypass V+ to PGND with a 0.1F ceramic capacitor. 15 V+ 16, 17 PGND 18 DIN 19 CLK 20 LE 21-28 OUT0-OUT7 29 RTCT Serial-Data Output. Data is clocked out of the 16-bit internal shift register to DOUT on CLK's rising edge. Power Ground Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK's rising edge. Serial-Clock Input Latch-Enable Input. Data is loaded transparently from the internal shift register(s) to the output latch(es) while LE is high. Data is latched into the output latch(es) on LE's falling edge, and retained while LE is low. LED Driver Outputs. OUT0-OUT7 are open-drain, constant-current-sinking outputs rated for 36V. PWM Controller Timing Resistor/Capacitor Connection. A resistor RT from RTCT to REF and a capacitor CT from RTCT to AGND set the oscillator frequency. 30 CS 33 AGND 34 OUT MOSFET Driver Output OUT. Connects to the gate of the external n-channel MOSFET. 35 VCC Power-Supply Input. Bypass VCC to AGND with a 0.1F ceramic capacitor or a parallel combination of a 0.1F and a higher value ceramic capacitor. 37 REF -- EP PWM Controller Current-Sense Input Analog Ground 5V Reference Output. Bypass REF to AGND with a 0.1F ceramic capacitor. Exposed Paddle. Connect to the ground plane for improved power dissipation. Do not use as the only ground connection. Detailed Description The MAX16809 LED driver includes an internal switchmode controller that can be used as a boost or buckboost (SEPIC) converter to generate the voltage necessary to drive the multiple strings of LEDs. This device incorporates an integrated low-side driver, a programmable oscillator (20kHz to 1MHz), an error amplifier, a low-voltage (300mV) current sense for higher efficiency, and a 5V reference to power up external circuitry (see Figures 1a and 1b). The MAX16809 LED driver includes a 4-wire serial interface and a current-mode PWM controller to generate the necessary voltage for driving 16 open-drain, constant-current-sinking output ports. The driver uses current-sensing feedback circuitry (not simple current mirrors) to ensure very small current variations over the full allowed range of output voltage (see the Typical Operating Characteristics). The 4-wire serial interface comprises a 16-bit shift register and a 16-bit transparent latch. The shift register is written through a clock input, CLK, and a data input, DIN, and the data propagates to a data output, DOUT. The data output allows multiple drivers to be cascaded and operated together. The contents of the 16-bit shift register are loaded into the transparent latch through a latch-enable input, LE. The latch is transparent to the shift register outputs when high and latches the current state on the falling edge of LE. Each driver output is an open-drain, constant-current sink that should be connected to the ______________________________________________________________________________________ 11 MAX16809 Pin Description cathode of a string of LEDs connected in series. The constant-current capability is up to 55mA per output, set for all 16 outputs by an external resistor, RSET. The device can operate in a stand-alone mode (see the Typical Operating Circuits). The number of channels can be expanded by using the MAX6970 and MAX6971 family in conjunction with the MAX16809. UVLO REFERENCE 2.5V VOLTAGEDIVIDER PREREG 5V VCC 26.5V THERMAL SHUTDOWN EN_REF MAX16809 BG SNS VDD REF 5V REG REG_OK DELAY VOLTAGE DIVIDER AGND VCC 300mV ILIM S R OUT Q CS CPWM 2R VEA CLK FB COMP R OSC Q RTCT CLK SERIAL-TO-PARALLEL SHIFT REGISTER DIN D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D9 D10 D11 D12 D13 D14 D15 DOUT OUTPUT LATCHES LE D0 D1 D2 D3 D4 D5 D6 D7 D8 POWER-ON RESET V+ OE V+ CONSTANT-CURRENT SINK THERMAL SHUTDOWN D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 CURRENT REFERENCE OUT15 OUT14 OUT13 OUT12 OUT11 OUT10 OUT9 OUT8 OUT7 OUT6 OUT5 OUT4 OUT3 OUT2 OUT1 PGND OUT0 MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller Figure 1a. Internal Block Diagram 12 ______________________________________________________________________________________ SET Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller MAX16809 68W/L 1.23V W/L OUT_ _ 1.23 REST 945R R SET PGND pMOS typically 3.5 and the on-resistance of the nMOS typically 4.5. The driver can source 2A and sink 1A typically. This allows for the MAX16809 to quickly turn on and off high gate-charge MOSFETs. Bypass VCC with one or more 0.1F ceramic capacitors to AGND, placed close to VCC. The average current sourced to drive the external MOSFET depends on the total gate charge (QG) and operating frequency of the converter. The power dissipation in the MAX16809 is a function of the average output drive current (IDRIVE). Use the following equation to calculate the power dissipation in the device due to IDRIVE: IDRIVE = (QG x fSW) PD = (IDRIVE + ICC) x VCC where I CC is the operating supply current. See the Typical Operating Characteristics for the operating supply current at a given frequency. Figure 1b. OUT_ _ Driver Internal Diagram Error Amplifier Switch-Mode Controller Current-Mode Control Loop The advantages of current-mode control over voltagemode control are twofold. First, there is the feed-forward characteristic brought on by the controller's ability to adjust for variations in the input voltage on a cycleby-cycle basis. Second, the stability requirements of the current-mode controller are reduced to that of a single-pole system unlike the double pole in the voltagemode control scheme. The MAX16809 uses a current-mode control loop where the output of the error amplifier is compared to the current-sense voltage (VCS). When the current-sense signal is lower than the inverting input of the CPWM comparator, the output of the comparator is low and the switch is turned on at each clock pulse. When the current-sense signal is higher than the inverting input of the CPWM comparator, the output is high and the switch is turned off. Undervoltage Lockout (UVLO) The turn-on supply voltage for the MAX16809 is 8.4V (typ). Once VCC reaches 8.4V, the reference powers up. There is a 0.8V of hysteresis from the turn-on voltage to the UVLO threshold. Once V CC reaches 8.4V, the MAX16809 operates with VCC down to 7.6V. Once VCC goes below 7.6V (typ), the device is in UVLO. When in UVLO, the quiescent supply current into VCC falls back to 32A (typ), and OUT and REF are pulled low. MOSFET Driver OUT drives an external n-channel MOSFET and swings from AGND to VCC. Ensure that VCC remains below the absolute maximum VGS rating of the external MOSFET. OUT is a push-pull output with the on-resistance of the The MAX16809 includes an internal error amplifier. The inverting input is at FB and the noninverting input is internally connected to a 2.5V reference. Set the output voltage using a resistive divider between output of the converter VOUT, FB, and AGND. Use the following formula to set the output voltage: R1 VOUT = 1 + x VFB R2 where VFB = 2.5V. Oscillator The oscillator frequency is programmable using an external capacitor and a resistor at RTCT (see RT and CT in the Typical Operating Circuits). RT is connected from RTCT to the 5V reference (REF), and CT is connected from RTCT to AGND. REF charges CT through RT until its voltage reaches 2.8V. CT then discharges through an 8.3mA internal current sink until CT's voltage reaches 1.1V, at which time CT is allowed to charge through RT again. The oscillator's period is the sum of the charge and discharge times of CT. Calculate the charge time as follows: tC = 0.57 x RT x CT where t C is in seconds, R T in ohms (), and C T in Farads (F). The discharge time is then: tD = (RT x CT x 1000) / [(4.88 x RT) - (1.8 x 1000)] where t D is in seconds, R T in ohms (), and C T in Farads (F). ______________________________________________________________________________________ 13 MAX16809 V+ MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller The oscillator frequency is then: R CS = 1 f OSC = ( tC + tD ) Reference Output REF is a 5V reference output that can source 20mA. Bypass REF to AGND with a 0.1F capacitor. Current Limit The MAX16809 includes a fast current-limit comparator to terminate the ON cycle during an overload or a fault condition. The current-sense resistor, RCS, connected between the source of the external MOSFET and AGND, sets the current limit. The CS input has a voltage trip level (VCS) of 0.3V. Use the following equation to calculate RCS: VIN C1 L1 VCS IP -P IP-P is the peak current that flows through the MOSFET. When the voltage produced by this current (through the current-sense resistor) exceeds the current-limit comparator threshold, the MOSFET driver (OUT) turns the switch off within 60ns. In most cases, a small RC filter is required to filter out the leading-edge spike on the sense waveform. Set the time constant of the RC filter at 50ns. Buck-Boost (SEPIC) Operation Figure 2 shows a buck-boost application circuit using the MAX16809 in a stand-alone mode of operation. SEPIC topology is necessary when the total forward voltage of the LEDs in a string is such that VOUT can be below or above VIN. VOUT D COUT L2 Q1 R1 CC2 RCS CC1 RC1 R2 OUT CS AGND COMP VCC FB CIN 3V TO 5.5V OUT0 V+ OUT1 CBYP OUT2 PGND OUT3 DIN LE EXTERNAL CLOCK INPUT EXTERNAL DIM INPUT OUT4 MAX16809 OUT5 OUT6 OUT7 OUT8 CLK DOUT OE OUT9 OUT10 OUT11 OUT12 OUT13 OUT14 OUT15 SET RTCT REF RT RSET CREF CT Figure 2. Buck-Boost (SEPIC) Operation 14 ______________________________________________________________________________________ Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller LE is the latch-enable input of the MAX16809 that transfers data from the 16-bit shift register to its 16-bit output latches (transparent latch). The data latches on the falling edge of LE (Figure 4). The fourth input (OE) provides output-enable control of the output drivers. When OE is driven high, the outputs (OUT0-OUT15) are forced to high impedance without altering the contents of the output latches. Driving OE low enables the outputs to follow the state of the output latches. OE is independent of the serial interface operation. Data can be shifted into the serial-interface shift register and latched, regardless of the state of OE. DOUT is the serial-data output that shifts data out from the MAX16809's 16-bit shift register on the rising edge of CLK. Data at DIN propagates through the shift register and appears at DOUT 16 clock cycles later. Table 1 shows the 4-wire serial-interface truth table. 4-Wire Interface The MAX16809 also operates in a stand-alone mode (see the Typical Operating Circuits). For use with a microcontroller, the MAX16809 features a 4-wire serial interface using DIN, CLK, LE, OE inputs and DOUT as a data output. This interface is used to write the LED channels' data to the MAX16809. The serial-interface data word length is 16 bits, D0-D15. See Figure 3. The functions of the five interface pins are as follows: DIN is the serial-data input, and must be stable when it is sampled on the rising edge of CLK. Data is shifted in MSB first. This means that data bit D15 is clocked in first, followed by 15 more data bits, finishing with the LSB, D0. CLK is the serial-clock input that shifts data at DIN into the MAX16809's 16-bit shift register on its rising edge. Table 1. 4-Wire Serial-Interface Truth Table BLANKING OUTPUT CONTENTS SERIAL CLOCK SHIFT REGISTER CONTENTS LOAD LATCH CONTENTS INPUT INPUT INPUT CURRENT AT OUT_ _ DATA INPUT CLK D0 D1 D2 ... Dn-1 Dn LE D0 D1 D2 ... Dn-1 Dn OE D0 D1 D2 ... Dn-1 Dn DIN H H R0 R1 ... Rn-2 Rn-1 L L R0 R1 ... Rn-2 Rn-1 X R0 R1 R2 ... Rn-1 X X X P0 P1 P2 ... Pn-1 ... X Rn X L R0 R1 R2 ... Rn-1 Rn Pn H P0 P1 P2 ... Pn-1 Pn L P0 X X X ... H L X X P1 P2 L L ... Pn-1 Pn ... L L L = Low Logic Level H = High Logic Level X = Don't Care P = Present State (Shift Register) R = Previous State (Latched) ______________________________________________________________________________________ 15 MAX16809 LED Driver MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller LE tLW tCL tCH tLS tCP CLK tDH tDS D15 DIN D14 D1 D0 tDO D15 DOUT tOEW OE tOEF tOER 80% OUT_ _ 20% tF tR Figure 3. 4-Wire Serial-Interface Timing Diagram Selecting External Component RSET to Set LED Output Current LE tLRF OUT_ _ LE tLRR OUT_ _ The MAX16809 uses an external resistor, RSET, to set the LED current for outputs OUT0-OUT15. The minimum allowed value of RSET is 311, which sets the output currents to 55mA. The maximum allowed value of R SET is 5k (I OUT_ _ = 3.6mA) and the maximum allowed capacitance at SET is 100pF. Use the following formula to set the output current: R SET = 17,100V IOUT _ _ CLK tCRF OUT_ _ where IOUT_ _ is the desired output current in milliamps and the value for RSET is in ohms. Overtemperature Cutoff CLK tCRR OUT_ _ Figure 4. LE and CLK to OUT_ _ Timing 16 The MAX16809 contains an internal temperature sensor that turns off all outputs when the die temperature exceeds +165C. The outputs are enabled again when the die temperature drops below +140C. Register contents are not affected, so when a driver is overdissipating, the external symptom is the load LEDs cycling on and off as the driver repeatedly overheats and cools, alternately turning itself off and then back on again. ______________________________________________________________________________________ Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller LED Dimming PWM Dimming All the output channels can be dimmed simultaneously by applying a PWM signal (50Hz to 30kHz) to OE. This allows for a wide range of dimming up to a 5000:1 ratio. Each channel can be independently turned on and off using a 4-wire serial interface. The dimming is proportional to the PWM duty cycle. LED Current Amplitude Adjustment Using an analog or digital potentiometer as RSET allows for LED current amplitude adjustment and linear dimming. Computing Power Dissipation where: V+ = supply voltage I+ = V+ operating supply current DUTY = PWM duty cycle applied to OE VOUTi = MAX16809 port output voltage when driving load LED(s) IOUTi = LED drive current programmed by RSET PD = power dissipation PCB Layout Guidelines Careful PCB layout is critical to achieve low switching losses and clean, stable operation. Use a multilayer board whenever possible for better noise immunity. Protect sensitive analog grounds by using a star ground configuration. Minimize ground noise by connecting AGND, PGND, the input bypass-capacitor ground lead, and the output-filter ground lead to a single point (star ground configuration). Also, minimize trace lengths to reduce stray capacitance, trace resistance, and radiated noise. The trace between the output voltage-divider and the FB pin must be kept short, as well as the trace between AGND and PGND. Use the following equation to estimate the upper limit power dissipation (PD) for the MAX16809: i = 15 PD = DUTY x (V + x I+) + VOUTi x I OUTi i=0 + (VCC x I CC) ______________________________________________________________________________________ 17 MAX16809 Stand-Alone Operation In stand-alone operation, the MAX16809 does not use the 4-wire interface (see the Typical Operating Circuits). Connect DIN and LE to V+ and provide at least 16 external clock pulses to CLK to enable 16 output ports. This startup pulse sequence can be provided either using an external clock or the PWM signal. The external clock can also be generated using the signal at RTCT and an external comparator. Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller MAX16809 Typical Operating Circuits (continued) VIN L VOUT D LEDs COUT R1 CC2 RCS CC1 RC1 R2 OUT CS AGND COMP VCC FB CIN 3V TO 5.5V OUT0 V+ OUT1 CBYP OUT2 PGND OUT3 OUT4 MAX16809 OUT5 OUT6 SCLK C MOSI MISO LOAD ENABLE OUT7 OUT8 CLK DIN DOUT OUT9 OUT10 LE OE OUT11 OUT12 OUT13 OUT14 SET OPERATION WITH MICROCONTROLLER RT RSET CREF 18 OUT15 RTCT REF CT ______________________________________________________________________________________ Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller Chip Information LE OUT0 OUT1 OUT2 OUT3 OUT4 OUT5 OUT6 OUT7 CS N.C. RTCT PROCESS: BiCMOS TOP VIEW 31 30 29 28 27 26 25 24 23 22 21 20 N.C. 32 19 CLK Package Information AGND 33 18 DIN 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. OUT 34 17 PGND VCC 35 16 PGND MAX16809 N.C. 36 15 V+ REF 37 14 SET N.C. 38 13 DOUT 9 10 11 12 PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 38 TQFN-EP T3857-1 21-0172 OE 8 OUT15 OUT9 7 OUT14 OUT8 6 OUT13 5 OUT12 4 OUT11 3 OUT10 2 FB N.C. 1 COMP + TQFN ______________________________________________________________________________________ 19 MAX16809 Pin Configuration MAX16809 Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller Revision History REVISION NUMBER REVISION DATE 0 10/06 1 3/07 Released the MAX16810 on the data sheet. 2 8/09 Removed the MAX16810 from the data sheet. DESCRIPTION Initial release PAGES CHANGED -- 1, 14, 16, 22, 23 1-20 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. 20 ____________________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.