19-0706; Rev 0; 12/06 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming The MAX16819/MAX16820, step-down constant-current high-brightness LED (HB LED) drivers provide a costeffective solution for automotive interior/exterior lighting, architectural and ambient lighting, LED bulbs such as MR16 and other LED illumination applications. The MAX16819/MAX16820 operate from a 4.5V to 28V input voltage range and feature a 5V/10mA on-board regulator. A high-side current-sense resistor adjusts the output current and a dedicated PWM input (DIM) enables a wide range of pulsed dimming. The MAX16819/MAX16820 are well suited for applications requiring a wide input voltage range. The high-side current-sensing and an integrated current-setting circuitry minimize the number of external components while delivering an LED current with ±5% accuracy. A hysteretic control algorithm ensures excellent input-supply rejection and fast response during load transients and PWM dimming. The MAX16819 features a 30% inductor current ripple and the MAX16820 features a 10% current ripple. These devices operate up to 2MHz switching frequency, thus allowing for small component size. The MAX16819/MAX16820 operate over the -40°C to +125°C automotive temperature range and are available in 3mm x 3mm x 0.8mm, 6-pin TDFN packages. Applications Architectural, Industrial, and Ambient Lighting Features ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ High-Side Current Sense Dedicated Dimming Control Input 20kHz Maximum Dimming Efficiency Hysteretic Control: No Compensation Up to 2MHz Switching Frequency ±5% LED Current Accuracy Adjustable Constant LED Current 4.5V to 28V Input Voltage Range Over 25W Output Power 5V, 10mA On-Board Regulator -40°C to +125°C Operating Temperature Range Ordering Information PART PIN-PACKAGE PKG CODE TOP MARK MAX16819ATT+T 6 TDFN–EP* T633-2 +ATB MAX16820ATT+T 6 TDFN-EP* T633-2 +ATC Note: All devices are specified over the -40°C to +125°C operating temperature range. +Denotes lead-free package. *EP = Exposed paddle. Automotive RCL, DRL, and Fog Lights MR16 and Other LED Bulbs Typical Operating Circuit Indicators and Emergency Lighting VIN RSENSE Pin Configuration VCC DRV GND TOP VIEW 6 5 4 L CIN CVCC MAX16819 MAX16820 CSN + MAX16819 MAX16820 DRV 3 DIM 2 CSN IN 1 VCC IN DIM GND TDFN ________________________________________________________________ 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 MAX16819/MAX16820 General Description MAX16819/MAX16820 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming ABSOLUTE MAXIMUM RATINGS IN, CSN, DIM to GND .............................................-0.3V to +30V VCC, DRV to GND ....................................................-0.3V to +6V CSN to IN...............................................................-0.3V to +0.3V Maximum Current into Any Pin (except IN, VCC, and DRV)............................................±20mA Continuous Power Dissipation (TA = +70°C) 6-Pin TDFN (derate 18.17mW/oC* above +70°C).......1454mW 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 Pin-to-Pin ESD Ratings (HB Model).....................................2.5kV *As per JEDEC51 Standard (Single-Layer 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 (VIN = 12V, VDIM = VIN, CVCC = 1µF, RSENSE = 0.5Ω, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Input Voltage Range VIN Maximum Current Regulator Switching Frequency fSW Ground Current IGND Supply Current IIN Undervoltage Lockout UVLO CONDITIONS MIN TYP MAX UNITS 28.0 V 2 MHz DRV open 1.5 mA VDIM < 0.6V 425 µA 4.5 VIN = VCSN = VDIM, VIN rising from 4V until VDRV > VCC - 0.5V 4.7 5.0 V VIN = VCSN = VDIM, VIN falling from 6V, VDRV < 0.5V 4.5 Undervoltage Lockout Hysteresis 0.5 V SENSE COMPARATOR Sense Voltage Threshold High Sense Voltage Threshold Low VSNSHI VSNSLO (VIN - VCSN) rising from 0V until VDRV < 0.5V (MAX16820) 195 210 225 (VIN - VCSN) rising from 0V until VDRV < 0.5V (MAX16819) 213 230 246 (VIN - VCSN) falling from 0.26V until VDRV > (VCC - 0.5V) (MAX16820) 176 190 204 (VIN - VCSN) falling from 0.26V until VDRV > (VCC - 0.5V) (MAX16819) 158 170 182 mV mV Propagation Delay to Output High tDPDH Falling edge of (VIN - VCSN) from 0.26V to 0V to DRV high, CDRV = 1nF 82 ns Propagation Delay to Output Low tDPDL Rising edge of (VIN - VCSN) from 0V to 0.26V to DRV low, CDRV = 1nF 82 ns Current-Sense Input Current ICSN (VIN - VCSN) = 200mV Current-Sense Threshold Hysteresis 2 CSHYS 1 µA MAX16819 56 70 mV MAX16820 17 35 mV _______________________________________________________________________________________ 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming (VIN = 12V, VDIM = VIN, CVCC = 1µF, RSENSE = 0.5Ω, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS GATE DRIVER Gate Driver Source Current VCSN = VIN, VDRV = 0.5 x VCC Gate Driver Sink Current VCSN = VIN - 250mV, VDRV = 0.5 x VCC Gate Driver Output-Voltage High VOH IDRV = 10mA Gate Driver Output-Voltage Low VOL IDRV = -10mA 0.5 A 1 A VCC - 0.5 V 0.5 V 20 kHz DIM INPUT Maximum DIM Frequency fDIM DIM Input-Voltage High VIH VCSN = VIN, increase DIM until VDRV > (VCC - 0.5V) DIM Input-Voltage Low VIL VCSN = VIN, decrease DIM until VDRV < 0.5V DIM Hysteresis DIMHYS DIM Turn-On Time tDIMON DIM Turn-Off Time tDIMOFF 2.8 V 0.6 V 200 mV DIM rising edge to VDRV = 0.5 x VCC, CDRV = 1nF 100 ns DIM falling edge to VDRV = 0.5 x VCC, CDRV = 1nF 100 ns DIM Input Leakage High VDIM = VIN 10 µA DIM Input Leakage Low VDIM = 0V -1 +1 µA IVCC = 0.1mA to 10mA, VIN = 5.5V to 28V 4.5 5.5 V IVCC = 0.1mA to 10mA, VIN = 4.5V to 28V 4.0 5.5 VCC REGULATOR Regulator Output Voltage VCC Load Regulation Line Regulation Power-Supply Rejection Ratio Current Limit PSRR ILIM Regulator Startup Time tSTRAT V 4 Ω VIN = 6V to 28V, IVCC = 10mA 11 mV VIN = 12V, IVCC = 5mA, fIN = 10kHz -35 dB VIN = 4.5V, VCC = 0V 45 mA VIN = 4.5V, VCC = 4V 18 mA VCC = 0 to 4.5V 350 µs IVCC = 0.1mA to 10mA, VIN = 12V Note 1: All devices are 100% production tested at TJ = +25°C and +125°C. Limits to -40°C are guaranteed by design. _______________________________________________________________________________________ 3 MAX16819/MAX16820 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VIN = VDIM = 12V, CVCC = 1µF, RSENSE = 0.5Ω connected between IN and CSN. Typical values at TA = +25°C, unless otherwise noted.) DRV SWITCHING FREQUENCY vs. VIN LED 3 80 LED 2 70 65 LED 1 60 5 10 15 20 LED 1 L = 47µH 30 25 4 VIN (V) 8 12 16 20 24 ILED(NOMINAL) = 400mA L = 47µH 1.5 1.0 LED 1 LED 2 0.5 0 -0.5 -1.0 -1.5 LED 4 LED 3 VCC vs. VIN 28 5 10 15 MAX16819 toc04 5.40 5.3 5.38 5.37 5.1 5.36 VCC (V) 5.2 5.0 5.34 4.8 5.33 4.7 5.32 VIN = 12V 4.5 300 250 200 150 100 50 5.31 ILED = 0 VDIM = 0V 5.30 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 27.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 VIN (V) TEMPERATURE (°C) PWM DIMMING AT 200Hz (10% DUTY CYCLE) VDIM = 0V 0 4.5 8.5 12.5 16.5 MAX16819 toc07 24.5 MAX16819 toc08 VIN = 12V, L = 47µH, 1 LED MAX16819 VDIM 2V/div VDIM 2V/div 0V 0V ILED 200mA/div ILED 200mA/div 0A 4 20.5 VIN (V) PWM DIMMING AT 200Hz (90% DUTY CYCLE) VIN = 12V, L = 47µH, 1 LED MAX16819 1ms/div 30 25 SUPPLY CURRENT vs. VIN 5.35 4.9 4.6 VIN = 24V 5.39 20 VIN (V) VCC vs. TEMPERATURE 5.4 LED 5 -2.0 VIN (V) 5.5 MAX16819 toc03 2.0 MAX16819 toc06 75 LED 2 SUPPLY CURRENT (µA) 85 LED 3 MAX16819 toc05 EFFICIENCY (%) 90 LED 5 LED 4 LED CURRENT VARIATION vs. VIN LED CURRENT VARIATION FROM SET CURRENT (%) L = 47µH LED 4 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 MAX16819 toc02 LED 5 95 DRV SWITCHING FREQUENCY (kHz) 100 MAX16819 toc01 EFFICIENCY vs. VIN VCC (V) MAX16819/MAX16820 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming 0A 1ms/div _______________________________________________________________________________________ 28.5 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming PWM DIMMING AT 200Hz (1% DUTY CYCLE) PWM DIMMING EXPANDED (50% DUTY CYCLE) MAX16819 toc09 VIN = 12V, L = 47µH, 1 LED MAX16819 MAX16819 toc11 VIN = 24V, L = 33µH, 4 LEDS MAX16820 VIN = 12V, L = 47µH, 1 LED MAX16819 VDIM 2V/div VDIM 2V/div VDIM 2V/div 0V 0V 0V ILED 200mA/div ILED 200mA/div ILED 200mA/div 0A 0A 0A 10µs/div 1µs/div PWM DIMMING AT 20kHz (10% DUTY CYCLE) PWM DIMMING AT 20kHz (90% DUTY CYCLE) 4µs/div VDIM 2V/div VDIM 2V/div 0V 0V ILED 200mA/div ILED 200mA/div 0A 0A 10µs/div 2.0 ILED(NOMINAL) = 400mA L = 47µH 1.5 1.0 MAX16819 toc14 VIN = 24V, L = 33µH, 4 LEDS MAX16820 VIN = 24V, L = 47µH, 4 LEDS MAX16820 LED CURRENT VARIATION FROM SET CURRENT (%) ILED VARIATION vs. TEMPERATURE MAX16819 toc13 MAX16819 toc12 10µs/div PWM DIMMING EXPANDED (50% DUTY CYCLE) MAX16819 toc10 VIN = 24V 0.5 0 -0.5 -1.0 VIN = 12V -1.5 VDIM = 0V -2.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX16819/MAX16820 Typical Operating Characteristics (continued) (VIN = VDIM = 12V, CVCC = 1µF, RSENSE = 0.5Ω connected between IN and CSN. Typical values at TA = +25°C, unless otherwise noted.) 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming MAX16819/MAX16820 Pin Description PIN NAME 1 IN FUNCTION 2 CSN Current-Sense Input 3 DIM Logic-Level Dimming Input. Drive DIM low to turn off the current regulator. Drive DIM high to enable the current regulator. 4 GND Ground 5 DRV Gate Drive Output. Connect to the gate of an external n-channel MOSFET. 6 VCC Voltage Regulator Output. Connect a 1µF capacitor from VCC to GND. EP — Positive Supply Voltage Input. Bypass with a 1µF or higher value capacitor to GND. Exposed Paddle. Connect to a large-area ground plane for improved power dissipation. Do not use as the only ground connection for the device. Functional Diagram REGULATOR IN VCC + CS COMPARATOR CSN GATE DRIVER 1.23V BANDGAP REF DRV + - UVLO COMPARATOR GND DIM DIM BUFFER Detailed Description The MAX16819/MAX16820 are step-down, constantcurrent, high-brightness LED (HB LED) drivers. These devices operate from a 4.5V to 28V input voltage range and provide up to 0.5A of source and 1A of sink drive capability to the gate of an external MOSFET. A highside current-sense resistor sets the output current and 6 MAX16819 MAX16820 a dedicated PWM dimming input (DIM) allows for a wide range of independent pulsed dimming. The high-side current-sensing scheme and on-board current-setting circuitry minimize the number of external components while delivering LED current with a ±5% accuracy, using a 1% sense resistor. See the Functional Diagram. _______________________________________________________________________________________ 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming 5V Regulator VCC is the output of a 5V regulator capable of sourcing 10mA. Bypass VCC to GND with a 1µF capacitor. DIM Input The MAX16819/MAX16820 allow dimming with a PWM signal at the DIM input. A logic level below 0.6V at DIM forces the MAX16819/MAX16820’s DRV output low, turning off the LED current. To turn the LED current on, the logic level at DIM must be at least 2.8V. Applications Information Selecting RSENSE to Set the LED Current The MAX16819/MAX16820 feature a programmable LED current using a resistor connected between IN and CSN. Use the following equation to calculate the sense resistor: RSENSE (Ω) = 1 (VSNSHI + VSNSLO )(V ) 2 ILED (A ) For the values of VSNSHI and VSNSLO, see the Electrical Characteristics. Current Regulator Operation The MAX16819/MAX16820 regulate the LED output current using an input comparator with hysteresis (Figure 1). As the current through the inductor ramps up and the voltage across the sense resistor reaches the upper threshold, the voltage at DRV goes low, turning off the external MOSFET. The MOSFET turns on again when the inductor current ramps down through the freewheeling diode until the voltage across the sense resistor equals the lower threshold. Use the following equation to determine the operating frequency: fSW = (VIN − n × VLED ) × n × VLED × RSENSE VIN × ∆V × L where n = number of LEDs, VLED = forward voltage drop of one LED, and ∆V = (VSNSHI - VSNSLO). For proper component selection, please use the design tool available at: http://www.maxim-ic.com/MAX1681920-Tool. HYSTERETIC MODE TSW = 1 fSW ILED ∆I AVG. LED CURRENT t VDIM t Figure 1. Current Regulator Operation _______________________________________________________________________________________ 7 MAX16819/MAX16820 Undervoltage Lockout (UVLO) The MAX16819/MAX16820 include a 4.5V undervoltage lockout (UVLO) with 500mV hysteresis. When VIN falls below 4.5V, DRV goes low, turning off the external n-channel MOSFET. DRV goes high once VIN is 5V or higher. MAX16819/MAX16820 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming MOSFET Selection PCB Layout Guidelines The MAX16819/MAX16820’s gate driver is capable of sourcing 0.5A and sinking 1A of current. MOSFET selection is based on the maximum input operating voltage VIN, output current ILED, and operating switching frequency. Choose a MOSFET that has a higher breakdown voltage than the maximum operation voltage, low R DS(ON), and low total charge for better efficiency. MOSFET threshold voltage must be adequate if operated at the low end of the input-voltage operating range. Careful PCB layout is critical to achieve low switching losses and stable operation. Use a multilayer board whenever possible for better noise immunity. Minimize ground noise by connecting high-current ground returns, the input bypass-capacitor ground lead, and the output-filter ground lead to a single point (star ground configuration). In normal operation, there are two power loops. One is formed when the MOSFET is on and the high current flows through IN—RSENSE— LEDs—Inductor—MOSFET—GND. The other loop is formed when the MOSFET is off when the high current circulates through R SENSE —LEDs—Inductor—freewheeling diode. To minimize noise interaction, each loop area should be as small as possible. Place RSENSE as close as possible to the input filter and IN. For better noise immunity, a Kelvin connection is strongly recommended between CSN and RSENSE. Connect the exposed paddle to a large-area ground plane for improved power dissipation. Freewheeling Diode Selection The forward voltage of the freewheeling diode should be as low as possible for better efficiency. A Schottky diode is a good choice as long as the breakdown voltage is high enough to withstand the maximum operating voltage. The forward current rating of the diode must be at least equal to the maximum LED current. LED Current Ripple The LED current ripple is equal to the inductor current ripple. In cases when a lower LED current ripple is needed, a capacitor can be placed across the LED terminals. 8 Chip Information PROCESS: BiCMOS _______________________________________________________________________________________ 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming 6, 8, &10L, DFN THIN.EPS PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm 21-0137 H 1 2 _______________________________________________________________________________________ 9 MAX16819/MAX16820 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.) MAX16819/MAX16820 2MHz High-Brightness LED Drivers with High-Side Current Sense and 5000:1 Dimming 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.) COMMON DIMENSIONS PACKAGE VARIATIONS SYMBOL MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b A 0.70 0.80 T633-1 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF [(N/2)-1] x e E 2.90 3.10 T833-1 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF A1 0.00 0.05 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF L 0.20 0.40 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF 2.00 REF k 0.25 MIN. T1033-1 10 1.50±0.10 A2 0.20 REF. T1033-2 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm -DRAWING NOT TO SCALE- 21-0137 H 2 2 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. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.