19-0589; Rev 0; 7/06 High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control The MAX16804 current regulator operates from a 5.5V to 40V input voltage range and delivers 35mA to 350mA to one or more strings of high-brightness LEDs (HB LEDs). The output current of the MAX16804 is set by using an external current-sense resistor in series with the LEDs. A dual-mode DIM pin and on-board 200Hz ramp generator allow PWM dimming with an analog or PWM input signal. The analog control signal at dimming input DIM allows for a theater-dimming effect to be implemented. Fast turn-on and turn-off times ensure a wide-range PWM operation, while wave-shaping circuitry minimizes EMI. The differential current-sense input increases LED current accuracy and noise immunity. The MAX16804 is well suited for applications requiring high-voltage input and is able to withstand automotive load-dump events up to 45V. An on-board pass element minimizes external components while providing 3% output-current accuracy. Additional features include a 5V regulated output and short-circuit and thermal protection. The MAX16804 is available in a thermally enhanced, 5mm x 5mm, 20-pin TQFN package and is specified over the automotive -40°C to +125°C temperature range. Applications Automotive Interior: Map, Dome, and Courtesy Lighting Automotive Exterior: Rear Combination Light (RCL) Daytime Running Light (DRL) Adaptive Front Light Warning Lights for Emergency Vehicles Navigation and Marine Indicators Signage, Canopies, and Beacons Features ♦ Flexible Dimming Control, Analog or PWM Control Signal for PWM and Theater Dimming ♦ 200Hz On-Board Ramp Generator ♦ Sinks to External PWM Signal (Up to 2kHz) ♦ 5.5V to 40V Operating Range ♦ 35mA to 350mA Adjustable LED Current ♦ 3% LED Current Accuracy ♦ High-Voltage (Up to 40V) DIM Pin ♦ Integrated Pass Element with Low-Dropout Voltage (0.5V typ) ♦ Additional +5V On-Board Regulator with 2mA Capability ♦ Differential LED Current Sense ♦ Low 200mV Current-Sense Reference Reduces Power Losses ♦ Wave-Shaped Edges Minimize EMI During PWM Dimming ♦ Output Short-Circuit and Thermal-Shutdown Protection ♦ Available in Small, Thermally Enhanced, 5mm x 5mm, 20-Pin TQFN Package ♦ -40°C to +125°C Operating Temperature Range Ordering Information PART TEMP RANGE MAX16804ATP+ -40°C to +125°C PINPACKAGE PKG CODE 20 TQFN-EP* T2055M-5 +Denotes lead-free package. *EP = Exposed pad. Pin Configuration appears at end of data sheet. Simplified Diagrams ILED +5.5V TO +40V IN +5.5V TO +40V OUT 0.1μF +5V REG MAX16804 LEDs EN RSENSE GND 0.1μF CS+ DIM CS- ANALOG CONTROL PWM DIMMING +5V REG V5 0.1μF EN OUT 0.1μF V5 V5 ILED IN MAX16804 LEDs CS+ RSENSE PWM DIMMING DIM GND CS- PWM CONTROL DIMMING ________________________________________________________________ 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 MAX16804 General Description MAX16804 High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +45V DIM, OUT, EN to GND .................................-0.3V to (VIN + 0.3V) IN Slew Rate (20V < VIN < 45V) ...................................250mV/µs CS+, V5 to GND .......................................................-0.3V to +6V CS- to GND............................................................-0.3V to +0.3V OUT Short Circuited to GND Duration (at VIN < +16V).................................................................1hour Maximum Current Into Any Pin (except IN and OUT).........±20mA Continuous Power Dissipation (TA = +70°C) 20-Pin TQFN (derate 34.5mW/°C above +70°C) ......2758.6mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = VEN = 12V, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω (see the Typical Operating Circuit), VDIM = 4V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP UNITS Supply Voltage Range VIN (Note 2) 40.0 V Ground Current IG ILOAD = 350mA 2.5 4.5 mA VEN ≤ 0.3V 12 40 µA Shutdown Supply Current Guaranteed Output Current ISHDN IOUT 350 mA 35mA < IOUT < 350mA, not including RSENSE tolerance Output Current Accuracy Dropout Voltage (Note 3) RSENSE = 0.55Ω 5.5 MAX ΔVDO 3 IOUT = 350mA, 12V < VIN < 40V 0.4 1.2 IOUT = 350mA, 6.5V < VIN < 12V 0.5 1.5 Output Current Slew Rate (External PWM Signal at DIM) Current rising, DIM rising to 4V 17 Current falling, DIM falling to 0.6V 17 Short-Circuit Current VOUT = 0V 600 % V mA/µs mA ENABLE INPUT EN Input Current IEN EN Input-Voltage High VIH EN Input-Voltage Low VIL Enable Turn–On Time tON 100 2.8 V 0.6 EN rising edge to 90% of OUT nA 250 V µs CURRENT SENSE (Note 4) Regulated RSENSE Voltage VRSENSE VSENSE = VCS+ - VCS- Input Current (CS+) VCS+ = 220mV Input Current (CS-) VCS+ = 220mV 192 198 204 mV +14 µA -75 µA INTERNAL RAMP GENERATOR Internal Ramp Frequency External Sync Frequency Range fRAMP 180 fDIM 80 200 External Sync Voltage Low External Sync Voltage High 220 Hz 2000 Hz 0.4 V 2.8 V EXTERNAL PWM DIMMING INPUT DIM Input Current 1 µA Turn-On Time tON After DIM rising to 4V (Note 5) 28 52 µs Turn-Off Time tOFF After DIM falling to 0.6V (Note 5) 19 38 µs 2 _______________________________________________________________________________________ High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control (VIN = VEN = 12V, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω (see the Typical Operating Circuit), VDIM = 4V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS THERMAL PROTECTION Thermal-Shutdown Temperature TJ(SHDN) Thermal-Shutdown Hysteresis +155 °C 23 °C +5V REGULATOR Output Voltage Regulation V5 V5 Short-Circuit Current 0 ≤ IV5 ≤ 2mA 4.8 5.1 V5 = 0V (Note 6) 5.4 V 12 mA Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. Note 2: Resistors were added from OUT to CS+ to aid with the power dissipation during testing. Note 3: Dropout is measured as follows: Connect a resistor from OUT to CS+. Connect RSENSE = 0.56Ω from CS+ to CS-. Set VIN = VOUT +3V (record VOUT as VOUT1). Reduce VIN until VOUT = 0.97 x VOUT1 (record as VIN2 and VOUT2). ΔVDO = VIN2 - VOUT2. Note 4: IV5 = 0mA. Note 5: tON time includes the delay and the rise time needed for IOUT to reach 90% of its final value. tOFF time is the time needed for IOUT to drop below 10%. See the Typical Operating Characteristics. tON and tOFF are tested with 13Ω from OUT to CS+. Note 6: Thermal shutdown does not function if the output of the 5V reference is shorted to ground. Shorting V5 to GND disables the output. Typical Operating Characteristics (VIN = 12V, VEN = VIN, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, TA = +25°C, unless otherwise noted.) 300 250 200 150 ILOAD = 200mA ILOAD = 100mA 100 50 MAX16804 toc02 0.201 0.200 0.199 0.198 0.197 0.196 0.195 ILOAD = 35mA 0 400 350 IOUT = 350mA OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) ILOAD = 350mA 350 VIN = 12V 0.202 (VCS+ - VCS-) (V) 400 0.203 MAX16804 toc01 450 OUTPUT CURRENT vs. INPUT VOLTAGE (VCS+ - VCS-) vs. OUTPUT CURRENT MAX16804 toc03 OUTPUT CURRENT vs. TEMPERATURE 300 250 200 150 100 IOUT = 100mA 50 0.194 0.193 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 20 50 80 110 140 170 200 230 260 290 320 350 TEMPERATURE (°C) OUTPUT CURRENT (mA) 0 14 16 _______________________________________________________________________________________ 3 2 4 6 8 10 12 INPUT VOLTAGE (V) MAX16804 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = 12V, VEN = VIN, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, TA = +25°C, unless otherwise noted.) 0.6 0.5 0.4 0.3 0.2 VIN = 20V 20 15 VIN = 12V 10 5 0 0 VIN = 6.5V -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) (VCS+ - VCS-) vs. IV5 200Hz DIMMED OPERATION MAX16804 toc07 ILOAD = 2mA MAX16804 toc09 ILOAD = 350mA VIN = 12V 0.1989 0.1988 (VCS+ - VCS-) (V) 5.10 ILOAD = 1mA VDIM 2V/div 0.1987 0V 0.1986 ILOAD = 350mA VIN = 12V DIM PULSED AT 200Hz (1% DUTY CYCLE) 0.1985 0.1984 0.1983 5.05 ILOAD = 2mA 5.05 -40 -25 -10 5 20 35 50 65 80 95 110 125 0.1990 5.15 5.10 VIN = 12V +5V REGULATOR OUTPUT vs. VIN NO LOAD NO LOAD ILOAD = 1mA 5.15 5.00 TEMPERATURE (°C) 5.20 MAX16804 toc05 25 0.1 -40 -25 -10 5 20 35 50 65 80 95 110 125 VIN = 40V 30 +5V REGULATOR OUTPUT (V) 0.7 35 5.20 MAX16804 toc08 DROPOUT VOLTAGE (V) 0.8 40 SHUTDOWN CURRENT (μA) VIN = 12V ILOAD = 350mA MAX16804 toc04 1.0 0.9 +5V REGULATOR OUTPUT vs. TEMPERATURE SHUTDOWN CURRENT vs. TEMPERATURE ILOAD 200mA/div 0A 0.1982 0.1981 5.00 0.1980 5 10 15 20 25 30 35 40 0 1 2 VIN (V) 3 4 5 6 7 8 9 10 20μs/div IV5 (mA) LED CURRENT FALL TIME (EXPANDED) LED CURRENT RISE TIME (EXPANDED) MAX16804 toc10 DIM PULSED AT 200Hz 20μs/div 4 MAX16804 toc06 DROPOUT VOLTAGE vs. TEMPERATURE +5V REGULATOR OUTPUT (V) MAX16804 High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control MAX16804 toc11 VDIM 2V/div DIM PULSED AT 200Hz VDIM 2V/div 0V 0V ILED 200mA/div ILED 200mA/div 0A 0A 20μs/div _______________________________________________________________________________________ High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control OUTPUT CURRENT DUTY CYCLE vs. ANALOG DIM VOLTAGE IDIM vs. VDIM VIN = 12V 100 MAX16804 toc13 300 MAX16804 toc12 VIN = 16V 250 200 80 IDIM (μA) OUTPUT CURRENT DUTY CYCLE (%) 120 60 150 40 100 20 50 0 0 1 0 2 3 0 4 2 4 6 8 10 12 14 16 VDIM (V) ANALOG DIM VOLTAGE (V) Pin Description PIN NAME 1, 20 OUT FUNCTION Current-Regulated Output. Connect pin 1 to pin 20. 2, 3 IN 4, 9, 11, 18 N.C. No Connection. Leave unconnected (internal connection). Input Supply. Bypass IN with a 0.1µF (min) capacitor to GND. Connect pin 2 to pin 3. 5–8, 10, 16 GND Ground 12, 15 V5 13 CS+ Positive Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS+ and CS- to program the output current level. 14 CS- Negative Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS- and CS+ to program the output current level. 17 DIM Dimming Input. See the Dimming Input (DIM) section. 19 EN Enable Input. Drive EN high to enable the output and the 5V LDO. — EP Exposed Pad. Connect to the ground plane for effective power dissipation. Do not use as the only ground connection. +5V Regulated Output. Connect a 0.1µF capacitor from V5 to GND. _______________________________________________________________________________________ 5 MAX16804 Typical Operating Characteristics (continued) (VIN = 12V, VEN = VIN, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, TA = +25°C, unless otherwise noted.) High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control MAX16804 Functional Diagram V5 IN IN REGULATOR EN TRIMMED BANDGAP 1.25V I_REG OUT GND DIFFERENTIAL SENSE AMPLIFIER MAX16804 CS+ CS- THERMAL SHUTDOWN 210mV 200Hz RAMP GENERATOR MUX DIM POR PULSE DETECTOR Detailed Description The MAX16804 is a high-current regulator capable of providing up to 350mA of current to one or more strings of HB LEDs. A wide operating input voltage range of 5.5V to 40V makes the MAX16804 ideal for automotive applications. A +5V regulated output provides up to 2mA of current to power external circuitry. In addition, the MAX16804 features thermal and output short-circuit protection. The wide operating voltage range helps protect the MAX16804 against large transients such as those found in load-dump situations up to 45V. The MAX16804 uses a feedback loop to control the output current. The differential voltage across the sense resistor is compared to a fixed reference voltage, and the error is amplified to serve as the drive to the internal pass device (see the Functional Diagram). The regulation point is factory-set at (VCS+ - VCS-) = 198 ±6mV. The regulated current is user-defined by the value of RSENSE. 6 The MAX16804 is a current controller internally optimized for driving the impedance range expected from one to ten or more HB LEDs. Dimming Input (DIM) The MAX16804’s dimming input functions with either an analog or PWM control signal. If the pulse detector detects three edges of a PWM signal with a frequency range between 80Hz to 2kHz, the MAX16804 synchronizes to external PWM input signal and pulse-widthmodulates the LED current. If an analog control signal is applied to DIM, the MAX16804 compares the DC input to an internally generated 200Hz ramp to pulsewidth-modulate the LED current. The output current duty cycle is adjustable from 0% to 100% (0.21V < VDIM < 3.1V). Use the following formula to calculate the output current duty cycle: Duty cycle = (VDIM - 0.21V) / (2.895V) (1) _______________________________________________________________________________________ High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control +5V Regulator The MAX16804 includes a fixed +5V output regulator that delivers up to 2mA of load current throughout the 6.5V to 40V input voltage range. Connect a 0.1µF compensation capacitor from V5 to ground. Shorting V5 to ground disables the thermal shutdown. When EN is low, V5 is off. V5 stays on during PWM dimming. Thermal Protection The MAX16804 enters a thermal-shutdown mode in the event of overheating. This typically occurs in overload or short-circuit conditions on the output. If the junction temperature exceeds TJ = +155°C (typ), the internal thermal-protection circuitry turns off the series pass device. The MAX16804 recovers from thermal-shutdown mode once the junction temperature drops by 23°C (typ). The part therefore protects itself by thermally cycling in the event of a short-circuit or overload condition. Applications Information Programming the LED Current The MAX16804 uses a sense resistor across CS+ and CS- to set the LED current. The differential sense amplifier connected across RSENSE provides ground-loop immunity and low-frequency noise rejection. The LED current is given by ILED = VSENSE / RSENSE (2) Input-Voltage Considerations For proper operation, the minimum input voltage must always be: VIN(MIN) ≥ VRSENSE(MAX) + VFT(MAX) + ΔVDO(MAX) (3) where VFT(MAX) is the maximum forward voltage of all series connected LEDs and ΔVDO(MAX) is the maximum drop output voltage. The minimum operating voltage of the device is +5.5V. Two Brightness Levels for TAIL/STOP Lights Figure 2 shows two-level brightness adjustment using the MAX16804 with minimum external components. Set the dimming level with a resistive divider connected to DIM. See Equation 1 for details. STOP VIN IN D1 OUT TAIL +5V REG EN V5 D2 IN OUT EN V5 LEDs 0.1μF THEATER DIMMING SIGNAL MAX16804 CS+ MAX16804 R1 RSENSE LEDs DIM CS+ DIM CS- R2 RSENSE GND GND Figure 1. Theater Dimming CS- Figure 2. Two-Level Brightness Operation _______________________________________________________________________________________ 7 MAX16804 The dimming feature can be used for LED brightness adjustment (see the Simplified Diagrams) and theater dimming. If an external PWM signal is used, the theaterdimming effect can be achieved by varying the PWM duty cycle. Figure 1 shows a simple circuit that implements theater dimming with a DC input signal. MAX16804 High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control LED Current Thermal Foldback Other Applications With a minimum number of external components, the MAX16804 provides LED current thermal foldback using a negative temperature coefficient (NTC) thermistor. Figure 3 shows a thermistor connected to V5 and the CS+ of the MAX16804. As the temperature increases, the voltage drop across R2 increases causing the LED current to decrease. (4) ILED = [VSENSE - [R2 / (R2 + RT)] x V5] / R1 Figure 4 shows an application circuit with the MAX16804 using a single BJT to provide high output current. For proper operation: VIN(MIN) > VCESAT(MAX) + VFT(MAX) + VRSENSE (5) where VCESAT(MAX) is the maximum saturation voltage of the external BJT. VIN IN OUT EN V5 C1 LEDs C2 MAX16804 RT PWM DIMMING R2 DIM CS+ R1 CS- GND Figure 3. LED Current Thermal Foldback Operation with an NTC Thermistor LEDs VIN IN OUT EN V5 Q1 C1 C2 MAX16804 PWM DIMMING DIM CS+ RSENSE GND CS- Figure 4. Increased Output Current (Amper Range) with a Single BJT 8 _______________________________________________________________________________________ High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control ANALOG OR PWM CONTROL SIGNAL 20 1 VIN OUT OUT 19 18 17 16 EN N.C. DIM GND V5 15 LEDs CS- 14 2 IN C1 3 IN V5 12 4 N.C. 5 GND GND 6 RSENSE CS+ 13 MAX16804 GND GND N.C. 7 8 9 N.C. 11 GND C2 10 Pin Configuration Chip Information PROCESS: BiCMOS V5 CS- CS+ V5 N.C. TOP VIEW 15 14 13 12 11 GND 16 10 GND DIM 17 9 N.C. 8 GND 7 GND 6 GND N.C. 18 MAX16804 EN 19 1 2 3 4 5 IN IN N.C. GND + OUT OUT 20 THIN QFN _______________________________________________________________________________________ 9 MAX16804 Typical Operating Circuit Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) QFN THIN.EPS MAX16804 High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control 10 ______________________________________________________________________________________ High-Voltage, 350mA LED Driver with Analog and PWM Dimming Control 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 ____________________ 11 © 2006 Maxim Integrated Products Heaney is a registered trademark of Maxim Integrated Products, Inc. MAX16804 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.)