19-4029; Rev 1; 5/08 High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator Features The MAX16836 current regulator operates from a 6.5V to 40V input-voltage range and delivers up to a total of 350mA to one or more strings of high-brightness LEDs (HB LEDs). The output current of the MAX16836 is adjusted by using an external current-sense resistor in series with the LEDs. A dimming input allows widerange “pulsed” PWM operation. Wave-shaping circuitry reduces EMI. The differential current-sense input increases noise immunity. The MAX16836 is well suited for applications requiring a high-voltage input and is able to withstand automotive load-dump events up to 40V. An on-board pass element minimizes external components while providing ±3.5% output-current accuracy. Additional features include a 5V regulated output and short-circuit and thermal protection. o o o o o The MAX16836 is available in a thermally enhanced, 5mm x 5mm, 16-pin TQFN package and is specified over the automotive -40°C to +125°C temperature range. o Applications Automotive Interior: Map, Courtesy, and Cluster Lighting o o o o o o o o o +6.5V to +40V Operating Range Adjustable LED Current (35mA to 350mA) ±3.5% LED Current Accuracy High-Voltage DIM Pin for Dimming Interface Integrated Pass Element with Low-Dropout Voltage (0.55V typ) +5V Regulated Output with 4mA Source Capability Parallel Operation for LED Current > 350mA Differential LED Current Sense Low Shutdown Supply Current (35µA typ) Low 200mV Current-Sense Reference Reduces Power Losses Wave-Shaped Edges Reduce Radiated EMI During PWM Dimming Thermal Shutdown Output Short-Circuit Protection Available in Small, Thermally Enhanced, 5mm x 5mm, 16-Pin TQFN Package -40°C to +125°C Operating Temperature Range Automotive Exterior: Tail Lights and CHMSL Ordering Information Emergency Vehicle Warning Lights PART Navigation and Marine Indicators TEMP RANGE MAX16836ATE+ General Lighting -40°C to +125°C +Denotes a lead-free package. *EP = Exposed pad. Signage, Gasoline Canopies, Beacons GND V5 CS- CS+ Pin Configuration TOP VIEW 12 11 10 9 PIN-PACKAGE 16 TQFN-EP* Simplified Diagram +6.5V TO +40V IN OUT 0.1μF +5V REG 8 DIM 13 V5 N.C. LEDs 0.1μF N.C. 14 MAX16836 EN 15 OUT 16 + 7 N.C. 6 N.C. 5 N.C. EN MAX16836 CS+ RSENSE PWM DIMMING 2 3 4 OUT IN IN N.C. DIM 1 CSGND TQFN ________________________________________________________________ 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 MAX16836 General Description MAX16836 High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +45V OUT, DIM, and EN to GND ..........................-0.3V to (VIN + 0.3V) CS+, CS-, V5 to GND ...............................................-0.3V to +6V OUT Short Circuited to GND Duration (at VIN = +16V) .........................................................60 minutes Maximum Current into Any Pin (except IN and OUT) .........±20mA Continuous Power Dissipation (TA = +70°C) 16-Pin TQFN 5mm x 5mm (derate 33.3mW/°C above +70°C) ............................2666.7mW Junction to Case Thermal Resistance (θJC) (Note 1) ........2°C/W Junction to Ambient Thermal Resistance (θJA) (Note 1) .....30°C/W Operating Junction 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 Note 1: Package thermal resistances obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, see 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 = VEN = +12V, CV5 = 0.1µF to GND, IV5 = 0, VCS- = 0V, VDIM = +4V, connect RSENSE = 0.58Ω between CS+ and CS-. TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS Supply Voltage Range VIN (Note 3) Ground Current IG ILOAD = 350mA Shutdown Supply Current Guaranteed Output Current ISHDN IOUT Output Current Accuracy Dropout Voltage (Note 4) ΔVDO Output Current Slew Rate Short-Circuit Current MIN VEN ≤ 0.6V RSENSE = 0.55Ω TYP 6.5 MAX V 1.28 3 mA 35 70 350 µA mA 35mA < IOUT < 350mA ±3.5 IOUT = 350mA (current pulsed), 12V < VIN < 40V 0.55 1.2 IOUT = 350mA (current pulsed), 6.5V < VIN < 12V 0.55 1.5 Current rising, VDIM rising to 4V 7.8 Current falling, VDIM falling to 0.6V 7.8 VIN = 12V, VCS+ = 0V UNITS 40.0 % V mA/µs 400 500 650 mA -1.0 -0.2 µA LOGIC INPUT EN Input Current IEN -2.5 EN Input Voltage High VIH 2.8 EN Input Voltage Low VIL Turn-On Time tON VEN rising edge to 90% of OUT V 0.6 V 110 350 µs 200 207 mV CURRENT SENSE Regulated RSENSE Voltage VSENSE VSENSE = VCS+ - VCS- CS- Voltage Range 193 -0.3 Input Current (CS+) VCS+ = 220mV Input Current (CS-) VCS+ = 220mV DIM Input Current DIM Input Voltage High VIH DIM Input Voltage Low VIL 2.7 -50 17.2 -2.5 -1.0 +4.1 V 7.0 µA µA -0.2 4 µA V 0.6 V Turn-On Time tON After VDIM rising to 4V (Note 5) 110 µs Turn-Off Time tOFF After VDIM falling to 0.6V (Note 5) 70 µs 2 _______________________________________________________________________________________ High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator (VIN = VEN = +12V, CV5 = 0.1µF to GND, IV5 = 0, VCS- = 0V, VDIM = +4V, connect RSENSE = 0.58Ω between CS+ and CS-. TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS THERMAL OVERLOAD Thermal-Shutdown Temperature +159 °C 24 °C Thermal-Shutdown Hysteresis +5V REGULATOR Output Voltage Regulation VV5 (Note 6) V5 Short-Circuit Current 4.85 5.00 VV5 = 0V (Note 7) 5.20 V 15 mA Note 2: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. Note 3: Resistors were added from OUT to CS+ to aid with the power dissipation during testing. Note 4: Dropout is measured as follows: Connect RO = 27Ω from OUT to CS+. Connect RSENSE = 0.58Ω from CS+ to CS-. Set VIN = +12V (record VOUT as VOUT1). Reduce VIN until VOUT = 0.97 x VOUT1 (record as VIN2 and VOUT2). ΔVDO = VIN2 - VOUT2. 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: Current regulation varies with V5 load (see the Typical Operating Characteristics). Note 7: Thermal shutdown does not function if the output of the 5V reference is shorted to ground. Typical Operating Characteristics (VIN = VEN = +12V, TA = +25°C, unless otherwise noted.) OUTPUT CURRENT vs. TEMPERATURE 300 250 ILOAD = 200mA 200 150 ILOAD = 100mA 100 50 ILOAD = 35mA 0 0.206 0.204 0.202 MAX16836 toc03 400 350 OUTPUT CURRENT (mA) 350 0.208 MAX16836 toc02 ILOAD = 350mA (VCS+ - VCS-) (V) OUTPUT CURRENT (mA) 400 MAX16836 toc01 450 OUTPUT CURRENT vs. INPUT VOLTAGE (VCS+ - VCS-) vs. OUTPUT CURRENT 300 250 200 150 100 0.200 50 0 0.198 -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 5 10 15 20 25 30 35 40 INPUT VOLTAGE (V) _______________________________________________________________________________________ 3 MAX16836 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = VEN = +12V, TA = +25°C, unless otherwise noted.) ILOAD = 350mA 0.6 0.5 0.4 0.3 70 VIN = 20V 60 50 40 30 0.2 20 0.1 10 0 VIN = 40V 80 MAX16836 toc06 90 5.2 +5V REGULATOR OUTPUT (V) 0.8 100 MAX16836 toc05 0.9 SHUTDOWN CURRENT (μA) MAX16836 toc04 1.0 0.7 +5V REGULATOR OUTPUT vs. TEMPERATURE SHUTDOWN CURRENT vs. TEMPERATURE DROPOUT VOLTAGE vs. TEMPERATURE DROPOUT VOLTAGE (V) 5.1 IV5 = 1mA NO LOAD 5.0 4.9 VIN = 12V IV5 = 5mA VIN = 6.5V 4.8 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -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) (VCS+ - VCS-) vs. IV5 +5V REGULATOR OUTPUT vs. VIN 0.202 0.200 ILOAD = 350mA 0.198 MAX16836 toc08 0.204 5.2 +5V REGULATOR OUTPUT (V) MAX16836 toc07 0.206 (VCS+ - VCS-) (V) MAX16836 High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator 5.1 IV5 = 5mA NO LOAD 5.0 4.9 IV5 = 5mA 0.196 4.8 0 1 2 3 4 5 6 5 IV5 (mA) 10 15 20 25 30 200Hz DIMMED OPERATION MAX16836 toc10 VDIM 2V/div 0V 100μs/div 4 40 200Hz DIMMED OPERATION (EXPANDED) MAX16836 toc09 ILOAD = 350mA VIN = VEN = 12V DIM PULSED AT 200Hz (5% DUTY CYCLE) 35 VIN (V) ILOAD = 350mA VIN = VEN = 12V DIM PULSED AT 200Hz (50% DUTY CYCLE) VDIM 2V/div 0V ILOAD 200mA/div ILOAD 200mA/div 0A 0A 20μs/div _______________________________________________________________________________________ High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator 200Hz DIMMED OPERATION (EXPANDED) ILOAD = 350mA VDIM 2V/div 0V ILOAD 200mA/div 0A 204 VSENSE (mV) ILOAD = 350mA VIN = VEN = 12V DIM PULSED AT 200Hz (50% DUTY CYCLE) 206 MAX16836 toc12 VSENSE vs. VCS- MAX16836 toc11 202 200 198 20μs/div 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VCS- (V) Pin Description PIN NAME 1, 16 OUT FUNCTION 2, 3 IN 4–8, 14 N.C. No Connection. Not internally connected. 9 CS+ Positive Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS+ and CS- to program the output current level. 10 CS- Negative Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS- and CS+ to program the output current level. 11 V5 +5V Regulated Output. Connect a 0.1µF capacitor from V5 to GND. 12 GND Ground 13 DIM Pulsed Dimming Input. Drive DIM low to disable the output. Drive DIM high or leave unconnected to enable the output. 15 EN Enable Input. Drive EN high to enable the output. — EP Exposed Pad. Connect to the ground plane for effective power dissipation. Do not use as the only ground connection. Current-Regulated Output. Connect pin 1 to pin 16. Positive Input Supply. Bypass IN with a 0.1µF (min) capacitor to GND. Connect pin 2 to pin 3. _______________________________________________________________________________________ 5 MAX16836 Typical Operating Characteristics (continued) (VIN = VEN = +12V, TA = +25°C, unless otherwise noted.) High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator MAX16836 Functional Diagram V5 IN DIM IN REGULATOR 1μA IN EN ENABLE REFERENCE GENERATOR I_REG OUT DIFFERENTIAL SENSE AMPLIFIER MAX16836 CS+ CS- THERMAL SHUTDOWN Detailed Description The MAX16836 is a high-current regulator capable of providing up to a total of 350mA of current to one or more strings of HB LEDs. A wide operating input voltage range of +6.5V to +40V makes the MAX16836 ideal for automotive applications. A +5V regulated output provides up to 4mA of current to power external circuitry. In addition, the MAX16836 features thermal and output short-circuit protection. The wide operating voltage range helps protect the MAX16836 against large transients such as those found in load-dump situations up to 40V. The MAX16836 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 power series pass device (see the Functional Diagram). The regulation point is factory-set at (VCS+ VCS-) = 200mV ±3.5%. The regulated current is user defined by the value of RSENSE. The MAX16836 is a current controller internally optimized for driving the impedance range expected from one or more HB LEDs. 6 +5V Regulator The MAX16836 includes a fixed +5V output regulator that delivers up to 4mA 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, using the DIM input. Thermal Protection The MAX16836 enters a thermal-shutdown mode in the event of overheating. This typically occurs in overload or output short-circuit conditions. If the junction temperature exceeds TJ = +159°C (typ), the internal thermal-protection circuitry turns off the series pass device. The MAX16836 recovers from thermal-shutdown mode once the junction temperature drops by 24°C (typ). The part therefore protects itself by thermally cycling in the event of a short-circuit or overload condition. Shorting V5 to ground disables the thermal shutdown. Applications Information Programming the LED Current The MAX16836 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 _______________________________________________________________________________________ High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator where VFT(MAX) is the total forward voltage of all series connected LEDs. The minimum operating voltage of the device is +6.5V. The device operates below +6.5V; however, output current may not meet the full regulation specification. Paralleling Multiple MAX16836s to Drive One High-Power LED For applications that require more than 350mA of LED current, two or more MAX16836s can be paralleled (see Figure 3). VCS- should not exceed 4.1V. R1 IN OUT EN V5 Low-Frequency PWM Dimming at the Output The MAX16836 provides pulsed or chopped current dimming input (DIM). The other method is to connect DIM to V5 and EN to IN and pulse EN. Both methods generate a regulated-amplitude PWM current (variable duty cycle) that can provide control over the LED brightness (see Figures 1 and 2). C2 C1 MAX16836 V5 CS+ DIM CS- VDIM GND 1 OUT 2 IN 3 IN 16 15 14 13 OUT EN N.C. DIM ILED GND 12 D1 VIN V5 11 C1 4 C2 MAX16836 RSENSE CS- 10 VIN R2 CS+ 9 N.C. N.C. N.C. N.C. N.C. 5 6 7 8 IN OUT EN V5 C4 C3 Figure 1. Dimming with EN Connected to VIN at a Constant Voltage and DIM Pulsed MAX16836 V5 DIM CS+ LEDs CS- VIN 1 OUT 2 IN 3 IN 4 N.C. 16 15 14 13 OUT EN N.C. DIM GND ILED GND 12 D1 V5 11 C1 C2 MAX16836 CS- 10 RSENSE Figure 3. Paralleling MAX16836s CS+ 9 N.C. N.C. N.C. N.C. 5 6 7 8 Figure 2. Dimming with DIM Connected to V5, EN Connected to VIN _______________________________________________________________________________________ 7 MAX16836 Input-Voltage Considerations For proper operation, the minimum input voltage must always be: VIN(MIN) ≥ VSENSE(MAX) + VFT(MAX) + ΔVDO(MAX) MAX16836 High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator Two Brightness Levels for TAIL/STOP Lights Figure 4 shows PWM dimming operation for the MAX16836 with an ICM7555 timer. The ICM7555 provides adjustable duty cycle using two external resistors and a capacitor. In TAIL operation, the output of the ICM7555 feeds into DIM and lights up the LEDs. The LED’s brightness depends on the duty cycle of the ICM7555. When VSTOP is present, DIM is pulled up to VSTOP. The PWM dimming operation is disabled and the LEDs light up to full brightness. See the ICM7555 data sheet for formulas to calculate the dimming frequency and the duty cycle. LED Current Thermal Foldback With a minimum number of external components, the MAX16836 provides LED current thermal foldback using a negative temperature coefficient (NTC) thermistor. Figure 5 shows a thermistor connected to V5 and the CS+ of the MAX16836. As the temperature increases, the voltage drop across R2 increases causing the LED current to decrease. ⎛ R + R2 ⎞ ILED = [VSENSE − [R2 /(R2 + RT)] × V5] × ⎜ T ⎟ ⎝ R1RT ⎠ (assuming IRT < < ILED). D1 STOP D2 TAIL IN OUT R1 D5 R2 C1 EN V5 MAX16836 LEDs C2 D3 D4 IN DIS +5V REG DIM OUT CS+ ICM7555 R3 RSENSE R4* TH TRG GND CS- GND C3 *R4 ≤ 300kΩ Figure 4. PWM Dimming Operation with ICM7555 Timer VIN IN OUT EN V5 LEDs C2 MAX16836 RT PWM DIMMING R2 C1 DIM CS+ R1 GND CS- Figure 5. LED Current Thermal Foldback with an NTC Thermistor 8 _______________________________________________________________________________________ High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator Figure 7 shows an application circuit with the MAX16836 using a single BJT to provide high output current. For proper operation: VIN(MIN) > VCESAT(MAX) + VFT(MAX) + VSENSE where VCESAT(MAX) is the maximum saturation voltage of the external BJT. STOP TAIL IN OUT EN V5 C2 MAX16836 V5 LEDs C1 DIM CS+ R2 R1 Q1 CS- GND Figure 6. Two Brightness Level with Current Level Switch for Tail/Stop Lights LEDs VIN IN OUT EN V5 Q1 C2 MAX16836 PWM DIMMING C1 DIM CS+ RSENSE GND CS- Figure 7. Increased LED Current (Ampere Range) with a Single BJT _______________________________________________________________________________________ 9 MAX16836 Other Applications The application circuit in Figure 6 implements a twolevel brightness current for TAIL/STOP lights. In TAIL operation, Q1 is off and the R1 sets the output current. In STOP operation, Q1 turns on and the output current is set by a parallel combination of R1 and R2. MAX16836 High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator Multichannel HB LED Driver controller, provides the input power to each LED driver preregulated voltage to multiple MAX16836 drivers. Figure 8 shows an array of MAX16836s with independent DIM control. The MAX5094C, a current-mode PWM D1 L1 VIN CREF REF C3 VCC IN IN OUT IN OUT OUT C2 R3 U2 LEDs MAX5094C CCOMP COMP Q1 OUT EN C4 MAX16836 U4 EN V5 RCOMP LEDs MAX16836 GND R4 CS C9 C8 DIM CS+ CS- DIM CS+ R5 CT/RT V5 C11 C10 DIM GND LEDs MAX16836 EN V5 C7 C6 FB U3 CS+ R7 GND CS- R6 GND CS- CT R2 Figure 8. Multichannel HB LED Driver for LCD Backlight Chip Information Typical Operating Circuit PROCESS: BiCMOS VDIM 1 OUT 2 IN 16 15 14 13 OUT EN N.C. DIM GND 12 D1 VIN V5 11 C1 10 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 3 IN 4 N.C. C2 MAX16836 CS- 10 PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 16 TQFN T1655-3 21-0140 RSENSE CS+ 9 N.C. N.C. N.C. N.C. 5 6 7 8 ______________________________________________________________________________________ High-Voltage, 350mA, High-Brightness LED Driver with PWM Dimming and 5V Regulator REVISION NUMBER REVISION DATE 0 2/08 Initial release 1 5/08 Updated Ordering Information, Electrical Characteristics, and Package Information. DESCRIPTION PAGES CHANGED — 1, 2, 11, 12 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 © 2008 Maxim Integrated Products Quijano is a registered trademark of Maxim Integrated Products, Inc. MAX16836 Revision History