 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| 19-4028; Rev 1; 5/08 High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver General Description The MAX16835 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 MAX16835 is adjusted by using an external current-sense resistor in series with the LEDs. An enable input allows widerange "pulsed" dimming. Wave-shaping circuitry reduces EMI. The differential current-sense input increases noise immunity. The MAX16835 is well suited for applications requiring 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. The MAX16835 is available in a thermally enhanced, 5mm x 5mm, 16-pin TQFN package and is specified over the automotive -40C to +125C temperature range. o o o o o o o o o o o o o o Features +6.5V to +40V Operating Range Adjustable LED Current (35mA to 350mA) 3.5% Output Current Accuracy Integrated Pass Element with Low-Dropout Voltage (0.55V typ) Output Short-Circuit Protection +5V Regulated Output with 4mA Source Capability Thermal Shutdown Differential LED Current Sense High-Voltage Enable Pin for Dimming Interface Low Shutdown Supply Current (35A typ) Low 200mV Current-Sense Reference Reduces Power Losses Wave-Shaped Edges Reduce Radiated EMI During PWM Dimming Available in Small, Thermally Enhanced, 5mm x 5mm, 16-Pin TQFN Package -40C to +125C Operating Temperature Range MAX16835 Applications Automotive Interior: Map, Courtesy, and Cluster Lighting Automotive Exterior: Tail Lights and CHMSL Warning Lights for Emergency Vehicles Navigation and Marine Indicators General Illumination Signage, Gasoline Canopies, Beacons Ordering Information PART MAX16835ATE+ TEMP RANGE -40C to +125C PIN-PACKAGE 16 TQFN-EP* +Denotes a lead-free package. *EP = Exposed pad. Pin Configuration GND CS+ CS- Simplified Diagram +6.5V TO +40V IN 0.1F OUT +5V REG V5 0.1F LEDs TOP VIEW 12 11 V5 10 9 N.C. 13 N.C. 14 EN 15 OUT 16 8 7 N.C. N.C. N.C. N.C. MAX16835 CS+ PWM DIMMING EN CSGND RSENSE MAX16835 6 5 + 1 OUT 2 IN 3 IN 4 N.C. TQFN ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver MAX16835 ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +45V OUT, EN to GND..........................................-0.3V to (VIN + 0.3V) CS+, CS-, and 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 = +70C) 16-Pin TQFN 5mm x 5mm (derate 33.3mW/C above +70C) ...........................2666.7mW Junction to Case Thermal Resistance (JC) (Note 1) ........2C/W Junction to Ambient Thermal Resistance (JA) (Note 1) ....30C/W Operating Junction Temperature Range ...........-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C 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 = 0.1F to GND, IV5 = 0, CS- = GND, connect RSENSE = 0.58 between CS+ and CS-. TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 2 and 3) PARAMETER Supply Voltage Range Ground Current Shutdown Supply Current Guaranteed Output Current Output Current Accuracy SYMBOL VIN IG ISHDN IOUT (Note 2) ILOAD = 350mA VEN 0.6V RSENSE = 0.55 35mA < IOUT < 350mA IOUT = 350mA (current pulsed), 12V < VIN < 40V IOUT = 350mA (current pulsed), 6.5V < VIN < 40V Current rising Current falling VIN = 12V, VCS+ = 0V IEN VIH VIL tON VSENSE VEN rising edge to 90% of OUT VSENSE = VCS+ - VCSVCS+ = 220mV VCS+ = 220mV -50 193 110 200 2.7 -17.2 400 -2.5 2.8 0.6 350 207 7.0 350 3.5 0.55 0.55 7.8 7.8 500 -1.0 650 -0.2 1.2 1.5 CONDITIONS MIN 6.5 1.28 35 TYP MAX 40.0 3 70 UNITS V mA A mA % V V mA/s mA A V V s mV A A Dropout Voltage (Note 4) VDO Output Current Slew Rate Short-Circuit Current LOGIC INPUT EN Input Current EN Input Voltage High EN Input Voltage Low Turn-On Time CURRENT SENSE Regulated RSENSE Voltage Input Current (CS+) Input Current (CS-) 2 _______________________________________________________________________________________ High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver ELECTRICAL CHARACTERISTICS (continued) (VIN = VEN = +12V, CV5 = 0.1F to GND, IV5 = 0, CS- = GND, connect RSENSE = 0.58 between CS+ and CS-. TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 2 and 3) PARAMETER THERMAL OVERLOAD Thermal-Shutdown Temperature Thermal-Shutdown Hysteresis +5V REGULATOR Output Voltage Output Voltage Load Regulation V5 Short-Circuit Current VV5 V5 0 < ILOAD < 4mA (Note 5) V5 = 0V (Note 6) 4.85 5.00 12 15 5.20 20 V mV/mA mA +159 24 C C SYMBOL CONDITIONS MIN TYP MAX UNITS MAX16835 Note 2: Resistors were added from OUT to CS+ to aid with the power dissipation during testing. Note 3: All devices 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design. Note 4: Dropout is measured as follows: Connect RO = 27 from OUT to CS+. Connect RSENSE = 0.58 from CS+ to CS-. Set VIN = +12V (record VOUT as VOUT1). Reduce VIN until VOUT = 0.97 x VOUT1 (record as VIN2 and VOUT2). VDO = VIN2 - VOUT2. Note 5: Current regulation varies with V5 load (see the Typical Operating Characteristics). Note 6: Thermal shutdown does not function if the output of the 5V reference is shorted to ground. Typical Operating Characteristics (VIN = VEN = +12V, TA = +25C, unless otherwise noted.) OUTPUT CURRENT vs. TEMPERATURE MAX16835 toc01 (VCS+ - VCS-) vs. OUTPUT CURRENT MAX16835 toc02 OUTPUT CURRENT vs. INPUT VOLTAGE 350 OUTPUT CURRENT (mA) 300 250 200 150 100 50 MAX16835 toc03 450 400 OUTPUT CURRENT (mA) 350 300 250 200 150 100 50 0 ILOAD = 35mA ILOAD = 100mA ILOAD = 200mA ILOAD = 350mA 0.208 400 0.206 (VCS+ - VCS-) (V) 0.204 0.202 0.200 0.198 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) 20 50 80 110 140 170 200 230 260 290 320 350 OUTPUT CURRENT (mA) 0 0 5 10 15 20 25 30 35 40 INPUT VOLTAGE (V) _______________________________________________________________________________________ 3 High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver MAX16835 Typical Operating Characteristics (continued) (VIN = VEN = +12V, TA = +25C, unless otherwise noted.) DROPOUT VOLTAGE vs. TEMPERATURE MAX16835 toc04 SHUTDOWN CURRENT vs. TEMPERATURE MAX16835 toc05 +5V REGULATOR OUTPUT vs. TEMPERATURE MAX16835 toc06 1.0 0.9 0.8 DROPOUT VOLTAGE (V) 100 90 SHUTDOWN CURRENT (A) 80 70 60 50 40 30 20 10 0 VIN = 12V VIN = 6.5V VIN = 20V VIN = 40V 5.2 +5V REGULATOR OUTPUT (V) 5.1 IV5 = 1mA 5.0 NO LOAD 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 ILOAD = 350mA 4.9 IV5 = 5mA 4.8 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) -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) (VCS+ - VCS-) vs. IV5 MAX16835 toc07 +5V REGULATOR OUTPUT vs. VIN MAX16835 toc08 200Hz DIMMED OPERATION MAX16835 toc09 0.206 5.2 +5V REGULATOR OUTPUT (V) 0.204 (VCS+ - VCS-) (V) 5.1 NO LOAD 5.0 IV5 = 5mA VIN 5V/div 0V 0.202 0.200 ILOAD = 350mA ILOAD 200mA/div 4.9 IV5 = 5mA ILOAD = 350mA, VIN = VEN, VIN PULSED AT 200Hz (50% DUTY CYCLE) 30 35 40 1ms/div 0 0.198 0.196 0 1 2 IV5 (mA) 3 4 5 4.8 5 10 15 20 25 VIN (V) 200Hz DIMMED OPERATION EXPANDED MAX16835 toc10 200Hz DIMMED OPERATION EXPANDED MAX16835 toc11 200Hz DIMMED OPERATION MAX16835 toc12 VIN 5V/div 0V ILOAD = 350mA VIN = VEN VIN PULSED AT 200Hz (50% DUTY CYCLE) ILOAD 200mA/div 0 ILOAD = 350mA VIN = VEN VIN PULSED AT 200Hz (50% DUTY CYCLE) VIN 5V/div 0V ILED 200mA/div 0 ILOAD = 350mA, VIN = 12V, EN PULSED AT 200Hz (50% DUTY CYCLE) EN 10V/div 0V ILED 200mA/div 0 20s/div 4s/div 1ms/div 4 _______________________________________________________________________________________ High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver Pin Description PIN 1, 16 2, 3 4-8, 13, 14 9 10 11 12 15 -- NAME OUT IN N.C. CS+ CSV5 GND EN EP FUNCTION Current-Regulated Output. Connect pin 1 to pin 16. Positive Input Supply. Bypass IN with a 0.1F (min) capacitor to GND. Connect pin 2 to pin 3. No Connection. Not internally connected. Positive Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS+ and CS- to program the output current level. Negative Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS- and CS+ to program the output current level. +5V Regulated Output. Connect a 0.1F capacitor from V5 to GND. Ground Enable Input. Drive EN high to enable the output. Exposed Pad. Connect to the ground plane for effective power dissipation. Do not use as the only ground connection. MAX16835 Functional Diagram IN V5 REGULATOR IN EN ENABLE REFERENCE GENERATOR I-REG OUT DIFFERENTIAL SENSE AMPLIFIER THERMAL SHUTDOWN CS+ CS- MAX16835 Detailed Description The MAX16835 is a high-current regulator capable of providing up to a total of 350mA of current to one or more strings of high-brightness LEDs. A wide operating input voltage range of +6.5V to +40V makes the MAX16835 ideal for automotive applications. A +5V regulated output provides up to 4mA of current to power external circuitry. In addition, the MAX16835 features thermal and output short-circuit protection. The wide operating voltage range helps protect the MAX16835 against large transients such as those found in load-dump situations up to 40V. The MAX16835 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 5 _______________________________________________________________________________________ High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver MAX16835 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 MAX16835 is a current controller internally optimized for driving the impedance range expected from one or more HB LEDs. connected across RSENSE provides ground-loop immunity and low-frequency noise rejection. The LED current is given by the equation below: ILED = VSENSE/RSENSE Input Voltage Considerations For proper operation, the minimum input voltage must always be: VIN(MIN) VSENSE(MAX) + VFT(MAX + VDO(MAX) where VFT(MAX) is the total forward voltage of all seriesconnected LEDs. The minimum operating voltage of the device is +6.5V. The device operates below +6.5V; However, the output current may not meet the full regulation specification. +5V Regulator The MAX16835 includes a fixed +5V output regulator that delivers up to 4mA of load current for low-power applications throughout the +6.5V to +40V input voltage range. Connect a 0.1F compensation capacitor from V5 to ground. Shorting V5 to ground disables the thermal shutdown. When EN is low, V5 is off. Thermal Protection The MAX16835 enters a thermal-shutdown mode in the event of overheating. This typically occurs in overload or output short-circuit conditions. When the junction temperature exceeds TJ = +159C (typ), the internal thermal-protection circuitry turns off the series pass device. The MAX16835 recovers from thermal-shutdown mode once the junction temperature drops by 24C (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. Low-Frequency PWM at the Output The MAX16835 provides pulsed or chopped current dimming. Generally, HB LEDs are binned to match at their full-rated current; however, LEDs from the same bin exhibit poor matching at currents other than fullrated current. To achieve uniformity, HB LED manufacturers recommend PWM pulsing of the LED current at their full-rated value. There are two methods for producing a PWM output. One method is by pulsing the enable input (EN) while having a constant voltage at IN. The other method is to connect EN to IN and pulse both EN and IN. Both methods generate a regulated-amplitude PWM current (variable duty cycle) that can provide control over the LED brightness (see Figures 1 and 2). Applications Information Programming the LED Current The MAX16835 uses a sense resistor across CS+ and CS- to set the LED current. The differential sense amplifier VEN 16 OUT 1 VIN C1 3 4 IN N.C. N.C. 5 2 OUT IN 15 EN 14 N.C. 13 N.C. GND 12 D1 V5 11 C2 CS- 10 CS+ 9 RSENSE ILED VIN C1 3 4 IN N.C. 1 2 OUT IN 16 OUT 15 EN 14 N.C. 13 N.C. GND 12 D1 V5 11 C2 CS- 10 CS+ 9 RSENSE ILED MAX16835 MAX16835 N.C. 6 N.C. 7 N.C. 8 N.C. 5 N.C. 6 N.C. 7 N.C. 8 Figure 1. Pulse Application with VIN at a Constant Voltage Figure 2. Pulse Application with EN Connected to VIN 6 _______________________________________________________________________________________ High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver Typical Operating Circuit PROCESS: BiCMOS Chip Information MAX16835 16 OUT 1 VIN C1 3 4 IN N.C. N.C. 5 2 OUT IN 15 EN 14 N.C. 13 N.C. GND 12 D1 V5 11 C2 CS- 10 CS+ 9 RSENSE Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 16 TQFN PACKAGE CODE T1655-3 DOCUMENT NO. 21-0140 MAX16835 N.C. 6 N.C. 7 N.C. 8 _______________________________________________________________________________________ 7 High-Voltage, 350mA, Adjustable Linear High-Brightness LED Driver MAX16835 Revision History REVISION NUMBER 0 1 REVISION DATE 2/08 5/08 Initial release Updated Ordering Information, Electrical Characteristics, and Package Information. DESCRIPTION PAGES CHANGED -- 1, 2, 8, 9 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. Quijano |
Price & Availability of MAX16835
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |