19-1107; Rev 1; 1/08 High-Voltage, Three-Channel Linear High-Brightness LED Drivers The MAX16824/MAX16825 three-channel LED drivers operate over a 6.5V to 28V input voltage range. These devices provide three open-drain constant-current-sinking outputs that are rated to 36V and deliver up to 150mA of current to each string of high-brightness LEDs (HB LEDs). The current at each output is programmable by means of an external current-sense resistor. The MAX16824 features three PWM inputs that control the duty cycle of the output current, allowing a wide LED dimming range to be implemented. The PWM inputs also function as on/off control for each corresponding output. The MAX16825 offers a 4-wire serial interface, a 3-bit shift register, and a 3-bit transparent latch. The serial interface allows a microcontroller to configure the output channels using four inputs (DIN, CLK, LE, OE) and a data output (DOUT). DOUT allows multiple drivers to be cascaded and operated together. The MAX16824/MAX16825’s on-board pass elements minimize the need for external components, while at the same time, providing ±5% LED current accuracy. Additional features include a +5V (±5%) regulated output with 4mA output current capability and thermal protection. The MAX16824/MAX16825 are available in a thermally enhanced 16-pin TSSOP-EP package and specified over the -40°C to +125°C temperature range. Features o 6.5V to 28V Operating Range o Outputs Connected to 36V Supply for Long LED Strings o Three 36V-Rated Output Channels with Independently Adjustable LED Current o 150mA Output Current Per Channel o ±5% LED Current Accuracy o PWM Dimming Three Independent Dimming Control Inputs (MAX16824) 4-Wire Serial Interface LED Current Chopping (MAX16825) o +5V (±5%) Regulated Output with 4mA Source Capability o Fast Transient Dimming Response o 200mV Current-Sense Reference Reduces Power Loss o Thermal Shutdown o -40°C to +125°C Operating Temperature Range o Thermally Enhanced, 16-Pin TSSOP Exposed Paddle Package Ordering Information Applications PART Industrial Lighting Architectural and Decorative Lighting PIN PACKAGE TEMP RANGE PKG CODE MAX16824AUE+ -40°C to +125°C 16 TSSOP-EP* U16E-3 MAX16825AUE+ -40°C to +125°C 16 TSSOP-EP* U16E-3 Mood Lighting Indoor and Outdoor LED Video Displays Automotive Lighting +Denotes a lead-free package. *EP = Exposed paddle. LCD Display Backlighting Pin Configurations appear at end of data sheet. Typical Operating Circuits UP TO 36V VIN UP TO 36V VIN CIN CIN 3 3 7 8 9 4 IN 1 OUT2 16 7 PWM2 OUT3 CS1 REG GND CS2 CS3 CLK 12 9 OE 4 15 RCS1 13 RCS2 RCS3 CREG 11 1 OUT2 16 12 OUT3 LE 2 OUT1 DIN 8 MICROCONTROLLER PWM3 IN MAX16825 6 PWM1 MAX16824 CREG 11 OUT1 CS1 CS2 2 15 REG CS3 RCS1 13 RCS2 GND RCS3 ________________________________________________________________ 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 MAX16824/MAX16825 General Description MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +30V OUT1, OUT2, OUT3 to GND ..................................-0.3V to +40V CS1, CS2, CS3, REG to GND...................................-0.3V to +6V PWM1, PWM2, PWM3 to GND .................................-0.3V to +6V DIN, CLK, LE, OE, DOUT to GND ............................-0.3V to +6V Maximum Current into Any Pin (except OUT1, OUT2, OUT3) ........................................±20mA Maximum Current into OUT1, OUT2, OUT3......................160mA Continuous Power Dissipation (TA = +70°C) 16-Pin TSSOP-EP (derate 18.9mW/°C above +70°C)....1500mW 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 = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TJ = TA = +25°C.) (Note 1) PARAMETER SYMBOL Supply Voltage Range CONDITIONS VIN GND Current IGND LED Current-Sense Accuracy (Note 2) ΔVDO Dropout Voltage (Note 3) Output Current Slew Rate Output Current Leakage MIN TYP 6.5 IOUT1 = IOUT2 = IOUT3 =100mA 5 MAX 28.0 V 10 mA 10mA < IOUT_ < 100mA 5 10mA < IOUT_ < 150mA 7 IOUT_ = 100mA (current pulsed) 0.75 1.5 IOUT_ = 150mA (current pulsed) 1.2 2.25 Current rising, VOUT = 4V 100 ILEAK PWM1 = PWM2 = PWM3 = 0V VCS_ VCS1 = VCS2 = VCS3 UNITS % V mA/µs 1 µA 210 mV CURRENT SENSE Regulated CS_ Voltage 190 200 OVERTEMPERATURE PROTECTION Thermal Shutdown Temperature 165 °C Thermal Shutdown Hysteresis 23 °C +5V REGULATOR (REG) Output Voltage VREG IREG = 0mA (Note 4) IREG 4.75V < VREG 4 VREG = 0V (Note 5) 15 REG Output Current REG Short-Circuit Current IREGSC 4.75 5 5.25 V 40 90 mA 1 µA mA LOGIC INPUT (PWM1, PWM2, PWM3) PWM_ Input Bias Current IPWM PWM_ Input-Voltage High VIH PWM_ Input-Voltage Low VIL VPWM1 = VPWM2 = VPWM3 = 5V 4 V 0.6 V PWM_ Turn-On Delay 50% of VPWM_ to 50% of ΔVOUT_ 475 ns PWM_ Turn-Off Delay 50% of VPWM_ to 50% of ΔVOUT_ 150 ns 2 _______________________________________________________________________________________ High-Voltage, Three-Channel Linear High-Brightness LED Drivers (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TJ = TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS Turn-On Time tR Turn-Off Time tF MIN TYP MAX UNITS PWM_ rising time, tR, is measured from 20% to 80% of IOUT 1 µs PWM_ falling time, tF, is measured from 80% to 20% of IOUT 1 µs 1 µA OUTPUTS (OUT1, OUT2, OUT3) SPI INTERFACE (CLK, LE, OE, DIN, DOUT) (Figures 3 and 4) DIN, CLK, LE, OE Input Bias Current DIN = CLK = LE = OE = 0 or 5V DIN, CLK, LE, OE Input-Voltage High VIH DIN, CLK, LE, OE Input-Voltage Low VIL CLK Clock Period tCP 50% of CLK rising to 50% of next CLK rising, Figure 3 50 ns CLK Pulse-Width High tCH 50% of CLK rising to 50% of CLK falling, Figure 3 24 ns CLK Pulse-Width Low tCL 50% of CLK falling to 50% of CLK rising, Figure 3 24 ns DIN Setup Time tDS 50% of DIN rising to 50% of CLK rising, Figure 3 5 ns DIN Hold Time tDH 50% of CLK rising to 50% of DIN falling, Figure 3 10 ns DOUT Propagation Delay tDO 50% of CLK rising to 50% of DOUT rising/ falling, Figure 3 5 ns 2.2 V 0.5 DOUT Rise/Fall Time tDR/tDF CDOUT = 10pF, 10% to 90% of DOUT rising/falling edge (Note 6) DOUT Voltage High VDOH ISOURCE = 4mA DOUT Voltage Low VDOL ISINK = 4mA 15 4.5 V ns V 0.5 V LE Pulse-Width High tLW 50% of LE rising to 50% of LE falling, Figure 3 20 ns LE Setup Time tLS 50% of CLK rising to 50% of LE rising, Figure 3 15 ns LE Rising to OUT_ Rising Delay tLRR 50% of LE rising to 50% of OUT_ rising, Figure 4 150 ns LE Rising to OUT_ Falling Delay tLRF 50% of LE rising to 50% of OUT_ falling, Figure 4 475 ns _______________________________________________________________________________________ 3 MAX16824/MAX16825 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TJ = TA = +25°C.) (Note 1) PARAMETER SYMBOL MAX UNITS CLK Rising to OUT_ Rising Delay tCRR 50% of CLK rising to 50% of OUT_ rising, Figure 4 150 ns CLK Rising to OUT_ Falling Delay tCRF 50% of CLK rising to 50% of OUT_ falling, Figure 4 475 ns OE Rising to OUT_ Rising Delay tOEH 50% of OE rising to 50% of OUT_ rising, Figure 3 150 ns OE Falling to OUT_ Falling Delay tOEL 50% of OE falling to 50% of OUT_ falling, Figure 3 475 ns CONDITIONS MIN TYP Note 1: All devices are 100% production tested at TJ = +25°C and TJ = +125°C. Limits to -40°C are guaranteed by design. Note 2: This specification does not include sense resistor tolerance and ground error. Note 3: Dropout is measured as follows: RSC_ = 1.21Ω from CS_ to GND. Force 100mA into OUT_ and measure the dropout voltage from OUT_ to CS_. DVDO = (ΔOUT_ - VCS_). Note 4: OUT’s current regulation varies with load across REG (see the Typical Operating Characteristics). Note 5: Overtemperature protection does not function if the output of the 5V reference (REG) is shorted to ground. Note 6: Guaranteed by design, not production tested. Typical Operating Characteristics (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TA = +25°C, unless otherwise noted. Typical values are at TA = +25°C.) 0.202 0.7 VCS_ (V) 0.6 0.5 0.197 0.4 0.192 0.3 0.2 0.1 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 170 ILOAD = 150mA 150 130 110 ILOAD = 100mA 90 70 50 0.187 30 0.182 -10 10 ILOAD = 100mA 0 4 0.207 190 OUTPUT CURRENT (mA) 0.8 MAX16824 toc02 MAX16824toc01 0.9 OUTPUT CURRENT vs. INPUT VOLTAGE CS_ VOLTAGE vs. OUTPUT CURRENT MAX16824 toc03 DROPOUT VOLTAGE vs. TEMPERATURE 1.0 DROPOUT VOLTAGE (V) MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers 0 15 30 45 60 75 90 105 120 135 150 OUTPUT CURRENT (mA) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 VIN (V) _______________________________________________________________________________________ High-Voltage, Three-Channel Linear High-Brightness LED Drivers SUPPLY CURRENT vs. TEMPERATURE 120 IOUT = 95mA 100 80 60 40 5.04 2.85 ILOAD = 0 5.02 5.00 4.98 2.65 4.96 ILOAD = 4mA ILOAD = 1mA 4.94 4.92 VPWM = VPWM = VPWM = 0 2.25 4.90 -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) OUTPUT VOLTAGE vs. INPUT VOLTAGE LED CURRENT FALL TIME CS_ VOLTAGE vs. REG OUTPUT CURRENT MAX16824 toc09 5.000 MAX16824 toc07 0.200 0.199 0.198 0.197 0.196 0.195 0.194 0.193 0.192 0.191 0.190 0.189 0.188 0.187 0.186 0.185 0.184 0.183 0.182 4.995 IREG = 0 4.990 ILOAD = 100mA VREG (V) VCS_ (V) VIN = 6.5V 2.45 0 5.06 3.05 IOUT = 10mA 20 5.08 MAX16824 toc08 OUTPUT CURRENT (mA) 140 VIN = 28V 3.25 SUPPLY CURRENT (mA) IOUT = 150mA 160 5.10 VREG (V) 180 OUTPUT VOLTAGE vs. TEMPERATURE 3.45 MAX16824 toc06 MAX16824toc04 200 MAX16824 toc05 OUTPUT CURRENT vs. TEMPERATURE ILED = 150mA VIN = 12V PULSED AT 200Hz (50% DUTY CYCLE) VPWM_ 2V/div 4.985 4.980 IREG = 1mA 0V IREG = 4mA IOUT_ 100mA/div 4.975 ILOAD = 150mA 4.970 4.965 0A 4.960 0 1 2 3 4 5 6 7 8 9 0 10 4 8 IREG (mA) 12 16 20 24 28 2μs/div VIN (V) 330Hz DIMMED OPERATION LED CURRENT RISE TIME MAX16824 toc11 MAX16824 toc10 VPWM_ 2V/div ILOAD = 150mA VIN = 12V PWM_ PULSED AT 330Hz (1% DUTY CYCLE) 0V 0V ILED = 150mA VIN = 12V PULSED AT 200Hz (50% DUTY CYCLE) 2μs/div VPWM_ 2V/div IOUT_ 100mA/div IOUT_ 100mA/div 0A 0A 20μs/div _______________________________________________________________________________________ 5 MAX16824/MAX16825 Typical Operating Characteristics (continued) (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TA = +25°C, unless otherwise noted. Typical values are at TA = +25°C.) High-Voltage, Three-Channel Linear High-Brightness LED Drivers MAX16824/MAX16825 Pin Description PIN 6 NAME FUNCTION MAX16824 MAX16825 1 1 OUT1 Channel 1 LED Driver Output. OUT1 is an open-drain, constant-current-sinking output rated to 36V. 2 2 CS1 Channel 1 Sense Amplifier Negative Input. Connect a current-sense resistor between CS1 and GND to program the output current level for channel 1. 3 3 IN Positive Input Supply. Bypass with a 0.1µF (min) capacitor to GND. 4 4 REG +5V-Regulated Output. Connect a 1µF capacitor from REG to GND. 5, 6, 10, 14 5, 14 N.C. No Connection. Must be left unconnected. 7 — PWM1 Dimming Input 1. PWM1 is a dimming input for channel 1. A logic-low turns off OUT1 and a logic-high turns on OUT1. 8 — PWM2 Dimming Input 2. PWM2 is a dimming input for channel 2. A logic-low turns off OUT2 and a logic-high turns on OUT2. 9 — PWM3 Dimming Input 3. PWM3 is a dimming input for channel 3. A logic-low turns off OUT3 and a logic-high turns on OUT3. 11 11 GND Ground 12 12 OUT3 Channel 3 LED Driver Output. OUT3 is an open-drain, constant-current-sinking output rated to 36V. 13 13 CS3 Channel 3 Sense Amplifier Negative Input. Connect a current-sense resistor between CS3 and GND to program the output current level for channel 3. 15 15 CS2 Channel 2 Sense Amplifier Negative Input. Connect a current-sense resistor between CS2 and GND to program the output current level for channel 2. 16 16 OUT2 Channel 2 LED Driver Output. OUT2 is an open-drain, constant-current-sinking output rated to 36V. — 7 DIN Serial-Data Input. Data is loaded into the internal 3-bit shift register on the rising edge of CLK. — 8 LE Latch-Enable Input. Data loaded transparently from the internal shift register to the output latch while LE is high. Data is latched into the output latch on the LE’s falling edge and retained while LE is low. — 9 OE Output Enable Input. Drive OE high to place all outputs into a high-impedance mode without altering the contents of the output latches. Drive OE low to force all outputs to follow the state of the output latches. — 10 DOUT — 6 CLK — — EP Serial-Data Output. Data is clocked out of the internal 3-bit shift register to DOUT on the rising edge of CLK. DOUT is a replica of the shift register’s last bit. Clock Input Exposed Paddle. Connect EP to a large-area ground plane for effective power dissipation. Do not use as the IC ground connection. _______________________________________________________________________________________ High-Voltage, Three-Channel Linear High-Brightness LED Drivers MAX16824/MAX16825 OUT1 200mV IN BANDGAP AND 5V REGULATOR REG CS1 OUT2 THERMAL SHUTDOWN CS2 OUT3 PWM1 PWM2 PWM CONTROL AND LOGIC CS3 PWM3 MAX16824 GND Figure 1. Internal Block Diagram (MAX16824) Detailed Description The MAX16824/MAX16825 are three-channel LED drivers that operate from a 6.5V to 28V input voltage range. These devices provide three independent opendrain, constant-current-sinking outputs rated to 36V and deliver up to 150mA of current to each HB LED string. The current in each channel is programmable using an external current-sense resistor in series with each internal power MOSFET’s source. The MAX16824 features three separate PWM inputs that allow a wide range of independent dimming level at each of the three outputs. The PWM inputs also function as on/off control inputs for each corresponding output (Figure 1). The MAX16825 includes a 4-wire serial interface to control the state of each output (Figure 2). The 4-wire serial interface comprises a 3-bit shift register and a 3-bit transparent latch. The shift register is updated using a clock input CLK and a data input DIN. DOUT is the last bit of the shift register. This feature allows multiple drivers to be cascaded and operated together. The latch is transparent from the shift register outputs to the LED output when LE is high while it latches the shift register state on the falling edge of LE. The output-enable input OE allows simultaneous enabling or disabling of all three outputs. _______________________________________________________________________________________ 7 MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers OUT1 IN 200mV BANDGAP AND 5V REGULATOR REG CS1 OUT2 THERMAL SHUTDOWN CS2 OUT3 DIN CS3 CLK DOUT LE OE SHIFT REGISTER SHIFT REGISTER SHIFT REGISTER LATCH LATCH LATCH LOGIC MAX16825 GND Figure 2. Internal Block Diagram (MAX16825) 8 _______________________________________________________________________________________ High-Voltage, Three-Channel Linear High-Brightness LED Drivers +5V Regulator (REG) The MAX16824/MAX16825 include a fixed +5V output regulator that delivers up to 4mA of load current for auxiliary low power applications throughout the 6.5V to 28V input voltage range. Connect a 1µF compensation capacitor from REG to ground. Thermal Protection The MAX16824/MAX16825 enter a thermal shutdown mode in the event of overheating. When the junction temperature exceeds TJ = +165°C, the internal thermal protection circuit turns off the series pass elements. The MAX16824/MAX16825 recover from thermal shutdown mode when the junction temperature drops by 23°C. The thermal protection does not operate if the regulator (REG) is in a short-circuit condition. 4-Wire Serial Interface (MAX16825) The MAX16825 features a 4-wire serial interface (DIN, CLK, LE, OE) and a data output (DOUT) that allows the use of a microcontroller to write brightness data to the MAX16825. The serial-interface data word length is 3 bits (D0, D1, D2). The functions of the interface inputs are as follows: DIN is the serial-data input, which must be stable when it is sampled by the MAX16825 on the rising edge of CLK. Data shifts in with the MSB first. This means that data bit D2 is clocked in first, followed by 2 more data bits (D1 and finishing with the LSB D0). CLK is the serial-clock input, which shifts data at DIN into the MAX16825’s 3-bit shift register on the rising edge. LE is the latch-enable input that allows the transfer of data from the MAX16825’s 3-bit shift register to its 3-bit latch when LE is high (transparent latch) and latches the data on the falling edge of LE (Figure 4). Output enable (OE) provides simultaneous control of the output drivers. Driving OE high places outputs OUT1, OUT2, and OUT3 into a high-impedance mode without altering the contents of the output latches. Driving OE low allows outputs OUT1, OUT2, and OUT3 to follow the state of the output latches. OE is independent of the operation of the serial interface. 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 MAX16825’s 3-bit shift register on the rising edge of CLK. Data at DIN propagates through the shift register and appears at DOUT three clock cycles later. Applications Information Programming the LED Current The MAX16824/MAX16825 use sense resistors to set the output current in each channel. To set the LED current for a particular channel, connect a sense resistor across the corresponding current-sense input (CS_) and GND. For better performance, connect the low side of the current-sense resistors to the IC’s ground terminal and the high side to the CS_ terminal with short traces. The value of the sense resistor for a given desired current is calculated with the following equation: RCS _ (Ω) = VCS _ (V) IOUT _ (A) where V CS_ is 200mV and I OUT_ is I LED (see the Electrical Characteristics table). Input Voltage Considerations For proper operation, the minimum input voltage must always be: VIN(MIN) ≥ VCS _ + VFT(MAX) + ΔVDO where VCS_ is the voltage drop across the sense resistor RCS_, VFT(MAX) is the total forward voltage of all series connected LEDs and ΔV DO is the maximum dropout voltage of the regulator. The minimum operating voltage of the device is 6.5V. If the device is operated below 6.5V, the output current may not meet the full regulation specification (see the Typical Operating Characteristics). Pulse-Width Dimming (MAX16824) The MAX16824 includes pulsed-width current dimming inputs (PWM_) to control the LED brightness. An application of up to 5kHz signal or less is recommended at PWM_ input for proper operation. PWM_ also functions as an active-high enable input for each output channel. A logic-low at PWM_ turns off OUT_ and a logic-high turns on OUT_. _______________________________________________________________________________________ 9 MAX16824/MAX16825 On-board pass elements minimize the need for external components while providing ±5% LED current accuracy. Additional features include a +5V (±5%) regulated output with 4mA output current capability and thermal protection. The MAX16824/MAX16825 use a feedback loop to linearly control the current at each output. The voltage across each sense resistor is regulated to 200mV by the internal feedback loop. The output current is set by selecting the value of RCS. MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers 50% tLW 50% LE tCH tCL 50% 50% 50% 50% tLS tCP CLK tDH tDS DIN 50% DO D1 50% D2 tDO 50% DOUT DO tOEW 50% 50% OE tOEH tOEL 80% OUT_ 20% tF tR Figure 3. 4-Wire Serial-Interface Timing Diagram Pulse-Width Dimming (MAX16825) The MAX16825 provides three methods of pulsed-width current dimming. One method of pulse dimming the output channels is to drive OE low while latching a different set of three bits 10 data. Holding OE low allows the output channels to follow the state of the output latches. The duty cycle depends on LE’s frequency. All output channels are affected at the same time. ______________________________________________________________________________________ High-Voltage, Three-Channel Linear High-Brightness LED Drivers MAX16824/MAX16825 50% LE tLRF OUT_ 50% 50% LE tLRR 50% OUT_ 50% CLK tCRF OUT_ 50% 50% CLK tCRR 50% OUT_ Figure 4. LE and CLK to OUT_ Timing ______________________________________________________________________________________ 11 MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers Another method of pulse dimming the outputs is to hold LE high and drive OE with a PWM signal. Because the input bits are always latched, the serial input constantly refreshes the register. The control bits must be carefully selected to dim the outputs properly. A third method is to hold both LE and OE in the enabled state. This allows the data bits to directly control the output channels, and hence, pulse dim the output current. Make sure that the clock frequency does not exceed the maximum rate at which the device can change the state of the output channels. Power Dissipation The power dissipation (P D ) of the MAX16824/ MAX16825 is determined from the following equation: PD = (VIN × IIN ) + (VINL − VLED1 − VCS1) × (ILED1 × DUTY1) + (VINL − VLED2 − VCS2 ) × (ILED2 × DUTY2) The worst-case power dissipation occurs when the drop across each internal MOSFET is at its maximum with all three channels delivering the maximum allowable output current. The maximum drop across the internal MOSFETs is determined by: VINL - VLED_ - VCS_ when VLED_ is at its minimum. Higher ambient temperature increases the thermal stress even further due to the reduction in voltage drop across the LEDs. The MAX16824/MAX16825 thermal specifications are given according to the JEDEC-51 guidelines. Good mechanical/thermal design practices must be applied to help maintain the device junction temperature below the absolute maximum ratings at all times. Chip Information PROCESS: BiCMOS-DMOS + (VINL − VLED3 − VCS3 ) × (ILED3 × DUTY3) where: VIN = supply voltage VINL = supply Voltage to the LED strings IIN = supply current VLED_ = total forward voltage for one LED string ILED_ = LED current VCS = 200mV drop across RCS_ DUTY = PWM_ duty cycle 12 ______________________________________________________________________________________ High-Voltage, Three-Channel Linear High-Brightness LED Drivers TOP VIEW TOP VIEW OUT1 1 + CS1 2 16 OUT2 OUT1 1 15 CS2 CS1 2 + 16 OUT2 15 CS2 14 N.C. 14 N.C. IN 3 REG 4 13 CS3 REG 4 13 CS3 N.C. 5 12 OUT3 N.C. 5 12 OUT3 IN 3 MAX16825 MAX16824 N.C. 6 11 GND CLK 6 11 GND PWM1 7 10 N.C. DIN 7 10 DOUT PWM2 8 9 PWM3 TSSOP-EP 9 OE LE 8 TSSOP-EP ______________________________________________________________________________________ 13 MAX16824/MAX16825 Pin Configurations 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.) AA AA 14 ______________________________________________________________________________________ TSSOP 4.4mm BODY.EPS MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers High-Voltage, Three-Channel Linear High-Brightness LED Drivers REVISION NUMBER REVISION DATE 0 11/07 Initial release 1 1/08 Update data sheet with automotive temperature specification DESCRIPTION PAGES CHANGED — 1, 2, 3, 4, 7 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 ____________________ 15 © 2008 Maxim Integrated Products Boblet Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX16824/MAX16825 Revision History