Atmel LED Drivers MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface Datasheet Brief Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface General Description The Atmel(R) LED DriversMSL1061 and MSL1064 are LED drivers with integrated boost regulators capable of driving six LED strings at 30mA up to 48V for lighting applications to 8W, allowing up to 72 LEDs per driver backlighting applications. The MSL1061/64 incorporates a current mode PWM boost regulator with 50V internal switch and a wide, 4.75V to 36V input voltage range. The 1.1MHz switching frequency uses a small-sized inductor and output capacitors while maintaining high efficiency and low ripple voltage and noise. The boost regulator uses digital control and requires no external compensation. An I2C/SMB compatible serial interface operates up to 1MHz, giving access to internal 8-bit PWM dimming and 4-bit analog current adjustment for 12bit current control. Individual string enable and fault reporting are available. The MSL1061 operates with one of four I2C slave addresses selected from a single input pin (AD0), whereas the lower cost MSL1064 has one fixed I2C slave address. The MSL1061/64 is also easy to employ without using an I2C interface, dimming with an external PWM signal. Analog dimming of LED string current is available for use with an ambient light sensor (ALS) and/or temperature management with a thermistor or IC temperature sensor. The MSL1064 comes in a 5 x 5mm, 24-pin TQFN package, and the MSL1061 in a 5 x5mm, 28-pin TQFN. Both packages are lead-free, halogen-free and RoHS-compliant, and operate over a -40C to 85C temperature range. Applications Long Life, Efficient LED Backlighting for: * Notebook PCs and Desktop PC Monitors * Medical and Industrial Instrumentation * Portable Media Players (PMPs) * Automotive Audio-visual Displays Traffic Lights Signage Ordering Information 2 PART DESCRIPTION PACKAGE MSL1061AV 6-ch LED driver 28-pin, 5x5x0.75mm TQFN MSL1064AW 6-ch LED driver 24-pin, 5x5x0.75mm TQFN Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface Key Features * Drives 6 Strings of up to 12 LEDs per String * Individual Open-circuit and Short-circuit Fault Detection * Drives 72 White LEDs at 30mA for 8W Backlight * Faults Automatically Disable the Faulty String * Better than 1.5% String-to-string Current Accuracy * Fault Reporting and Fault Reset Through I2C/SMB * 4.75V to 36V Wide Input Supply Range * FLTB Logic Output Indicates Faults * Integrated Boost Regulator with 50V Internal Switch * Enable Input Simplifies Operation Without I2C/SMB * 1.1MHz Current Mode PWM Boost for Low Noise * PWM Input Synchronizes PWM to System Clock and Allows Logic PWM Control Without I2C * Up to 92% Boost Converter Efficiency * Internal, Automatic Power Supply Management * Adjustable Over-voltage Protection * Adjustable LED Current up to 30mA per String * Serial I2C/SMB Compatible Interface to 1MHz * String Outputs can be Paralleled for >30mA LEDs * Four selectable I2C Slave Addresses (MSL1061) * 256:1 Internal PWM Dimming Range Through I2C * GUI Software for Ease of Evaluation * 16:1 Internal Analog Dimming Range Through I2C * -40C - +85C Operating Temperature Range * 12-Bit Total Internal PWM + Analog Dimming Range * Lead-free, Halogen-free, RoHS-compliant Package * ALS Interface for Automatic Brightness Setting * NTC Interface for Temperature Derating Application Circuit VIN = 4.75V to 36V VOUT = 48V max EN Fault Alert OVP Up to 12 White LEDs per String FLTB OSC ALS or NTC .... SW VIN IADJ ILED MSL1061 MSL1064 STR0 . . .. STR5 SDA PWM SCL GND Atmel LED Drivers-MSL1061/MSL1064 AD0 Set String current 1.5% maximum current mismatch between Strings I C or SMBus I C address selection (MSL1061 only) 3 Quick Start Guide This section summarizes for quick evaluation the capabilities of, and differences between, the MSL1061 and MSL1064. The MSL1061 and MSL1064 are LED string drivers with integrated boost regulators, which power, monitor, and dim multiple LEDs at high efficiency for backlighting and signage applications. Each MSL1061/64 contains six outputs, each capable of sinking up to 30mA through a string of series-connected LEDs. How Many LEDs Can the Atmel LED Drivers-MSL1061/64 Drive? The MSL1061/64 includes 6 current sinks (STR0 through STR5) that each control the LED current of multiple series-connected white LEDs. Any combination of the 6-strings may be enabled, and not all the strings need to be used. Make sure that each enabled string contain the same number of the same type of LED so that the total voltage drop for each string is the same because the single boost regulator supplies power to all six strings. Use a single MSL1061/64 LEDs of a single color/chemistry, such as white LED backlighting or single-color signage. For multicolor applications (e.g. RG, RGB, RGGB, RGBA), use separate MSL1061/64s per LED color/chemistry type. Each MSL1061/64 manages its integrated boost regulator to optimize efficiency for its strings of identical LEDs with matched electrical characteristics. 4 The maximum number of LEDs allowed in a string is determined by the maximum voltage rating of the boost regulator's internal power FET, which is 50V minus 2V for switching noise transients, leaving 48V. The FET is protected by the OVP trip, which has a 2% voltage tolerance, plus another 1% for the external setting resistors R8 and R9 (Figure 6 on page 15) reducing the maximum voltage to 46.5V. The total voltage needed to drive a string is the forward voltage drop across the desired LED strings, plus the headroom needed across a string output's current sink (600mV) to maintain regulation, plus the boost regulator's rectifier forward voltage (normally under 900mV) leaves 46.5V - 0.6V 0.9V = 45V maximum for the LED string. The number of LEDs that the MSL1061/4 can drive per string is 45V / {maximum LED forward voltage per LED}, or 12 LEDs per string using 3.75V maximum forward voltage LEDs. Differences Between Atmel LED Drivers-MSL1061/64 Use the MSL1061 for applications where multiple drivers are connected to a single I2C bus such as RGB and RGGB lighting. Use the lower cost MSL1064 for single-driver applications, and multi-driver applications that do not require all drivers on the same I2C interface (Table 1). Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface Table 1. Atmel LED Drivers-MSL1061 and MSL1064 Comparison FEATURE I2C interface Package IPC2221A-2003 compliance MSL1061 MSL1064 APPLICATION AND SUITABILITY 4 selectable slave addresses by AD0 pin (0x60, 0x61, 0x62, 0x63) 1 fixed slave address (0x62) 28-lead, 5mm x 5mm TQFN, 0.5mm pitch 24-lead, 5mm x 5mm TQFN, 0.65mm pitch 0.2mm min gap between SW pins and adjacent conductors. Compliant to 100V with board coating, 15V without coating 0.6mm min total gap between SW pins and adjacent conductors. Compliant to 100V with or without board coating Only one MSL1064 is uniquely addressed on an I2C bus If compliance is necessary use the MSL1064 or MSL1061 with board coating. Capabilities With and Without Using the Serial Interface MSL1061/64 operates as stand alone LED drivers with full digital (PWM) and analog (DAC) LED brightness control and fault reporting through I/O controls. Alternatively, LED dimming and fault reporting is managed over an I2C or SMB serial interface, allowing software/firmare LED intensity control. More detailed fault management reporting and software controlled shutdown (Table 2) via the serial interface. Table 2. Atmel LED Drivers-MSL1061/64 Stand Alone Capabilities and I2C Controlled Features FUNCTION CONTROLS AVAILABLE ON PINS ADDITIONAL CONTROLS AVAILABLE VIA I2C Global on/off control EN pin (Table 3 on page 9) Run mode/sleep mode Individual LED string on/off control Not available String enables register Analog LED current adjustment ILED pin (Table 3 on page 8) Current setting register PWM LED current adjustment PWM pin (Table 3 on page 8) PWM frequency register PWM duty ratio register Ambient light sensor (ALS) and/ or auto-matic temperature LED current adjustment IADJ pin (Table 3 on page 9) Current setting register Fault monitoring FLTB pin indicates open-string, shortedstring, and over-temperature faults Status register identifies open/short circuit and overtemperature faults to individual strings Atmel LED Drivers-MSL1061/MSL1064 5 Packages and Pin Connections VIN EN N/C SW SW N/C Atmel LED Drivers-MSL1061/64 - 24-pin, 5mm x 5mm x 0.75mm TQFN package with 0.65mm lead pitch 24 23 22 21 20 19 VCC 1 18 OVP VDD 2 17 STR0 TEST1 3 16 STR1 TEST2 4 MSL1064 15 STR2 SDA 5 (TOP VIEW) 14 STR3 SCL 6 Figure 1. 24-pin, 5mm x 5mm x 0.75mm TQFN (0.65mm pin pitch) with Exposed Pad 7 8 9 10 11 12 PWM FLTB OSC ILED IADJ STR5 13 STR4 Figure 2. 24-pin TQFN Package Dimensions 6 Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 VIN EN SW SW SW SW N/C 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface 28 27 26 25 24 23 22 3 19 STR0 TEST2 4 MSL1061 18 STR1 SDA 5 (TOP VIEW) 17 STR2 SCL 6 16 STR3 AD0 7 15 STR4 8 9 10 11 12 13 14 STR5 TEST1 IADJ 20 TEST3 ILED 2 N/C VDD OSC 21 OVP FLTB 1 PWM VCC Figure 3. 28-pin, 5mm x 5mm x 0.75mm TQFN (0.5mm pin pitch) with Exposed Pad Figure 4. 28-pin TQFN Package Dimensions Atmel LED Drivers-MSL1061/MSL1064 7 Pin Descriptions Table 3. Pin Assignments PIN NAME MSL1064 PIN DESCRIPTION VCC 1 1 6V internal linear regulator output VCC powers the internal power FET switch driver. Bypass VCC to GND either with a 10F or greater ceramic capacitor, or with a 10F or greater tantalum capacitor in parallel with a 1F ceramic capacitor. If the voltage at VIN is less than 6.5V, connect VCC directly to VIN to bypass the internal linear regulator, and power the driver directly from VIN VDD 2 2 2.9V internal linear regulator output VDD powers internal logic. Bypass VDD to GND with at least a 4.7F ceramic capacitor TEST1 3 3 Factory test connection. Leave unconnected TEST2 4 4 Factory test connection. Connect to GND SDA 5 5 IC serial data I/O SDA is the data I/O for the IC serial interface SCL 6 6 IC serial clock input SCL is the clock input for the IC serial interface AD0 7 - IC slave ID selection input For MSL1061, connect AD0 to GND, VDD, SCL, or SDA to set the IC slave ID to 0x60, 0x61, 0x62, or 0x63. The MSL1064 IC slave ID is fixed at 0x62, and is not user-selectable PWM 8 7 PWM control input Drive PWM with a PWM signal up to 40kHz to pulse-width-modulate the LED current FLTB 9 8 Fault indication output (active low) FLTB sinks current to GND whenever the MSL1061/64 detects a fault. Once a fault is detected, FLTB remains low until EN is toggled low/high, input power is cycled off/on, or the fault status is reset through the IC interface. OSC 10 9 Oscillator control input Connect a 115k, 1% resistor from OSC to GND to set the internal oscillator frequency to 11MHz and the boost regulator switching frequency to 1.1MHz TEST3 11 - Factory test connection with internal 1.8k pull-up to VDD. Leave unconnected ILED 8 MSL1061 12 10 Maximum LED current control input Connect a resistor from ILED to GND to set the full-scale LED string current. For example, connect a 100k resistor to GND to set a 20mA sink current through each LED string Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface PIN NAME MSL1061 MSL1064 PIN DESCRIPTION IADJ 13 11 Analog LED current dimming input Apply a voltage between 0V to 1.22V to linearly control the LED current from 0 to 100%. Connect IADJ to VDD if unused STR5 14 12 LED string 5 current sink output Connect the cathode of LED String 5 to STR5. Connect STR5 to GND if unused STR4 15 13 LED string 4 current sink output Connect the cathode of LED String 4 to STR4. Connect STR4 to GND if unused STR3 16 14 LED string 3 current sink output Connect the cathode of LED String 3 to STR3. Connect STR3 to GND if unused STR2 17 15 LED string 2 current sink output Connect the cathode of LED String 2 to STR2. Connect STR2 to GND if unused STR1 18 16 LED string 1 current sink output Connect the cathode of LED String 1 to STR1. Connect STR1 to GND if unused STR0 19 17 LED string 0 current sink output Connect the cathode of LED String 0 to STR0. Connect STR0 to GND if unused OVP 21 18 Overvoltage detection input Connect a resistive voltage divider from the boost output voltage to OVP to set the overvoltage protection set point. OVP threshold is 1.28V N/C 22 19 No internal connection. Leave unconnected SW 23, 24, 25, 26 20, 21 N/C - 22 No internal connection. Leave unconnected EN 27 23 Enable input (active high) Drive EN high to turn on the MSL1061/64, and drive it low to turn it off. For automatic startup, connect EN to VIN through a 100k resistor Supply voltage input Connect the input supply voltage to VIN. VIN powers the internal linear regulator that powers VCC. Bypass VIN to GND with a 1F or greater ceramic capacitor VIN 28 24 GND Exposed pad Exposed pad Atmel LED Drivers-MSL1061/MSL1064 Drain of the internal boost power MOSFET switch Connect all SW pins together and to the boost regulator inductor and rectifier Ground 9 Absolute Maximum Ratings Voltage (With Respect to GND Exposed Pad on Package Underside) VIN.................................................................................................................................................................................................................. -0.3V to +40V VCC, EN.........................................................................................................................................................................................................-0.3V to +8V VDD, OVP, IADJ, FLTB, ILED, SDA, SCL, AD0, OSC, PWM..................................................................-0.3V to +3.6V SW................................................................................................................................................................................................................. -0.3V to +50V STR0, STR1, STR2, STR3, STR4, STR5.................................................................................................................... -0.3V to +45V Current (Into Pin) SW.............................................................................................................................................................................................................................................3A STR0, STR1, STR2, STR3, STR4, STR5..................................................................................................................................... 35mA All other pins...........................................................................................................................................................................................................20mA Continuous Power Dissipation at 70C 24-Pin TQFN (see Note 8, Note 9)......................................................................................................................................... 2286mW 28-Pin TQFN (see Note 8, Note 9)......................................................................................................................................... 2286mW Ambient Operating Temperature Range TA = TMIN to TMAX...................................................... -40C to +85C Junction Temperature ............................................................................................................................................................................. +125C Storage Temperature Range.................................................................................................................................... -65C to +125C Lead Soldering Temperature, 10s...............................................................................................................................................+300C 10 Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface Electrical Characteristics (Circuit of Figure 6, VVIN = 12V, default register settings of Table 7, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C) (Note 1) PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT DC ELECTRICAL CHARACTERISTICS VIN operating supply voltage V VIN = V VCC 4.75 6.5 V VCC unconnected 6.5 36 V VIN quiescent supply current VEN = 3V, VPWM = 0V VIN shutdown supply current VEN = VPWM = 0V VVIN = 12V 4 14 mA VVIN = 6V, VVCC = 6V 4 14 mA 4 10 A 5.6 6 6.3 V 1 2 5 mV VCC output voltage 1 VCC line regulation 6.5V < VVIN < 36V VCC dropout voltage VVIN = 6V, IVCC = 5mA, VPWM = 0V 100 300 550 mV VCC short-circuit current VVCC = 0V 30 80 150 mA VCC UVLO threshold VVCC rising, hysteresis = 150mV 4.1 4.3 4.5 V VDD output voltage IVDD = 1mA 2.7 2.9 3.1 V VDD short-circuit current VVDD = 0V 10 35 60 mA VDD UVLO threshold VVDD rising, hysteresis = 80mV 2.4 2.5 2.6 V Thermal shutdown threshold (rising) 135 C Thermal shutdown hysteresis 10 C PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT DC ELECTRICAL CHARACTERISTICS - LED CURRENT CONTROL STR0 TO STR5 ILED regulation voltage R5 = 100k 1.195 1.22 1.245 V STR0 to STR5 full scale sink current VSTRn = 1V, R5 = 100k, VIADJ = VPWM = 3V 19.7 20 20.3 mA STR0 to STR5 maximum sink current VSTRn = 1V, R5 = 60k, VIADJ = VPWM = 3V (Note 10) 30 STR0 to STR5 current matching VSTRn = 1V, R5 = 100k, VPWM = 3V (Note 11) STR0 to STR5 leakage current mA 1.5 % VEN = 0V, VSTRn = 40V 0.1 1 A VEN = 3V, VSTRn = 40V, VPWM = 3V 0.1 1 A 4.4 4.8 V STR0 to STR5 short circuit detection threshold 4 STR0 to STR5 open circuit detection threshold 0.1 PARAMETER CONDITIONS AND NOTES MIN TYP V MAX UNIT DC ELECTRICAL CHARACTERISTICS - LOGIC I/OS EN logic high input voltage 2.3 EN logic low input voltage EN logic input current Atmel LED Drivers-MSL1061/MSL1064 VEN = 3V V 0.8 V 20 A 11 PARAMETER EN logic input series resistance CONDITIONS AND NOTES MIN Between EN input package pin and internal Zener clamp EN logic input Zener clamp SCL, SDA, AD0, PWM logic high input voltage TYP k 5.8 V 2 V 0.9 SDA, SCL, AD0 input capacitance 10 SDA output low voltage Sinking 6mA FLTB output low voltage Sinking 1mA pF V 0.2 V 10 A TYP MAX UNIT 0.4 0.6 1.245 V 0.1 MIN V 0.4 IADJ, FLTB, PWM, SCL, SDA, AD0 leakage current CONDITIONS AND NOTES UNIT 10.5 SCL, SDA, AD0, PWM logic low input voltage PARAMETER MAX DC ELECTRICAL CHARACTERISTICS - BOOST REGULATOR SW on resistance ISW = 100mA SW current limit 2 OSC regulation voltage R4 = 115k 1% STR0-STR5 boost regulation voltage R5 = 100k, PWM=100% (Note 12) OVP threshold VOVP rising 1.195 1.22 A 600 1.25 OVP hysteresis 1.28 mV 1.31 60 OVP leakage current PARAMETER VOVP = 3.6V CONDITIONS AND NOTES V mV 1 A MAX UNIT 0 50 kHz 0 100 % MIN TYP AC ELECTRICAL CHARACTERISTICS PWM input frequency PWM input duty ratio PWM input minimum string on time INTPWM bit D3=0 in control register to select external PWM input to be used for direct LED string dimming control PWM input minimum string off time PWM input frequency, external PWM clock mode PWM input duty ratio, external PWM clock mode PWM frequency (internal oscillator) INTPWM bit D3=1, EXTCLK bit D2=1 in control register to select external PWM input to be used as clock for internal PWM dimming control R4 = 115k 1%, INTPWM bit D3=1, EXTCLK bit D2=0 in control register to select internal oscillator to be used as clock for internal PWM dimming control 14 s 3.2 s 0 12 MHz 30 70 % 9 11 12 MHz 1.21 MHz Boost regulator switching frequency R4 = 115k 1% 0.99 1.1 Boost regulator maximum duty ratio R4 = 115k 1% 89 92 Boost regulator startup time 12 100 % 120 ms Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface PARAMETER SYMBOL CONDITIONS AND NOTES MIN TYP MAX UNIT 1000 kHz IC SWITCHING CHARACTERISTICS SCL clock frequency 1/tSCL TOEN bit D1=0 in control register to disable bus timeout 0 TOEN bit D1=1 in control register to enable bus timeout 0.066 tTIMEOUT 15 tBUF 0.5 s Repeated START condition hold time tHD:STA 0.26 s Repeated START condition set-up time tSU:STA 0.26 s STOP condition set-up time tSU:STOP 0.26 s SDA data hold time tHD:DAT 5 ns SDA data valid acknowledge time tVD:ACK (Note 3) 0.05 0.55 s SDA data valid time tVD:DAT (Note 4) 0.05 0.55 s SDA data set-up time tSU:DAT 100 ns SCL clock low period tLOW 0.5 s SCL clock high period tHIGH 0.26 s Bus time-out period STOP to START condition bus free time SDA, SCL fall time tF SDA, SCL rise time tR SDA, SCL input suppression filter period tSP 25 (Note 5, Note 6) (Note 7, Note 10) 50 ms 120 ns 120 ns ns Note 1. All parameters are tested at TA=25C, unless otherwise noted. Specifications at temperature are guaranteed by design Note 2. Minimum SCL clock frequency is limited by the bus timeout feature, which resets the serial bus interface if either SDA or SCL is held low for ttimeout. Disable the bus timeout feature for DC operation Note 3. tVD:ACK = SCL LOW to SDA (out) low acknowledge time Note 4. tVD:DAT = minimum SDA output data-valid time following SCL low transition Note 5. A master device must internally provide an SDA hold time of at least 300ns to ensure an SCL low state Note 6. The maximum SDA and SCL rise times is 300ns. The maximum SDA fall time is 250ns. This allows series protection resistors to be connected between SDA and SCL inputs and the SDA/SCL bus lines without exceeding the maximum allowable rise time Note 7. MSL1061/64 includes input filters on SDA, SCL, and AD0 inputs that suppress noise less than 50ns Note 8. Subject to thermal dissipation characteristics of the device Note 9. When mounted according to JEDEC JEP149 and JESD51-12 for a two-layer PCB, JA = 24.1C/W, and JC = 2.7C/W Note 10. Guaranteed by design and characterization. Not production tested Note 11. STR0 to STR5 current matching is the difference of any one string current and the average of all string currents divided by the average of all string currents Note 12. The MSL1061/64 selects the string (STR0 through STR5) with the lowest voltage to control the boost regulator voltage Atmel LED Drivers-MSL1061/MSL1064 13 Block Diagram The block diagram for the 28-pin MSL1061 is shown in Figure 5. The differences for the 24-pin MSL1064 are that the MSL1064 provides only two pins for SW instead of four pins on the MSL1061, and the AD0 pin is not pinned out but is instead bonded internally to SCL. The MSL1061 I2C slave address is selected using AD0 from one of the four address pairs, 0xC0/0xC1 - 0xC6/0xC7, whereas the MSL1064 I2C slave address is fixed at 0xC4/0xC5. Figure 5. Atmel LED Driver-MSL1061 Block Diagram 14 Atmel LED Drivers-MSL1061/MSL1064 Typical Application Circuit Figure 6. Backlight Example Driving 60 White LEDs 4.7 Table 4. Typ. Application Circuit Parameters PARAMETER Minimum input voltage Maximum input voltage (set by minimum LEDs string voltage) Table 5. Typ. Application Circuit Bill of Materials VALUE 4.75V 30V Number of LEDs 60 Number of LED strings 6 Number of LED per string 10 LED forward current (set by R5) White LED 20mA Osram LWY3SG COMPONENT C4, C5, C6, C7* DESCRIPTION VENDOR PART NUMBER 1F, 50V, X7R C2 10F, 10V, X7R or tantalum (see note) C3 33F, 35V, X7R C1 4.7F, 6.3V, X7R R8 1M, 1% R9 28.7k, 1% R4 115k, 1% Minimum LED forward voltage 2.9V R5 100k, 1% Typical LED forward voltage 3.3V R7 100k, 5% Maximum LED forward voltage 3.6V R2 1M, 5% Minimum LED string voltage 29V L1 10H, 1.7A Maximum LED string voltage 36V D1 60V, 2A Schottky Central Semi CMSH2-60M 60 x 30mA LED Osram LW-Y2SG Oscillator frequency (set by R4) Overvoltage protection (OVP) trip point (set by R8 and R9) 1.1MHz 45.9V LEDs LED driver MSL1060 Sumida CDRH6D28-100 MSL1060 * Note: C7 is only required if tantalum capacitor is used for C2 Atmel LED Drivers-MSL1061/MSL1064 15 Detailed Description The MSL1061/64 is an LED driver with integrated boost regulator for driving an array of LEDs with up to 8W of power. The IC/SMB serial interface, logic controls, and fault management make the MSL1061/64 especially suited to drive up to 72 white LEDs for portable device backlighting. It is also ideal for industrial lighting and signage applications, and can, for example, drive a 6 string x 18 series LED array totaling 108 red LEDs (2.5V LED forward voltage drop). Internal Oscillator - R4 The MSL1061/64 includes six current sinks (STR0 through STR5) that each control the LED current of series-connected LEDs. A built-in step-up (boost) regulator supplies power to the LEDs. The MSL1061/64 controls the output voltage of the boost regulator such that all LED strings have sufficient voltage to maintain regulated LED current. This control loop operates automatically without any user interaction or set-up. Setting the Full-scale LED String Current - R5 Application Information The MSL1061/64 uses an internal oscillator with frequency set by resistor R4 from OSC to GND (Figure 6). Use 115k 1% resistance value for R4. This sets the internal LED dimming PWM frequency to 11MHz and the boost regulator PWM frequency to 1.1MHz. When using different values for R4 the MSL1061/64 performance is not guaranteed. R5 sets the full-scale static LED current for all enabled strings (Figure 6) from ILED to GND. The maximum fullscale LED current is 30mA. The equation for calculating external resistor R5 (Figure 6) to set the full-scale LED string current IILED is: I ILED = 2000 R5 VCC and VDD Regulators where R5 is in kilohms and ILED is in milliamperes. The MSL1061/64 includes two linear voltage regulators to generate the internal voltage rails, VDD and VCC. The regulators allow the MSL1061/64 to operate directly from the same higher voltage supply, VIN, which supplies the LED boost regulator. Use the VDD and VCC regulators only to power the MSL1061/64's internal circuitry, therefore do not draw any external current from them. A value of 100k for resistor R5 sets 20mA full-scale LED current. The minimum allowed value for R5 is 66.7k, which sets 30mA full-scale LED current. Reduce the static LED current from full-scale using the LED string current register. This register reduces LED current proportional to the 4-bit IDAC register. The VCC regulator generates a nominally 6V rail from VIN. VCC powers the boost regulator's power switch and the VDD regulator. Bypass VCC to GND either with a 10F or greater ceramic capacitor or with a 10F or greater tantalum capacitor in parallel with a 1F ceramic capacitor. In applications where there is a local 4.75V to 6.5V supply available, power VCC and VIN directly from this supply. In this case use this supply or a separate higher voltage supply to power the LED boost regulator. When using a higher voltage supply connect it to the inductor, L1 (Figure 6), and not to the MSL1061/64. The VDD regulator generates a nominally 2.9V rail from VCC. VDD operates the internal low-voltage circuits. Bypass VDD to GND with a 4.7F or greater capacitor. 16 Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface Boost Regulator Components The boost regulator is internally compensated, includes an internal high voltage power switch, and requires only an inductor, rectifier, and bypass capacitors. The currentmode boost regulator operates in either continuous conduction mode (CCM) or discontinuous conduction mode (DCM). In CCM, the inductor current does not fall to zero when operating at full power, keeping inductor ripple current low and switching noise at a minimum. The boost regulator switching frequency is 1.1MHz set by the 115k resistor R4 from OSC pin to GND (Figure 6). Select the inductor, rectifier diode, and output capacitors per the following guidelines. Boost Supply Over-voltage Protection (OVP) - R8 and R9 The OVP input sets the boost regulator's output voltage upper limit, and protects the boost regulator from an open-circuit LED fault. Set the OVP voltage VTRIP by resistors R8 and R9 (Figure 6): VTRIP = VOVP ( R8 + R 9 ) R9 where VOVP=1.28V, nominal. To minimize losses in the rectifier, choose one with fast switching and low forward voltage drop. Ensure that the rectifier can withstand a reverse voltage equal to the regulator output voltage. The average forward current is equal to the total LED string current (for example 6 strings x 30mA = 180mA), while the peak current is equal to the inductor peak current (2A). The boost output capacitor holds the voltage at the output of the boost regulator while the internal power switch is on and the rectifier is not conducting. Use ceramic capacitors for small size and high ripple current capacity, and derate them for operating voltage because of the voltage coefficient of capacitance which decreases the effective capacitance with increased operating voltage. Use two parallel-connected 1F 100V X7R ceramic capacitors and a 10H inductor with a 1.7A peak current rating. Atmel LED Drivers-MSL1061/MSL1064 17 Register Map Summary Control the MSL1061/64 through an I2C interface using nine registers (Table 6). The power-up defaults (Table 7) are such that an MSL1061/64 operates as a standalone LED driver if the I2C interface is not used. The Internal register addressing auto-increments through the register map allowing sequential reads or writes without needing to write separate addresses for each byte. Table 6. Atmel LED Drivers-MSL1061/64 Register Map REGISTER FUNCTION ADDRESS MSTRCNTRL Run/sleep mode REGISTER DATA D7 D6 D5 D4 D3 D2 D1 D0 0x00 - - - - - - - SLEEP CNTRL PWM source, I2C/ SMB bus timeout, fault pin enable 0x01 - - - - INTPWM EXTCLK TOEN FLTEN - UNUSED 0X02 STATUS Fault status summary 0x03 - OTDET SCDET OCDET - - - FLTDET OCSTATUS Open circuit fault status 0x04 - - OC5 OC4 OC3 OC2 OC1 OC0 SCSTATUS Short circuit fault status 0x05 - - SC5 SC4 SC3 SC2 SC1 SC0 PWMFREQ PWM frequency prescaler 0x06 D7 D6 D5 D4 D3 D2 D1 D0 PWMDUTY PWM duty ratio 0x07 D7 D6 D5 D4 D3 D2 D1 D0 - UNUSED 0X08 STREN String enables 0x09 - unused 0x0A writes to this register address are ignored, and reads return the value 0x00 - unused 0x0B writes to this register address are ignored, and reads return the value 0x00 - unused 0x0C writes to this register address are ignored, and reads return the value 0x00 - unused 0x0D writes to this register address are ignored, and reads return the value 0x00 - unused 0x0E writes to this register address are ignored, and reads return the value 0x00 - unused 0x0F writes to this register address are ignored, and reads return the value 0x00 IDAC LED string current 0x10 18 WRITES TO THIS REGISTER ADDRESS ARE IGNORED, AND READS RETURN THE VALUE 0X00 WRITES TO THIS REGISTER ADDRESS ARE IGNORED, AND READS RETURN THE VALUE 0X00 - - - - STR5EN - STR4EN - STR3EN DAC3 STR2EN DAC2 STR1EN DAC1 STR0EN DAC0 Atmel LED Drivers-MSL1061/MSL1064 Atmel LED Drivers-MSL1061/MSL1064 6-string PWM LED Driver with Digitally Compensated, 1.1MHz, 48V Boost Regulator, 1.5% Current Balance, I2C Interface Register Map Power-up Defaults Table 7. Atmel LED Drivers-MSL1061/64 Register Power-up Defaults REGISTER MSTRCNTRL POWER-UP CONDITION ADDRESS REGISTER DATA D7 D6 D5 D4 D3 D2 D1 D0 Run mode 0x00 0 0 0 0 0 0 0 0 CNTRL Fault detection is enabled IC bus timeout is disabled PWM internal 11MHz clock is used, prescaled by PWMFREQ PWM control is by PWM pin. PWMDUTY register is ignored 0x01 0 0 0 0 0 0 0 1 STATUS No faults (open, short, or temperature) are detected 0x03 0 0 0 0 0 0 0 0 OCSTATUS None of the six LED outputs STR0 to STR5 has an open circuit fault 0x04 0 0 0 0 0 0 0 0 SCSTATUS None of the six LED outputs STR0 to STR5 has a short circuit fault 0x05 0 0 0 0 0 0 0 0 PWMFREQ Internal PWM frequency is the maximum 43kHz 0x06 0 0 0 0 0 0 0 0 PWMDUTY Internal PWM duty ratio is 0.39% 0x07 0 0 0 0 0 0 0 0 STREN All of the six LED outputs STR0 to STR5 are enabled 0x09 0 0 1 1 1 1 1 1 LED string current is 100% of the value programmed by resistor R5 0x10 0 0 0 0 1 1 1 1 IDAC Atmel LED Drivers-MSL1061/MSL1064 19 Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: (+1)(408) 441-0311 Fax: (+1)(408) 487-2600 www.atmel.com Atmel Asia Limited Unit 01-5 & 16, 19F BEA Tower, Millennium City 5 418 Kwun Tong Road Kwun Tong, Kowloon HONG KONG Tel: (+852) 2245-6100 Fax: (+852) 2722-1369 Atmel Munich GmbH Business Campus Parkring 4 D-85748 Garching b. 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