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atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface datasheet brief
2 atmel led driver-MSL3085 general description the atmel led driver- MSL3085 compact, high- power 8 led strings controller uses external mosfets to sink up to 350ma per string, with current accuracy and matching better than 1.5%. the MSL3085 drives eight parallel strings of leds, and offers fault detection and management of open and short circuit leds. atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface the MSL3085 features a 1mhz i 2 c serial interface. the interface supports video frame-by-frame led string intensity control for up to eight interconnected devices, allowing active area dimming and phase shifted pwm timing for video displays. it includes an advanced pwm engine that synchronizes led timing with the video signal for reduced motion blur and waterfall noise. the MSL3085 adaptively controls the dc-dc converters that power the led strings using patented atmel adaptive sourcepower? technology. these fault monitored efficiency optimizers minimize power use while maintaining led current accuracy, and allow up to eight interconnected devices to automatically negotiate the optimum power supply voltage. a unique combination of peak current control and pulse width dimming management offers simple full-screen brightness control, versatile area dimming, and a consistent white point. led string current is set for each string using a current sense (fet source) resistor. led current is also digitally controlled for all eight led strings. global string drive pulse width is adjusted with an 8-bit global intensity register, and individual string pulse width is modulated with 12-bit control. the MSL3085 monitors for string open circuit, led short circuit, loss-of-sync and over temperature faults, and provides a hardware fault output to notify the mcu. detailed fault status and control are available through the serial interface. additionally, the MSL3085 includes an on-chip eeprom that allows the power-up default register settings to be customized via the serial interface. the MSL3085 is offered in a 6 x 6 x 0.75mm, 40-pin tqfn package, and operates over a -40c to +105c temperature range. applications long life, efficient led backlighting for: ? televisions and desktop monitors ? medical and industrial instrumentation ? automotive audio-visual displays channel signs architectural lighting ordering information eight-channel led string driver part interface package MSL3085bt i 2 c 40-pin, 6 x 6 x 0.75mm tqfn
3 atmel led driver-MSL3085 atmel led driver-MSL3085 atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface key features application circuit ? 12-bit pwm string dimming ? fast, 1mhz i 2 c serial interface supports up to eight devices per bus ? 8-bit adaptive power correction maximizes efficiency of up to two string power supplies ? multiple MSL3085s share string power supplies and automatically negotiate the optimum supply voltage ? external mosfets for high voltage and/or current ? drives up to eight parallel led strings ? supports adaptive, real-time area dimming for highest dynamic range in lcd tvs and monitors ? programmable string phase reduces motion blur and improves efficiency ? global intensity control via serial interface ? 1.5% current accuracy and current balance ? video frame (vsync) and line (hsync) sync inputs ? sync loss detectors optionally disable led strings ? eeprom saves power-on default settings ? led open circuit and short circuit fault detection ? individual fault detection enable for each string ? over-temperature shut-off protection ? broadcast write simplifies configuration ? -40c to +105c operating temperature range
4 atmel led driver-MSL3085 atmel led driver MSL3085 overview the MSL3085 controls eight strings of series-connected leds at up to 350ma per string. eight MSL3085s can share a serial interface. the MSL3085 fet gate drive output is optimized for fets requiring no more than 10nc of charge. the MSL3085 pwm engine generates the pwm signal that drives the strings, or optionally accepts an external pwm signal. led power supplies and efficiency optimizers the MSL3085 features two efficiency optimizer outputs that dynamically adjust the led string power supplies to their minimum voltage necessary to drive the led strings, while assuring accurate led current flow. one of the efficiency optimizers features an input that allows up to eight devices to be connected in a chain configuration. when implemented, the chain automatically negotiates, controls, and optimizes the string power supply for all led strings driven by the chain. the power supplies can use any topology, and are typically dc-dc boost converters. the efficiency optimizers rely on close matching of the leds connected to a string supply. the better the matching, the better the overall efficiency. timing, pwm, intensity controls and synchronization the pwm led drive signals synchronize to video frame timing via the phi input, and to pixel timing via the gsc input. area led dimming is supported for contrast and color gamut improvement. with area dimming, motion blur is reduced by setting each led strings pwm phasing to synchronize string off times with the lcd update timing. the MSL3085 also includes internal pwm timing generation for standalone (non-video) led lighting applications. table 1 presents the available methods of led intensity control. table 1. led intensity controls led intensity control effect register resolution global led string current adjust reduces string current globally from maximum set by fet source resistors istr (0x31) 8 bits global led string pwm global pwm scaling gint (0x2f) and altgint (0x30) 8 bits individual led string pwm pwm individual string control pwmn (0x60 thru 0x7d) and altpwmn (0xa0 thru 0xbd) 12 bits external resistor from fet source to ground sets maximum individual string current - - external pwm input optionally controls all string pwm drives - -
5 atmel led driver-MSL3085 package pin-out figure 1. atmel led driver-MSL3085 pin-out, 40-pin tqfn. figure 2. package dimensions: 40-pin, 6mm x 6mm x 0.75mm tqfn (0.5mm pin pitch) with exposed pad. ( t o p v i e w ) s 4 d 2 g 2 s 2 d 0 g 0 s 0 vdd v i n e n 4 0 3 9 3 8 3 7 3 6 3 5 3 4 3 3 3 2 3 1 g 4 1 3 0 p w m d 4 2 2 9 g s c s 6 3 2 8 phi g 6 4 2 7 vcc d 6 5 2 6 d 1 4 n c 6 2 5 g 1 4 sda 7 2 4 s 1 4 scl 8 2 3 d 1 2 g n d 9 2 2 g 1 2 f l t b 1 0 msl 3085 2 1 s 1 2 1 1 1 2 1 3 4 1 4 1 5 1 6 1 7 1 8 1 9 2 0 addr fbo 2 fbi 1 fbo 1 s 9 g 9 d 9 s 1 1 g 1 1 d 1 1 atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
6 atmel led driver-MSL3085 pin descriptions note: to ensure register compatibility with the 16-string device of the same family (atmel led driver-msl2161), pin names for gate, drain and source connections are not sequential. pin pin name pin description 1 g4 gate output 4 gate drive output for external mosfet 4. connect g4 to the gate of the external mosfet driving led string 4. 2 d4 drain sense input 4 drain sense input for external mosfet 4. connect d4 through a 10m resistor to the drain of the external mosfet driving led string 4. 3 s6 source sense input 6 source sense input for external mosfet 6. connect s6 to the source of the external mosfet, and to the current sense resistor for led string 6. the full-scale led current is reached when 500mv is across the current sense resistor. 4 g6 gate output 6 gate drive output for external mosfet 6. connect g6 to the gate of the external mosfet driving led string 6. 5 d6 drain sense input 6 drain sense input for external mosfet 6. connect d6 through a 10m resistor to the drain of the external mosfet driving led string 6. 6 nc no connection make no connection to nc. 7 sda i2c serial data i/o sda is the data i/o for the i2c serial interface. 8 scl i2c serial clock input scl is the clock input for the i2c serial interface. 9 gnd ground connect gnd to system ground and to ep with short, wide traces. 10 fltb fault indication output (active low) open drain output fltb sinks current to gnd whenever a fault is detected and verifed. fltb remains low until the fault registers are read, and reasserts if the fault persists. 11 addr slave id selection inputs connect addr to a resistor to gnd to set the device address for the serial interface. 12 fbo2 effciency optimizer output 2 connect fbo2 to the second power supplys feedback node. if unused, leave fbo2 unconnected. 13 fbi1 effciency optimizer input 1 connect fbi1 to fbo1 of the next device, when chaining the effciency optimizers connect fbi1 to gnd if unused. 14 fbo1 effciency optimizer output 1 connect fbo1 to the frst power supplys feedback node. if unused, leave fbo1 unconnected. 15 s9 source sense input 9 source sense input for external mosfet 9. connect s9 to the source of the external mosfet, and to the current sense resistor for led string 9. the full-scale led current is reached when 500mv is across the current sense resistor. 16 g9 gate output 9 gate drive output for external mosfet 9. connect g9 to the gate of the external mosfet driving led string 9. 17 d9 drain sense input 9 drain sense input for external mosfet 9. connect d9 through a 10m resistor to the drain of the external mosfet driving led string 9. 18 s11 source sense input 11 source sense input for external mosfet 11. connect s11 to the source of the external mosfet, and to the current sense resistor for led string 11. the full-scale led current is reached when 500mv is across the current sense resistor. 19 g11 gate output 11 gate drive output for external mosfet 11. connect g11 to the gate of the external mosfet driving led string 11. 20 d11 drain sense input 11 drain sense input for external mosfet 11. connect d11 through a 10m resistor to the drain of the external mosfet driving led string 11.
7 atmel led driver-MSL3085 pin pin name pin description 21 s12 source sense input 12 source sense input for external mosfet 12. connect s12 to the source of the external mosfet, and to the current sense resistor for led string 12. the full-scale led current is reached when 500mv is across the current sense resistor. 22 g12 gate output 12 gate drive output for external mosfet 12. connect g12 to the gate of the external mosfet driving led string 12. 23 d12 drain sense input 12 drain sense input for external mosfet 12. connect d12 through a 10m resistor to the drain of the external mosfet driving led string 12. 24 s14 source sense input 14 source sense input for external mosfet 14. connect s14 to the source of the external mosfet, and to the current sense resistor for led string 14. the full-scale led current is reached when 500mv is across the current sense resistor. 25 g14 gate output 14 gate drive output for external mosfet 14. connect g14 to the gate of the external mosfet driving led string 14. 26 d14 drain sense input 14 drain sense input for external mosfet 14. connect d14 through a 10m resistor to the drain of the external mosfet driving led string 14. 27 vcc 5v internal ldo regulator output vcc powers the fbo outputs. bypass vcc to gnd with a 4.7f ceramic capacitor placed close to vcc. 28 phi phase synchronization input drive phi with an external signal of typically 100hz to 480hz to synchronize the MSL3085 led pwm timing. 29 gsc gate shift clock input drive gsc with the gate shift clock of the video signal. 30 pwm pwm input pwm allows external control of the brightness of all led strings. drive pwm with a pulse-width-modulated signal with a duty cycle of 0% to 100% and a frequency up to 5khz. when not confgured as an input, pwm is high impedance. 31 en enable input (active high) drive en high to turn on the MSL3085, and drive en low to turn off the MSL3085. for automatic start-up, connect en to vin. when en is low, the entire device, including the serial interface, is turned off. driving en high initiates a boot load of the eeprom data into the control registers, simulating a cold start-up. 32 vin supply voltage input connect a 12v 10% supply to vin. bypass vin to gnd with a 10f ceramic capacitor placed close to vin. 33 vdd 2.5v internal ldo regulator output vdd powers internal logic. bypass vdd to gnd with a 4.7f ceramic capacitor placed close to vdd. 34 s0 led string 0 external mosfet source input source sense input for external mosfet 0. connect s0 to the source of the external mosfet, and to the current sense resistor for led string 0. the full-scale led current is reached when 500mv is across the current sense resistor. 35 g0 gate output 0 gate drive output for external mosfet 0. connect g0 to the gate of the external mosfet driving led string 0. 36 d0 drain sense input 0 drain sense input for external mosfet 0. connect d0 through a 10m resistor to the drain of the external mosfet driving led string 0. 37 s2 led string 2 external mosfet source input source sense input for external mosfet 2. connect s2 to the source of the external mosfet, and to the current sense resistor for led string 2. the full-scale led current is reached when 500mv is across the current sense resistor. 38 g2 gate output 2 gate drive output for external mosfet 2. connect g2 to the gate of the external mosfet driving led string 2. 39 d2 drain sense input 2 drain sense input for external mosfet 2. connect d2 through a 10m resistor to the drain of the external mosfet driving led string 2. 40 s4 led string 4 external mosfet source input source sense input for external mosfet 4. connect s4 to the source of the external mosfet, and to the current sense resistor for led string 4. the full-scale led current is reached when 500mv is across the current sense resistor. ep ep exposed pad, power ground connect ep to system ground and to gnd using short, wide traces. ep provides thermal relief for the die. atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
8 atmel led driver-MSL3085 absolute maximum ratings voltage (with respect to gnd) vin, en, d0 thru d14, g0 thru g14 ................................................................................................................ -0.3v to +18v vcc ........................................ ............................................................................................................................................................. -0.3v to +6v vdd, addr, s0 thru s14 ....................................................................................................................................... -0.3v to +2.75v fbo1, fbo2, fltb ........................................................................................................................................................... -0.3v to +5.5v phi, gsc, pwm ............................................................................................................................................... -0.3v to (vcc + 0.3v) sda, scl ....................................... ............................................................................................................................................ -0.3v to +5.5v current (into pin) vin ....................................... ............................................................................................................................................................................... 50ma fbo1, fbo2 ....................................... .............................................................................................................................. +0a to -800a g0 thru g14 ........................................ ................................................................................................................................................. 100ma all other pins ........................................ ........................................................................................................................................................ 20ma continuous power dissipation 40-pin 6mm x 6mm qfn (derate 38mw/c above t a = +70c) ................................................. 2100mw ambient operating temperature range t a = t min to t max ........................................... -40c to +105c junction temperature ............................................................................................................................................................... +125c storage temperature range .......................................................................................................................... -65c to +125c lead soldering temperature, 10s .................................................................................................................................. +300c electrical characteristics typical application circuit, v vin = 12v, t a = t min to t max , unless otherwise noted. typical values are at v vin = 12v, t a = +25c parameter symbol conditions and notes min typ max unit dc electrical characteristics vin operating supply voltage vin 10.8 12 13.2 v vin operating supply current i vin normal operation, all led strings driven 25 32.5 ma vin shutdown supply current i sleep sleep = 1, sda, scl, addr, pwm, phi and gsc at gnd or vdd 500 a vcc regulation voltage vcc i vcc = -1.0ma 4.5 5.0 5.5 v vdd regulation voltage vdd i vdd = -1.0ma 2.4 2.5 2.6 v en input high voltage 1.4 v
9 atmel led driver-MSL3085 parameter symbol conditions and notes min typ max unit i 2 c logic levels sda, scl input high voltage 0.7 x vdd v sda, scl input low voltage 0.3 x vdd v sda output low voltage i sink = 6ma 0.4 v parameter symbol conditions and notes min typ max unit ac electrical characteristics osc frequency f osc f osc = 20mhz, t a = 25c 19.4 20 20.6 mhz phi frequency f phi 0.04 10 khz gsc frequency f gsc 0 10 mhz pwm frequency f pwm 5 khz pwm duty cycle 0 100 % phi lock 4 phi cycles parameter symbol conditions and notes min typ max unit en input low voltage 0.9 v pwm, phi, gsc input high voltage v ih 0.7 x vdd v pwm, phi, gsc input low voltage v il 0.3 x vdd v phi, gsc output high voltage v oh i source = 5ma vdd C 0.4 phi, gsc, fltb output low voltage v ol i sink = 6ma 0.4 v fbo feedback output current compliance voltage 3.5v, minimum 0 360 a fbo feedback output current step size 1.2 a d0 thru d7 short circuit fault detection threshold 8 v g0 thru g7 open circuit fault detection threshold 8 v g0 thru g14 gate drive charge (note 2) 10 c s0 thru s7 regulation voltage 492 500 508 mv s0 thru s7 voltage matching istr = 0x7f -1.5 1.5 % thermal shutdown temperature tbd c atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
10 atmel led driver-MSL3085 parameter symbol conditions and notes min typ max unit i2c timing characteristics scl clock frequency 1/t scl bus timeout disabled (note 3) 0 1 mhz bus time-out period t timeout f osc = 20mhz, t a = 25c 29 30 31 ms f osc = 16mhz to 23mhz 600,000 / f osc s stop to start condition bus free time t buf 0.5 s repeated start condition hold time t hd:sta 0.26 s repeated start condition set-up time t su:sta 0.26 s stop condition set-up time t su:stop 0.26 s sda data hold time t hd:dat 0 ns sda data valid acknowledge time t vd:ack (note 4) 0.05 0.45 s sda data valid time t vd:dat (note 5) 0.05 0.45 s sda data set-up time t su:dat 100 ns scl clock low period t low 0.5 s scl clock high period t high 0.26 s sda, scl fall time t f (note 6) (note 7) 120 ns sda, scl rise time t r 120 ns sda, scl input suppression flter period t sp (note 8) 50 ns note 1. subject to thermal dissipation characteristics of the device. note 2. guaranteed by design, and is not production tested. note 3. minimum scl clock frequency is limited by the bus time-out feature, which resets the serial bus interface if either sda or scl is held low for t timeout . disable bus time-out via the fault enable register 0x03[6]. note 4. t vd:ack = scl low to sda (out) low acknowledge time. note 5. t vd:dat = minimum sda output data valid time following scl low transition. note 6. a master device must internally provide an sda hold time of at least 300ns to ensure an scl low state. note 7. the maximum sda and scl rise times are 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 8. input filters on sda, scl, and addr suppress noise less than 50ns.
11 atmel led driver-MSL3085 typical application circuit figure 3. atmel led driver-MSL3085 driving 80 white leds in eight strings. atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
12 atmel led driver-MSL3085 detailed description the MSL3085 is a highly integrated, flexible, multi-string led driver that uses external mosfets to allow high led string currents, and includes power supply control to maximize efficiency. the driver optionally connects to a video subsystem to offer a simple architecture for use in lcd tv backlight applications. up to eight devices easily connect together to drive a large number of led strings in a system. the drivers provide multiple methods of controlling led brightness through both peak current control and pulse width control of the string drive signals. peak current control offers excellent color consistency, while pulse width control allows brightness management. an on-chip eeprom holds all the default control register values. at power-up, the data in the eeprom is automatically copied directly to the control registers, setting up the device for operation. the factory programmed eeprom values are changeable through the serial interface if a different power-up condition is desired. the device interfaces to an mcu via the i 2 c interface. the robust, 1mhz i 2 c interface supports up to eight devices on the bus. while typically the led drive pwm signal is internally generated, the device also accepts an external direct pwm drive signal applied to the pwm input that sets the pwm duty cycle and the frequency of the led drive signals. the MSL3085 also allows phase spreading of the led drive signals, which helps reduce both the transient load on the led power supplies and the power supply input capacitor size requirements. the MSL3085 is an eight string version of the msl2161, squeezed into a smaller package, with two efficiency optimizer (eo) outputs and one eo input. (the msl2161 offers 16 string drives, three eo outputs, and three eo inputs.) this offers the advantage of small size, but to ensure register compatibility with the msl2161, pin names of the fet drive outputs are not sequential. the fet drive outputs are named 0, 2, 4, 6, 9, 11, 12, and 14 (not 0 through 7). all control registers also follow this naming convention. additionally, this has a small impact on the automatic phase-shift feature, whose sequential phase shifts for outputs 9 and 12 are spaced at 1/16 th the pwm frame, while the others are spaced at 1/8 th the pwm frame. the pwm frequency of the drivers is easily synchronized to an external video signal applied to phi, synchronized to the internal oscillator for standalone applications, or set directly by a signal at the pwm input. typically, the vsync signal from the video system is used as the phi input. a frequency multiplier (1x to 32x) processes this signal for use by the pwm engine. the on time of each string is individually programmed via the device registers, providing a peak resolution of 12 bits when using the on-chip pwm generator. the actual resolution of the pwm frequency depends on the ratio of the gsc frequency (typically provided by a systems hsync signal, but can be internally generated) to the phi frequency because the on time of a string is programmed as a 12-bit count of the number of gsc clock cycles. this count can be further scaled by an 8-bit global intensity register, when enabled. the gsc clock is also used to precisely set each strings phase delay so that it is synchronized to its physical position relative to the video frame. the efficiency optimizers control a wide range of different external dc-dc and ac/dc converter architectures. multiple drivers in a system communicate in real time among themselves to select an optimized operating voltage for the leds. this allows design of the power supply for the worst case forward voltage (v f ) of the leds without concern about excessive power dissipation issues. during the start-up sequence, the MSL3085 automatically reduces the power supply voltage to the minimum voltage required to keep the leds in current regulation. the devices are configured to periodically perform this optimization to compensate for changes in led forward voltage, and to assure continued optimum power savings. internal regulators and enable input the MSL3085 includes two internal linear regulators that provide vcc (5v) and vdd (2.5v) for internal circuitry. vin (12v nominal) supplies the vcc and vdd regulators. bypass vin to gnd with a 10f capacitor close to the device. bypass vcc to gnd with a 4.7f capacitor close to the device. bypass vdd to gnd with a 4.7f capacitor close to the device.
13 atmel led driver-MSL3085 the MSL3085 enable input, en, enables the device. drive en low to enter low power operation, which lowers quiescent current draw to less than 20 a . with en low, the serial interface is ignored, the efficiency optimizer is disabled, and all strings are turned off. drive en high to turn on the device. when en is driven high, the contents of the eeprom are boot loaded into the control registers, simulating a cold start-up, and all bits in the fault registers are cleared to 0. setting the maximum led string current with a source resistor the maximum string current, i led , for each string is set by a resistor, r s , connected to ground from the source terminal of the external string drive mosfet. the feedback threshold is 500mv. determine the resistor value using: led s i r 5 . 0 = , where i led is in amperes and r s is in ohms. for example, a full-scale led current of 100ma returns r s = 5 . the current for all led strings is reduced from the full-scale value with 8-bit resolution using istr, the string current control register 0x31. connecting the efficiency optimizer to an led string power supply and selecting resistors the MSL3085 is designed to control an external led string power supply that uses a voltage divider (r top and r bottom in figure 4) to set output voltage, and whose regulation feedback voltage is not more than 3.5v. the efficiency optimizer improves power efficiency by injecting a current of between 0 and 255a into the voltage divider of the external power supply, dynamically adjusting the power supply's output to the minimum voltage required by the led strings. to select the resistors, first determine v out(min) and v out(max) , the minimum and maximum string supply voltage limits, using: v out(min) = ( v f (min) * [# ofleds ] ) + 0.5 , and v out(max) = ( v f (max) * [# ofleds ] ) + 0.5 , where v f(min) and v f(max) are the led minimum and maximum forward voltage drops at the peak current set by r s . for example, if the led data are v f(min) = 3.5v and v f(max) = 3.8v, and ten leds are used in a string, then the total minimum and maximum voltage drops across a string are 35v and 38v, respectively. adding an allowance of 0.5v for the string drive mosfet headroom brings v out(min) to 35.5v and v out(max) to 38.5v. then, determine r top using: ) ( ) ( ) ( max fbon min out max out top i v v r ? = . where i fbon(max) is the 255 a maximum output current of the efficiency optimizer outputs fbon. finally, determine r bottom using: fb max out fb top bottom v v v r r ? ? = ) ( , where v fb is the regulation feedback voltage of the power supply. place a diode (1n4148 or similar) between fbon and the supplys feedback node to protect the MSL3085 against current flow into fbon. assign all strings powered by a common supply to the proper fbo output using string set registers 0x40 - 0x5d. once configured, determine the change in power supply output voltage in response to a change in fbon output current using: . figure 4. fbon connects to the power supply voltage divider through a diode. top fbo out r i v ? ? = ? atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
14 atmel led driver-MSL3085 using multiple atmel led driver-MSL3085s to control a common power supply cascade multiple MSL3085 devices into a chain configuration (figure 5), with the fbi1 of one device connected to the fbo1 of the next. connect the first fbo1 to the power supply feedback resistor node through a diode, and the unused fbi1 input to ground as close to the MSL3085 as possible. assure that all strings powered by the common supply are assigned to fbo1 using string set registers (strnset) 0x20 - 0x3d (fbo1 is the power-up default setting for all strings). the chained devices work together to ensure that the system operates at optimum efficiency. note that the accuracy of the feedback chain can degrade through each link of the fbi1/fbo1 chain by as much as 2%. determine the potential worst case maximum fbo1 current, i fbon(max/min) , using: i fbo(max / min) = 255 a * (0.98) n -1 , where n is the number of MSL3085s connected in series. use this result in the above r top resistor equation for the term i fbon(max) instead of using 255a. take care in laying out the traces for the efficiency optimizer connections. minimize the fbi1/fbo1 trace lengths as much as possible. do not route the signals close to traces with large variations in voltage or current because noise may couple into fbi1. if these traces must be routed near noisy signals, shield them from noise by using ground planes or guard traces. figure 5. example of cascading multiple devices to optimize a common string power supply.
15 atmel led driver-MSL3085 register map and the eeprom register map summary control the MSL3085 using the registers in the range 0x00 - 0xbd (table 2). two additional registers, 0xc0 and 0xc1, allow access to, and programming of, the eeprom. the power-up default values for all control registers are stored within the on-chip eeprom, and any of these eeprom values may be changed through the serial interface table 2. atmel led driver-MSL3085 register map address and register name function register data d7 d6 d5 d4 d3 d2 d1 d0 0x00 stringen0 led string enables - str6en - str4en - str2en - str0en 0x01 stringen1 - str14en - str12en str11en - str9en - 0x02 config confguration sleep - - - fldbken strscdly[2:0] 0x03 flten fault enable - - i 2 ctoen phimaxfen gscmaxfen strscfen strocfen fboocfen 0x04 strflten0 string fault enable - fen6 - fen4 - fen2 - fen0 0x05 strflten1 - fen14 - fen12 fen11 - fen9 - 0x06 fltstatus* fault status fltbdrv - - phimaxflt gscmaxflt strscflt strocflt fboocflt 0x07 ocstat0* string open circuit fault status - oc6 - oc4 - oc2 - oc0 0x08 ocstat1* - oc14 - oc12 oc11 - oc9 - 0x09 scstat0* string short circuit fault status - sc6 - sc4 - sc2 - sc0 0x0a scstat1* - sc14 - sc12 sc11 - sc9 - 0x0b - 0x0e unused 0x0f oscfreq oscillator frequency - - - - - oscfreq[2:0] 0x10 fboctrl0 effciency optimizer control hdrmstep[1:0] recaldly[1:0] settle[1:0] ierrconf[1:0] 0x11 fboctrl1 incrstep[1:0] decrstep[1:0] initpwm acal100 acalen ichkdis 0x12 fboctrl2 - - - - - fbo2ocen fbo1ocen fboen 0x13 fbodac1* effciency optimizer dac readback fbodac1[7:0] 0x14 fbodac2* fbodac2[7:0] 0x15 unused 0x16 fbostat* effciency optimizer status - fbo2oc fbo1oc - fbo2act fbo1act fbocal fboinitcal direct pwm control of the led strings an external pwm signal applied to the pwm input allows direct pwm control over the strings when pwmen and pwmdirect (bits d0 and d1 in pwm control register 0x2d) are set to 1. this configuration bypasses phi and gsc, but allows led string phase delay via the phase delay enable bit, phadlyen (bit d0 of register 0x2e). with phase delay enabled, a progressive delay based on the period of the pwm frame is calculated and applied successively to each string drive signal. the delay is typically 1/8 th the pwm frame, but outputs 9 and 12 have sequential delays of 3/16 th and 1/16 th of the pwm frame, respectively. the pwm input can also be configured as a gate for the output of the pwm engine using pwm global enable (bit d2 of the pwm control register 0x2d). atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
16 atmel led driver-MSL3085 address and register name function register data d7 d6 d5 d4 d3 d2 d1 d0 0x17 - 0x1f unused 0x20 gscctrl gsc processing control gscchk- sel - - - gscmaxen gscpol gscphi- syncen gscinten 0x21 gsccntr internal clock counter for gsc gsccntr[7:0] 0x22 gsccntr[15:8] 0x23 gscmul gsc multiplier - - - gscmul[4:0] 0x24 gscdiv gsc divider gscdiv[7:0] 0x25 gscmax max oscillator cycles between gsc pulses gscmax[7:0] 0x26 gscmax[15:8] 0x27 phictrl phi processing control phichk sel - - - - phimaxen phipol phiinten 0x28 phicntr internal clock counter for phi phicntr[7:0] 0x29 phicntr[15:8] 0x2a phimul phi multiplier - - - phimul[4:0] 0x2b phimax max gsc cycles between phi pulses phimax[7:0] 0x2c phimax[15:8] 0x2d pwmctrl0 pwm control gint+1en ginten alten ovrflozen ovrfloen pwm glblen pwmdirect pwmen 0x2e pwmctrl1 - - - - extalten phovr flozen phovr floen phadlyen 0x2f gint global pwm scaling gint[7:0] 0x30 altgint alternate global pwm scaling altgint[7:0] 0x31 istr 8-bit global string current scaling istr[7:0] 0x32 pwmstatus* pwm and counter status phimaxerrcnt[2:0] phimax1flt phisigflt gscsigflt phicntrflt gint- mulerr 0x33 phipcntr* phi pulse counter and status phicntr- max - - phimulcntr[0:4] 0x34 gscpcntr* gsc pulse counter gscpulsecntr[7:0] 0x35 - - - gscpulsecntr[12:8] 0x36 - 0x3f unused table 2. atmel led driver-MSL3085 register map
17 atmel led driver-MSL3085 address and register name function register data d7 d6 d5 d4 d3 d2 d1 d0 0x40 str0set phase delay and eo assignment for string 0 phdly0[7:0] 0x41 fboset0[1:0] - - phdly[11:8] 0x5c str14set phase delay and eo assignment for string 14 phdly14[7:0] 0x5d fboset14[1:0] - - phdly[11:8] 0x5e and 0x5f unused 0x60 pwm0 pwm setting for string 0 pwm0[7:0] 0x61 - - - - pwm0[11:8] 0x7c pwm14 pwm setting for string 14 pwm14[7:0] 0x7d - - - - pwm14[11:8] 0x7e and 0x7f unused 0x80 altstr0set alternate phase delay for string 0 altphdly0[7:0] 0x81 - - - - altphdly[11:8] 0x9c altstr14set alternate phase delay for string 14 altphdly14[7:0] 0x9d - - - - altphdly[11:8] 0x9e and 0x9f unused 0xa0 altpwm0 alternate pwm setting for string 0 altpwm0[7:0] 0xa1 - - - - altpwm0[11:8] 0xbc altpwm14 alternate pwm setting for string 14 altpwm14[7:0] 0xbd - - - - altpwm14[11:8] 0xbe and 0xbf unused 0xc0 e2addr eeprom read/write access - e2addr[6:0] 0xc1 e2ctrlsta e2busy bldact e2err - - rwctrl[2:0] atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
18 atmel led driver-MSL3085 register name and address power-up condition registers initialized from eeprom register data d7 d6 d5 d4 d3 d2 d1 d0 hex 0x00 stringen0 led strings 0, 2, 4, 6, 9, 11, 12, and 14 enabled 0 1 0 1 0 1 0 1 55 0x01 stringen1 0 1 0 1 1 0 1 0 5a 0x02 config string short circuit confrmation delay = 256s string current fold-back enabled device awake 0 0 0 0 1 1 0 1 0d 0x03 flten fbo open circuit fault detect globally enabled string open circuit fault detect globally enabled led short circuit fault detect globally enabled gsc max fault detect globally disabled phi max fault detect globally disabled i 2 c timeout enabled 0 0 1 0 0 1 1 1 27 0x04 strflten0 fault detection individually enabled for all strings (0, 2, 4, 6, 9, 11, 12, and 14) 0 1 0 1 0 1 0 1 55 0x05 strflten1 0 1 0 1 1 0 1 0 5a 0x0f oscfreq f osc = 20mhz 0 0 0 0 0 1 0 0 04 0x10 fboctrl0 current sink error confrmation delay = 2s fbo power supply correction delay = 4ms effciency optimizer auto-recalibration delay = 1s effciency optimizer headroom steps = 3 mosfet current sink error detection enabled effciency optimizer auto-recalibration enabled pwm settings used during auto-recalibration pwm settings used during initial calibration effciency optimizer correction step size = 1 lsb (1a) effciency optimizer initial calibration step size = 1 lsb (1a) fbo outputs globally enabled fbo1 open circuit detection enabled fbo2 open circuit detection disabled 0 1 0 0 1 0 0 1 49 0x11 fboctrl1 0 0 0 1 1 0 1 0 1a 0x12 fboctrl2 0 0 0 0 0 0 1 1 03 0x20 gscctrl external signal at gsc is selected for input to the pwm engine gsc not internally synchronized to phi pwm drive synchronized to falling edge of external gsc signal gsc maximum count fault detect is disabled although disabled, gsc max fault monitors f pgsc 0 0 0 0 0 0 0 0 00 0x21 gsccntr although disabled, internal gsc frequency f ggen = 20mhz / (80 + 1) = 246khz 0 1 0 1 0 0 0 0 50 0x22 0 0 0 0 0 0 0 0 00 0x23 gscmul gsc multiplexer output is multiplied by 4 (register setting + 1) 0 0 0 0 0 0 1 1 03 0x24 gscdiv gsc multiplier output is divided by 1 (register setting + 1) 0 0 0 0 0 0 0 0 00 0x25 gscmax although disabled, gsc max count is set to 174 clock cycles 1 0 1 0 1 1 1 0 ae 0x26 0 0 0 0 0 0 0 0 00 0x27 phictrl external signal at phi selected for input to pwm engine pwm engine is synchronized to the falling edge of phi phi maximum count fault detect is disabled although disabled, phi max count monitors f pphi 0 0 0 0 0 0 0 0 00 register power-up defaults register power-up default values are shown in table 3. table 3. atmel led driver-MSL3085 register power-up defaults
19 atmel led driver-MSL3085 register name and address power-up condition registers initialized from eeprom register data d7 d6 d5 d4 d3 d2 d1 d0 hex 0x28 phicntr although disabled, internal phi frequency f pgen = 20mhz / (8 * (10416 + 1)) = 240hz 1 0 1 1 0 0 0 0 b0 0x29 0 0 1 0 1 0 0 0 28 0x2a phimul phi multiplier = 1 (register setting + 1) 0 0 0 0 0 0 0 0 00 0x2b phimax although disabled, phi maximum count = 4148 0 0 1 1 0 1 0 0 34 0x2c 0 0 0 1 0 0 0 0 10 0x2d pwmctrl0 pwm operation enabled individual led string drive pulse widths internally determined pwm input does not gate the output of the pwm engine string on times allowed to extend beyond end of pwm frame string on times allowed to extend into frame zero alternate timing not used global intensity (gint) disabled although disabled, (gint + 1) is provided to the pwm engine string drive phasing enabled delayed string turn on beginning after pwm frame allowed delayed turn on occurring in frame zero allowed alternate timing not selected by pwm input state 1 0 0 1 1 0 0 1 99 0x2e pwmctrl1 0 0 0 0 0 1 1 1 07 0x2f gint global intensity set to (127 + 1) / 255 = 50.2% 0 1 1 1 1 1 1 1 7f 0x30 altgint alternate global intensity set to (95 + 1) / 255 = 37.6% 0 1 0 1 1 1 1 1 5f 0x31 istr strings current set at 50% of r s setting 0 1 1 1 1 1 1 1 7f 0x40 str0set all strings phase delay = zero all strings assigned to fbo1 0 0 0 0 0 0 0 0 00 0x41 0 1 0 0 0 0 0 0 40 0x5c str14set 0 0 0 0 0 0 0 0 00 0x5d 0 1 0 0 0 0 0 0 40 0x60 pwm0 all strings have pwm value = 512 gsc cycles 0 0 0 0 0 0 0 0 00 0x61 0 0 0 0 0 0 1 0 02 0x7c pwm14 0 0 0 0 0 0 0 0 00 0x7d 0 0 0 0 0 0 1 0 02 0x80 altstr0set all strings alternate phase delay = zero 0 0 0 0 0 0 0 0 00 0x81 0 0 0 0 0 0 0 0 00 0x9c altstr14set 0 0 0 0 0 0 0 0 00 0x9d 0 0 0 0 0 0 0 0 00 0xa0 altpwm0 all strings set with alternate pwm value = 512 gsc cycles 0 0 0 0 0 0 0 0 00 0xa1 0 0 0 0 0 0 1 0 02 0xbc altpwm14 0 0 0 0 0 0 0 0 00 0xbd 0 0 0 0 0 0 1 0 02 registers with fixed initial values 0xc0 e2addr eeprom 7-bit address = 0x00 0 0 0 0 0 0 0 0 00 0xc1 e2ctrlsta eeprom read/write disabled 0 0 0 0 0 0 0 0 00 atmel led driver-MSL3085 8-string white and rgb led driver with adaptive power control, eeprom, and i 2 c/smbus serial interface
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