Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Datasheet Brief Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus General Description The Atmel LED DriverMSL2162 compact, highpower LED string driver uses external current control MOSFETs to sink up to 350mA per string, with current accuracy and matching better than 1.5%. The MSL2162 drives 16 parallel strings of LEDs, and offers fault detection and management of open and short circuit LEDs. The MSL2162 features a 20 MHz SPI bus that supports video frame-by-frame LED string intensity control for up to eight interconnected devices. Frame-byframe control allows active area dimming and phase shifted PWM timing for improved backlight performance. The advanced PWM engine synchronizes PWM dimming to the video signals for reduced motion blur and waterfall noise. The MSL2162 adaptively controls the DC-DC converters powering the LED strings, using Atmel efficiency optimizers to minimize power use while maintaining LED current accuracy. A unique combination of regulation current control and pulse width dimming management offers simple, full-screen brightness control, versatile area dimming, and a consistent white point. A current sense resistor sets LED current for each string, offering the flexibility to drive each string with a different current. 8-bit control adjusts LED current equally for all 16 LED strings. Separate 12-bit registers control individual string pulse width dimming. The MSL2162 monitors LED strings for open circuit, short circuit, loss-of-videosync, and over-temperature faults, and provides a hardware fault output to notify a microcontroller. Use the serial interface for detailed fault status and control. Additionally, the MSL2162 includes on-chip EEPROM that allows customization of the power-up defaults, accessible through the serial interface. The MSL2162 is packaged in a 9 x 9 x 0.85mm, 64-lead TQFN, and operates over a -40°C to 105°C 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 16-CHANNEL LED STRING DRIVERS 2 PART INTERFACE PACKAGE MSL2162DQ SPI 64-pin, 9 x 9 x 0.85mm TQFN Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Key Features • 12-bit PWM String Dimming Control • ±1.5% Current Accuracy and Current Balance • Fast 20MHz SPI Bus Supports up to Eight MSL2162s per SPI Bus Chip Select • Flexible Video Frame (VSYNC) and Line (HSYNC) Sync Includes Frequency Multipliers and Dividers • 8-bit Adaptive Power Correction Maximizes System Efficiency by Controlling up to Two Power Supply Voltages • External Current Control MOSFETs for High Voltage and/or Current • Drives up to 16 Parallel LED Strings per Device • Supports Adaptive, Real-time Area Dimming for Highest Dynamic Range LCD TVs and Monitors • Programmable String Phase Reduces Motion Blur and Improves Efficiency • Second Set of PWM Registers Allows Alternate Brightness and Timing Selection with a Single Control • EEPROM Saves Power-on Default Settings • LED Open Circuit and Short Circuit Fault Detection • Individual Per-String Fault Detection Enable • Over-temperature Shut-off Protection • Broadcast Write Simplifies Configuration • -40°C To +105°C Operating Temperature Range • Global Intensity Control via Serial Interface Application Circuit Atmel LED Driver-MSL2162 3 Quick Start Guide The MSL2162 LED string controller drives, monitors, and dims multiple LEDs at high efficiency for LCD backlighting and signage applications. This section summarizes the capabilities of the MSL2162 for quick evaluation. How Many LEDs and Drivers? The MSL2162 controls 16 strings of series-connected LEDs at up to 350mA per string. Up to eight MSL2162s share a serial interface. The maximum number of LEDs per string is determined by the maximum power supply voltage, the LED forward voltage drop (VF), and the gate drive outputs of the MSL2162. The MSL2162 FET gate drive outputs are optimized for FETs requiring up to 10nC of charge. LED Power Supplies and Efficiency Optimizers (EOs) The MSL2162 Efficiency Optimizer (EO) circuits dynamically adjust up to two LED string power supplies to the minimum voltage necessary to accurately drive the LED strings while assuring accurate current flow. The power supplies can use any topology, and are typically DC-DC boost or buck, or AC-DC off-line switcher supplies. The EOs rely on close matching of the LED strings connected to a string supply. The better the matching, the better is the overall efficiency. Multiple devices easily link together to optimize a single power supply. Timing, PWM, Intensity Controls, and Synchronization For video applications, the PWM LED drive signals synchronize to the LCD’s video frame timing via the PHI input, and to the LCD’s pixel timing via the GSC input. This synchronization eliminates beating artifacts. Suitability for LED backlight architectures is shown in Table 1. Area LED dimming for direct backlighting is supported for contrast and color gamut improvement. Motion blur is reduced by setting each LED string’s PWM phasing individually to synchronize PWM off-times with the LCD update timing. The MSL2162 also includes easily controlled internal PWM timing generation for standalone (non-video) LED lighting applications that do not provide external timing sources. One MSL2162 simply generates PWM timing for itself, and for the other devices in a multiple device application. Optionally, a single external PWM signal applied to the PWM input controls all of the strings on-times, with automatic progressive phase delay available through a single control bit. Table 1. LED Common Backlight Drive Architectures and Features MOTION BLUR REMOVAL AREA DIMMING MANAGEMENT White LED - bottom edge-Lit No No White LED - top/bottom edge-Lit No No White LED - 4 sides edge-lit No No White LED - direct back-lit Yes, LED string phasing Higher contrast ratio (area dimming) RGB LED - direct back-lit Yes, LED string phasing Higher contrast ratio and color gamut BACKLIGHT TYPE 4 STRING SUPPLY OPTIONS Up to two Efficiency Optimized power supplies Two Efficiency Optimized power supplies Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Table 2. Timing and LED Intensity Control Capability LED INTENSITY CONTROL RESOLUTION Global LED string current adjust 8-bit DAC reduces string current globally from maximum set external resistors Global LED string PWM 8-bit global PWM control Individual LED string PWM 12-bit PWM individual string control Total LED string PWM control 12-bit LED String PWMs, computed from global and individual PWM settings Package Pinout S4 D3 G3 S3 D2 G2 S2 D1 G1 S1 D0 G0 S0 VDD VIN EN 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 Figure 1. Atmel LED Driver-MSL2162 Pinout, 64-pin TQFN G4 1 48 PWM D4 2 47 GSC S5 3 46 PHI G5 4 45 VCC D5 5 44 D15 S6 6 43 G15 G6 7 42 S15 D6 8 41 D14 S7 9 40 G15 G7 10 39 S14 D7 11 38 D13 MISO 12 37 G13 MOSI 13 36 S13 SCK 14 35 D12 CSB 15 34 G12 FLTB 16 33 S12 Atmel LED Driver-MSL2162 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 ADDR FBO2 FBI1 FBO1 S8 G8 D8 S9 G9 D9 S10 G10 D10 S11 G11 D11 MSL2162 5 Figure 2. Package Dimensions: 64-lead, 9mm x 9mm x 0.85mm TQFN (0.5mm lead pitch) with Exposed Pad Figure 2. Package Dimensions: 64 Pin 9mm x 9mm x 0.85mm TQFN (0.5mm pin pitch) with exposed pad Package Connection Description Table 3. Atmel LED Driver-MSL2162 Connection Description 6 NO. NAME 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 10MΩ resistor to the drain of the external MOSFET driving LED string 4. Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Table 3. Atmel LED Driver-MSL2162 Connection Description NO. NAME DESCRIPTION 3 S5 Current sense input 5 Current sense input for LED string 5. Connect S5 to the source of the external MOSFET and to the current sense resistor for LED string 5. The full-scale LED current threshold is 500mV is across the current sense resistor. 4 G5 Gate output 5 Gate drive output for external MOSFET 5. Connect G5 to the gate of the external MOSFET driving LED string 5. 5 D5 Drain sense input 5 Drain sense input for external MOSFET 5. Connect D5 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 5. 6 S6 Current sense input 6 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 7 G6 Gate output 6 Gate drive output for external MOSFET 6. Connect G6 to the gate of the external MOSFET driving LED string 6. 8 D6 Drain sense input 6 Drain sense input for external MOSFET 6. Connect D6 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 6. 9 S7 Current sense input 7 Current sense input for LED string 7. Connect S7 to the source of the external MOSFET and to the current sense resistor for LED string 7. The full-scale LED current threshold is 500mV is across the current sense resistor. 10 G7 Gate output 7 Gate drive output for external MOSFET 7. Connect G7 to the gate of the external MOSFET driving LED string 7. 11 D7 Drain sense input 7 Drain sense input for external MOSFET 7. Connect D7 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 7. 12 MISO Master input, slave output MISO is the MSL2162 SPI bus data output. 13 MOSI Master output, slave input MOSI is the MSL2162 SPI bus data input. 14 SCK SPI serial shift clock SCK is the MSL2162 clock input for the SPI bus. Atmel LED Driver-MSL2162 7 8 NO. NAME DESCRIPTION 15 CSB Chip select bar CSB is the MSL2162 SPI bus chip select input for SPI transactions. Drive CSB low to enable serial interface communication. 16 FLTB Fault indication output (active low) Open drain output FLTB sinks current to ground whenever the MSL2162 detects and verifies a fault. FLTB remains low until the fault registers are read, and reasserts if the fault persists. 17 ADDR Slave ID selection inputs Connect ADDR to ground through a resistor to set the SPI bus address. 18 FBO2 Efficiency Optimizer output 2 Connect FBO2 to the second power supply’s feedback node. Connect FBO2 to ground if unused. 19 FBI1 Efficiency Optimizer input 1 Connect FBI1 to FBO1 of the next device when connecting MSL2162s in series. If unused connect FBI1 to ground. 20 FBO1 Efficiency Optimizer output 1 Connect FBO1 to the first power supply’s feedback node. Connect FBO1 to ground if unused. 21 S8 Current sense input 8 Current sense input for LED string 8. Connect S8 to the source of the external MOSFET and to the current sense resistor for LED string 8. The full-scale LED current threshold is 500mV is across the current sense resistor. 22 G8 Gate output 8 Gate drive output for external MOSFET 8. Connect G8 to the gate of the external MOSFET driving LED string 8. 23 D8 Drain sense input 8 Drain sense input for external MOSFET 8. Connect D8 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 8. 24 S9 Current sense input 9 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 25 G9 Gate output 9 Gate drive output for external MOSFET 9. Connect G9 to the gate of the external MOSFET driving LED string 9. 26 D9 Drain sense input 9 Drain sense input for external MOSFET 9. Connect D9 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 9. Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus NO. NAME DESCRIPTION 27 S10 Current sense input 10 Current sense input for LED string 10. Connect S10 to the source of the external MOSFET and to the current sense resistor for LED string 10. The full-scale LED current threshold is 500mV is across the current sense resistor. 28 G10 Gate output 10 Gate drive output for external MOSFET 10. Connect G10 to the gate of the external MOSFET driving LED string 10. 29 D10 Drain sense input 10 Drain sense input for external MOSFET 10. Connect D10 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 10. 30 S11 Current sense input 11 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 31 G11 Gate output 11 Gate drive output for external MOSFET 11. Connect G11 to the gate of the external MOSFET driving LED string 11. 32 D11 Drain sense input 11 Drain sense input for external MOSFET 11. Connect D11 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 11. 33 S12 Current sense input 12 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 34 G12 Gate output 12 Gate drive output for external MOSFET 12. Connect G12 to the gate of the external MOSFET driving LED string 12. 35 D12 Drain sense input 12 Drain sense input for external MOSFET 12. Connect D12 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 12. 36 S13 Current sense input 13 Current sense input for LED string 13. Connect S13 to the source of the external MOSFET and to the current sense resistor for LED string 13. The full-scale LED current threshold is 500mV is across the current sense resistor. 37 G13 Gate output 13 Gate drive output for External MOSFET 13. Connect G13 to the gate of the external MOSFET driving LED string 13. Atmel LED Driver-MSL2162 9 NO. NAME 38 D13 Drain sense input 13 Drain sense input for external MOSFET 13. Connect D13 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 13. 39 S14 Current sense input 14 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 40 G14 Gate output 14 Gate drive output for external MOSFET 14. Connect G14 to the gate of the external MOSFET driving LED string 14. 41 D14 Drain sense input 14 Drain sense input for external MOSFET 14. Connect D14 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 14. 42 S15 Current sense input 15 Current sense input for LED string 15. Connect S15 to the source of the external MOSFET and to the current sense resistor for LED string 15. The full-scale LED current threshold is 500mV is across the current sense resistor. 43 G15 Gate output 15 Gate drive output for external MOSFET 15. Connect G15 to the gate of the external MOSFET driving LED string 15. 44 D15 Drain Sense Input 15 Drain sense input for external MOSFET 15. Connect D15 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 15. 45 VCC 5V internal LDO regulator output VCC powers the FBO outputs. Bypass VCC to ground with a 4.7µF ceramic capacitor placed close to VCC. 46 PHI Phase synchronization input Drive PHI with an external signal from 40Hz to 10khz kHz to synchronize the MSL2162 clock. In TV applications drive PHI with the VSYNC signal. 47 GSC Gate shift clock input Drive GSC with the gate shift clock of the video signal, from 0 to 10khz MHz. In TV applications drive GSC with the HSYNC signal. PWM PWM input PWM allows external control of the brightness of all LED strings. Drive PWM with a pulse-width modulated signal with duty ratio ranging from 0% to 100% and frequency up to 5kHz. When not configured as an input, PWM is high impedance. 48 10 DESCRIPTION Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus NO. NAME DESCRIPTION 49 EN Enable input (active high) Drive EN high to turn on the MSL2162, drive EN low to turn off the MSL2162. For automatic start-up, connect EN to VIN. When EN is low, the entire device, including the serial interface, is turned off. Drive EN high to initiate a boot load of the EEPROM data into the control registers to set the startup condtions. 50 VIN Supply voltage input Connect a 12V ±10% supply to VIN. Bypass VIN to ground with a 10µF ceramic capacitor placed close to VIN. 51 VDD 2.5V internal LDO regulator output VDD powers internal logic. Bypass VDD to ground with a 4.7µF ceramic capacitor placed close to VDD. 52 S0 Current sense input 0 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 53 G0 Gate output 0 Gate drive output for external MOSFET 0. Connect G0 to the gate of the external MOSFET driving LED string 0. 54 D0 Drain sense input 0 Drain sense input for external MOSFET 0. Connect D0 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 0. 55 S1 Current sense input 1 Current sense input for LED string 1. Connect S1 to the source of the external MOSFET and to the current sense resistor for LED string 1. The full-scale LED current threshold is 500mV is across the current sense resistor. 56 G1 Gate output 1 Gate drive output for external MOSFET 1. Connect G1 to the gate of the external MOSFET driving LED string 1. 57 D1 Drain sense input 1 Drain sense input for external MOSFET 1. Connect D1 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 1. 58 S2 Current sense input 2 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. 59 G2 Gate output 2 Gate drive output for external MOSFET 2. Connect G2 to the gate of the external MOSFET driving LED string 2. 60 D2 Drain sense input 2 Drain sense input for external MOSFET 2. Connect D2 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 2. Atmel LED Driver-MSL2162 11 NO. NAME DESCRIPTION 61 S3 Current sense input 3 Current sense input for LED string 3. Connect S3 to the source of the external MOSFET and to the current sense resistor for LED string 3. The full-scale LED current threshold is 500mV is across the current sense resistor. 62 G3 Gate output 3 Gate drive output for external MOSFET 3. Connect G3 to the gate of the external MOSFET driving LED string 3. 63 D3 Drain sense input 3 Drain sense input for external MOSFET 3. Connect D3 through a 10MΩ resistor to the drain of the external MOSFET driving LED string 3. 64 S4 Current sense input 4 Current sense input for LED string 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 threshold is 500mV is across the current sense resistor. EP EP Exposed pad, power ground Connect EP to system ground using short, wide traces. EP is also the thermal relief pad for the device. Absolute Maximum Ratings Voltage (With Respect to ground) VIN, EN, D0 - D15, G0 - G15....................................................................................................................... -0.3V to +16V VDD, ADDR, S0 - S15................................................................................................................................... -0.3V to +2.75V FBO1, FBO2, FBI1, FLTB, PHI, GSC, PWM............................................................................................ -0.3V to +5.5V VCC................................................................................................................................................................................. -0.3V to +6V MISO, MOSI, CSB, SCK.................................................................................................................................... -0.3V to +5.5V Current (Into Pin) VIN................................................................................................................................................................................................ 50mA FBO1, FBO2.......................................................................................................................................................+0µA to -800µA G0 - G15...............................................................................................................................................................................±100mA All other pins.............................................................................................................................................................................20mA Continuous Power Dissipation 64-Pin 9mm x 9mm QFN (derate 38mW/°C above TA = +70°C)......................................................2100mW Ambient Operating Temperature Range TA = TMIN to TMAX............................................................. -40°C to +105°C Junction Temperature .......................................................................................................................................................... +125°C Storage Temperature Range......................................................................................................................... -65°C to +125°C Lead Soldering Temperature, 10s................................................................................................................................... +300°C 12 Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Electrical Characteristics Typical Application Circuit, VVIN = 12V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VVIN = 12V, TA = +25°C PARAMETER SYMBOL CONDITIONS AND NOTES MIN TYP MAX UNIT 10.8 12 13.2 V Normal Operation, all LED strings driven 25 32.5 mA 500 DC ELECTRICAL CHARACTERISTICS VIN Operating Supply Voltage VIN VIN Operating Supply Current IVIN VIN Shutdown Supply Current ISLEEP SLEEP = 1, SDA, SCL, ADDR, PWM, PHI and GSC at ground or VDD VCC Regulation Voltage VCC IVCC = -1.0mA 4.5 5.0 5.5 V VDD Regulation Voltage VDD IVDD = -1.0mA 2.4 2.5 2.6 V EN Input High Voltage 1.4 V EN Input Low Voltage 0.9 0.7 x VDD PWM, PHI, GSC, Input High Voltage VIH PWM, PHI, GSC, Input Low Voltage VIL PHI, GSC Output High Voltage VOH ISOURCE = 5mA PHI, GSC, FLTB Output Low Voltage VOL ISINK = 6mA FBO Feedback Output Current Range Compliance voltage 3.5V minimum V V 0.3 x VDD V 0.4 V 360 μA VDD – 0.4 0 FBO Feedback Output Current Step Size FBI Feedback Input Current µA 1.2 0 FBI Input Disable Threshold μA 365 μA TBD mV D0 - D15 Short Circuit Fault Detection Threshold 8 V G0 - G15 Open Circuit Fault Detection Threshold 8 V Atmel LED Driver-MSL2162 13 PARAMETER SYMBOL G0 - G15 Gate Drive Charge CONDITIONS AND NOTES MIN (Note 2) S0 - S15 Regulation Voltage 492 S0 - S15 Voltage Matching ISTR = 0x7F 500 -1.5 Thermal Shutdown Temperature PARAMETER TYP MAX UNIT 10 µC 508 mV 1.5 % 135 SYMBOL CONDITIONS AND NOTES MIN TYP °C MAX UNIT SPI LOGIC LEVELS MOSI, SCK, CSB Input High Voltage 0.7 x VDD V 0.3 x VDD MOSI, SCK, CSB Input Low Voltage MISO Output High Voltage VOH ISOURCE = 5mA MISO Output Low Voltage VOL ISINK = 6mA PARAMETER SYMBOL CONDITIONS AND NOTES VIN – 0.4 V V 0.4 V MIN TYP MAX UNIT 19.4 20 20.6 MHz AC ELECTRICAL CHARACTERISTICS OSC Frequency fOSC PHI Frequency fPHI 0.04 10 kHz GSC Frequency fGSC 0 10 MHz PWM Frequency fPWM 5 kHz 100 % PWM Duty Cycle PHI Lock 14 fOSC = 20MHz, TA = 25°C 0 4 PHI cycles Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus PARAMETER SYMBOL CONDITIONS AND NOTES MIN TYP MAX UNIT 20 MHz SPI TIMING CHARACTERISTICS SCK Frequency CSB Falling Edge to SCK Rising Edge set-up Time tCSB:SCK(SU) 100 ns SCK Falling Edge to CSB Rising Edge set-up Time tSCK:CSB(SU) 50 ns tMOSI(SU) 16 ns tMOSI(HOLD) 20 ns MOSI to Falling Edge of SCK set-up Time SCK Falling Edge to MOSI set-up Time MOSI, CSB, SCK Signal Rise Time tR(SPI) 5.0 ns MOSI, CSB, SCK Signal Fall Time tF(SPI) 5.0 ns CSB Falling Edge to MISO Data Valid tCSB:MISO(DV) 50 ns CSB Rising Edge to MISO High Impedance tCSB:MISO(HIZ) 50 ns SCK Rising Edge to MISO Data Valid tVALID 80 ns SCK capacitive load = 200pF 25 Note 1. Subject to thermal dissipation characteristics of the device. Note 2. Guaranteed by design, not production tested. Atmel LED Driver-MSL2162 15 Typical Application Circuit Figure 3. Atmel LED Driver-MSL2162 Driving 160 white LEDs in 16 Strings 16 Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Detailed Description The MSL2162 is a highly integrated, flexible, multi-string LED driver. It drives 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 large numbers of LED strings in a system. The driver provides multiple methods of controlling LED brightness, through both peak current control and through 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 E2PROM holds all the default control register values. At power-up the data in the E2PROM automatically copy directly to the control registers, setting up the device for operation. The factory programmed E2PROM values are changed using the serial interface when a different power-up condition is desired. The device interfaces to a microcontroller using an SPI compatible serial interface. The 20MHz SPI compatible interface supports up to eight devices per Chip Select line. While typically the LED drive PWM signal is internally generated, the driver also accepts an external direct PWM drive signal applied to the PWM input that sets the PWM duty and the frequency of the string drive signals. The MSL2162 also allows phase spreading when external PWM direct drive is used. With phase spreading enabled, a progressive 1/16 phase delay per string helps reduce both the transient load on the LED power supplies, and the power supply input capacitor size requirements. The PWM frequency of the drivers is either synchronized to an external signal applied to PHI, or generated from the internal oscillator for stand-alone applications. Typically the VSYNC signal from the video system is used for the PHI input. A frequency multiplier (1x to 32x) processes this signal for use by the internal 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 Atmel LED Driver-MSL2162 depends upon 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 value, when enabled. The GSC clock is also used to precisely set each string’s 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 architectures of external DC/DC and AC/DC converters. Multiple drivers in a system communicate with each other in real time to select an optimized operating voltage for the LEDs. This allows design of the power supply for the worst case Forward Voltage (Vf) of the LEDs without worrying about excessive power dissipation issues. During the start-up sequence the MSL2162 automatically reduces the power supply voltage to the minimum voltage required to keep the LEDs in current regulation. The devices can be configured to periodically perform this optimization to compensate for changes of the LED’s forward voltage, and to assure continued optimum power savings. Internal Regulators and Enable Input The MSL2162 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 ground with a 10µF capacitor close to the device. Bypass VCC to ground with a 4.7μF capacitor close to the device. Bypass VDD to ground with a 4.7μF capacitor close to the device. The MSL2162 enable input, EN, enables the device. Drive EN low to enter low power operation, which lowers quiescent current draw to less than 20µA. With EN low the serial interface is ignored. Drive EN high to turn on the device. When EN is driven high the contents of the E2PROM are boot loaded into the control registers, simulating a cold start-up. 17 Setting the Maximum LED String Current with the Source Resistor The maximum string current, ILEDn, for each string is set by a shunt resistor connected to ground from the Source terminal of the string drive MOSFET. The feedback threshold is 500mV. Determine the resistor value using: RSn = 0.5 I LEDn Ω. . For example, a full-scale LED current of 100mA returns RSn = 5Ω. The current for all LED strings is reduced from 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 MSL2162 is designed to control LED string power supplies that use a voltage divider (RTOP and RBOTTOM in Figure 4) to set output voltage, and whose regulation feedback voltage is not more than 3.5V. VOUT POWER SUPPLY RTOP FB FBOn G0 RS0 MSL2162 G15 RS15 Figure 4. FBOn Connects to the Power Supply Voltage Divider Through a Diode 18 VOUT(MIN) = (Vf (MIN) *[#ofLEDs])+ 0.5 , and VOUT(MAX) = (Vf (MAX) *[#ofLEDs])+ 0.5 , where Vf(MIN) and Vf(MAX) are the LED’s minimum and maximum forward voltage drops at the peak current set by RSn (page 10). For example, if the LED data are Vf(MIN) = 3.5V and Vf(MAX) = 3.8V, and ten LEDs are used in a string, then the total minimum and maximum voltage drop across a string is 35V and 38V. Adding an allowance of 0.5V of for the string drive MOSFET headroom brings VOUT(MIN) to 35.5V and VOUT(MAX) to 38.5V. Then determine RTOP using: RTOP = VOUT ( MAX ) − VOUT ( MIN ) I FBOn ( MAX ) , where IFBOn(MAX) is the 255µA maximum output current of the Efficiency Optimizer outputs FBOn. Finally, determine RBOTTOM using: RBOTTOM = RTOP * COUT 1N4148 RBOTTOM To select the resisters first determine VOUT(MIN) and VOUT(MAX), the minimum and maximum string supply voltage limits, using: VFB VOUT(MAX) _ VFB , where VFB is the regulation feedback voltage of the power supply. Place a diode (1N4148 or similar) between FBO and the supply’s feedback node to protect the MSL2162 against current flow into FBOn. Assign all strings powered by a common supply to the proper FBO output using String Set registers 0x40 0x5F; default assignments are presented in Table 5. Once configured, determine the change in power supply output voltage in response to a change in FBO output current using: ∆VOUT = ∆I FBO ∗ RTOP . Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Using Multiple Atmel LED Driver-MSL2162s to Control a Common Power Supply Multiple MSL2162s connect in a chain configuration to control a single string power supply (Figure 5) when driving more than 16 LED stings. Cascade multiple devices 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 MSL2162 as possible. Assure that all strings powered by the common supply are assigned to FBO1 using String Set registers (STRnSET) 0x40 - 0x5F (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 may degrade through each link of the FBI1/FBO1 chain by as much as 2%. Determine the potential worst case maximum FBO1 current IFBOn(MAX/MIN) using: IFBOn(MAX / MIN) = 255µA* (0.98)N-1 , where N is the number of MSL2162s connected in series. Use this result in the above RTOP resistor equation for the term IFBOn(MAX) instead of using 255µA. 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. Note that Figure 5 also shows the connections for an unused string. VOUT STRING POWER SUPPLY FB RTOP RBOTTOM 1N4148 G0 FBO1 FBO2 G15 FBI1 G0 FBO1 FBO2 G15 FBI1 DEVICE 1 DEVICE 2 MSL2162 MSL2162 G0 FBO1 FBO2 G14 FBI1 DEVICE N G15 D15 S15 MSL2162 Figure 5. Example of Cascading Multiple Devices to Optimize a Common String Power Supply Atmel LED Driver-MSL2162 19 Direct PWM Control of the LED Strings An external PWM signal applied to the PWM input allows direct PWM control over the strings when bits 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 of 1/16 the PWM frame is calculated and applied successively to each string drive signal. Register Map and the E2PROM Register Map Summary Control the MSL2162 using the registers in the range 0x00 - 0xBF (Table 4). Two additional registers, 0xC0 and 0xC1, allow access to, and programming of, the E2PROM. The power-up default values for all control registers (Table 5) are stored within the on-chip E²PROM, and any of these E²PROM values may be changed through the serial interface Table 4. Atmel LED Driver-MSL2162 Register Map ADDRESS AND REGISTER NAME 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 STRINGEN0 STRINGEN1 CONFIG FLTEN STRFLTEN0 STRFLTEN1 FLTSTATUS OCSTAT0 0x08 OCSTAT1 0x09 SCSTAT0 0x0A SCSTAT1 0x0B THRU 0x0E 0x0F OSCFREQ 0x10 0x11 FBOCTRL0 FBOCTRL1 0x12 FBOCTRL2 0x13 FBODAC0 0x14 FBODAC1 0x15 FBODAC2 0x16 FBOSTAT 0x17 THRU 0x1F 0x20 0x21 0x22 GSCCTRL GSCCNTR 0x23 GSCMUL 0x24 GSCDIV 20 FUNCTION LED string enables Configuration Fault enable String fault enable Fault status String open circuit fault status String short circuit fault status Oscillator frequency Efficiency Optimizer control REGISTER DATA D7 STR7EN STR15EN SLEEP FEN7 FEN15 FLTBDRV OC7 D6 D5 D4 GSC processing control Internal clock counter for GSC GSC multiplier GSC Divider D2 D1 D0 STR2EN STR10EN STR1EN STR0EN STR9EN STR8EN STRSCDLY[2:0] STRSCFEN STROCFEN FBOOCFEN FEN2 FEN1 FEN0 FEN10 FEN9 FEN8 STRSCFLT STROCFLT FBOOCFLT OC2 OC1 OC0 OC15 OC14 OC13 OC12 OC11 OC10 OC9 OC8 SC7 SC6 SC5 SC4 SC3 SC2 SC1 SC0 SC15 SC14 SC13 SC12 SC11 SC10 SC9 SC8 UNUSED - - HLDSTEP[1:0] INCRSTEP[1:0] - - - - - FBCLDLY[1:0] DECRSTEP[1:0] - OSCFREQ[2:0] FBSDLY[1:0] INITPWM ACAL100 - - FBCFDLY[1:0] ACALEN TRIDIS FBO1OCEN FBO0OCEN FBOEN FBO2ACT FBO1ACT FBOCAL FBOINITCAL GSCMAXEN GSCPOL GSCPHISYNCEN GSCINTEN FBODAC1[7:0] Efficiency optimizer DAC readback Efficiency optimizer status D3 STR6EN STR5EN STR4EN STR3EN STR14EN STR13EN STR12EN STR11EN FLDBKEN I2CTOEN PHIMAXFEN GSCMAXFEN FEN6 FEN5 FEN4 FEN3 FEN14 FEN13 FEN12 FEN11 PHIMAXFLT GSCMAXFLT OC6 OC5 OC4 OC3 FBODAC2[7:0] FBODAC3[7:0] - FBO2OC FBO1OC UNUSED GSCCHKSEL - - - GSCCNTR[7:0] GSCCNTR[15:8] - - - GSCMUL[4:0] GSCDIV[7:0] Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus Table 4. Atmel LED Driver-MSL2162 Register Map ADDRESS AND REGISTER NAME FUNCTION 0x25 GSCMAX Max oscillator cycles between GSC pulses PHICTRL PHI processing control 0x26 0x27 0x28 0x29 0x2A 0x2B 0x2C PHICNTR PHIMUL PHIMAX Internal clock counter for PHI PHI multiplier Min GSC pulses over PHI period REGISTER DATA D7 D6 D5 D4 D3 PHICHKSEL - - - - - - - - - - - GINT+1EN GINTEN ALTEN OVRFLOZEN OVRFLOEN - - - - EXTALTEN GINT Global PWM scaling GINT[7:0] 0x30 ALTGINT Alternate global PWM scaling ALTGINT[7:0] 0x31 ISTR 0x32 PWMSTATUS 0x33 PHIPCNTR ↓ 0x5F 0x60 0x61 ↓ 0x7E 0x7F 0x80 0x81 ↓ 0x9E 0x9F 0xA0 0xA1 8-bit global string current PWM and counter PHIMAXERRCNT[2:0] status PHI pulse counter and PHICNTRMAX status ↓ STR15SET PWM0 PWM15 ALTSTR0SET - - - FBOSET0[1:0] - PHIMAX1FLT PHIMULFLT - PWM0[7:0] - - - - Atmel LED Driver-MSL2162 PWM0[11:8] ↓ PWM15[7:0] - - - - PWM15[11:8] ALTPHDLY0[7:0] - - - - ALTPHDLY[11:8] ↓ Phase delay and EO ALTSTR15SET assignment for string 15 12-bit ALTPWM0 PWM setting for string 0 GINTMULERR PHDLY[11:8] ↓ ↓ GSCMULFLT PHICNTRFLT PHDLY[11:8] ↓ 12-bit PWM setting for string 15 Phase delay and EO assignment for string 0 PHADLYEN GSCPULSECNTR[7:0] GSCPULSECNTR[12:8] UNUSED PHDLY0[7:0] PHDLY15[7:0] - PWMEN PHIMULCNTR[0:4] ↓ FBOSET15[1:0] PHIMAX[11:8] PWM PWMDIRECT GLBLEN PHOVR PHOVR FLOZEN FLOEN ISTR[7:0] Phase delay and EO assignment for string 15 12-bit PWM setting for string 0 ↓ PHIINTEN PHIMUL[4:0] 0x2F 0x5E PHIPOL PHIMAX[7:0] PWMCTRL1 Phase delay and EO assignment for string 0 PHIMAXEN PHICNTR[7:0] 0x2E GSC pulse counter D0 PHICNTR[15:8] PWMCTRL0 0x34 GSCPCNTR 0x35 0x36 THRU 0x3F 0x40 STR0SET 0x41 D1 GSCMAX[15:8] 0x2D PWM control D2 GSCMAX[7:0] ↓ ALTPHDLY15[7:0] - - - - - - - ALTPHDLY[11:8] ALTPWM0[7:0] - ALTPWM0[11:8] 21 ADDRESS AND REGISTER NAME ↓ ↓ 0xBE 0xBF ALTPWM15 0xC0 E2ADDR 0xC1 E2CTRLSTA REGISTER DATA FUNCTION D7 ↓ 12-bit PWM setting for string 15 EEPROM read/write access D6 D5 D4 D3 D2 D1 D0 ↓ ALTPWM15[7:0] - - - - BLDACT E2ERR - E2BUSY ALTPWM15[11:8] E2ADDR[6:0] - RWCTRL[2:0] * Read-Only Registers Register Power-up Defaults Register power-up default values are shown in Table 5. Table 5. Atmel LED Driver-MSL2162 Register Power-Up Defaults REGISTER NAME AND ADDRESS 0x00 STRINGEN0 0x01 STRINGEN1 0x02 CONFIG 0x03 FLTEN 0x04 STRFLTEN0 0x05 STRFLTEN1 0x0F OSCFREQ 0x10 FBOCTRL0 0x11 FBOCTRL1 0x12 FBOCTRL2 POWER- UP CONDITION REGISTERS INITIALIZED FROM E²PROM REGISTER DATA D7 D6 1 1 1 1 1 1 1 1 FF 1 1 1 1 1 1 1 1 FF String short circuit confirmation delay = 8µs String current fold-back disabled Device is not asleep 0 0 0 0 0 0 0 0 00 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 0 0 0 0 0 1 1 1 07 Fault detection individually enabled for all strings 1 1 1 1 1 1 1 1 FF 1 1 1 1 1 1 1 1 FF fOSC = 20MHz 0 0 0 0 0 1 0 0 04 0 1 0 0 1 0 0 1 49 0 0 0 1 1 0 1 0 4A 0 0 0 0 0 1 1 1 07 0 0 0 0 0 0 0 0 00 All LED String Drive Outputs Enabled Current sink error confirmation delay = 2µs FBO power supply settling time allowance = 4ms Efficiency Optimizer auto-recalibration occurs every 1 second Efficiency Optimizer headroom steps = 3 MOSFET current sink error detection enabled Efficiency Optimizer auto-recalibration enabled PWM settings used during auto-recalibration PWM settings used during initial calibration Efficiency Optimizer correction step size = 1 LSBs (1µA) Efficiency Optimizer initial calibration step size = 1 LSBs (1µA) FBO outputs are globally enabled Open circuit detection enabled for both FBO outputs D5 D4 D3 D2 D1 D0 HEX GSCCTRL External signal at GSC is selected for input to the PWM engine GSC not internally synchronized to PHI pGSC is synchronized to falling edge of external GSC signal GSC maximum count fault detect is disabled Although disabled, GSC max fault monitors pGSC GSCCNTR Although disabled, internal GSC frequency is set to 20MHz / (19 + 1) = 1.0MHz 0 0 0 1 0 0 1 1 13 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 GSCMAX Although disabled, GSC max count is set to 19 clock cycles 0 0 0 1 0 0 1 1 13 0 0 0 0 0 0 0 0 00 0x20 0x21 0x22 0x25 0x26 22 Atmel LED Driver-MSL2162 Atmel LED Driver-MSL2162 16-string White and RGB LED Driver with Adaptive Configuration, EEPROM, and SPI Bus REGISTER NAME AND ADDRESS 0x28 0x29 0x2A 0x2B 0x2C 0 1 1 0 0 0 0 B0 0 0 1 0 1 0 0 0 28 PHIMUL PHI multiplier = 1 (register setting + 1) 0 0 0 0 0 0 0 0 00 PHIMAX Although disabled, PHI max count is zero 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 1 0 0 0 1 0 0 1 89 0 0 0 0 0 0 0 1 01 Although disabled, global intensity set to (127 + 1) / 256 = 50% (1 added in numerator because bit D7 of 0x2D = 1) 0 1 1 1 1 1 1 1 7F Although disabled, Alternate global intensity set to (127 + 1) / 256 = 50% (1 added in numerator because bit D7 of 0x2D = 1) 0 1 1 1 1 1 1 1 7F Strings current globally scaled to 50% of RSn setting 0 1 1 1 1 1 1 1 7F 0 0 0 0 0 0 0 0 00 0 1 0 0 0 0 0 0 40 0 0 0 0 0 0 0 0 00 0 1 0 0 0 0 0 0 40 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 1 0 02 PWMCTRL1 0x2F GINT 0x30 ALTGINT 0x31 ISTR 0x5F 0x60 0x61 0x7E 0x7F 0x80 0x81 0x9E 0x9F 0xA0 0xA1 0xBE 0xBF REGISTER DATA D5 D4 D3 D2 D1 D0 HEX 1 0x2E 0x5E D6 Although disabled, internal PHI frequency is set to 20MHz / (8 * (10416 + 1)) = 240Hz PWMCTRL0 0x41 D7 PHICNTR 0x2D 0x40 POWER- UP CONDITION REGISTERS INITIALIZED FROM E²PROM STR0SET … STR15SET 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 not 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 not allowed Alternate timing not selected by PWM input state All strings set to zero phase delay with strings assigned to FBO outputs as follows: FBO1: All Strings FBO2: No Strings PWM0 … All strings set with PWM tON = 512 GSC cycles PWM15 ALTSTR0SET … … 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 1 0 02 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 1 0 02 All strings set with alternate phase delay of zero ALTSTR15SET ALTPWM0 … … … All strings set with Alternate PWM tON = 512 GSC cycles … 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 1 0 02 E²PROM 7 bit address = 0x00 0 0 0 0 0 0 0 0 00 E²PROM read/write disabled 0 0 0 0 0 0 0 0 00 ALTPWM15 REGISTERS WITH FIXED INITIAL VALUES 0xC0 E2ADDR 0xC1 E2CTRLSTA Atmel LED Driver-MSL2162 23 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 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