MSL3082

MSL3082CS ATMEL | Alldatasheet

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8-string, High-power, White or RGB LED Driver for TV, Blacklighting, or Intelligent Solid-state Lighting Datasheet Brief

The Atmel® LED Driver- MSL3082 compact, high- power LED string driver uses external MOSFETs to provide up to at least 500mA per string, with current accuracy and matching better than ±1%. The MSL3082 drives eight parallel strings of LEDs, and offers fault detection and management of open and short circuit LEDs. The MSL3082 features a 1MHz I2C serial interface. The interface supports video frame-by-frame LED string intensity control for up to 16 interconnected devices, allowing active area dimming when used for video displays. The advanced PWM engine synchronizes with the video signal, and offers phase shifted string drive, virtually eliminating waterfall noise and motion blur. The MSL3082 adaptively controls the DC-DC converters that power the LED strings, using patented Atmel's Adaptive SourcePower™ technology. These 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 a 6-bit global intensity register, and individual string pulse width is modulated with 8-bit control. Additionally, the MSL3082 optionally throttles back the PWM on time of all strings when the temperature of the LEDs exceeds a programmable threshold. The MSL3082 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 MSL3082 includes an on-chip EEPROM that allows the power-up default register settings to be customized via the serial interface. The MSL3082 is offered in a 7 x 7 x 0.85mm, 44-pin QFN package, and operates over a -40°C to +105°C temperature range.

Applications

• Edge-lit LED Backlit TVs
• High-contrast Monitors
• Medical and Industrial Displays
• High-power LED Arrays
• Multi-string LED Lighting
• Intelligent Solid-state Lighting (SSL)

Ordering Information

MSL3082CS 8-channel LED driver 44-pin, 7x7x0.85mm QFN Atmel LED Driver-MSL3082 8-string, High-power, White or RGB LED Driver for TV, Blacklighting, or Intelligent Solid-state Lighting

8-string, High-power, White or RGB LED Driver for TV, Blacklighting, or Intelligent Solid-state Lighting Key Features Application Circuit

• 8-bit PWM String Dimming
• Fast, 1MHz I2C/Smbus Interface Supports up to

16 Devices per Bus

• 4-bit Adaptive Power Correction Maximizes Efficiency
• External Mosfets Allow >0.5a LED String Current
• Drives up to Eight Parallel, High-power Led Strings
• Multiple MSL3082s Share String Supply and Automatically Negotiate Optimum Voltage
• Supports Adaptive, Real-time 2-D Area Dimming for Highest Dynamic Range LCD TVs and Monitors
• Programmable String Phase Virtually Eliminates Motion Blur and Improves Efficiency
• Global LED Intensity Control via Serial Interface
• Supports Direct Pwm Control of all Led Strings with a Single Pwm Input Signal
• ±1% Current Accuracy and Current Balance
• Video Frame (Vsync) and Line (Hsync) Sync Inputs
• Sync Loss Detectors Optionally Disable Led Strings
• Internal Eeprom Allows Custom Power-up Default Settings
• String Open Circuit and Led Short Circuit Fault Detection
• <1µA LED String Off-leakage Current
• External Resistors Set Individual String Peak Current
• Programmable LED Over-temperature Compensation
• Automatic Die Over-temperature Protection
• I2C/SMBus Broadcast Mode Simplifies Configuration
• -40°C to +105°C Operating Temperature Range
• Lead-free, Halogen-free, RoHS-compliant Package

strings, or optionally accepts an external PWM signal. supply for all LED strings driven by the chain. better the matching, the better the overall efficiency. string supplies (for RGB LEDs, for example). synchronize string off times with the LCD update timing. LED strings are updated with only 92 I2C/SMBus clocks. for frame rates up to 640Hz. Table 1. Atmel LED Driver-MSL3082 LED Common Backlight Drive Architectures

PIN # NAME DESCRIPTION

1 SCL I²C serial clock Input

SCL is the I²C serial interface clock input.

2 SDA I²C serial data I/O

SDA is the I²C serial interface data I/O. 3, 44 AD1, AD0 I²C slave ID selection inputs AD0 and AD1 select the device I²C slave address.

4 FLTB

Fault output (open drain, active low) FLTB sinks current to GND when the MSL3082 detects a fault. FLTB remains low until the fault registers have been read or EN is toggled low.

5 FBI

Efficiency Optimizer input Connect FBI to FBO of the next device when chaining the Efficiency Optimizers. If unused connect FBI to GND close to the device.

6 FBO

Efficiency Optimizer output Connect FBO through a Schottky diode to the string power supply’s feedback node (Figure 4), or to FBI of the previous device (Figure 5). If unused leave FBO unconnected. 7, 43 GND Power ground Connect GND to system ground, to CGND and to EP with short, wide traces. 8, 11, 14, 17, 20, 23, 26, 29 S0 - S7 String 0 thru 7 source sense inputs Connect Sn to the source of external MOSFETn, and to the current sense resistor for LED stringn. The full-scale LED current is reached when 500mV is across the current sense resistor. 9, 12, 15, 18, 21, 24, 27, 30 G0 - G7 String 0 thru 7 external MOSFET gate drive outputs Connect Gn to the gate of the external MOSFETn. 10, 13, 16, 19, 22, 25, 28, 31 D0 - D7 String 0 thru 7 external MOSFET drain sense inputs Connect Dn to the drain of external MOSFETn through a 10MΩ resistor.

32 VIN Supply voltage input

Connect a 12V ±10% supply to VIN. Bypass VIN to GND with a 1µF ceramic capacitor placed close to VIN. 33 VDD Internal 2.5V regulator capacitor connection Bypass VDD to GND with a 10µF ceramic capacitor placed close to the device. 34 EN Enable input (active high) Drive EN high to turn on the MSL3082, drive EN low to turn off the MSL3082. For automatic start-up, connect EN to VIN through a 100kΩ resistor. 35, 39 NC No connection Make no connection to NC. 36, 37, 38 CGND Connect to ground Connect CGND to system ground, to GND and to EP using short, wide traces.

40 PHI

Phase synchronization input Drive PHI with an external signal from 40Hz to 10kHz to synchronize the PWM dimming to the signal at PHI. Connect PHI to GND if unused.

41 GSC

Drive GSC with the gate shift clock of the video signal up to 5MHz. GSC sets the resolution of PWM dimming. Connect GSC to GND if unused.

42 PWM

Drive PWM with a pulse-width-modulated signal with a duty cycle of 0% to 100% and frequency of 20Hz to 50kHz to control the brightness of all LED strings. Exposed Pad EP Power ground Connect EP to system ground, GND and CGND using short, wide traces. EP offers thermal relief to the die. Pin Descriptions

Voltage (With Respect to GND) Current (Into Pin) Continuous Power Dissipation (See Note 8, Note 9)

Electrical Characteristics

(Circuit of Figure 3, VIN = 12V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VIN = 12V, TA = +25°C) PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT DC ELECTRICAL CHARACTERISTICS VIN operating supply voltage 10.8 12.0 13.2 V VIN operating supply current All drivers on at 100% duty, I²C serial interface idle 25.0 32.5 mA VIN shutdown supply current EN = 0, all digital inputs tied to VDD or GND 10 20 μA VDD regulation voltage 2.3 2.5 2.6 V Input high voltage SDA, SCL, AD0, AD1 2.31 V Input low voltage SDA, SCL, AD0, AD1 0.9 V Input high voltage PHI, GSC, PWM 1.8 V Input low voltage PHI, GSC, PWM 0.7 V Input high voltage EN 0.9 1.36 V Input low voltage EN 0.7 V Input hysteresis EN 50 mV Continued to Next Page Atmel LED Driver-MSL3082 8-string, High-power, White or RGB LED Driver for TV, Blacklighting, or Intelligent Solid-state Lighting

PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT Input quiescent current EN 1 20 μA SDA, FLTB output low voltage Sinking 6mA 0.4 V S0 thru S7 regulation resolution 1 % of Full Scale Open circuit detect voltage 7.3 8.3 9.0 V Short circuit detect voltage 6.5 7.8 9.0 V D0 thru D7 leakage current Voltage under 9V 0.1 μA Voltage between 9V to 16V 15 G0 thru G7 maximum gate drive voltage 10 V G0 thru G7 gate drive current -20 20 mA Current sense regulation voltage ISTRx = 0x3F 488 500 508 mV ISTRx = 0x1F 235 250 255 mV G0 thru G7 output current slew rate Current rising (Note 7, Note 8) 10 mA/µs Current falling (Note 7, Note 8) 10 Thermal cutoff temperature 135 °C FBI to FBO current transfer error Up to FBO maximum output current ±2 % FBO current step size 3 μA FBO feedback output current maximum VFBO_= 0 to 1.8V 35 45 55 μA PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT AC ELECTRICAL CHARACTERISTICS OSC initial accuracy fOSC OSCCTRL = 0x04 (fOSC=20MHz); TA=25°C 18 20 22 MHz PHI frequency fPHI (Note 7) 40 10000 Hz GSC frequency fGSC (Note 7) 5 MHz PWM frequency fPWM PWMDIRECT = PWMEN = 1 20 50000 Hz PWM duty cycle PWMDIRECT = PWMEN = 1 0 100 % PHI DLL Lock Cycles 4 PHI Cycles PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT I²C SWITCHING CHARACTERISTICS SCL clock frequency 1/t SCL Bus timeout disabled (Note 1) 0 1000 kHz Bus timeout period tTIMEOUT OSCCTRL = 0x04 (fOSC=20MHz); TA=25°C 27 30 33 ms STOP to START condition bus free time tBUF 0.5 µs Repeated START condition hold time t HD:STA 0.26 µs Repeated START condition set-up time t SU:STA 0.26 µs STOP condition set-up time t SU:STOP 0.26 µs SDA data hold time t HD:DAT 15 ns

Note 1. 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 bus timeout feature for DC operation Note 2. tVD:ACK = SCL low to SDA (out) low acknowledge time Note 3. tVD:DAT = minimum SDA output data-valid time following SCL low transition Note 4. A master device must internally provide an SDA hold time of at least 300ns to ensure an SCL low state Note 5. 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 6. The MSL3082 includes input filters on SDA, SCL, AD0, and AD1 inputs that suppress noise less than 50ns Note 7. Parameter is guaranteed by design, and is not production tested Note 8. Subject to thermal dissipation characteristics of the device Note 9. When mounted according to JEDEC JEP149 and JESD51-12 for a one-layer PCB, θJA = 21°C/W and θJC = 1.3°C/W Block Diagram PARAMETER CONDITIONS AND NOTES MIN TYP MAX UNIT SDA data valid acknowledge time t VD:ACK (Note 2) 0.05 0.55 µs SDA data valid time t VD:DAT (Note 3) 0.05 0.55 µs SDA data set-up time t SU:DAT 100 ns SCL clock low period tLOW 0.5 µs SCL clock high period tHIGH 0.26 µs SDA, SCL fall time tF (Note 4, Note 5) 120 ns SDA, SCL rise time tR 120 ns SDA, SCL input suppression filter period tSP (Note 6) 50 ns Atmel LED Driver-MSL3082 8-string, High-power, White or RGB LED Driver for TV, Blacklighting, or Intelligent Solid-state Lighting

Figure 3. Typical Application Circuit if a different power-up condition is desired.

The device interfaces to an MCU via the I 2C/SMBus interface. The robust 1MHz I 2C/SMBus interface supports up to sixteen devices on the bus, and is fast enough to support area dimming for 16 interconnected devices. While typically the LED drive PWM signal is internally generated by the PWM engine, the device also accepts an external direct PWM drive signal applied to the PWM input to set the frequency and duty cycle of the LED drive signals. When using the PWM engine, the MSL3082 allows phase spreading of the LED drive signals, which helps reduce the transient load on the LED power supply. Phase spreading is not supported for direct PWM drive. The PWM frequency of the drivers is easily synchronized to an external video signal applied to PHI. Typically, the VSYNC signal from the video system is used as the PHI input. A frame-rate multiplier (1x to 16x) 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 10 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) to the PHI frequency because the on time of a string is programmed as a function (8-bit count) of the number of GSC cycles. This count can be further scaled by a 6-bit global intensity register, when enabled. The GSC clock is also used to precisely set each string’s phase delay to be synchronized with its physical position relative to the video frame. Additionally, the MSL3082 features programmable temperature compensation, which throttles back the PWM on time of all strings when the temperature of the LEDs exceeds a programmable threshold. 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 (Vf) of the LEDs without concern about excessive power dissipation issues. During the start-up sequence, the MSL3082 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 MSL3082 includes an internal linear regulator powered from VIN that provides 2.5V, VDD, to power the internal circuitry. Bypass VDD to GND with a 10µF or greater capacitor. The enable input, EN, turns the VDD regulator on and off. To turn on the MSL3082 force EN high with a 5V logic level, and force EN low to turn it off. When EN is low, the MSL3082 enters low-power mode, and the serial interface is ignored. Toggling EN low also clears all fault registers and releases FLTB. Faults re-establish if the conditions that generated them persist. Setting LED String Currents The maximum string current, I LED, for each string is set by a resistor, R Sn, connected to ground from the source terminal of the external string drive MOSFET. The feedback threshold is 500mV. Determine the resistor value using: LED Sn I R 5.0= , where ILED is in amperes and RSn is in ohms. For example, a full-scale LED current of 500mA returns RSn = 1.00Ω. The current for the LED strings is individually reduced from the full-scale resistor set value with 6-bit resolution using ISTRn, the string current control registers 0x10 through 0x1F. Atmel LED Driver-MSL3082 8-string, High-power, White or RGB LED Driver for TV, Blacklighting, or Intelligent Solid-state Lighting

to protect the MSL3082 against current flow into FBO. Figure 4. FBO Connection to Power Supply Voltage Divider input to ground as close to the MSL3082 as possible. using ground planes and/or guard traces.

Figure 5. Cascade Multiple Atmel LED Driver-MSL3082s to Control a Common Power Supply within the on-chip EEPROM, and any of these EEPROM values may be changed through the serial interface. Table 3. Atmel LED Driver-MSL3082 Register Map

Register power-up default values are shown in Table 4. Table 4. Atmel LED Driver-MSL3082 Register Power-up Defaults

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Kwun Tong, Kowloon HONG KONG Tel: (+852) 2245-6100 Fax: (+852) 2722-1369 Atmel Munich GmbH Business Campus Parkring 4 D-85748 Garching b. Munich GERMANY Fax: (+49) 89-3194621 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 JAPAN REGISTER NAME AND ADDRESS POWER-UP CONDITION REGISTERS INITIALIZED FROM EEPROM REGISTER DATA D7 D6 D5 D4 D3 D2 D1 D0 HEX 0x10 0x17 ISTR0 thru ISTR7 Individual peak string current 0 0 1 0 0 0 0 0 20 0x20 0x27 PHDLY0 thru PHDLY7 All string phase delays set to zero processed GSC cycles0 0 0 0 0 0 0 0 00 0x30 0x37 PWM0 thru PWM7 All strings PWM settings equal 48 processed GSC cycles0 0 1 1 0 0 0 0 30 0x40 GSCMAX Maximum GSC pulse count is 0 0 0 0 0 0 0 0 0 00 0x41 0 0 0 0 0 0 0 0 00 0x42 PHIMIN Minimum PHI pulse count is 0 0 0 0 0 0 0 0 0 00 0x43 0 0 0 0 0 0 0 0 00 0x47 FAULTEN Fault detection is enabled for all strings 1 1 1 1 1 1 1 1 FF 0x50 FBOCTRL0 Current source error confirmation delay is 4µs FBO power supply settling time allowance is 8ms Efficiency Optimizer auto recalibration delay is 1s Efficiency Optimizer gives three steps for headroom 0 0 0 0 1 1 0 0 0C 0x51 FBOCTRL1 Current source error detection enabled Auto recalibration disabled String short circuit confirmation delay is 4µs 0 0 0 0 0 0 0 0 00 0x90 E2ADDR User EEPROM 7-bit address = 0x00 0 0 0 0 0 0 0 0 00 0x91 E2CTRLSTA User EEPROM read/write disabled 0 0 0 0 0 0 0 0 00 325.0 ∗= SnR