LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 Compact Sequential Mode RGB LED Driver with I2C Control Interface Check for Samples: LM3435 FEATURES KEY SPECIFICATIONS * * * * * 1 23 * * * * * * Sequential RGB Driving Mode Low Component Count and Small Solution Size Stable with Ceramic and Other Low ESR capacitors, No Loop Compensation Required Fast Transient Response Programmable Converter Switching Frequency up to 1 MHz MCU Interface Ready With I2C Bus Peak Current Limit Protection for the Switcher LED Fault Detection and Reporting via I2C Bus * * * * * Support up to 2A LED current Typical 3% LED current accuracy Integrated N-Channel main and P-Channel synchronous MOSFETs 3 Integrated N-Channel current regulating pass switches LED Currents programmable via I2C bus independently Input voltage range: 2.7 - 5.5 V Thermal shutdown Thermally enhanced WQFN package APPLICATIONS DESCRIPTION * * The LM3435, a Synchronously Rectified non-isolated Flyback Converter, features all required functions to implement a highly efficient and cost effective RGB LED driver. Different from conventional Flyback converter, LEDs connect across the VOUT pin and the VIN pin through internal passing elements at corresponding LED pins. Thus, voltage across LEDs can be higher than, equal to or lower than the input supply voltage. Li-ion Batteries/USB Powered RGB LED Driver Pico/Pocket RGB LED Projector TYPICAL APPLICATION Load current to LEDs is up to 2A with voltage across LEDs ranging from 2.0V to 4.5V. Integrated NChannel main MOSFET, P-Channel synchronous MOSFET and three N-Channel current regulating pass switches allow low component count, thus reducing complexity and minimize board size. The LM3435 is designed to work exceptionally well with ceramic output capacitors with low output ripple voltage. Loop compensation is not required resulting in a fast load transient response. Non-overlapping RGB LEDs are driven sequentially through individual control. Output voltage hence can be optimized for different forward voltage of LEDs during the nonoverlapping period. I2CTM interface eases the programming of the individual RGB LED current up to 1,024 levels per channel. The LM3435 is available in the thermally enhanced 40-pin WQFN package. 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. I C is a trademark of NXP. All other trademarks are the property of their respective owners. 2 2 3 PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2011-2013, Texas Instruments Incorporated LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com CONNECTION DIAGRAM Figure 1. Top View 40-Pin WQFN See RSB0040A Package Pin Descriptions 2 Pin Name Type Description Application Information 1, 2, 38, 39, 40 PGND Ground Power Ground Ground for power devices, connect to GND. 3 CG Output GREEN LED capacitor Connect a capacitor to Ground for GREEN LED. Minimum 1nF. 4 CB Output BLUE LED capacitor Connect a capacitor to Ground for BLUE LED. Minimum 1nF. 5 CR Output RED LED capacitor Connect a capacitor to Ground for RED LED. Minimum 1nF. 6 IREFG Output Current Reference for GREEN LED Connect a resistor to Ground for GREEN LED current reference generation. 7 IREFB Output Current Reference for BLUE LED Connect a resistor to Ground for BLUE LED current reference generation. 8 IREFR Output Current Reference for RED LED Connect a resistor to Ground for RED LED current reference generation. 9 GND Ground Ground 10, 29 SGND Ground I2C Ground Ground for I2C control, connect to GND. 2 11 SVDD Power I C VDD VDD for I2C control. 12 SDATA Input / Output DATA bus Data bus for I2C control. 13 SCLK Input CLOCK bus Clock bus for I2C control. 14, 15, 16, 17, 37 VIN Power Input supply voltage Supply pin to the device. Nominal input range is 2.7V to 5.5V. 18 GCTRL Input GREEN LED control On/Off control signal for GREEN LED. Internally pull-low. 19 BCTRL Input BLUE LED control On/Off control signal for BLUE LED. Internally pull-low. 20 RCTRL Input RED LED control On/Off control signal for RED LED. Internally pull-low. 21, 22 RLED Output RED LED cathode Connect RED LED cathode to this pin. 23, 24 BLED Output BLUE LED cathode Connect BLUE LED cathode to this pin. 25, 26 GLED Output GREEN LED cathode Connect GREED LED cathode to this pin. 27 FAULT Output Fault indicator Pull-up when LED open or short is being detected. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 Pin Descriptions (continued) Pin Name Type Description Application Information 28 EN Input Enable pin Internally pull-up. Connect to a voltage lower than 0.2 x VIN to disable the device. 30, 31, 32 VOUT Input / Output Output voltage Connect anodes of LEDs to this pin. 33 RT Input ON-time control An external resistor connected from VOUT to this pin sets the main MOSFET on-time, hence determine the switching frequency. 34, 35, 36 SW Output Switch node Internally connected to the drain of the main N-channel MOSFET and the P-channel synchronous MOSFET. Connect to the output inductor. EP EP Ground Exposed Pad Thermal connection pad, connect to the GND pin. These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. ABSOLUTE MAXIMUM RATINGS (1) VALUE / INPUTS VIN to GND -0.3V to 6.0V VOUT, RT to VIN -0.3V to 5.5V RLED, GLED, BLED to VIN -0.3V to 5.5V SW to GND -0.3V to 11.5V SW to GND (Transient) -2V to 13V (<100 ns) All other inputs to GND ESD Rating -0.3V to 6.0V Human Body Model (2) 1.5 kV Storage Temperature -65C to +150C Junction Temperature (TJ) -40C to +125C (1) (2) Absolute Maximum Ratings are limits which damage to the device may occur. Operating ratings are conditions under which operation of the device is intended to be functional. For specifications and test conditions, see the electrical characteristics. The human body model is a 100 pF capacitor discharged through a 1.5 k resistor into each pin. RECOMMENDED OPERATING CONDITIONS (1) VALUE / INPUTS Supply Voltage Range (VIN) 2.7V to 5.5V Junction Temp. Range (TJ) -40C to +125C Thermal Resistance (JB) (2) 28C/W (1) (2) Absolute Maximum Ratings are limits which damage to the device may occur. Operating ratings are conditions under which operation of the device is intended to be functional. For specifications and test conditions, see the electrical characteristics. JB is junction-to-board thermal characteristic parameter. For packages with exposed pad, JB is significantly dependent on PC boards. So, only when the PC board under end-user environments is similar to the 2L JEDEC board, the corresponding JB can be used to predict the junction temperature. JB value is obtained by NS Thermal Calculator(c) for reference only. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 3 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com ELECTRICAL CHARACTERISTICS Specification with standard type are for TA = TJ = +25C only; limits in boldface type apply over the full Operating Junction Temperature (TJ) range. Minimum and Maximum are specified through test, design or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25C, and are provided for reference purposes only. Unless otherwise stated the following conditions apply: VIN = 5V and VOUT - VIN = 3V. Symbol Parameter Conditions Min Typ Max Units Supply Characteristics IIN IIN operating current No switching 5 10 mA IIN-SD IIN Shutdown current VEN = 0V 8 30 A 1 A 2 ISVDD SVDD standby supply current VSVDD = 5V, I C Bus idle VINUVLO VIN under-voltage lock-out VIN decreasing VINUVLO_hys VIN under-voltage lock-out hysteresis VIN increasing EN Pin input threshold VEN rising 2.5 V 0.2 V Enable Input VEN 0.8 x VIN V VEN falling IEN Enable Pull-up Current 0.2 x VIN VEN = 0V 5 V A Logic Inputs (RCTRL, GCTRL and BCTRL) VCTRL CTRL pins input threshold VCTRL rising (VIN = 2.7V to 5.5V) 1.35 V VCTRL falling (VIN = 2.7V to 5.5V) 0.63 Switching Characteristics RDS-M-ON Main MOSFET RDS(ON) VGS(MAIN) =VIN = 5.0V ISW(sink) = 100mA 0.04 0.1 RDS-S-ON Syn. MOSFET RDS(ON) VGS(SYN) = VOUT - 5.0V ISW(source) = 100mA 0.06 0.2 6 8.5 A Current Limit ICL Peak current limit through main MOSFET threshold ON/OFF Timer tON ON timer pulse width 750 ns tON-MIN ON timer minimum pulse width RRT = 499 k 80 ns tOFF OFF timer minimum pulse width 155 ns RGB Driver Characteristics (RLED, BLED and GLED) RDS(RED) Red LED Switch RDS VOUT - VIN = 3.3V ILED = 1.5A I2C code = 3FFh 0.1 0.2 RDS(BLU) Blue LED Switch RDS VOUT - VIN = 3.3V ILED = 1.5A I2C code = 3FFh 0.1 0.2 RDS(GRN) Green LED Switch RDS VOUT - VIN = 3.3V ILED = 1.5A I2C code = 3FFh 0.1 0.2 ILEDMAX Max. LED current (1) VIN = 4.5V to 5.5V, 0C TA 50C I1.5A,3FFh Current accuracy (3FFh) VIN = 2.7V to 5.5V RIREF = 16.5 k, VOUT - VIN = 2.4V (RLED), 3.3V (GLED/BLED) I1.5A,1FFh Current (1FFh) I1.5A,001h Current (001h) (1) 4 2 1.455 1.5 1.425 A 1.545 A 1.575 A 0.8 A 1.2 mA Maximum LED current measured at VIN = 4.5V to 5.5V with heat sink on top of LM3435 with no air flow at 0C TA 50C. Operating conditions differ from the above is not ensured. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 ELECTRICAL CHARACTERISTICS (continued) Specification with standard type are for TA = TJ = +25C only; limits in boldface type apply over the full Operating Junction Temperature (TJ) range. Minimum and Maximum are specified through test, design or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25C, and are provided for reference purposes only. Unless otherwise stated the following conditions apply: VIN = 5V and VOUT - VIN = 3V. Symbol Parameter Conditions Min Typ Max Units FAULT Output Characteristics VOH VOL Output high voltage Output low voltage VIN = 2.7V to 5.5V, IOH = -100A VIN - 0.1 V VIN = 2.7V to 5.5V, IOH = -5mA VIN - 0.5 V VIN = 2.7V to 5.5V, IOL = 100A 0.1 V VIN = 2.7V to 5.5V, IOL = 5mA 0.5 V Thermal Shutdown TSD Thermal shutdown temperature TJ rising 163 C TSD-HYS Thermal shutdown temperature hysteresis TJ falling 20 C I2C Logic Interface Electrical Characteristics (1.7 V < SVDD < VIN ) Logic Inputs SCL, SDA VIL Input Low Level VIH Input High Level IL Logic Input Current fSCL Clock Frequency 0.2 x SVDD 0.8 x SVDD V V -1 1 A 400 kHz Logic Output SDA VOL Output Low Level ISDA = 3mA IL Output Leakage Current VSDA = 2.8V 0.3 0.5 V 2 A Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 5 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS All curves taken at VIN = 5V with configuration in typical application for driving one red (OSRAM LRW5AP-KZMX), one green (OSRAM LTW5AP-LZMY) and one blue (OSRAM LBW5AP-JYKX) LEDs with IOUT per channel = 1.5A under TA = 25C, unless otherwise specified. IIN-SD vs VIN IIN (no switching) vs VIN 12 6.0 125C 5.5 25C 8 125C 5.0 IIN(mA) IIN-SD( A) 10 6 -40C 4 4.0 2 3.5 0 3.0 2 3 4 VIN(V) 5 25C 4.5 6 -40C 2 3 Figure 2. 5 6 Figure 3. ISVDD vs VIN RDS-M-ON vs VIN 25 70 20 60 125C RDS-M-ON(m ) ISVDD(nA) 4 VIN(V) 25C 15 10 125C 50 25C 40 -40C 5 30 -40C 0 20 2 3 4 5 6 2 3 VSVDD(V) Figure 4. RDS-S-ON vs VIN 6 RIREFx vs ILEDx 2.5 80 125C 2.0 70 25C ILEDx(A) RDS-S-ON(m ) 5 Figure 5. 90 60 1.5 1.0 50 -40C 40 0.5 30 0.0 2 3 4 VIN(V) 5 6 Figure 6. 6 4 VIN(V) 5 15 25 35 RIREFx(k ) 45 55 Figure 7. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) All curves taken at VIN = 5V with configuration in typical application for driving one red (OSRAM LRW5AP-KZMX), one green (OSRAM LTW5AP-LZMY) and one blue (OSRAM LBW5AP-JYKX) LEDs with IOUT per channel = 1.5A under TA = 25C, unless otherwise specified. ILED(RED) vs VIN RDS(RED) vs VIN 1.54 160 125C RDS(RED)(m ) ILED(RED)(A) 140 125C 1.52 25C 1.50 -40C 120 25C 100 80 -40C 1.48 60 1.46 40 2 3 4 VIN(V) 5 6 2 3 Figure 8. 5 6 5 6 5 6 Figure 9. ILED(GRN) vs VIN RDS(GRN) vs VIN 1.54 160 140 125C 1.52 -40C RDS(GRN)(m ) ILED(GRN)(A) 4 VIN(V) 1.50 25C 125C 120 25C 100 80 -40C 1.48 60 1.46 40 2 3 4 VIN(V) 5 6 2 3 Figure 10. 4 VIN(V) Figure 11. ILED(BLU) vs VIN RDS(BLU) vs VIN 1.54 160 140 125C 125C RDS(BLU)(m ) ILED(BLU)(A) 1.52 1.50 -40C 25C 120 25C 100 80 -40C 1.48 60 1.46 40 2 3 4 VIN(V) 5 6 Figure 12. 2 3 4 VIN(V) Figure 13. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 7 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) All curves taken at VIN = 5V with configuration in typical application for driving one red (OSRAM LRW5AP-KZMX), one green (OSRAM LTW5AP-LZMY) and one blue (OSRAM LBW5AP-JYKX) LEDs with IOUT per channel = 1.5A under TA = 25C, unless otherwise specified. RED Efficiency vs VIN @ TA = 25C GREEN Efficiency vs VIN @ TA = 25C 100 GREEN EFFICIENCY, GRN(%) RED EFFICIENCY, RED(%) 100 90 80 70 60 50 90 80 70 60 50 2 3 4 VIN(V) 5 6 2 3 4 VIN(V) 5 Figure 14. Figure 15. BLUE Efficiency vs VIN @ TA = 25C Power Up Transient 6 BLUE EFFICIENCY, BLU(%) 100 90 80 70 60 50 2 8 3 4 VIN(V) 5 6 Figure 16. Figure 17. (10ms/DIV) RGB Sequential Mode Operation Color Transition Delay Figure 18. (1ms/DIV) Figure 19. (100s/DIV) Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM GLED BLED RLED VIN SW VOUT Feedback H.S. Driver L.S. Driver Flyback Converter Control Logic GCTRL Ch. Select BCTRL RCTRL RGB Current Regulator And Logic Control ON-timer RT OFF-timer Gint Bint Rint EN VFB IREFG,B,R SENG,B,R FAULT Gint SENG IREFG Gm CG Comp CB 10 bit 10 bit 10 bit SVDD SDATA Sample & Hold Bint SENB IGRN IBLU IRED SCLK IREFB Gm 2 I C Interface Logic Sample & Hold CR Comp MUX Rint SENR IREFG VREF IREFR Gm Sample & Hold Comp PGND SGND IREFB Bias and Vref GND IREFR OPERATION DESCRIPTION INTRODUCTION The LM3435 is a sequential LED driver for portable and pico projectors. The device is integrated with three high current regulators, low side MOSFETs and a synchronous flyback DC-DC converter. Only single LED can be enabled at any given time. The DC-DC converter quickly adjusts the output voltage to an optimal level based on each LED's forward voltage. This minimizes the power dissipation at the current regulators and maximizes the system efficiency. The I2C compatible synchronous serial interface provides access to the programmable functions and registers of the device. I2C protocol uses a two-wire interface for bi-directional communications between the devices connected to the bus. The two interface lines are the Serial Data Line (SDA), and the Serial Clock Line (SCL). These lines should be connected to a positive supply, via a pull-up resistor and remain HIGH even when the bus is idle. Every device on the bus is assigned an unique address and acts as either a Master or a Slave depending on whether it generates or receives the serial clock (SCL). SYNCHRONOUS FLYBACK CONVERTER The LM3435 integrates a synchronous flyback DC-DC converter to power the three-channel current regulator. The LEDs are connected across VOUT of the flyback converter and VIN through an internal power MOSFET connecting to corresponding LED channel. The maximum current to LED is 2A and the maximum voltage across VOUT and VIN is limited at around 4.7V. The LM3435 integrates the main N-channel MOSFET, the synchronous P-channel MOSFET of the flyback converter and three N-channel MOSFETs as internal passing elements connecting to LED channels in order to minimize the solution components count and PCB space. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 9 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com The flyback converter of LM3435 employs a proprietary Projected On-Time (POT) control scheme to determine the on-time of the main N-channel MOSFET with respect to the input and output voltages together with an external switching frequency setting resistor connected to RT pin, RRT. POT control use information of the current passing through RRT from VOUT, voltage information of VOUT and VIN to find an appropriate on-time for the circuit operations. During the on-time period, the inductor connecting to the flyback converter is charged up and the output capacitor is discharged to supply power to the LED. A cycle-by-cycle current limit of typical 6A is imposed on the main N-channel MOSFET for protection. After the on-time period, the main N-channel MOSFET is turned off and the synchronous P-channel MOSFET is turned on in order to discharge the inductor. The off state will last until VOUT is dropped below a reference voltage. Such reference voltage is derived from the required LED current to be regulated at a particular LED channel. The flyback converter under POT control can maintain a fairly constant switching frequency that depends mainly on value of the resistor connected across VOUT and RT pins, RRT. The relationship between the flyback converter switching frequency, FSW and RRT is approximated by the following relationship: RRT in and FSW in kHz (1) In addition, POT control requires no external compensation and achieves fast transient response of the output voltage changes that perfectly matches the requirements of a sequential RGB LED driver. The POT flyback converter only operates at Continuous Conduction Mode. Dead-time between main MOSFET and synchronous MOSFET switching is adaptively controlled by a minimum non-overlap timer to prevent current shoot through. Initial VOUT will be regulated at around 3.2V to 3.5V above VIN before any control signals being turned on. Three small capacitors connected to CR, CG and CB pins are charged by an internal current source and act as soft-start capacitors of the flyback converter during start-up. Once initial voltage of VOUT is settled, the capacitors will be used as a memory element to store the VOUT information for each channel respectively. This information will be used for VOUT regulation of respective LED channel during channel switching. In between the channel switching, a small I2C programmable blank out time of 5 s to 35 s is inserted so that the LED current is available after the correct VOUT for the color is stabilized. This control scheme ensures the minimal voltage headroom for different color LED and hence best conversion efficiency can be achieved. HIGH CURRENT REGULATORS The LM3435 contains three internal current regulators powered by the output of the synchronous Flyback Converter, VOUT. Three low side power MOSFETs are included. These current regulators control the current supplied to the LED channels individually and maintain accurate current regulation by internal feedback and control mechanism. The regulation is achieved by a Gm-C circuit comparing the sensing voltage of the internal passing N-channel MOSFET and an internal LED current reference voltage generated from the external reference current setting resistor, RIREFx connect to IREFG, IREFB or IREFR pin, of the corresponding LED channel. The nominal maximum LED current is governed by the equation in below: RIREFx in and ILEDx in Ampere (2) The LED current setting can be in the range of 0.5A up to 2A maximum. The nominal maximum of the device is 1.5A and for applications need higher than 1.5A LED current, VIN and thermal constrains must be complied. The actual LED current can be adjusted on-the-fly by the internal ten bits register for individual channel. The content of these registers are user programmable via I2C bus connection. The user can control the LED output current on-the-fly during normal operation. The resolution is 1 out of 1024 part of the LED current setting. The user can program the registers in the range of 1(001H) to 1023(3FFH) for each channel independently, provided the converter is not entered the Discontinuous Conduction Mode. Whenever the converter operation entered the Discontinuous Conduction Mode, the regulation will be deteriorated. A value of "0" may cause false fault detection, so it must be avoided. 10 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 SEQUENTIAL MODE RGB TIMING LM3435 is a sequential mode RGB driver dedicatedly designed for pico and portable projector applications. By using this device, the system only require one power driver stage for three color LEDs. With LM3435, only single LED can be enabled at any given time period and the DC-DC converter can quickly adjusts the output voltage to an optimized level by controlling the current flowing into the respective LED channel. This approach minimizes the power dissipation of the internal current regulator and effectively maximizes the system efficiency. Timing of the RGB LEDs depends solely on the RCTRL, GCTRL and BCTRL inputs. The Timing Chart in below shows a typical timing of two cycles of even RGB scan. In real applications, the RGB sequence is totally controlled by the system or the video processor. It's not mandatory to follow the simple RGB sequence, but for any change instructed by the I2C control will only take place at the falling edge of the corresponding CTRL signal. 1/FPWM 1/FPWM RED GREEN BLUE RED GREEN BLUE 1/3 1/3 1/3 1/3 1/3 1/3 RCTRL GCTRL BCTRL Figure 20. RGB Control Signals Timing Chart PRIORITIES OF LED CONTROL SIGNALS The LM3435 does not support color overlapping mode operation. At any instant, only one LED will be enabled even overlapping control signals applied to the control inputs. The decision logics of the device determine which LED channel should be enabled in case overlapping control signals are detected at the control inputs. The GREEN channel has the higher priority over BLUE channel and the RED channel has the lowest priority. However, if a low priority channel is already turned on before the high priority channel control signal comes in, the low priority channel will continue to take the control until the control signal ceased. The timing diagram in below illustrates some typical cases during operation. GREEN BLUE RED BLUE GREEN GCTRL BCTRL RCTRL Green Transition Delay IGLED IBLED Blue Transition Delay IRLED Red Transition Delay Figure 21. Priorities of LED Control Signals Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 11 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com LED OPEN FAULT REPORTING The fly-back converter tries to keep VOUT to the forward voltage required by the LED with the desired LED current output. However, if the LED channel is being opened no matter it is due to LED failure or no connection, the fly-back converter will limit the VOUT voltage at around 4.7V above VIN. Once such voltage is achieved, an open-fault-suspect signal will go high. If this open-fault-suspect signal is being detected at 3 consecutive falling edges of the opened channel control signal, "Fault" pin will be latched high and the corresponding channel open fault will be reported through I2C. The open fault report can be removed either by pulling EN pin low for less than 100ns (a true shutdown will be triggered if the negative pulse on EN is more than 100ns) or by writing a "0" to "bit 0" of the I2C register "05h". The "Fault" pin will be cleared and the I2C fault register will be reset. In order to reinstate the fault reporting feature, the system need to write a "1" to "bit 0" of the I2C register "05h". LED SHORT FAULT REPORTING If the VOUT is prohibited to regulate at a potential higher than 1.5V above VIN at a LED channel, such LED is considered being shorted and a short-fault-suspect signal will go high. If this short-fault-suspect signal is being detected at 3 consecutive falling edges of the shorted channel control signal, "Fault" pin will be latched high and the corresponding channel short fault will be reported through I2C. The short fault report can be removed either by pulling EN pin low for less than 100ns (a true shutdown will be triggered if the negative pulse on EN is more than 100ns) or by writing a "0" to "bit 0" of the I2C register "05h". The "Fault" pin will be cleared and the I2C fault register will be reset. In order to reinstate the fault reporting feature, the system need to write a "1" to "bit 0" of the I2C register "05h". Persistently short of LED can cause permanent damage to the device. Whenever the short fault is detected, the system should turn off the faulty channel immediately by pulling the corresponding PWM control pin to GND. THERMAL SHUTDOWN Internal thermal shutdown circuitry is included to protect the device in the event that the maximum junction temperature is exceeded. The threshold for thermal shutdown in LM3435 is around 160C and it will be resumed to normal operation again once the temperature cools down to below around 140C. I2C Compatible Interface INTERFACE BUS OVERVIEW The I2C compatible synchronous serial interface provides access to the programmable functions and registers on the device. This protocol uses a two-wire interface for bi-directional communications between the devices connected to the bus. The two interface lines are the Serial Data Line (SDA), and the Serial Clock Line (SCL). These lines should be connected to a positive supply, via a pull-up resistor and remain HIGH even when the bus is idle. Every device on the bus is assigned a unique address and acts as either a Master or a Slave depending on whether it generates or receives the serial clock (SCL). DATA TRANSACTIONS One data bit is transferred during each clock pulse. Data is sampled during the high state of the serial clock (SCL). Consequently, throughout the clock's high period, the data should remain stable. Any changes on the SDA line during the high state of the SCL and in the middle of a transaction, aborts the current transaction. New data should be sent during the low SCL state. This protocol permits a single data line to transfer both command/control information and data using the synchronous serial clock. 12 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 I2C DATA VALIDITY The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, state of the data line can only be changed when CLK is LOW. SCL SDA data change allowed data valid data change allowed data change allowed data valid Figure 22. I2C Signals : Data Validity I2C START and STOP CONDITIONS START and STOP bits classify the beginning and the end of the I2C session. START condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. STOP condition is defined as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates START and STOP bits. The I2C bus is considered to be busy after START condition and free after STOP condition. During data transmission, I2C master can generate repeated START conditions. First START and repeated START conditions are equivalent, function-wise. SDA SCL S P START condition STOP condition Figure 23. I2C Start and Stop Conditions I2C ADDRESSES AND TRANSFERRING DATA Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) being transferred first. Each byte of data has to be followed by an acknowledge bit. The acknowledge bit related clock pulse is generated by the master. The transmitter releases the SDA line (HIGH) during the acknowledge clock pulse. The receiver must pull down the SDA line during the 9th clock pulse, signifying an acknowledgement. A receiver which has been addressed must generate an acknowledge bit after each byte has been received. After the START condition, the I2C master sends a chip address. This address is seven bits long followed by an eighth bit which is a data direction bit (R/W). The LM3435 address is 50h or 51H which is determined by the R/W bit. I2C address (7 bits) for LM3435 is 28H. For the eighth bit, a "0" indicates a WRITE and a "1" indicates a READ. The second byte selects the register to which the data will be written. The third byte contains data to write to the selected register. MSB ADR6 Bit7 LSB ADR5 bit6 ADR4 bit5 ADR3 bit4 ADR2 bit3 ADR1 bit2 ADR0 bit1 R/W bit0 2 I C SLAVE address (chip address) Figure 24. I2C Chip Address Register changes take an effect at the SCL rising edge during the last ACK from slave. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 13 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com ack from slave ack from slave msb Chip Address lsb start w ack msb Register Add lsb ack addr = 02h ack ack from slave msb DATA lsb ack stop ack stop SCL SDA start id = 28h w ack address 02h data w = write (SDA = "0") r = read (SDA = "1") ack = acknowledge (SDA pulled down by either master or slave) rs = repeated start id = 7-bit chip address, 50H (ADDR_SEL=0) or 51H (ADDR_SEL=1) for LM3435. Figure 25. I2C Write Cycle When a READ function is to be accomplished, a WRITE function must precede the READ function, as shown in the Read Cycle waveform. ack from slave msb Chip Address lsb start w ack from slave repeated start msb Register Add lsb ack from slave data from slave nack from master rs msb Chip Address lsb rs id = 28h r msb DATA lsb stop SCL SDA start id = 28h w ack addr = h00 ack r ack Address 00h data nack stop Figure 26. I2C Read Cycle I2C TIMING PARAMETERS (VIN = 2.7V to 5.5V, SVDD = 1.7V to VIN) SDA 10 8 7 6 1 8 2 7 SCL 1 5 3 4 9 Figure 27. I2C Timing Diagram 14 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 Symbol Limit (1) Parameter Min (1) Units Max 1 Hold Time (repeated) START Condition 0.6 s 2 Clock Low Time 1.3 s 3 Clock High Time 600 ns 4 Setup Time for a Repeated START Condition 600 ns 5 Data Hold Time (Output direction) 300 ns 5 Data Hold Time (Input direction) 0 ns 6 Data Setup Time 100 ns 7 Rise Time of SDA and SCL 20+0.1Cb 300 ns 8 Fall Time of SDA and SCL 15+0.1Cb 300 ns 9 Set-up Time for STOP condition 600 10 Bus Free Time between a STOP and a START Condition 1.3 Cb Capacitive Load for Each Bus Line 10 ns s 200 pF Note: Data specified by design. I2C REGISTER DETAILS The I2C bus interacts with the LM3435 to realize the features of LED current program inter-color delay time program and Fault reporting function. The operation of these functions requires the writing and reading of the internal registers of the LM3435. In below is the master register map of the device. Table 1. Master Register Map ADDR REGISTER D7 D6 00h LEDLO 0 0 01h GLEDH D5 D4 D3 RLED[1:0] BLED[9:2] RLED[9:2] 05h FLT_RPT 06h DELAY 07h FAULT RDLY[1:0] GO 0 1 GS 1111 1111 0 0 BDLY[1:0] 0 BO DEFAULT 0011 1111 1111 1111 BLEDH RLEDH 0 D0 GLED[1:0] 1111 1111 03h 0 D1 GLED[9:2] 02h 0 D2 BLED[1:0] 1 BS 0 0 FLT_RPT GDLY[1:0] RO RS 0000 0001 1111 1111 0000 0000 LED Current Register Definitions The LED currents for each color can be accurately adjusted by 10 bits resolution (1024 steps) independently. By writing control bytes into the LM3435 LED current Registers, the LED currents can be precisely set to any value in the range of IMIN to IREF. In below is the LED Current Low register bit definition: ADDR REGISTER D7 D6 00h LEDLO 0 0 D5 D4 D3 RLED[1:0] Bits D2 BLED[1:0] D1 D0 GLED[1:0] DEFAULT 0011 1111 Description 7:6 Reserved. These bits always read zeros. 5:4 The least significant bits of the 10-bit RLED register. This register is for programming the level of current for the Red LED. 3:2 The least significant bits of the 10-bit BLED register. This register is for programming the level of current for the Blue LED. 1:0 The least significant bits of the 10-bit GLED register. This register is for programming the level of current for the Green LED. In below is the LED Current High register bit definition: ADDR REGISTER 01h GLEDH D7 D6 D5 D4 GLED[9:2] D3 D2 D1 D0 1111 1111 DEFAULT 02h BLEDH BLED[9:2] 1111 1111 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 15 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 ADDR REGISTER 03h RLEDH D7 www.ti.com D6 D5 D4 Bits 7:0 D3 D2 D1 D0 RLED[9:2] DEFAULT 1111 1111 Description The most 8 significant bits of the 10-bit GLED, BLED and RLED registers respectively. These registers are for programming the level of current of the Green LED, Blue LED and Red LED independently. Fault Reporting Register Definition The fault reporting feature of the LM3435 can be selected by the system designer according to their application needs. To select or de-select this feature is realized by writing one bit into the FLT_RPT register. ADDR REGISTER D7 D6 D5 D4 D3 D2 D1 D0 DEFAULT 05h FLT_RPT 0 0 0 0 0 0 0 FLT_RPT 0000 0001 Bits 7:1 Description Reserved. These bits always read zeros. 0 This bit defines the mode of fault report feature. Writing a " 1 " into this bit enables the fault reporting feature, otherwise no Fault signal output at Pin 27. Color Transition Delay Register Definition The transition of one color into next color is not executed immediately. Certain delay is inserted in between to ensure the LED rail voltage stabilized before turning the next LED on. This delay is user programmable by writing control bits into the DELAY register for each color individually. The power up default delay time is 35s and this delay can be programmed from 5 s to 35 s maximum in step of 10 s. ADDR REGISTER 06h DELAY D7 D6 RDLY[1:0] D5 1 D4 Bits 7:6 5 D3 BDLY[1:0] D2 1 D1 D0 GDLY[1:0] DEFAULT 1111 1111 Description These two bits are for programming the Red transition delay. Reserved. This bit always read " 1". 4:3 2 These two bits are for programming the Blue transition delay. Reserved. This bit always read " 1". 1:0 These two bits are for programming the Green transition delay. Fault Register Definition The LM3435 features LED fault detection capability. Whenever a LED fault is detected (open or short), the FAULT output (pin 27) will go high to indicate a LED fault is detected. The details of the fault can be investigated by reading the FAULT register. The FAULT register is read only. The fault status can be cleared by clearing and then re-enabling the FLT_RPT register or power up reset of the device. ADDR REGISTER D7 D6 D5 D4 D3 D2 D1 D0 DEFAULT 07h FAULT GO GS 0 BO BS 0 RO RS 0000 0000 Bits 16 Description 7 GO - Green Open. This read only register bit indicates the presence of an OPEN fault of the GREEN LED. 6 GS - Green Short. This read only register bit indicates the presence of an SHORT fault of the GREEN LED. 5 Reserved. This bit always read " 0 ". 4 BO - Blue Open. This read only register bit indicates the presence of an OPEN fault of the BLUE LED. 3 BS - Blue Short. This read only register bit indicates the presence of an SHORT fault of the BLUE LED. 2 Reserved. This bit always read " 0 ". 1 RO - Red Open. This read only register bit indicates the presence of an OPEN fault of the RED LED. 0 RS - Red Short. This read only register bit indicates the presence of an SHORT fault of the RED LED. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 Design Procedures This section presents a design example of a typical pico projector application. By using LM3435, the system requires only single DC-DC converter to drive three color LEDs instead of using three DC-DC converters with conventional design. The suggested approach not only saves components cost, but also releases invaluable PCB space to the system and enhances system reliability. The handy projector is powered by a single lithium battery cell or a 5Vdc wall mount adaptor. The key specifications of the design are as in below: * Supply voltage range, VIN = 2.7V to 5.5V * Preset LED current per channel, ILED = 1.5A * Minimum LED current per channel, ILED(MIN) = 600mA * Maximum LED forward voltage drop, VLED = 3.5V at 1.5A * Flyback converter switching Frequency, FSW = ~500kHz SETTING THE FLYBACK CONVERTER SWITCHING FREQUENCY, FSW The LM3435 employs a proprietary Projected On-Time (POT) control scheme, the switching frequency, FSW of the converter is simply set by an external resistor, RRT across RT pin of LM3435 and VOUT of the converter. The flyback converter under POT control can maintain a fairly constant switching frequency that depends mainly on the value of RRT. The relationship between the flyback converter switching frequency, FSW and RRT is approximated by the following relationship: RRT in and FSW in kHz (3) In order to set the flyback converter switching frequency, FSW to 500kHz, the value of RRT can be calculated as in below: (4) A standard resistor value of 499k can be used in place and the period of switching, TSW is about 2s. SETTING THE NOMINAL LED CURRENT The nominal LED current of the LEDs are set by resistors connected to IREFR, IREFG and IREFB pins. The current for each channel can be set individually and it is not mandatory that all channel currents are the same. Just for simplicity, we assume all channels are set to 1.5A in this example. The LED current and the value of RIREFR, RIREFG and RIREFB is governed by the following equation. RIREFx in and ILEDx in Ampere (5) The resistance value for the current setting resistors is calculated as in below: (6) In order to achieve the required LED current accuracy, high quality resistors with tolerance not higher than +/-1% are recommended. Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 17 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com INDUCTOR SELECTION Selecting the correct inductor is one of the major task in application design of a LED driver system. The most critical inductor parameters are inductance, current rating, DC resistance and size. As an rule of thumb, for same physical size inductor, higher the inductance means higher the DC resistance, consequently more power loss with the inductor and lower the DC-DC conversion efficiency. With LM3435, the inductor governs the inductor ripple current and limits the minimum LED current that can be supported. However for the POT control in LM3435, a minimum inductor ripple current of about 300mApk-pk is required for proper operation. The relationship of the ON-Duty, D and the input/output voltages can be derived by applying the Volt-Second Balance equation across the inductor. The waveforms of the inductor current and voltage are shown in below. IL Slope = VIN Slope = L -VLED L ILripple(MAX) IL(AVG) ILripple(MIN) t 0 VL = VIN - VSW VIN t 0 VLED TON (TSW x D) TOFF (TSW x (1-D)) Figure 28. Inductor Switching Waveforms Applying the Volt-Second Balance equation with the inductor voltage waveform, (7) Referring to the inductor current waveform, the average inductor current, IL(AVG) can be derived as in below: (8) The minimum LED current, ILED(MIN) happens when the inductor current just entered the Critical Conduction Mode operation, i.e. ILripple(MIN)=0. Applying this condition to the last equation: 18 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 (9) The relationship of the LED current, ILED and the average inductor current, IL(AVG) is shown in below: (10) By combining last two equations, the minimum LED current, ILED(MIN) can be calculated as in below: (11) By rearranging the terms, the inductance, L required for any specific minimum LED current, ILED(MIN) can be found with the equation in below: (12) From the equation, it can be noted that for lower minimum LED current, the inductance required will be higher. As mentioned in before, higher the inductance means higher DC resistance in same size inductor. Additionally, the POT control in LM3435, a minimum inductor ripple current is required to maintain proper operation. The restrictions limit the lowest current can be programed by I2C control. In this example, the ILED(MIN)=600mA and the highest ripple will happen when the input voltage is maximum, i.e. VIN=5.5V. The ON Duty, D with average LED forward voltage of 3.5V is calculated in below: (13) The required inductance for this case is: (14) A standard inductance value of 2.2H is suggested and the minimum LED current, ILED(MIN) is about 595mA @ VIN=5.5V. Other than the inductance, the worst case inductor current, IL(MAX) must be calculated so that an inductor with appropriate saturation current level can be specified. The maximum inductor current, IL(MAX) can be calculated with the equation in below: (15) The highest inductor current occurs when the input voltage is minimum, i.e. VIN=2.7V. The ON Duty, D for this condition can be calculated as in below: (16) The maximum inductor current, IL(MAX) is calculated in below: (17) Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 19 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com The calculated maximum inductor current is 4.1A, however the inductance can drop as temperature rise. In order to accommodate all possible variations, an inductor with saturation current specification not less than 5A is suggested. INPUT CAPACITORS SELECTION Input capacitors are required for all supply input pins to ensure that VIN does not drop excessively during high current switching transients. LM3435 have supply input pins located in different sides of the device. Individual capacitors are needed for the supply input pins locally. All capacitors must be placed as close as possible to the supply input pins and have low impedance return ground path to the device grounds and back to supply ground. Capacitors CIN1 and CIN2 are the main input capacitors and additionally, CIN3 is added to de-couple high frequency interference. The capacitance for CIN1 and CIN2 is recommended in the range of 22F to 47F and CIN3 is 0.1F. Compact applications normally have stringent space limitations, small size surface mount capacitors are usually preferred. Low ESR Multi-Layer Ceramic Capacitors (MLCC) are the best choices. MLCC capacitors with X5R and X7R dielectrics are recommended for its low leakage and low capacitance variation against temperature and frequency. OUTPUT CAPACITORS SELECTION Two output capacitors are required with LM3435 configuration, one for VOUT to Ground, COUT2 and one for decoupling the LED current ripple, COUT1. The LM3435 operates at frequencies high enough to allow the use of MLCC capacitors without compromising transient response. Low ESR characteristic of the MLCC allow higher inductor ripple without significant increase of the output ripple. The capacitance recommended for COUT1 is 10F and COUT2 is 22F. Again, high quality MLCC capacitors with X5R and X7R dielectrics are recommended. For certain conditions, acoustic problem may be encountered with using MLCC, Low Acoustic Noise Type capacitors are strongly recommended for all output capacitors. Alternatively, the acoustic noise can also be lowered by using smaller size capacitors in parallel to achieve the required capacitance. OTHER CAPACITORS SELECTION Three small startup capacitors connected to CG, CB and CR pins are needed for proper operation. The suggested capacitance for CCR, CCG and CCB is 1nF. Also three capacitors connected to GLED, BLED and RLED pins to protect the device from high transient stress due to the inductance of the connecting wires for the LEDs. The suggested capacitance for CG, CB and CR is 0.47H. MLCC capacitors with X5R and X7R dielectrics are recommended. All capacitors must be placed as close as possible to the device pins. DIODE SELECTION A schottky barrier diode is added across the SW and VOUT pins, equivalently, its across the internal P-channel MOSFET of the synchronous converter, that can help to improve the conversion efficiency by few percents. A very low forward voltage and 1A rated forward current part is suggested in the schematic diagram. The key selection criteria are the forward voltage and the rated forward current. PCB LAYOUT CONSIDERATIONS The performance of any switching converters depends as much upon the layout of the PCB as the component selection. PCB layout considerations are therefore critical for optimum performance. The layout must be as neat and compact as possible, and all external components must be as close as possible to their associated pins. The PGND connection to CIN and VOUT connection to COUT should be as short and direct as possible with thick traces. The inductor should connect close to the SW pin with short and thick trace to reduce the potential electromagnetic interference. It is expected that the internal power elements of the LM3435 will produce certain amount of heat during normal operation, good use of the PC board's ground plane can help considerably to dissipate heat. The exposed pad on the bottom of the IC package can be soldered to a copper pad with thermal vias that can help to conduct the heat to the bottom side ground plane. The bottom side ground plane should be as large as possible. 20 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 LM3435 www.ti.com SNVS724C - JUNE 2011 - REVISED MAY 2013 SCHEMATIC OF THE EXAMPLE APPLICATION FOR PICO PROJECTOR COUT1 10 PF/16V 2.2 PH/6A Vin VOUT L1 CIN1 CIN3 0.1 PF/25V SVDD *RSDA 10k VOUT RT SW SW SW VIN PGND CB FAULT DAP (PGND) CR IREFG GLED GLED 20 19 18 17 16 15 CIN2 47 PF/10V RCTRL RLED BCTRL SGND VIN RLED GCTRL GND VIN BLED VIN IREFR VIN BLED SCLK IREFB 14 CSVDD 1 PF/10V EN 13 10 PGND PGND 9 CG SDATA 8 SGND PGND SVDD 7 RIREFR VOUT 12 RIREFB PGND 11 6 31 16.5k RIREFG 32 16.5k 5 33 16.5k 4 34 1 nF/16V CCB CCR 35 1 nF/16V 3 36 1 nF/16V CCG 37 2 38 1 39 40 U1 RRT 499k VOUT 47 PF/10V SD1 RB160M-60 30 29 28 27 26 25 GRN CG 24 23 BLU CB 22 21 RED CR 3x 0.47 PF/25V COUT2 22 PF/16V *RSCK 10k I2C BUS SDATA SCLK GND * RSDA, RSCK I2C Pull-high resistors GCTRL PWM Controls And GPIO Bus BCTRL RCTRL FAULT EN GND Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 21 LM3435 SNVS724C - JUNE 2011 - REVISED MAY 2013 www.ti.com REVISION HISTORY Changes from Revision B (May 2013) to Revision C * 22 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 21 Submit Documentation Feedback Copyright (c) 2011-2013, Texas Instruments Incorporated Product Folder Links: LM3435 PACKAGE OPTION ADDENDUM www.ti.com 2-May-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish (2) MSL Peak Temp Op Temp (C) Top-Side Markings (3) (4) LM3435SQ/NOPB ACTIVE WQFN RSB 40 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 L3435SQ LM3435SQX/NOPB ACTIVE WQFN RSB 40 4500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 L3435SQ (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Top-Side Marking for that device. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. 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Addendum-Page 1 Samples PACKAGE MATERIALS INFORMATION www.ti.com 7-Jun-2018 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM3435SQ/NOPB Package Package Pins Type Drawing WQFN RSB 40 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 1000 178.0 12.4 Pack Materials-Page 1 5.3 B0 (mm) K0 (mm) P1 (mm) 5.3 1.3 8.0 W Pin1 (mm) Quadrant 12.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 7-Jun-2018 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3435SQ/NOPB WQFN RSB 40 1000 210.0 185.0 35.0 Pack Materials-Page 2 PACKAGE OUTLINE RSB0040A WQFN - 0.8 mm max height SCALE 2.700 PLASTIC QUAD FLATPACK - NO LEAD 5.1 4.9 A B 0.5 0.3 PIN 1 INDEX AREA 0.3 0.2 5.1 4.9 DETAIL OPTIONAL TERMINAL TYPICAL DIM A OPT 1 OPT 1 (0.1) (0.2) C 0.8 MAX SEATING PLANE 0.05 0.00 0.08 2X 3.6 11 (A) TYP EXPOSED THERMAL PAD 20 36X 0.4 10 21 2X 3.6 41 SYMM 3.6 0.1 SEE TERMINAL DETAIL 1 30 40X PIN 1 ID (OPTIONAL) 40 31 SYMM 0.5 40X 0.3 0.25 0.15 0.1 0.05 C A B (0.2) TYP 4215000/A 08/2016 NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com EXAMPLE BOARD LAYOUT RSB0040A WQFN - 0.8 mm max height PLASTIC QUAD FLATPACK - NO LEAD ( 3.6) SYMM 31 40 40X (0.6) 40X (0.2) 1 30 36X (0.4) 4X (1.55) 41 SYMM (1.23) (4.8) ( 0.2) TYP VIA 10 21 (R0.05) TYP 11 (1.23) TYP 20 4X (1.55) (4.8) LAND PATTERN EXAMPLE SCALE:15X 0.05 MIN ALL AROUND 0.05 MAX ALL AROUND SOLDER MASK OPENING METAL SOLDER MASK OPENING METAL UNDER SOLDER MASK NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK DEFINED SOLDER MASK DETAILS 4215000/A 08/2016 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature number SLUA271 (www.ti.com/lit/slua271). 5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown on this view. It is recommended that vias under paste be filled, plugged or tented. www.ti.com EXAMPLE STENCIL DESIGN RSB0040A WQFN - 0.8 mm max height PLASTIC QUAD FLATPACK - NO LEAD (1.23) TYP 9X ( 1.03) 40 31 40X (0.6) 1 41 30 40X (0.2) 36X (0.4) (1.23) TYP SYMM (4.8) (R0.05) TYP 10 21 METAL TYP 20 11 SYMM (4.8) SOLDER PASTE EXAMPLE BASED ON 0.1 mm THICK STENCIL EXPOSED PAD 41 73.7% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE SCALE:20X 4215000/A 08/2016 NOTES: (continued) 6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. 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