LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 LM2759 1A Switched Capacitor Flash LED Driver with I2C Compatible Interface Check for Samples: LM2759 FEATURES APPLICATIONS * * * * * * 1 2 * * * * * * * * * * Up to 1A Output Current Solution Area < 22 mm2 No Inductor Required 90% Peak Efficiency Adaptive 1x, 1.5x and 2x Gains for Maximum Efficiency Load Disconnect in Shutdown Accurate Input Current Control During Gain Transitions Flash Time-Out TX Input Pin Ensures Synchronization with RF Power Amplifier Pulse Torch, Flash, and Indicator Modes External Flash Enable via Strobe Input Pin Strobe Input Disable via I2C Programmable Flash Pulse Duration, and Torch and Flash Currents via I2C-Compatible Interface 1MHz Constant Frequency Operation Low Profile 12-Pin WSON (3mm x 3mm x 0.8mm) Camera Flash in Cellular Phones DESCRIPTION LM2759 is an integrated low-noise, high-current switched capacitor DC/DC converter with a regulated current source. The device requires only four small ceramic capacitors making the total solution area less than 22 mm2 and the height less than 1 mm. The LM2759 is capable of driving loads up to 1A from a single-cell Li-Ion battery. Maximum efficiency is achieved over the input voltage range by actively selecting the proper gain based on the LED forward voltage and current requirements. The LED current can be programmed up to 1A via an I2C-compatible interface, along with eight selectable Flash Time-Out durations. One high-current Flash LED can be driven either in a high-power Flash mode or a low-power Torch mode. The Strobe pin allows the flash to be toggled via a Flash enable signal from a camera module. The TX input pin limits the Flash LED current to the Torch current level during a RF PA pulse, to reduce high loads on the battery. Internal soft-start circuitry limits the amount of inrush current during start-up. LM2759 is offered in a small 12-pin thermally enhanced WSON package. Typical Application Circuit ILED = Up to 1A VIN = 3.0V - 5.5V VIN CIN 2.2 F C1 VOUT C 1+ 4.7 F COUT D1 2.2 F C 1C 2+ ISINK LM2759 C2 2.2 F C 2SDA SCL Strobe TX GND TDK: 2.2 F C1608X5R1C225 4.7 F C2012X5R1C475 1 2 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. All trademarks are the property of their respective owners. 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) 2008-2013, Texas Instruments Incorporated LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com Connection Diagram 1 12 12 1 2 11 11 2 3 10 10 3 4 9 9 4 5 8 8 5 6 7 7 6 Die-Attach Pad: GND Die-Attach Pad: GND Top View Bottom View Figure 1. 12-Pin WSON Package 3mm x 3mm x 0.8mm Package Number DQB0012A PIN DESCRIPTIONS Pin Name 10 VIN 3 VOUT 12 C1- 11 C1+ 2 C2+ Description Input voltage connection. Charge pump regulated output. Flying capacitor connections. 1 C2- 4 GND Ground connection. 6 ISINK Regulated current sink input. 8 SDA Serial data I/O pin. 7 Strobe 5 TX 9 SCL Manual flash enable pin. Flash will remain on for the duration that the Strobe pin is held high or when the Flash Timeout occurs, whichever comes first. Transmission pulse Flash interrupt pin. High = RF PA pulse active, LED current reduced to Torch level, Low = RF PA pulse off, LED at full programmed current level. Serial clock 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. 2 Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 Absolute Maximum Ratings (1) (2) (3) VIN pin: Voltage to GND -0.3V to 6.0V Strobe, TX, SDA, SCL, ISINK pins: Voltage to GND -0.3V to (VIN + 0.3V) w/ 6.0V max Continuous Power Dissipation (4) Internally Limited Junction Temperature (TJ-MAX) 150C Storage Temperature Range -65C to 150C (5) Maximum Lead Temp. (Soldering) ESD Rating (1) (2) (3) (4) (5) (6) Human Body Model (6) 2.5KV Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of the device is ensured. Operating Ratings do not imply ensured performance limits. For ensured performance limits and associated test conditions, see the Electrical Characteristics tables. All voltages are with respect to the potential to the GND pin. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications. Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=150C (typ.) and disengages at TJ = 120C (typ.). For detailed soldering specifications and information, please refer to Texas Instruments Application Note AN-1187 (SNOA401). The Human body model is a 100 pF capacitor discharged through a 1.5 k resistor into each pin. (MIL-STD-883 3015.7) Operating Ratings (1) (2) Input Voltage Range 2.7V to 5.5V LED Voltage Range 2.0V to 4.0V Junction Temperature Range (TJ) -30C to +125C Ambient Temperature Range (TA) (3) (1) (2) (3) -30C to +85C Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of the device is ensured. Operating Ratings do not imply ensured performance limits. For ensured performance limits and associated test conditions, see the Electrical Characteristics tables. All voltages are with respect to the potential to the GND pin. In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operation junction temperature (TJ-MAX-OP = 125C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (JA), as given by the following equation: TA-MAX = TJ-MAX-OP - (JA x PD-MAX). Thermal Information Junction-to-Ambient Thermal Resistance, (JA), (1) (1) 36.7C/W Junction-to-ambient thermal resistance (JA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC standard JESD51-7. The test board is a 4-layer FR-4 board measuring 102 mm x 76 mm x 1.6 mm with a 2x1 array of thermal vias. The ground plane on the board is 50 mm x 50 mm. Thickness of copper layers are 53m/35m/35m/53m (1.5oz/1oz/1oz/1.5oz). Ambient temperature in simulation is 22C, still air. Power dissipation is 1W.The value of JA of this product in the WSON package could fall in a range as wide as 30C/W to 150C/W (if not wider), depending on PWB material, layout, and environmental conditions. In applications where high maximum power dissipation exists (high VIN, high IOUT), special care must be paid to thermal dissipation issues. For more information on these topics, please refer to Application Note AN-1187 (SNOA401): and the Power Efficiency and Power Dissipation section of this datasheet. Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 3 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com Electrical Characteristics (1) (2) Limits in standard typeface are for TJ = 25C. Limits in boldface type apply over the full operating junction temperature range (-30C TJ +125 C). Unless otherwise noted, specifications apply to the LM2759 Typical Application Circuit (pg.1) with VIN = 3.6V, VTX = 0V, VSTROBE = 0V, CIN = C1 = C2 = 2.2 F, COUT = 4.7 F. (3) Symbol Parameter Conditions ILED LED Current Sink Accuracy Flash Mode ADDR xB0 = 0x02 IFLASH Max Flash Output Current Flash Mode ADDR xB0 = 0x0F VGDX Gain Transition Voltage Threshold on ISINK VOUT Output Voltage ROUT Min Typ Max Units 198 -10% 220 242 +10% mA 1 A ILED = 500mA (VISINK falling) 350 mV 1x Mode, IOUT = 0 mA (VIN >VOUT) (4) 4.7 4.9 1.5x Mode, IOUT = 0 mA 4.7 4.9 2x Mode, IOUT = 0 mA 5.1 5.4 x1 Mode Output Impedance IOUT = 200mA, VIN = 3.3V 0.33 1.5x Mode Output Impedance 1.9 IOUT = 500mA, VIN = 3.3V x2 Mode Output Impedance Switching Frequency 2.7V VIN 5.5V 0.7 VIH Input Logic High Pins: TX, Strobe 1.26 VIL Input Logic Low Pins: TX, Strobe IQ Quiescent Current Shutdown Current 2.25 FSW ISD V 1 1.3 MHz V 0.7 V IOUT = 0 mA, 1x Mode 0.6 0.9 IOUT = 0 mA, 1.5x Mode 3.4 4.0 IOUT = 0 mA, 2x Mode 5.9 7.0 Device Disabled 2.7V VIN 5.5V 5.8 9.7 A 0.72 V 300 mV mA I2C Compatible Interface Voltage Specifications (SCL, SDA) VIL Input Logic Low "0" 2.7V VIN 5.5V VIH Input Logic High "1' 2.7V VIN 5.5V VOL Output Logic Low "0" ILOAD = 3 mA 1.25 V I2C Compatible Interface Timing Voltage Specifications (SCL, SDA) (5) t1 SCL (Clock Period) 2.5 s t2 Data in Setup Time to SCL High 100 ns t3 Data Out Stable After SCL Low 0 ns t4 SDA Low Setup Time to SCL Low (Start) 100 ns t5 SDA High Hold Time After SCL High (Stop) 100 ns (1) (2) (3) (4) (5) 4 All voltages are with respect to the potential to the GND pin. Min and Max limits are specified by design, test, or statistical analysis. Typical (Typ) numbers are not ensured, but do represent the most likely norm. Unless otherwise specified, conditions for Typ specifications are: VIN = 3.6V and TA = 25C. CIN, COUT, C1, C2: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics. For input voltage below the regulation target during the gain of 1x, the output voltage will typically be equal to the input voltage. SCL and SDA should be glitch-free in order for proper brightness control to be realized. Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 Block Diagram COUT 4.7 F D FLASH LED MODULE VOUT Gain Control VIN CIN VREF 2.2 F C1+ 2.2 F Thermal Shutdown FLASH Timeout VOUT REG GND Current Control C1C2+ 2.2 F C2- STROBE 1x,1.5x, 2x Charge Pump TX 2 I C Control Logic Power on Reset LM2759 SCL SDA Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 5 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com Typical Performance Characteristics Unless otherwise specified: TA = 25C, VIN = 3.6V, CIN = C1 = C2 = 2.2F, COUT = 4.7F. Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's). Luxeon PWF3 Flash LED. 6 Efficiency vs VIN Input Current vs VIN Figure 2. Figure 3. Quiescent Current vs VIN, Gain = 1X Quiescent Current vs VIN, Gain = 2X Figure 4. Figure 5. ILED vs VISINK Shutdown Current vs VIN Figure 6. Figure 7. Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 Typical Performance Characteristics (continued) Unless otherwise specified: TA = 25C, VIN = 3.6V, CIN = C1 = C2 = 2.2F, COUT = 4.7F. Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's). Luxeon PWF3 Flash LED. Oscillator Frequency vs VIN Torch Code Levels Figure 8. Figure 9. Flash Code Levels Shutdown to Torch Mode, 100mA CH1: SDA; Scale: 2V/Div, DC Coupled CH2: VOUT; Scale: 2V/Div, DC Coupled CH3: IIN; Scale: 100mA/Div, DC Coupled CH4: ILED; Scale: 100mA/Div, DC Coupled Time scale: 400s/Div Figure 11. Figure 10. Shutdown to Flash Mode, 1A Torch to Flash Mode, 100mA to 1A CH1: SDA; Scale: 2V/Div, DC Coupled CH2: VOUT; Scale: 2V/Div, DC Coupled CH3: IIN; Scale: 1A/Div, DC Coupled CH4: ILED; Scale: 1A/Div, DC Coupled Time scale: 1ms/Div Figure 12. CH1: SDA; Scale: 2V/Div, DC Coupled CH2: VOUT; Scale: 2V/Div, DC Coupled CH3: IIN; Scale: 1A/Div, DC Coupled CH4: ILED; Scale: 1A/Div, DC Coupled Time scale: 1ms/Div Figure 13. Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 7 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified: TA = 25C, VIN = 3.6V, CIN = C1 = C2 = 2.2F, COUT = 4.7F. Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's). Luxeon PWF3 Flash LED. Flash Timeout, Timeout Code (x03) = 325ms Torch Level (x0F) = 180mA, Flash Level (x05) = 410mA CH1(bottom): IIN; Scale: 200mA/Div, DC Coupled CH2(middle): SDA; Scale: 2V/Div, DC Coupled CH3(top): VOUT; Scale: 2V/Div, DC Coupled Time scale: 100ms/Div Figure 14. 8 Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 APPLICATION INFORMATION CIRCUIT DESCRIPTION The LM2759 is an adaptive CMOS charge pump with gains of 1x, 1.5x, and 2x, optimized for driving Flash LEDs in camera phones and other portable applications. It provides a constant current of up to 1A (typ.) for Flash mode and 180 mA (typ.) for Torch mode. The LM2759 has selectable modes including Flash, Torch, Indicator and Shutdown. Flash mode for the LM2759 can also be enabled via the Strobe input pin. The LED is driven from VOUT and connected to the current sink. The LED drive current and operating modes are programmed via an I2C compatible interface. The LM2759 adaptively selects the next highest gain mode when needed to maintain the programmed LED current level. To prevent a high battery load condition during a simultaneous RF PA transmission and Flash event, LM2759 has a Flash interrupt pin (TX) to reduce the LED current to the programmed Torch current level for the duration of the RF PA transmission pulse. CHARGE PUMP AND GAIN TRANSITIONS The input to the 1x, 1.5x, 2x charge pump is connected to the VIN pin, and the loosely regulated output of the charge pump is connected to the VOUT pin. In 1x mode, as long as the input voltage is less than 4.7V (typ.), the output voltage is approximately equal to the input voltage. When the input voltage is over 4.7V (typ.) the output voltage is regulated to 4.7V (typ.). In 1.5x mode, the output voltage is regulated to 4.7V (typ.) over entire input voltage range. For the gain of 2x, the output voltage is regulated to 5.1V (typ.). When under load, the voltage at VOUT can be less than the target regulation voltage while the charge pump is still in closed loop operation. This is due to the load regulation topology of the LM2759. The charge pump's gain is selected according to the headroom voltage across the current sink of LM2759. When the headroom voltage VGDX (at the LED cathode) drops below 350 mV (typ.) the charge pump gain transitions to the next available higher gain mode. Once the charge pump transitions to a higher gain, it will remain at that gain for as long as the device remains enabled. Shutting down and then re-enabling the device resets the gain mode to the minimum gain required to maintain the load. SOFT START The LM2759 contains internal soft-start circuitry to limit inrush currents when the part is enabled. Soft start is implemented internally with a controlled turn-on of the internal voltage reference. CURRENT LIMIT PROTECTION The LM2759 charge pump contains current limit protection circuitry that protects the device during VOUT fault conditions where excessive current is drawn. Output current is limited to 1.4A typically. LOGIC CONTROL PINS LM2759 has two asynchronous logic pins, Strobe and TX. These logic inputs function according to the table below: TX STROBE FUNCTION 0 0 Current I2C programmed state (Off, Torch, Flash, Indicator) 1 0 Current I2C programmed state (Off, Torch, Flash, Indicator). If Flash is enabled via I2C and TX is logic High, the LED current will be at the programmed Torch level. 0 1 Flash Mode (Total LED "ON" Duration limited by Flash Timeout) 1 1 Torch Mode (Total LED "ON" Duration limited by Flash Timeout) Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 9 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com I2C COMPATIBLE INTERFACE START AND STOP CONDITIONS START and STOP conditions classify the beginning and the end of the I2C session. A START condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. A STOP condition is defined as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates START and STOP conditions. The I2C bus is considered to be busy after a START condition and free after a STOP condition. During data transmission, the 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 15. Start and Stop Conditions 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 SCL is LOW. SCL SDA data change allowed data valid data change allowed data valid data change allowed Figure 16. Data Validity Diagram A pull-up resistor between the controller's VIO line and SDA must be greater than [(VIO-VOL) / 3.5mA] to meet the VOL requirement on SDA. Using a larger pull-up resistor results in lower switching current with slower edges, while using a smaller pull-up results in higher switching currents with faster edges. TRANSFERING DATA Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) transferred first. Each byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated by the master. The master releases the SDA line (HIGH) during the acknowledge clock pulse. The LM2759 pulls down the SDA line during the 9th clock pulse, signifying an acknowledge. The LM2759 generates an acknowledge after each byte is 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 LM2759 address is 53h. 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. 10 Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 ack from slave ack from slave start msb Chip Address lsb w ack msb Register Add lsb ack start Id = 53h w ack addr = 10h ack ack from slave msb DATA lsb ack stop GDWD K03 (Flash) ack stop SCL SDA w = write (SDA = "0") r = read (SDA = "1") ack = acknowledge (SDA pulled down by either master or slave) id = chip address, 53h for LM2759 Figure 17. Write Cycle I2C COMPATIBLE CHIP ADDRESS The chip address for LM2759 is 1010011, or 53h. MSB LSB ADR6 ADR5 ADR4 ADR3 ADR2 ADR1 ADR0 R/W bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 0 1 10 1 0 0 1 1 1 0 2 I C SLAVE address (chip address) INTERNAL REGISTERS General Purpose Register Address: 0x10 MSB 1 bit7 1 bit6 1 bit5 1 bit6 1 bit5 1 bit6 1 bit5 G1 bit1 1 bit4 A3 bit3 1 bit4 B3 bit3 1 bit6 1 bit5 1 bit4 1 bit3 G0 bit0 LSB A2 bit2 A1 bit1 A0 bit0 LSB B2 bit2 B1 bit1 Flash Timeout Duration Register Address: 0xC0 MSB 1 bit7 G2 bit2 Flash Current Register Address: 0xB0 MSB 1 bit7 G4 bit3 Torch Current Register Address: 0xA0 MSB 1 bit7 1 bit4 LSB B0 bit0 LSB C2 bit2 C1 bit1 C0 bit0 Internal Hex Address Power On Value (lowest 4 bits) General Purpose Register 10h 0000 Flash Current Register B0h 1010 Torch Current Register A0h 0111 Register Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 11 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com Register Flash Timeout Duration Register Internal Hex Address Power On Value (lowest 4 bits) C0h 1011 GENERAL PURPOSE REGISTER AND STROBE INHIBIT FUNCTION The general purpose register (x10) is used set the mode of operation for the LM2759. The selectable operating modes using the lower 4 bits in the general purpose register are listed in the table below. The Strobe Input Pin can be disabled via I2C to ignore external signals into this pin when desired. This function is implemented through bit 3 of the General Purpose Register (See table below). In the default state, input signals on the Strobe Input are enabled. (Bit3 = "0", inputs into the Strobe Pin are not inhibited). Table 1. General Purpose Register (Reg x10) Bit3 Bit2 Bit1 Bit0 Mode X X X 0 Shutdown X 0 0 1 Torch X X 1 1 Flash X 1 0 1 Indicator (Lowest Torch Level) 1 X X X Inhibit Inputs into the Strobe Pin SETTING LED CURRENT The current through the LED is set by programming the appropriate register with the desired current level code for Flash and Torch. The time that Flash mode is active is dependent on the lesser of the duration that it is set to "ON" (via I2C or the Strobe pin), or the duration of the Flash Timeout. Use the tables below to select the desired current level. Using the part in conditions where the junction temperature might rise above the rated maximum requires that the operating ranges and/or conditions be de-rated. The printed circuit board also must be carefully laid out to account for high thermal dissipation in the part. Table 2. Flash Current Table (Reg xB0) 12 CODE (Hex) FLASH CURRENT (mA) 00 80 01 150 02 220 03 280 04 350 05 410 06 470 07 530 08 590 09 650 0A 710 0B 770 0C 830 0D 890 0E 950 0F 1010 Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 Table 3. Torch Current Table (Reg xA0) CODE (Hex) TORCH CURRENT (mA) 00 15 01 30 02 40 03 50 04 65 05 80 06 90 07 100 08 110 09 120 0A 130 0B 140 0C 150 0D 160 0E 170 0F 180 FLASH TIME-OUT FEATURE Time-out Protection Circuitry disables the current sink when either the Strobe pin is held at logic high or the Flash mode is enabled via the I2C compatible interface longer than the programmed timeout duration. This prevents the device from self-heating due to the high power dissipation during Flash conditions. During the timeout condition, voltage will still be present on VOUT but the current sink will be shut off, resulting in no current through the Flash LED. When the device goes into a time-out condition, disabling and then re-enabling the device will reset the time-out. Use the table below to set the desired Flash timeout duration. Table 4. Flash Timeout Duration (Reg xC0) CODE (Hex) TIME (ms) 00 60 01 125 02 250 03 375 04 500 05 625 06 750 07 1100 CAPACITOR SELECTION The LM2759 requires 4 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors are recommended. These capacitors are small, inexpensive and have very low equivalent series resistance (ESR <20 m typ.). Tantalum capacitors, OS-CON capacitors, and aluminum electrolytic capacitors are not recommended for use with the LM2759 due to their high ESR, as compared to ceramic capacitors. For most applications, ceramic capacitors with X7R or X5R temperature characteristic are preferred for use with the LM2759. These capacitors have tight capacitance tolerance (as good as 10%) and hold their value over temperature (X7R: 15% over -55C to 125C; X5R: 15% over -55C to 85C). Capacitors with Y5V or Z5U temperature characteristic are generally not recommended for use with the LM2759. Capacitors with these temperature characteristics typically have wide capacitance tolerance (+80%, -20%) and vary significantly over Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 13 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com temperature (Y5V: +22%, -82% over -30C to +85C range; Z5U: +22%, -56% over +10C to +85C range). Under some conditions, a nominal 1 F Y5V or Z5U capacitor could have a capacitance of only 0.1 F. Such detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum capacitance requirements of the LM2759. The voltage rating of the output capacitor should be 6.3V or more. For example, a 6.3V 0603 4.7 F output capacitor (TDK C1608X5R0J475) is acceptable for use with the LM2759, as long as the capacitance on the output does not fall below a minimum of 3F in the intended application. All other capacitors should have a voltage rating at or above the maximum input voltage of the application and should have a minimum capacitance of 1 F. Table 5. Suggested Capacitors and Suppliers MFG Part No. Type MFG Voltage Rating Case Size Inch (mm) 4.7 F for COUT C1608X5R0J475 Ceramic X5R TDK 6.3V 0603 (1608) JMK107BJ475 Ceramic X5R Taiyo-Yuden 6.3V 0603 (1608) C1608X5R0J225 Ceramic X5R TDK 6.3V 0603 (1608) JMK107BJ225 Ceramic X5R Taiyo-Yuden 6.3V 0603 (1608) 2.2 F for C1, C2, CIN POWER EFFICIENCY Efficiency of LED drivers is commonly taken to be the ratio of power consumed by the LED (PLED) to the power drawn at the input of the part (PIN). With a 1x, 1.5x, 2x charge pump, the input current is equal to the charge pump gain times the output current (total LED current). The efficiency of the LM2759 can be predicted as follows: PLED = VLED x ILED PIN = VIN x IIN PIN = VIN x (Gain x ILED + IQ) E = (PLED / PIN) (1) (2) (3) (4) For a simple approximation, the current consumed by internal circuitry (IQ) can be neglected, and the resulting efficiency will become: E = VLED / (VIN x Gain) (5) Neglecting IQ will result in a slightly higher efficiency prediction, but this impact will be negligible due to the value of IQ being very low compared to the typical Torch and Flash current levels (100mA - 1A). It is also worth noting that efficiency as defined here is in part dependent on LED voltage. Variation in LED voltage does not affect power consumed by the circuit and typically does not relate to the brightness of the LED. For an advanced analysis, it is recommended that power consumed by the circuit (VIN x IIN) be evaluated rather than power efficiency. THERMAL PROTECTION Internal thermal protection circuitry disables the LM2759 when the junction temperature exceeds 150C (typ.). This feature protects the device from being damaged by high die temperatures that might otherwise result from excessive power dissipation. The device will recover and operate normally when the junction temperature falls below 120C (typ.). It is important that the board layout provide good thermal conduction to keep the junction temperature within the specified operating ratings. POWER DISSIPATION The power dissipation (PDISSIPATION) and junction temperature (TJ) can be approximated with the equations below. PIN is the power generated by the 1x, 1.5x, 2x charge pump, PLED is the power consumed by the LED, TA is the ambient temperature, and JA is the junction-to-ambient thermal resistance for the 12 pin WSON package. VIN is the input voltage to the LM2759, VLED is the nominal LED forward voltage, and ILED is the programmed LED current. PDISSIPATION = PIN - PLED = (Gain x VIN x ILED) - (VLED x ILED) TJ = TA + (PDISSIPATION x JA) 14 (6) (7) (8) Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 LM2759 www.ti.com SNVS577D - JUNE 2008 - REVISED MAY 2013 The junction temperature rating takes precedence over the ambient temperature rating. The LM2759 may be operated outside the ambient temperature rating, so long as the junction temperature of the device does not exceed the maximum operating rating of 105C. The maximum ambient temperature rating must be derated in applications where high power dissipation and/or poor thermal resistance causes the junction temperature to exceed 105C. MAXIMUM OUTPUT CURRENT The maximum LED current that can be used for a particular application depends on the rated forward voltage of the LED used, the input voltage range of the application, and the Gain mode of the LM2759's charge pump. The following equation can be used to approximate the relationship between the maximum LED current, the LED forward voltage, the minimum input voltage, and the charge pump gain: (VIN_MIN x Gain) > (VF + VHR) + (ILED x ROUT_GAIN) (9) VHR or the voltage required across the current sink to remain in regulation can be approximated by (ILED x KHR), where KHR is 0.8 mV/mA (typ). ROUT_GAIN is the output impedance of the charge pump according to its gain mode. When using the equation above, keep in mind that the (VF + VHR) portion of the equation can not be greater than the nominal output regulation voltage for a particular gain. In other words, when making calculations for an application where the term (VF + VHR) is higher than a particular gain's regulation voltage, the next higher gain level must be used for the calculation. Example: VF = 4V @ 1A, Charge Pump in the Gain of 2x with a ROUT of 2.25 (typ.) VIN_MIN > [(4V + 0.8V) + (1A x 2.25) ] / 2 VIN_MIN > 3.53V (typ.) The maximum power dissipation in the LM2759 must also be taken into account when selecting the conditions for an application, such that the junction temperature of the device never exceeds its rated maximum. The input voltage range, operating temperature range, and/or current level of the application may have to be adjusted to keep the LM2759 within normal operating ratings. BOARD LAYOUT CONSIDERATIONS PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce, and resistive voltage loss in the traces. These can send erroneous signals to the DC-DC converter IC, resulting in poor regulation or instability. Poor layout can also result in re-flow problems leading to poor solder joints between the WSON package and board pads. Poor solder joints can result in erratic or degraded performance. Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 15 LM2759 SNVS577D - JUNE 2008 - REVISED MAY 2013 www.ti.com REVISION HISTORY Changes from Revision C (May 2013) to Revision D * 16 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 15 Submit Documentation Feedback Copyright (c) 2008-2013, Texas Instruments Incorporated Product Folder Links: LM2759 PACKAGE OPTION ADDENDUM www.ti.com 18-Aug-2017 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LM2759SD/NOPB ACTIVE WSON DQB 12 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -30 to 85 L2759 LM2759SDX/NOPB ACTIVE WSON DQB 12 4500 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -30 to 85 L2759 (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device 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 Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. 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 OPTION ADDENDUM www.ti.com 18-Aug-2017 Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 20-Sep-2016 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2759SD/NOPB WSON DQB 12 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1 LM2759SDX/NOPB WSON DQB 12 4500 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 20-Sep-2016 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2759SD/NOPB WSON DQB 12 1000 210.0 185.0 35.0 LM2759SDX/NOPB WSON DQB 12 4500 367.0 367.0 35.0 Pack Materials-Page 2 MECHANICAL DATA DQB0012A SDF12A (Rev B) www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated (TI) reserves the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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