TPS61058 TPS61059 (3,25 mm x 3,25 mm) www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 SYNCHRONOUS BOOST CONVERTER WITH DOWN MODE HIGH POWER WHITE LED DRIVER FEATURES • • • • • • • • • DESCRIPTION 80% Efficient Synchronous Boost Converter – 500-mA LED Current From 3.3-V Input (TPS61058) – 800-mA LED Current From 3.3-V Input (TPS61059) Input Voltage Range: 2.7 V to 5.5 V Fixed Frequency 650 kHz (Typ) Operation LED Disconnect During Shutdown Open/Shorted LED Protection Over-Temperature Protection Low Shutdown Current: 100 nA (Typ) Total Solution Of Less Than 80 mm2 Small 3mm x 3mm QFN-10 Package APPLICATIONS • Torch/Camera White LED Supply for Cell Phones, Smart-Phones and PDAs The TPS61058/9 devices are fixed frequency, synchronous boost dc-dc converters with an integrated down conversion mode. The devices are optimized for driving high power single cell white LEDs up to 800 mA from a 2.7-V to 5.5-V input. The LED current can be programmed to different levels (e.g. torch, flashlight) by a set of external resistors. The boost converter is based on a 650 frequency, pulse-width-modulation (PWM) using a synchronous rectifier to obtain efficiency. The maximum peak current in switch is limited to 1000 mA (TPS61058) mA (TPS61059). kHz fixed controller maximum the boost and 1500 The converter can be disabled to maximize battery life. In the shutdown mode, the load is completely disconnected and the current consumption is reduced to less than 1 µA. Built-in precharge and soft-start circuitry prevents excessive inrush current during start-up. The device is packaged in a 10-pin QFN PowerPAD™ package measuring 3 mm x 3 mm (DRC). VIN 4.7 µH C IN TPS61058 SW VOUT PVIN 22 µF x3 VIN 22 µF D1 R2 FB C3 1 nF (COG) R1 22 kΩ FLASH ON (0/1.8 V) 100 C1, C2, C3 EN GND GND 39 kΩ R3 56 kΩ Rs 1.5 Ω R5 IOK PGND 5.6 kΩ R4 62 kΩ Figure 1. 500 mA Flashlight Application LED Power Efficiency (PLED/PIN) - % L1 2.7 V . . 5.5 V ILED = 500 mA @ VF = 3.7 V 90 80 70 60 50 40 30 20 10 0 2.70 3.10 3.50 3.90 4.30 4.70 VI - Input Voltage - V 5.10 5.50 Figure 2. Flashlight Efficiency vs VIN 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. PowerPAD is a trademark of Texas Instruments. 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 © 2005, Texas Instruments Incorporated TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 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. AVAILABLE OPTIONS TA -40°C to 85°C (1) (2) CURRENT LIMIT PACKAGE MARKING 1000 mA BNF 1500 mA BNG PACKAGE 10-Pin QFN PART NUMBER (1) (2) TPS61058DRC TPS61059DRC The DRC package is available taped and reeled. Add R suffix to device type (e.g. TPS61058DRCR, TPS61059DRCR) to order quantities of 3000 devices per reel. For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (1) TPS61058/9 Input voltage range on PVIN, VIN, EN, FB, IOK, SW, VOUT -0.3 V to 7 V Power dissipation Internally limited Operation temperature range, TA -40°C to 85°C Maximum operating junction temperature, TJ(max) 150°C Storage temperature range, Tstg (1) -65°C to 150°C Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. DISSIPATION RATINGS TABLE 2 PACKAGE THERMAL RESISTANCE ΘJA POWER RATING TA≤ 25°C DERATING FACTOR ABOVE TA = 25°C DRC 48.7 °C/W 2040 mW 21 mW/°C TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 ELECTRICAL CHARACTERISTICS VIN = 3.6 V, ILED = 500 mA, EN = VIN, L = 4.7 µH, CO = 3x 22 µF, TA = –40°C to 85°C, typical values are at TA = 25°C (unless otherwise noted) DC/DC STAGE PARAMETER TEST CONDITIONS TYP MAX UNIT Input voltage range VOUT TPS61058/9 output voltage range VOVP Output overvoltage protection 5.9 6.1 6.3 V VFB TPS61058/9 feedback voltage 490 500 510 mV f Oscillator frequency 550 650 750 kHz ISW Switch current limit (TPS61058) VO = 3.3 V 900 1100 1300 mA Switch current limit (TPS61059) VO = 3.3 V 1200 1500 1800 mA Pre-charge current VO = 2.5 V, TA = -10°C to 85°C SWN switch on resistance VO = 3.3V 260 SWP switch on resistance VO = 3.3 V 290 rDS(on) VO > 2.0 V @ ILED = 50 mA MIN VIN Total accuracy (including line and load regulation) 2.7 5.5 V 2.5 5.5 V 84 mA -3% mΩ mΩ 3% IQ Quiescent current ILED = 0 mA, VO = 5.0 V, Device switching at 650 kHz 5.5 I(SD) Shutdown current EN = GND, TA = 25°C 0.1 mA 1 µA CONTROL STAGE IOK switch on-resistance VO = 5.0 V, IIOK = 100 µA 0.6 IOK output low current IOK output leakage current V(IL) EN low-level input voltage V(IH) EN high-level input voltage I(I) EN input leakage current VIOK = 7 V 0.8 1 kΩ 100 300 µA 0.01 0.1 µA 0.4 V 0.1 µA 1.4 Input tied to GND V 0.01 EN pull-down resistance 400 kΩ Overtemperature protection 140 °C Overtemperature hysteresis 20 °C 3 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 PIN ASSIGNMENTS DRC Package (TOP VIEW) EN VOUT FB IOK GND PGND SW VIN GND PVIN Terminal Functions TERMINAL NAME NO. I/O DESCRIPTION EN 1 I This is the enable pin of the device. Connect this pin to ground forces the device into shutdown mode. Pulling this pin above 1.4V enables the device. This pin has an internal pull-down resistor. VOUT 2 O This is the output of the dc-dc converter. FB 3 I This is the feedback pin of the device. The feedback pin measures the LED current through the sense resistor. The feedback voltage is set internally to 500mV. IOK 4 O This pin indicates that the dc-dc converter is ready for high current operation (open drain output). GND 5, 7 PVIN 6 I This is the input voltage pin of the device. Connect directly to the input bypass capacitor. VIN 8 I This pin needs to be tied to the input voltage pin of the device. SW 9 I This is the switching pin of the converter. PGND 10 PowerPAD™ 4 Control / logic ground. Power ground. Must be soldered to achieve appropriate power dissipation. Should be connected to PGND. TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 FUNCTIONAL BLOCK DIAGRAM (TPS61058/9) SW VIN PVIN VOUT 20 pF EN 10 kW Vmax control Gate Control PGND PGND PGND Regulator ErrorAmplifier FB Vref OVP Vref Control Logic Oscillator Temperature Control EN 400 kW IOK GND GND 5 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 PARAMETER MEASUREMENT INFORMATION L1 2.7 V . . 5.5 V VIN TPS61058/9 SW 4.7 mF CIN VOUT PVIN C1, C2, C3 22 mF VIN x3 D1 R2 FB 22 mF C3 1 nF (COG) Rs R1 22 kW TORCH ON (0/1.8 V) EN R3 R6 GND IOK GND PGND R5 C4 (Optional) R4 FLASH (0 . .2 V) List of Components: L1 = TDK VLF5014AT-4R7 T C1,C2,C3 = TDK C2012X5R0J226MTJ 500 mA Flashlight Application Rs = 1.3 W R2 = 56 kW R3 = 100 kW R4 = 2.4 kW R5 = 6.2 kW R6 = 91 kW 700 mA Flashlight Application Rs = 1.2 W R2 = 47 kW R3 = 51 kW R4 = 3.3 kW R5 = 4.3 kW R6 = 120 kW C4 = 100 nF TYPICAL CHARACTERISTICS Table of Graphs FIGURE (TPS61058) LED Power Efficiency vs. Input Voltage 3 (TPS61059) LED Power Efficiency vs. Input Voltage 4 (TPS61058) LED Power Efficiency vs LED Current 5 (TPS61058) DC Input Current vs. Input Voltage 6 (TPS61058) LED Current vs. Input Voltage 7 Oscillator Frequency 8 (TPS61059) Current Limit vs. Temperature 9 Waveforms Switching Waveforms in Boost Mode (TPS61058) 10 Switching Waveforms in Down-Mode (TPS61058) 11 High Current Flashlight Pulse Waveform (TPS61058) 12 Torch to Flashlight Transistion (TPS61058) 13 Start-Up After Enable (TPS61058) 14 Overvoltage Protection (TPS61058) 15 Duty Cycle Jitter (TPS61058) 16 6 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 TPS61058 LED POWER EFFICIENCY vs INPUT VOLTAGE TPS61059 LED POWER EFFICIENCY vs INPUT VOLTAGE 100 100 LED Power Efficiency (PLED/PIN) − % 90 LEDPowerEfficiency(PLED/PIN)-% ILED = 150 mA @ VF = 3.0 V ILED = 150 mA @ VF = 3.4 V 80 70 60 50 ILED = 500 mA @ VF = 3.7 V 40 30 20 10 0 2.70 90 80 70 60 50 ILED = 700 mA @ VF = 3.4 V 40 30 20 10 3.10 3.50 3.90 4.30 4.70 5.10 5.50 0 2.70 VI - Input Voltage - V 100 3.10 3.50 3.90 4.30 4.70 5.10 5.50 VI − Input Voltage − V Figure 3. Figure 4. TPS61058 EFFICIENCY vs LED CURRENT TPS61058 DC INPUT CURRENT vs INPUT VOLTAGE 1400 VIN = 3.3 V 90 Input DC Current - mA LED Power Efficiency (PLED/PIN) - % 1200 80 VIN = 4.2 V 70 60 VIN = 3.6 V 50 40 30 1000 800 600 400 ILED = 500 mA 20 200 10 0 100 0 150 200 250 300 350 LED Current - mA Figure 5. 400 450 500 2.70 3.10 3.50 3.90 4.30 4.70 VI - Input Voltage - V 5.10 5.50 Figure 6. 7 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 TPS61058 LED CURRENT vs INPUT VOLTAGE OSCILLATOR FREQUENCY 16 600 TA = 25C ILED = 500 mA 14 Percent of Units − % LED Current - mA 500 400 300 200 ILED = 150 mA 12 10 8 6 4 100 2 f − Oscillator Frequency − kHz Figure 7. Figure 8. TPS61059 CURRENT LIMIT vs TEMPERATURE TPS61058 SWITCHING WAVEFORMS IN BOOST MODE Switch Current Limit − mA 1750 VI = 3.6 V, ILED = 500 mA 1650 SW (2 V/div) 1550 IL (200 mA/div) 1450 ILED (200 mA/div) 1350 1250 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 Ambient Temperature − C Figure 9. 8 VOUT (10 mV/div - 3.8 V OFFSET) t - Time - 500 ns/div Figure 10. 672 664 657 650 643 0 636 5.50 629 5.10 622 3.50 3.90 4.30 4.70 VI - Input Voltage - V 615 3.10 606 0 2.70 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 TPS61058 SWITCHING WAVEFORMS IN DOWN MODE TPS61058 HIGH CURRENT FLASHLIGHT PULSE WAVEFORM EN (1 V/div) SW (2 V/div) VOUT(1 V/div) IL(200 mA/div) IL(200 mA/div) ILED (200mA/div) ILED(200 mA/div) VOUT (10 mV/div - 3.8 V OFFSET) VI = 4.5 V, ILED = 500 mA t - Time - 500 ns/div VI = 3.6 V t - Time - 5 ms/div Figure 11. Figure 12. TPS61058 TORCH TO FLASHLIGHT TRANSISTION TPS61058 START-UP AFTER ENABLE VOUT (1 V/div) EN (1 V/div) V OUT (1 V/div) IL (500 mA/div) I LED (50 mA/div) I L (100 mA/div) ILED (200 mA/div) t - Time - 50 ms/div Figure 13. t - Time - 200 ms/div Figure 14. 9 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 TPS61058 OVERVOLTAGE PROTECTION TPS61058 DUTY CYCLE JITTER VOUT (200 mV/div - 5 V OFFSET) SW (2 V/div) VI = 3.6 V Triggered On Falling Edge t - Time - 50 ms/div Figure 15. 10 ILED= 500 mA t - Time - 50 ns/div Figure 16. TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 DETAILED DESCRIPTION OPERATION The TPS61058/9 familly is based on a fixed frequency multiple feedforward controller topology. Input voltage, output voltage, and voltage drop on the NMOS switch are monitored and forwarded to the regulator. So changes in the operating conditions of the converter directly affect the duty cycle and must not take the indirect and slow way through the control loop and the error amplifier. The control loop, determined by the error amplifier, only has to handle small signal errors. The input for it is the feedback voltage on the FB pin. It is compared with the internal reference voltage to generate an accurate and stable LED current. The peak current of the NMOS switch is also sensed to limit the maximum current flowing through the switch and the inductor. The typical peak current limit is set to 1000mA (TPS61058) and 1500 mA (TPS61059). An internal temperature sensor prevents the device from getting overheated in case of excessive power dissipation. Synchronous Rectifier The device integrates an N-channel and a P-channel MOSFET transistor to realize a synchronous rectifier. Because the commonly used discrete Schottky rectifier is replaced with a low RDS(ON) PMOS switch, the power conversion stage itself can reach 96% efficiency. In order to avoid ground shift due to the high currents in the NMOS switch, two separate ground pins are used. The reference for all control functions is the GND pin. The source of the NMOS switch is connected to PGND. Both grounds must be connected on the PCB at only one point close to the GND pin. A special circuit is applied to disconnect the load from the input during shutdown of the converter. In conventional synchronous rectifier circuits, the backgate diode of the high-side PMOS is forward biased in shutdown and allows current flow from the battery to the output. This device however uses a special circuit which takes the cathode of the backgate diode of the high-side PMOS and disconnects it from the source when the regulator is not enabled (EN = Low). The benefit of this feature for the system design engineer is that the battery is not depleted during shutdown of the converter. No additional components have to be added to the design to make sure that the battery is disconnected from the output of the converter. Down Regulation In general, a boost converter only regulates output voltages which are higher than the input voltage. This device operates differently and is capable of driving high power single die white LEDs from a fully charged Li-Ion cell. To control this applications properly, a down conversion mode is implemented. If the input voltage reaches or exceeds the output voltage necessary to maintain the LED current within regulation, the converter changes to a down conversion mode. In this mode, the control circuit changes the behavior of the rectifying PMOS transitor. It sets the voltage drop across the PMOS as high as needed to regulate the output voltage. This means the power losses in the converter increase. This has to be taken into account for thermal consideration especially when operating with low VF LEDs, high battery voltages and high LED currents. Enable The device is put into operation when EN is set high. It is put into a shutdown mode when EN is set to GND. The EN input pin has an internal 400-kΩ pull-down resistor to disable the device when this pin is floating. In shutdown mode, the regulator stops switching, the internal control circuitry is switched off, and the load is isolated from the input (as described in the Synchronous Rectifier Section). This also means that the output voltage can drop below the input voltage during shutdown. 11 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 DETAILED DESCRIPTION (continued) Softstart To avoid high inrush current during start-up, special care is taken to control the inrush current. When the device is first enabled, the output capacitor is charged with a constant pre-charge current of 115mA (typ) until either the output voltage is typically 0.1V below the input voltage or the feedback voltage is 500mV (typ). The rectifying switch is current limited during the pre-charge phase. This also limits the output current under short circuit conditions at the output. The fixed pre-charge current during start-up allows the device to start up without problems when driving single die white LEDs as long as the LED start-up current is set to a value lower than the pre-charge current (84 mA min.). Refer to the application section for more details. When the device has finished start-up and is ready for high current operation, the device forces IOK output to ground, starts switching and regulates the LED current to the desired value (e.g. torch or flashlight current level). Overvoltage Protection (OVP) As with any current source, the output voltage rises when the load becomes high impedance or gets disconnected. To prevent the output voltage exceeding the maximum switch voltage rating (7 V) of the main switch, an overvoltage protection circuit is integrated. As soon as the output voltage exceeds the OVP threshold, the converter stops switching and the output voltage decreases. When the output voltage falls below the OVP threshold, the converter continues operation until the output voltage exceeds the OVP threshold again. Efficiency and Sense Voltage The voltage across the sense resistor (RS) has a direct effect of the converter efficiency. Because the sense voltage does not contribute to the output power (PLED), the lower this voltage the higher the efficiency. It is therefore recommended to operate with a sense voltage of approximately 0.75V at maximum LED current. Thermal Shutdown An internal thermal shutdown is implemented and turns off the internal MOSFETs when the typical junction temperature of 140°C is exceeded. The thermal shutdown has a hysteresis of typically 20°C. Refer to the Thermal Information section. 12 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 APPLICATION INFORMATION DESIGN PROCEDURE The standard application circuit (Figure 17) of the TPS61058/9 is a complete solution to drive high-power white LEDs with two discrete current steps. VIN TPS61058/9 4.7 µH CIN SW PVIN VIN VOUT MOVIE-LIGHT C1, C2, C3 22 µF x3 22 µF D1 R2 FB 1 nF (COG) R3 R1 22 kΩ MOVIE-LIGHT EN IOK nFLASH C4 R6 C5 R5 V SENSE L1 2.7 V . . 5.5 V Rs IOK Hi-Z Hi-Z Movie-Light Vx Flashlight 100nF R4 GND GND PGND ILED Pre-Charge nFLASH Figure 18. Waveform Profiles Figure 17. Typical Application The LED current is programmed using external resistors (RS, R2, R3, R4, R5, and R6). The first step to turn on the LED is to enable the device (EN = High). After charging the output capacitor, the device forces IOK to ground, starts switching, and regulates the LED current to the desired value. The control signal, nFLASH, injects current into the feedback network through R4, thereby, changing the LED current. For this reason, the nFLASH control signal needs at least to be biased up until IOK goes low. In case this is not done properly the converter stays stuck in the pre-chage phase. To faciliate the sizing of the external resistor network, it is recommended to use the calculation sheet available in the device product folder. 1. Sense resistor, RS The voltage across the sense resistor should be set to approximately 0.75 V at maximum LED current. V R SENSE S I LED (1) Check the power rating of the sense resistor (PD = RS× ILED 2). 2. LED current setting Figure 19 shows an equivalent circuit for the feedback network. The regulation loop is using an external control voltage (nFLASH) to set the LED current. With the help of this voltage the feedback bias current (IBIAS) can be adjusted which, in effect, controls the LED current without changing any externals. In most applications a variable control voltage is not available to set the LED current. In practical applications, nFLASH can either be: A constant bias voltage (2.8 V for example) which in combination with IOK can be used to switch between two LED currents (Off, Flashlight). A logic signal generated by the imaging processor. This configuration permits three different LED currents: Off, Movie-light (nFLASH = High), Flashlight (nFLASH = Low). 13 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 The circuit operation can be split into different phases: 1. Pre-Charge Phase (IOK = Hi-Z) During this phase IOK is kept high-impedance. For proper startup the external loop components need to be chosen so that the regulation loop can settle for a maximum LED current of less than 84 mA. This can be achieved by increasing the bias voltage (VX) of the feedback network. 0.5 R2 I I LED BIAS R S R5 I nFLASH 0.5 , assuming R4R5 is small compared R3. BIAS R3 (R4 R5) R3 (2) (3) 2. High-Current Operation (IOK = GND) After the pre-charge phase, IOK is automatically pulled to ground. This modifies the feedback divider network changing the potential of the VX node. As a consequence the LED current is adjusted accordingly. 0.5 R2 I BIAS2 1 R2 R2 Vx 2R 2 R3 R R3 R S S S S R5 I nFLASH 0.5 , with R5 R5 R6 BIAS2 R3 (R4 R5) R3 R5 R6 I LED R For operation at maximum LED current (flashlight mode), nFLASH needs to be set to ground level. I R2 R3 , assumingR4R5R6 is small compared R3. LED(FLASH) 2 R3 R S (4) (5) (6) For operation at other LED currents (movie-light or pre-charge), nFLASH applies a positive bias voltage (1.8 V for example) to the feedback divider network. The following equations show the relationship between LED current and bias voltage Vx. R3 R S Vx 1 R3 I LED(MOVIELIGHT,PRECHARGE) 2 2 R2 R2 (7) Vx R5 nFLASH, with R5 R5 R6 R4 R5 R5 R6 (8) For stable operation, it is recommended that R3 be set in the range of 50 kΩ to 150 kΩ and R5 in the range of 3.3 kΩ to 10 kΩ. Best performance is obtained with a pre-charge current of 45 mA typ. For single current level applications (e.g. torch or flashlight only) it is recommended to operate with R4 in the range of 50kΩ to 200 kΩ. In that case R5 is not need anymore. 14 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 The following example is used to explain the procedure to size the external components for a given set of requirements: • Movie-light mode: ILED = 150 mA • Flashlight mode: ILED = 500 mA • LED forward voltage: VF (MAX) = 4.4 V at 500 mA • nFLASH signal is 1.8 V logic compliant (0 V and 1.8 V ±4%) Step 1 – Current Sense Resistor Calculation – RS V R SENSE 0.75 1.5 V 4.4 0.75 5.15 V S OUT(MAX) 0.5 I LED (9) Step 2 – Feedback Divider Resistor Calculation – R2, R3 I LED(FLASH) R2 R3 2 R3 R R3 100 k (recommended value) R2 47 k (calculated) S (10) Step 3 – Bias Resistor Network Calculation – R4, R5, R6 Vx 1 R3 I LED 2 2 R2 R3 R S R2 V 1.1 V @ I 150 mA (movie−light) X LED V 1.4 V @ I 45 mA (pre−load) X LED During the pre-charge phase, IOK is high impedance. R5 0.78 R4 R5 R5 Vx nFLASH R4 R5 R5 10 k (recommended value) R4 2.7 k (calculated) (11) (12) In movie-light mode, IOK is grounded. Vx R5 0.61, R5 1.57 R4, R5 R5 R6 R4 R5 R5 R6 R5 nFLASH R4 R5 R6 7.5 k (calculated) (13) I LED FB = 500 mV R2 R3 IOK VSENSE RS I BIAS R6 VX M1 R5 R4 nFLASH Figure 19. Feedback Network Equivalent Circuit 15 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 INDUCTOR SELECTION A boost converter normally requires two main passive components for storing energy during the conversion. A boost inductor and a storage capacitor at the output are required. To select the boost inductor, it is recommended to keep the possible peak inductor current below the current limit threshold of the power switch in the chosen configuration. For example, the current limit threshold of the TPS61059 switch is 1700 mA at an output voltage of 5 V. The highest peak current through the inductor and the switch depends on the output load, the input voltage and the output voltage. Estimation of the maximum average inductor current can be done using Equation 14: V OUT I I L OUT V 0.8 IN (14) V V R I OUT F(LED) S LED (15) For example, for an output current of 500 mA at 4.5 V, at least 800 mA of average current flows through the inductor at a minimum input voltage of 3.3 V. The second parameter for choosing the inductor is the desired current ripple in the inductor. In order to optimized the solution size, inductor ripple currents as high as 40% of the average inductor current can be tolerated. A smaller ripple reduces the magnetic hysteresis losses in the inductor, as well as output voltage ripple and EMI. With those parameters, it is possible to calculate the value for the inductor by using Equation 16: V V V IN OUT IN L I ƒ V L OUT (16) Parameter f is the switching frequency and∆ IL is the ripple current in the inductor, i.e., 40% × IL. In this example, the desired inductor has the value of 4.5 µH. With this calculated value and the calculated currents, it is possible to choose a suitable inductor. In typical high current white LED applications a 4.7 µH inductance is recommended. Care has to be taken that load transients and losses in the circuit can lead to higher currents as estimated in Equation 16. Also, the losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for total circuit efficiency. The following inductor series from different suppliers have been used with the TPS61058/9 converters: Table 1. List of Inductors MANUFACTURER COILCRAFT TDK TAIYO YUDEN 16 SERIES LPS3015 DIMENSIONS REMARKS 3 mm x 3 mm x 1.5 mm max. height TPS61058 VLF3014AT 2.6 mm x 2.8 mm x 1.4 mm max. height TPS61058 VLF5014AT 4.5 mm x 4.7 mm x 1.4 mm max. height TPS61059 5 mm x 5 mm x 2.0 mm max. height TPS61059 NP04SZB TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 CAPACITOR SELECTION Input Capacitor For good input voltage filtering low ESR ceramic capacitors are recommended. At least a 10-µF input capacitor is recommended to improve transient behavior of the regulator and EMI behavior of the total power supply circuit. The input capacitor should be placed as close as possible to the input pin of the converter. Output Capacitor The major parameter necessary to define the output capacitor is the maximum allowed output voltage ripple of the converter. This ripple is determined by two parameters of the capacitor, the capacitance and the ESR. It is possible to calculate the minimum capacitance needed for the defined ripple, supposing that the ESR is zero, by using Equation 17: I C min V V OUT OUT IN ƒ V V OUT (17) Parameter f is the switching frequency and ∆V is the maximum allowed ripple. With a chosen ripple voltage of 10 mV, a minimum capacitance of 22 µF is needed. The total ripple is larger due to the ESR of the output capacitor. This additional component of the ripple can be calculated using Equation 18: V I R ESR OUT ESR (18) The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the capacitor. Additional ripple is caused by load transients. This means that the output capacitor has to completely supply the load during the charging phase of the inductor. A reasonable value of the output capacitance depends on the speed of the load transients and the load current during the load change. For the high current white LED application, a minimum of 20 µF effective output capacitance is usually required when operating with 4.7 µH (typ) inductors. For solution size reasons, this is usually one or more X5R/X7R ceramic capacitors. In order to maintain the control loop stable, the addition of a compensation network formed by R1 (22 kΩ) and C3 (1 nF COG) is necessary. CHECKING LOOP STABILITY The first step of circuit and stability evaluation is to look from a steady-state perspective at the following signals: • Switching node, SW • Inductor current, IL • Output ripple voltage, VOUT(AC) These are the basic signals that need to be measured when evaluating a switching converter. When the switching waveform shows large duty cycle jitter or the output voltage or inductor current shows oscillations, the regulation loop may be unstable. This is often a result of board layout and/or L-C combination. As a next step in the evaluation of the regulation loop, the load transient response is tested. VOUT can be monitored for settling time, overshoot or ringing that helps judge the converter's stability. Without any ringing, the loop has usually more than 45° of phase margin. Because the damping factor of the circuitry is directly related to several resistive parameters (e.g., MOSFET rDS(on)) that are temperature dependant, the loop stability analysis has to be done over the input voltage range, LED current range, and temperature range. 17 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 LAYOUT CONSIDERATIONS As for all switching power supplies, the layout is an important step in the design, especially at high peak currents and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground tracks. The input capacitor, output capacitor, and the inductor should be placed as close as possible to the IC. Use a common ground node for power ground and a different one for control ground to minimize the effects of ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC. The compensation network as well as the current setting resistors should be placed as close as possible to the control ground pin of the IC. To lay out the control ground, it is recommended to use short traces as well, separated from the power ground traces. This avoids ground shift problems, which can occur due to superimposition of power ground current and control ground current. Figure 20. Suggested Layout – Top Side Figure 21. Suggested Layout – Bottom Side 18 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 APPLICATION EXAMPLES TPS61058 L1 SW VOUT 4.7 H C1, C2, C3 22 F x3 PVIN 2.7 V . . 5.5 V CIN VIN VIN D1 R2 39 k FB 22 F C3 1 nF (COG) Rs 1.5 R3 56 k R1 22 k FLASH ON (0/1.8 V) R6 EN IOK GND 5.6 k GND PGND R4 68 k List of Components: L1 = COILCRAFT LPS3015−4R7 C1,C2, C3 = TDK C2012X5R0J226MTJ Figure 22. 500 mA Flashlight Application - 1.8 V Logic TPS61059 L1 2.7 V . . 5.5 V 4.7 H CIN V IN SW PVIN VOUT C1, C2, C3 22 F x3 VIN 22 F D1 R2 FB C4 1nF (COG) 33 k R3 75 k R1 22 k Rs 1.2 EN MOVIE−LIGHT (0/2.8V) R6 IOK 10 k GND GND R5 4.7 k PGND C5 100 nF R4 3.9 k nFLASH (0/2.8V) List of Components: L1 = TDK VLF5014AT−4R7 C1,C2, C3 = TDK C2012X5R0J226MTJ MOVIE− LIGHT 0 0 1 1 nFLASH 0 1 0 1 Note: Before turning into the flashlight mode, the device to be driven into movie−light mode. See the Design Procedure section for more details. ILED OFF OFF FLASHLIGHT MOVIE − LIGHT Figure 23. 150 mA Movie-Light/600 mA Flashlight Application - 2.8 V Logic 19 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 TPS61058 L1 2.7 V . . 5.5 V V IN 4.7 H CIN SW PVIN VIN VOUT C1, C2, C3 22 F x3 22 F D1 R2 FB C4 1nF (COG) 39 k Rs 1.5 R3 51 k R1 22 k EN FLASH ON (0/2.8V) R6 IOK 10 k GND GND R4 150 k PGND List of Components: L1 = COILCRAFT LPS3015−4R7 C1,C2, C3 = TDK C2012X5R0J226MTJ Figure 24. 500 mA Flashlight Application - 2.8 V Logic TPS61059 L1 2.7 V . . 5.5 V VIN 4.7 H C IN SW PVIN VIN VOUT C1, C2, C3 22 F x3 22 F D1 R2 FB C4 1nF (COG) R3 100 k R1 22 k MOVIE−LIGHT (0/1.8 V) EN IOK TX−TOFF (0/1.8 V) n FLASH (0/1.8 V) Rs 1.2 R6 12 k C5 R5 6.8 k GND GND 68 k 100nF R4 3.6 k PGND 1V8 LVC1G32 List of Components: L1 = TDK VLF5014AT−4R7 C1,C2, C3 = TDK C2012X5R0J226MTJ Figure 25. 150 mA Movie-Light/700 mA Flashlight with No-Latency Current Reduction 20 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 TPS61059 L1 2.7 V . . 5.5 V V IN 4.7 H CIN SW PVIN VIN VOUT C1, C2, C3 22 F x3 22 F D1 R3 R4 FB C3 1nF (COG) R1 22 k D2 75 k 75 k V1 R1 2.0 R5 75 k V2 R2 2.0 EN FLASH ON (0/2.8V) R7 IOK 5.1 k GND GND C5 100 nF PGND R6 110 k List of Components: L1 = TDK VLF5014AT−4R7 C1,C2, C3 = TDK C2012X5R0J226MTJ Figure 26. 2x 350 mA Flashlight Application - 2.8 V Logic 21 TPS61058 TPS61059 www.ti.com SLVS572B – APRIL 2005 – REVISED DECEMBER 2005 THERMAL INFORMATION Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits of a given component. Three basic approaches for enhancing thermal performance are listed below. • Improving the power dissipation capability of the PCB design • Improving the thermal coupling of the component to the PCB • Introducing airflow in the system The maximum recommended junction temperature (TJ) of the TPS61058/9 devices is 125°C. The thermal resistance of the 10-pin QFN 3 x 3 package (DRC) is RθJA = 48.7 °C/W, if the PowerPAD is soldered. Specified regulator operation is assured to a maximum ambient temperature TA of 85°C. Therefore, the maximum power dissipation is about 820 mW. More power can be dissipated if the maximum ambient temperature of the application is lower. T T J(MAX) A P 125°C 85°C 820 mW D(MAX) R 48.7 °CW JA (19) 22 PACKAGE OPTION ADDENDUM www.ti.com 5-Feb-2007 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty TPS61058DRCR ACTIVE SON DRC 10 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS61058DRCRG4 ACTIVE SON DRC 10 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS61059DRCR ACTIVE SON DRC 10 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS61059DRCRG4 ACTIVE SON DRC 10 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS61059DRCT ACTIVE SON DRC 10 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS61059DRCTG4 ACTIVE SON DRC 10 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Lead/Ball Finish MSL Peak Temp (3) (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. 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. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 17-May-2007 TAPE AND REEL INFORMATION Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com Device 17-May-2007 Package Pins Site Reel Diameter (mm) Reel Width (mm) A0 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TPS61058DRCR DRC 10 MLA 330 12 3.3 3.3 1.1 8 12 PKGORN T2TR-MS P TPS61059DRCR DRC 10 MLA 330 12 3.3 3.3 1.1 8 12 PKGORN T2TR-MS P TPS61059DRCT DRC 10 MLA 180 12 3.3 3.3 1.1 8 12 PKGORN T2TR-MS P TAPE AND REEL BOX INFORMATION Device Package Pins Site Length (mm) Width (mm) Height (mm) TPS61058DRCR DRC 10 MLA 346.0 346.0 29.0 TPS61059DRCR DRC 10 MLA 346.0 346.0 29.0 TPS61059DRCT DRC 10 MLA 190.0 212.7 31.75 Pack Materials-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 17-May-2007 Pack Materials-Page 3 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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