CSP-12 QFN-10 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 HIGH POWER WHITE LED DRIVER 2-MHz SYNCHRONOUS BOOST CONVERTER WITH STANDARD LOGIC INTERFACE FEATURES 1 APPLICATIONS • • • Camera White LED Torch/Flash for Cell Phones, Smart-Phones and PDAs General Lighting Applications Audio Amplifier Power Supply DESCRIPTION The TPS6105x device uses a high-frequency synchronous-boost topology with constant current sink to drive single white LEDs. The device uses an inductive fixed-frequency PWM control scheme using small external components, minimizing input ripple current. The 2-MHz switching frequency allows the use of small and low-profile 2.2-μH inductors. To optimize overall efficiency, the device operates with only a 250-mV LED feedback voltage. The TPS6105x device not only operates as a regulated current source, but also as a standard voltage-boost regulator. This additional operating mode can be useful to supply other high-power devices in the system, such as a hands-free audio power amplifier, or any other component requiring a supply voltage higher than the battery voltage. The LED current or the desired output voltage can be programmed via two logic signals (MODE0/1). To simplify flash synchronization with the camera module, the device offers a trigger pin (FLASH_SYNC) for fast LED turn-on time. When the TPS6105x is not in use, it can be put into shutdown mode, reducing the input current to 0.3 μA (typ). During shutdown, the LED pin is high impedance to avoid leakage current through the LED. TPS61054 VOUT CIN P LED MODE1 MODE0 L1 LED SENSE 4.7 mm P INDUCTOR C1 COUT 10 mF P AVIN AGND SW SW INPUT CAP 2.2 mH 4.7 mm + BATTERY PGND DIGITAL I/O L Tx-TOFF AGND PGND PGND P PGND OUTPUT CAP FLASH_SYNC C2 LED ANODE Figure 1. Typical Application Figure 2. Typical PC-Board Layout 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. NanoFree, PowerPAD are trademarks of Texas Instruments. PRODUCT PREVIEW information concerns products in the formative or design phase of development. Characteristic data and other specifications are design goals. Texas Instruments reserves the right to change or discontinue these products without notice. Copyright © 2007, Texas Instruments Incorporated PRODUCT PREVIEW • Four Operational Modes – Torch and Flash up to ILED = 700 mA – Voltage-Regulated Boost Converter: 5.0 V – Shutdown: 0.3 μA (typ) • Total Solution Circuit Area < 25 mm2 • Up to 96% Efficiency • Integrated LED Turn-On Safety Timer • Zero Latency TX-Masking Input • Integrated Low Light Dimming Mode • LED Disconnect During Shutdown • Open/Shorted LED Protection • Over-Temperature Protection • Available in a 12-Pin NanoFree™ (CSP) and 10-Pin QFN Packaging 2 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 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 PART NUMBER (1) (2) TORCH CURRENT (3) FLASH CURRENT (3) SAFETY TIMER MAXIMUM DURATION CURRENT LIMIT PACKAGE MARKING PACKAGE TPS61054YZG 75 mA 700 mA 820 ms 1500 mA (ILIM = 01) 61054 CSP-12 TPS61054DRC 75 mA 700 mA 820 ms 1500 mA (ILIM = 01) TPS61055YZG 75 mA 500 mA 820 ms 1000 mA (ILIM = 00) TPS61055DRC 75 mA 500 mA 820 ms 1000 mA (ILIM = 00) (1) (2) QFN-10 61055 CSP-12 QFN-10 All devices are specified for operation in the commercial temperature range, –40°C to 85°C. The YZG package is available in tape and reel. Add R suffix (TPS6105xYZGR, TPS6105xDRCR) to order quantities of 3000 parts. Add T suffix (TPS6105xYZGT, TPS6105xDRCT) to order quantities of 250 parts. For customized current settings, please contact the factory. (3) ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (1) PRODUCT PREVIEW Voltage range on AVIN, VOUT, SW, LED (2) Voltage range on MODE0, MODE1, FLASH_SYNC, Tx-TOFF TA TJ Operating ambient temperature range (2) (3) Maximum operating junction temperature (MAX) Tstg Storage temperature range Human body model ESD rating (4) Charge device model Machine model (1) (2) (3) (4) TPS6105X UNIT –0.3 to 7 V –0.3 to 7 V –40 to 85 °C 150 °C –65 to 150 °C 2 kV 1 kV 200 V 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. All voltage values are with respect to network ground terminal. 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 operating junction temperature (TJ(max)), 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 (θJA), as given by the following equation: TA(max)= TJ(max)–(θJA X PD(max)). The human body model is a 100-pF capacitor discharged through a 1.5-kΩ resistor into each pin. The machine model is a 200-pF capacitor discharged directly into each pin. DISSIPATION RATINGS PACKAGE (1) (2) 2 THERMAL RESISTANCE (1) (2) POWER RATING TA = 25°C DERATING FACTOR ABOVE (1) (2) TA = 25°C YZG θJA= 89°C/W θJB= 35°C/W 1.1 W 12 mW/°C DRC θJA= 49°C/W θJC= 3.2°C/W 2.4 W 20 mW/°C Measured with high-K board. Maximum power dissipation is a function of TJ(max), θJA and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max)–TA)/ θJA. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 ELECTRICAL CHARACTERISTICS Unless otherwise noted the specification applies for VIN = 3.6 V over an operating junction temp. of –40°C ≤ TJ ≤ 125°C. Typical values are for TA = 25°C. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT SUPPLY CURRENT Input voltage range VIN 2.5 6.0 V 2.5 V Minimum input voltage for start-up MODE0 = 1, MODE1 = 1, RL = 10 Ω IQ Operating quiescent current into AVIN MODE0 = 1, MODE1 = 1 8.5 ISD Shutdown current into AVIN MODE0 = 0, MODE1 = 0, –40°C ≤ TJ ≤ 85°C 0.3 3.0 μA VUVLO Undervoltage lockout threshold VIN falling 2.3 2.4 V mA OUTPUT Current regulator mode Output voltage range OVP Output overvoltage protection OVP VIN Voltage regulator mode VOUT rising 5.7 Output overvoltage protection hysterisis D 6.0 6.25 0.15 Minimum duty cycle V V V 7.5% LED current accuracy (1) 0.25 V ≤ VLED ≤ 2.0 V, ILED = ITORCH, TJ = 50°C –15% 0.25 V ≤ VLED ≤ 2.0 V, ILED = IFLASH, TJ = 50°C –12% LED current temperature coefficient VLED 5.5 5.0 15% 12% 0.08 DC output voltage accuracy 2.5 V ≤ VIN ≤ 0.9 VOUT, PWM operation LED sense voltage Boost Mode 250 LED input leakage current VLED = VOUT = 5 V, –40°C ≤ TJ ≤ 85°C 0.1 –3% %/°C PRODUCT PREVIEW VOUT 3% mV 1 μA POWER SWITCH rDS(on) Ilkg(SW) Ilim Switch MOSFET on-resistance 80 VOUT = VGS = 3.6 V Rectifier MOSFET on-resistance Switch MOSFET leakage VDS = 6.0 V, –40°C ≤ TJ ≤ 85°C Rectifier MOSFET leakage 2.5 V ≤ VIN ≤ 6.0 V, ILIM = 00 Switch current limit mΩ 80 2.5 V ≤ VIN ≤ 6.0 V, ILIM = 01 (1) Thermal shutdown (1) 0.1 1 0.1 1 μA 850 1000 1150 1275 1500 1725 140 160 °C 20 °C Thermal shutdown hysteresis (1) mA OSCILLATOR fSW Oscillator frequency 1.8 2.0 2.2 MHz MODE0, MODE1, Tx-TOFF, FLASH_SYNC V(IH) High-level input voltage V(IL) Low-level input voltage 1.2 V I(LKG) Logic input leakage current Input connected to VIN or GND, –40°C ≤ TJ ≤ 85°C 0.01 Tx-TOFF pull-down resistance Tx-TOFF ≤ 0.4 V 400 kΩ FLASH_SYNC pull-down resistance FLASH_SYNC ≤ 0.4 V 400 kΩ From shutdown into flash mode ILED = 700 mA 1.2 ms From shutdown into voltage mode MODE0 = 1, MODE1 = 1, IOUT = 0 mA 650 μs MODE0 = 0, MODE1 = 1, ILED = from 75mA to 700 mA 160 μs 20 μs 0.4 V 0.1 μA TIMING Start-up time (2) LED current settling time triggered by rising edge on FLASH_SYNC LED current settling time rising edge on Tx-TOFF (1) (2) (2) triggered by MODE0 = 0, MODE1 = 1, ILED = 700 mA to 75 mA Assured by design. Not tested in production. Settling time to ±15% of the target value Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 3 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 DEVICE INFORMATION PIN ASSIGMENTS TERMINAL FUNCTIONS TERMINAL I/O DESCRIPTION NO. (QFN) NO. (CSP) AVIN 5 D3 I This is the input voltage pin of the device. Connect directly to the input bypass capacitor. VOUT 9 A2 O Boost converter output. LED 6 D2 I LED return input. This feedback pin regulates the LED current through the internal sense resistor by regulating the voltage across it. The regulation operates with typically 250 mV dropout voltage. Connect to the cathode of the LED. FLASH_SYNC 10 A1 I Flash strobe pulse synchronization input. NAME PRODUCT PREVIEW FLASH_SYNC = LOW (GND): The device is operating and regulating the LED current to the torch current level (TC). FLASH_SYNC = HIGH (VIN): The device is operating and regulating the LED current to the flash current level (FC). MODE0 MODE1 2 1 B3 A3 I I Mode selection inputs. These pins must not be left floating and must be terminated. MODE0 = 0, MODE1 = 0: Device in shutdown mode MODE0 = 1, MODE1 = 0: Device in torch only mode MODE0 = 0, MODE1 = 1: Device in torch and flash mode MODE0 = 1, MODE1 = 1: Device in constant voltage regulation mode Tx-TOFF 3 C3 I RF PA synchronization input. Tx-TOFF = LOW : The device is operating normally. Tx-TOFF = HIGH : The device is forced into torch mode. SW 8 B1, B2 PGND 7 C1, C2 AGND 4 PowerPAD™ 4 I/O Inductor connection. Drain of the internal power MOSFET. Connect to the switched side of the inductor. SW is high impedance during shutdown. Power ground. Connect to AGND underneath IC. D1 Analog ground. N/A Internally connected to PGND. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 FUNCTIONAL BLOCK DIAGRAM AVIN SW Undervoltage Lockout Bias Supply VREF = 1.22 V Ramp Compensation Bandgap REF OVP COMPARATOR VOUT S ERROR AMPLIFIER Control Logic P COMPARATOR CURRENT REGULATION VOLTAGE REGULATION 2 MHz Oscillator SENSE FB MODE0 MODE1 FLASH_SYNC LED ON/OFF Max tON Timer Control Logic PRODUCT PREVIEW VREF DAC CURRENT CONTROL P LED Current Regulator Tx-TOFF P AGND PGND Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 5 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 TIMER BLOCK DIAGRAM LED CURRENT CONTROL Tx-TOFF ILED 0 0 Torch Current 0 1 Torch Current 1 0 Flash Current 1 1 Torch Current Tx-TOFF MODE0 400 kW MODE1 FLASH_SYNC 400 kW Edge Detect LED CURRENT CONTROL 0: TORCH CURRENT LEVEL 1: FLASH CURRENT LEVEL PRODUCT PREVIEW Start tSTIM 30.5 Hz 2 MHz CLOCK 16-bit Prescaler Safety Timer LED ON/OFF CONTROL 122 Hz Duty-Cycle Generator (6.3%) 0: LED OFF 1: TORCH CURRENT LEVEL PARAMETER MEASUREMENT INFORMATION TPS6105x L 2.2µH VIN SW SW VOUT C OUT 10 µF P AVIN CIN P P LED MODE1 MODE0 Tx-TOFF FLASH_SYNC AGND PGND PGND P List Of Components: - L = Wuerth Elektronik WE-PD S Series - CIN = COUT = TDK C1605X5R0J106MT 6 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 TYPICAL CHARACTERISTICS Table 1. Table of Graphs vs. Input Voltage Figure 3, Figure 4 DC Input Current vs. Input Voltage Figure 5 LED Current vs. LED Pin Headroom Voltage Figure 6 Voltage Mode Efficiency vs. Output Current Figure 7 DC Output Voltage vs. Load Current Figure 8 DC Output Voltage vs. Input Voltage Figure 9 Quiescent Current vs. Input Voltage Figure 10 Shutdown Current vs. Input Voltage Figure 11 Junction Temperature vs. GPIO Voltage Figure 12 PWM Operation Figure 13 Down-Mode Operation Figure 14 Voltage Mode Load Transient Response Figure 15 Down-Mode Line Transient Response Figure 16 Duty Cycle Jitter Figure 17 Input Ripple Voltage Figure 18 Low-Light Dimming Mode Operation Figure 19 Torch/Flash Sequence Figure 20 TX-Masking Operation Figure 21, Figure 22, Figure 23 Start-up Into Flash Operation Figure 24 LED POWER EFFICIENCY vs INPUT VOLTAGE 100 100 90 90 80 ILED = 75mA 70 60 50 40 30 20 ILIM = 1500 mA 10 0 2.5 2.9 3.3 3.7 4.1 4.5 VI - Input Voltage - V 4.9 LED Power Efficiency (PLED/PIN) - % LED Power Efficiency (PLED/PIN) - % LED POWER EFFICIENCY vs INPUT VOLTAGE PRODUCT PREVIEW FIGURE LED Power Efficiency 80 70 ILED = 500 mA 60 ILED = 700 mA 50 40 30 20 ILIM =1500 mA 10 5.3 5.5 0 2.5 2.9 Figure 3. 3.3 3.7 4.1 4.5 VI - Input Voltage - V 4.9 5.3 5.5 Figure 4. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 7 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 DC INPUT CURRENT vs INPUT VOLTAGE 2500 LED CURRENT vs LED PIN HEADROOM VOLTAGE 1400 ILIM = 1500 mA ILIM = 1500 mA 2250 1200 1000 1750 ILED = 700 mA LED Current - mA DC Input Current - mA 2000 1500 1250 1000 750 800 ILED = 700 mA 600 ILED = 500 mA 400 500 250 PRODUCT PREVIEW 0 2.5 200 ILED = 500 mA 2.9 3.3 3.7 4.1 4.5 VI - Input Voltage - V 4.9 0 250 5.3 5.5 350 450 650 750 850 950 1050 LED Pin Headroom Voltage - mV Figure 6. VOLTAGE MODE EFFICIENCY vs LOAD CURRENT DC OUTPUT VOLTAGE vs OUTPUT CURRENT 5.15 VIN = 4.2 V 90 VOUT = 5 V, ILIM = 1500 mA 5.10 80 VIN = 3.6 V DC Output Voltage - V VIN = 3 V 70 VIN = 2.5 V 60 50 40 30 5.05 VIN = 4.2 V 5 VIN = 3.6 V 4.95 VIN = 3 V VIN = 2.5 V 20 4.90 VOUT = 5 V, ILIM = 1500 mA 10 0 0 1 10 100 1000 IO - Output Current - mA 10000 4.85 0.1 1 Figure 7. 8 550 Figure 5. 100 Efficiency - % ILED = 75 mA 10 100 1000 IO - Output Current - mA 10000 Figure 8. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 DC OUTPUT VOLTAGE vs INPUT VOLTAGE 5.60 12 IOUT = 100 mA 5.40 Voltage Mode Regulation, VO = 5 V 14 13 Quiescent Current - mA DC Output Voltage - V 15 IOUT = 0 mA VOUT = 5.0 V, ILIM = 1500 mA 5.50 QUIESCENT CURRENT vs INPUT VOLTAGE 5.30 5.20 5.10 11 10 9 8 7 6 5 4 5 3 2 1 0 2.5 IOUT = 1000 mA 4.80 2.9 3.3 3.7 4.1 4.9 4.5 VI - Input Voltage - V 5.3 5.5 3.3 3.7 4.1 4.5 VI - Input Voltage - V Figure 10. SHUTDOWN CURRENT vs INPUT VOLTAGE JUNCTION TEMPERATURE vs GPIO VOLTAGE 5.3 5.5 200 175 TJ - Junction Temperature - °C TA = 85°C 1.20 1 0.80 0.60 TA = 25°C 0.40 TA = -40°C 0.20 GPIO = Input, IGPIO = -100 mA 150 125 100 75 50 25 GPIO Input Buffer 0 -25 0 2.5 4.9 Figure 9. 1.40 Shutdown Current - mA 2.9 VGPIO 2.5 PRODUCT PREVIEW 4.90 2.9 3.3 3.7 4.1 4.5 4.9 VI - Input Voltage - V 5.3 5.5 -50 -0.50 -0.45 Figure 11. -0.40 -0.35 -0.30 100 mA -0.25 -0.20 GPIO Voltage - V Figure 12. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 9 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 PWM OPERATION DOWN-MODE OPERATION ILED SW (2V/div) (50mA/div) VOUT (500 mV/div - 3.5 V Offset) LED Headroom Voltage (1V/div) IL (200mA/div - 0.6 A Offset) IL (50mA/div) VOUT (50mV/div - 5 V Offset) VI = 4.2 V, ILED = 75 mA VI = 3.6 V, VO = 5 V, IO = 500 mA, ILIM = 1500 mA t - Time = 250 ns/div Figure 14. PRODUCT PREVIEW t - Time = 125 ns/div Figure 13. VOLTAGE MODE LOAD TRANSIENT RESPONSE VOUT (200 mV/div - 4 V Offset) VI = 3.6 V, VO = 5 V, ILIM = 1500 mA VOUT (500 mV/div - 5 V Offset) IL (500 mA/div) DOWN-MODE LINE TRANSIENT RESPONSE Battery Voltage (200 mV/div - 4 V Offset) IL (200 mA/div - 0.3 A Offset) VI = 3.6 V to 3.9 V, ILED = 500 mA, ILIM = 1500 mA IOUT (500 mA/div) t - Time = 20 ms/div t - Time = 50 ms/div Figure 15. 10 ILED (100 mA/div - 0.3 A Offset) Figure 16. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 DUTY CYCLE JITTER INPUT RIPPLE VOLTAGE Battery Voltage (10 mV/div - 3.3 V Offset) TRIGGERED ON RISING EDGE SW (1 V/div) VOUT (20 mV/div - 4.2 V Offset) IL (200 mA/div - 0.5 A Offset) VI = 3.6 V, VO = 5 V, IO = 500 mA, ILIM = 1500 mA ILED (200 mA/div - 0.3 A Offset) Li-Polymer Battery at 3.3V, ILED = 700 mA, ILIM = 1500 mA t - Time = 50 ns/div Figure 17. t - Time = 500 ns/div LOW-LIGHT DIMMING MODE OPERATION PRODUCT PREVIEW Figure 18. TORCH/FLASH SEQUENCE FLASH_SYNC (2 V/div) SAFETY TIMER LIMITATION Frequency = 121 Hz Duty Cycle = 6.25% ILED (500 mA/div) ILED (20 mA/div) VOUT (200 mV/div - 3.5 V Offset) VIN = 3.6 V, ITORCH = 75 mA VOUT (500 mV/div - 3.40 V Offset) LED Pin Headroom Voltage (200 mV/div) VI = 3.2 V, ILIM = 1500 mA ILED = 75 mA (Torch) to 700 mA (Flash) t - Time = 2 ms/div Figure 19. t - Time = 100 ms/div Figure 20. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 11 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 TX-MASKING OPERATION TX-MASKING OPERATION VI = 3.6 V, ILIM = 1500 mA ITORCH = 75 mA, IFLASH = 700 mA FLASH_SYNC (2 V/div) Tx-TOFF (2 V/div) Tx-TOFF (2 V/div) ILED (200 mA/div) ILED (200 mA/div) IL (500 mA/div) IL (500 mA/div) VI = 3.6 V, ILIM = 1500 mA ITORCH = 75 mA, IFLASH = 700 mA t - Time = 10 ms/div t - Time = 200 ms/div PRODUCT PREVIEW Figure 21. Figure 22. TX-MASKING OPERATION START-UP IN FLASH OPERATION Tx-TOFF (2 V/div) VI = 3.6 V, ILIM = 1500 mA ,IFLASH = 700 mA MODE0 = GND, FLASH_SYNC = HIGH MODE1 (2 V/div) VOUT (2 V/div) ILED ILED (200 mA/div) (500 mA/div) IL (500 mA/div) IL (200 mA/div) VI = 3.6 V, ILIM = 1500 mA ITORCH = 75 mA, IFLASH = 700 mA t - Time = 200 ms/div t - Time = 50 ms/div Figure 23. 12 Figure 24. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 DETAILED DESCRIPTION OPERATION The TPS6105x family employs a 2-MHz constant-frequency, current-mode PWM converter to generate the output voltage required to drive high-power LEDs. The device integrates a power stage based on an NMOS switch and a synchronous NMOS rectifier. The device also implements a linear low-side current regulator to control the LED current when the battery voltage is higher than the diode forward voltage. In boost mode, the duty cycle of the converter is set by the error amplifier and the saw-tooth ramp applied to the comparator. Because the control architecture is based on a current-mode control, a compensation ramp is added to allow stable operation at duty cycles larger than 50%. The converter is a fully-integrated synchronous-boost converter, always operating in continuous-conduction mode. This allows low-noise operation, and avoids ringing on the switch pin, which would be seen on a converter when entering discontinuous-conduction mode. The TPS6105x device not only operates as a regulated current source but also as a standard voltage-boost regulator. This additional operating mode can be useful to properly synchronize the converter when supplying other high-power devices in the system, such as a hands-free audio power amplifier, or any other component requiring a supply voltage higher than the battery voltage. Table 2. TPS6105x Operating Modes MODE1 MODE0 OPERATING MODES 0 0 Power stage is in shutdown. The output is either connected directly to the battery via the rectifer’s body diode. 0 1 LED is turned-on for torch light operation. The converter is operating in the current regulation mode (CM). The output voltage is controlled by the forward voltage characteristic of the LED. 1 0 LED is turned-on for flashlight operation. The converter is operating in the current regulation mode (CM). The output voltage is controlled by the forward voltage characteristic of the LED. 1 1 LED is turned-off and the converter is operating in voltage regulation mode (VM). The output voltage is regulated to 5.0V. To simplify flash synchronization with the camera module, the device offers a FLASH_SYNC strobe input pin to switch (with zero latency) the LED current from flash to torch light. The LED is driven at the flashlight current level when a logic high signal is applied to the FLASH_SYNC pin. The maximum duration of the flash pulse can be limited by means of an internal safety timer (820ms). The safety timer starts on the rising edge of the FLASH_SYNC signal and stops either on its falling edge or after a timeout whatever occurs first. FLASH_SYNC FLASH_SYNC STIM TIMER FLASH LED CONTROL STIM TIMER TIME-OUT TORCH Figure 25. Level Sensitive Safety Timer (Timeout) FLASH LED CONTROL TIME-OUT TORCH Figure 26. Level Sensitive Safety Timer (Normal Operation + Timeout) Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 13 PRODUCT PREVIEW The mode of operation (shutdown, torch and flash modes, constant voltage regulation) selection is done via the MODE0/1 control inputs. TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 EFFICIENCY The sense voltage has a direct effect on the converter’s efficiency. Because the voltage across the low-side current regulator does not contribute to the output power (LED brightness), the lower the sense voltage, the higher the efficiency will be. When running in boost mode (VF(LED) > VIN), the voltage present at the LED pin of the low-side current regulator is typically 250 mV, which contributes to high power-conversion efficiency. When running in the linear down-ocnverter mode (VF(LED) < VIN), the low-side current regulator drops the voltage difference between the input voltage and the LED forward voltage. Depending on the input voltage and the LED forward voltage characteristic, the converter displays efficiency of approximately 80% to 90%. FLASH BLANKING The TPS6105x device also integrates a Tx-TOFF input that can be used as flash masking input. This blanking function turns the LED from flash to torch light, thereby reducing almost instantaneously the peak current loading from the battery. This function has no influence on the safety timer duration. IFLASH LED Current PRODUCT PREVIEW ITORCH FLASH_SYNC Tx-TOFF Figure 27. Synchronized Flash With Blanking Periods (MODE0 = 0, MODE1 = 1) LOW LIGHT DIMMING MODE The TPS6105x device features white LED drive capability at very low light intensity. To generate a reduced LED average current, the device employs a 122 Hz fixed frequency PWM modulation scheme. Operation is understood best by referring to the timer block diagram. The torch current is modulated with a 6.3% duty cycle. The low light dimming mode can only be activated in the torch only mode (MODE1 = 0, MODE0 = 1) together with a logic level high applied to the FLASH_SYNC input. I TORCH I LED(DC) = 0.063 x I TORCH 0 Figure 28. PWM Dimming Principle White-LED blinking can be achieved by turning on/off periodically the LED dimmer via the (DIM) bit, see Figure 29. LED OFF LED ON with Reduced Current ITORCH ITORCH 6.3% PWM Dimming Steps MODE0 Figure 29. White LED Blinking Control (MODE1 = 0, FLASH_SYNC = 1) 14 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 SOFT-START Since the output capacitor always remains biased to the input voltage, the TPS6105x can immediately start switching once it has been enabled. The device starts-up by smoothly ramping up it’s internal reference voltage, thus limiting the inrush current. SHUTDOWN In shutdown mode, the regulator stops switching and the LED pin is high impedance thus eliminating any DC conduction path. The internal switch and rectifier MOSFET are turned off. VOUT is one body-diode drop below the input voltage and the device consumes only a shutdown current of 0.3 μA (typ). The output capacitor remains biased to the input voltage. LED FAILURE MODES If the LED fails as a short circuit, the low-side current regulator limits the maximum output current. If the LED fails as an open circuit, the control loop initially attempts to regulate off of its low-side current regulator feedback signal. This drives VOUT higher. Because the open-circuited LED will never accept its programmed current, VOUT must be voltage-limited by means of a secondary control loop. In this failure mode, the TPS6105x limits VOUT to 6.0 V (typ.). The undervoltage lockout circuit prevents the device from misoperation at low input voltages. It prevents the converter from turning on the switch or rectifier MOSFET under undefined conditions. THERMAL SHUTDOWN As soon as the junction temperature, TJ, exceeds 160°C typical, the device goes into thermal shutdown. In this mode, the boost power stage and the low-side current regulator are turned off. To resume operation, the device needs to be cycled through a shutdown phase (MODE0 = 0, MODE1 = 0). Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 15 PRODUCT PREVIEW UNDERVOLTAGE LOCKOUT TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 APPLICATION INFORMATION INDUCTOR SELECTON A boost converter requires two main passive components for storing energy during the conversion. A boost inductor and a storage capacitor at the output are required. The TPS6105x device integrates a current limit protection circuitry. The peak current of the NMOS switch is sensed to limit the maximum current flowing through the switch and the inductor (e.g. 1000 mA or 1500 mA). In order to optimize solution size the TPS6105x device has been designed to operate with inductance values between a minimum of 1.3 μH and maximum of 2.9 μH. In typical high-current white LED applications a 2.2 μH inductance is recommended. 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. The highest peak current through the inductor and the power switch depends on the output load, the input and output voltages. Estimation of the maximum average inductor current and the maximum inductor peak current can be done using Equation 1 and Equation 2: V OUT I L [ I OUT + h VIN (1) I L(PEAK) + PRODUCT PREVIEW I OUT VIN D ) 2 f L (1 * D) V * V IN with D + OUT h VOUT (2) with: f = switching frequency (2 MHz) L = inductance value (2.2 μH) η = estimated efficiency (85%) For example, for an output current of 500 mA at 5 V, the TPS6105x device needs to be set for a 1000 mA current limit operation together with an inductor supporting this peak current. The losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for total circuit efficiency. Table 3. List of Inductors 16 MANUFACTURER SERIES DIMENSIONS TDK VLF3010AT 2,6 mm × 2,8 mm × 1,0 mm max. height TAIYO YUDEN NR3010 3,0 mm × 3,0 mm × 1,0 mm max. height FDK MIPSA2520 2,5 mm × 2,0 mm × 1,2 mm max. height TDK VLF3014AT 2,6 mm × 2,8 mm × 1,4 mm max. height COILCRAFT LPS3015 3,0 mm × 3,0 mm × 1,5 mm max. height MURATA LQH3NP 3,0 mm × 3,0 mm × 1,5 mm max. height TOKO FDSE0312 3,0 mm × 3,0 mm × 1,2 mm max. height Submit Documentation Feedback ILIM SETTINGS 1000 mA (typ.) 1500 mA (typ.) Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 CAPACITOR SELECTION Input Capacitor For good input voltage filtering low ESR ceramic capacitors are recommended. 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 primary 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 3: C min [ I OUT f ǒVOUT * VINǓ DV V OUT (3) Parameter f is the switching frequency and ΔV is the maximum allowed ripple. ΔVESR = IOUT × RESR 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 3 μF effective output capacitance is usually required when operating with 2.2 μH (typ) inductors. For solution size reasons, this is usually one or more X5R/X7R ceramic capacitors. For stable operation of the internally compensated control loop, a maximum of 50 μF effective output capacitance is tolerable. Depending on the material, size and margin to the rated voltage of the used output capacitor, degradation on the effective capacitance can be observed. This loss of capacitance is related to the DC bias voltage applied. It is therefore always recommended to check that the selected capacitors are showing enough effective capacitance under real operating conditions. 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. The next step in regulation loop evaluation is to perform a load transient test. Output voltage settling time after the load transient event is a good estimate of the control loop bandwidth. The amount of overshoot and subsequent oscillations (ringing) indicates the stability of the control loop. 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, output current range, and temperature range. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 17 PRODUCT PREVIEW With a chosen ripple voltage of 10mV, a minimum capacitance of 10 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 4: TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 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. 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. THERMAL INFORMATION Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependant 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. Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design. The maximum junction temperature (TJ) of the TPS6105x is 150°C. The maximum power dissipation gets especially critical when the device operates in the linear down mode at high LED current. For single pulse power thermal analysis (e.g., flash strobe), the allowable power dissipation for the device is given by Figure 30. 4 No Airflow 3.5 Single Pulse Power Disipation - W PRODUCT PREVIEW 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 3 2.5 2 1.5 tPCB = 85°C 1 0.5 0 0 Theta JB: 35°CW 100 200 300 400 500 600 700 800 900 1000 Pulse Width - ms Figure 30. Single Pulse Power Capability (CSP Package) 18 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 TYPICAL APPLICATIONS TPS61054 L VBAT 2.2 mH SW SW VOUT COUT 10 mF P AVIN Li-Ion CIN P WHITE LED FLASH-LIGHT P LED MODE1 MODE0 CAMERA ENGINE Tx-TOFF FLASH_SYNC AGND PGND PGND P RF PA TX ACTIVE PRODUCT PREVIEW Figure 31. High Power White LED Solution Featuring No-Latency Turn-Down via PA TX Signal TPS61054 L SW VBAT 2.2 mH SW VOUT COUT 10 mF AVIN Li-Ion C IN LED 1 P 1 .5 R P LED 2 1 .5 R P LED MODE1 LED 1, LED 2 VF variation should be with 100 mV from each other MODE0 Tx-TOFF FLASH _SYNC PGND AGND P PGND Figure 32. 2 × 350 mA Dual LED Camera Flash Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 19 TPS61054, TPS61055 www.ti.com SLUS760 – SEPTEMBER 2007 PACKAGE SUMMARY CHIP SCALE PACKAGE (BOTTOM VIEW) A3 A2 A1 B3 B2 B1 C3 C2 C1 D3 D2 D1 CHIP SCALE PACKAGE (TOP VIEW) YMLLLLS 6105x D A1 E Code: • Y — 2 digit date code • LLLL - lot trace code • S - assembly site code PACKAGE DIMENSIONS The dimensions for the YZG package are shown in Table 4. See the package drawing at the end of this data sheet. PRODUCT PREVIEW Table 4. YZG Package Dimensions 20 Packaged Devices D E TPS6105xYZG 1.96 ±0.05 mm 1.46 ±0.05 mm Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :TPS61054, TPS61055 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. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. 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