® RT8540A High Power Synchronous Boost Converter General Description Features The RT8540A is a high-efficiency, high-current Boost converter in all single-cell Lithium-ion / polymer battery operated products. The RT8540A maintains output current regulation by switching the internal high side and low side switch transistors. The transistor switches are pulse-width modulated at a fixed frequency of 2MHz. The high switching frequency allows the use of a small inductor and output capacitor, making the RT8540A ideally suited for small battery-powered applications. Output voltage can be set by an external resistor on the FB pin or by I2C interface. z The RT8540A contains over voltage protection, over current protection and over temperature protection to prevent the device from output open circuit or short circuit condition. Built-in soft-start circuitry prevents excessive inrush current during start-up. The shutdown feature reduces quiescent current to less than 5μA. Input Voltage Range : 2.8V to 5.5V True Load Disconnect z Internal Synchronous Rectifier z Up to 90% Efficiency with Small Magnetics z Current Mode PWM Operation with Internal Compensation z Internal Soft-Start Control 2 z Flexible on/off Control by I C or EN. z Short Circuit Protection z Input Current Limit up to 4A z Over Voltage, Over Temperature Protection z Shutdown Current : 2μ μA z − 40° °C to 85°°C Temperature Range z 20-Lead WQFN Package z RoHS Compliant and Halogen Free z Applications Marking Information z z 0R= : Product Code 0R=YM DNN z YMDNN : Date Code Cellular Phones Digital Cameras Probable Instruments Simplified Application Circuit L VBAT VOUT SW VIN COUT RT8540A VOUT CIN1 SELECT SCL SDA 2 I C Interface PGND Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8540A-00 June 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8540A Ordering Information Pin Configurations RT8540A EN GPIO/PGOOD SELECT AGND AGND (TOP VIEW) Package Type QW : WQFN-20L 4x4 (W-Type) (Exposed Pad-Option 1) Lead Plating System G : Green (Halogen Free and Pb Free) 20 19 18 17 16 VIN AGND AGND AGND FB/NC Note : Richtek products are : ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. 15 2 14 GND 3 4 12 5 11 6 Suitable for use in SnPb or Pb-free soldering processes. 13 21 7 8 9 NC NC SCL SDA NC 10 PGND SW SW VOUT VOUT ` 1 WQFN-20L 4x4 Functional Pin Description Pin No. Pin Name. Pin Function VIN Power Input. Connect VIN to the power supply. Connect a 4.7μF or larger ceramic capacitor from VIN to ground as close as possible to the IC. 2, 3, 4, 16, 17 AGND Analog Ground. Connect AGND to GND at single point as close to the IC as possible. 5 FB/NC Feedback Voltage Input. When the pin is floating, the output voltage is 2 controlled by I C interface. 6 PGND Power Ground. Connect PGND to GND at a single point as close to the IC as possible. 7, 8 SW Switch Node. Connect an inductor between SW and VIN. 9, 10 VOUT Output of the Boost Conductor. Connect a 10μF or larger ceramic capacitor from VOUT to ground as close as possible to the IC. NC No Internal Connection. 12 SDA Data Signal Input for I C. Open drain output, connect a 10kΩ pull-up resistor. 13 SCL Clock Signal Input for I C. Open drain output, connect a 10kΩ pull-up resistor. 18 SELECT Select IC I C/EN Control. 2 SELECT = HIGH. I C control. SELECT = LOW. EN control. 19 GPIO/PGOOD General Purpose Input Output Input or Power Good Indicator Output. 20 EN 1 11, 14, 15 2 2 2 21 (Exposed Pad) GND 2 Enable Control Input for non I C control Version (Active High). Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8540A-00 June 2013 RT8540A Function Block Diagram SDA SCL EN GPIO/PGOOD VOUT VIN SELECT Well Controller 2 I C Base Boost Controller OSC VREF FB/NC EA SW PWM PGND AGND Operation Boost Controller PWM The core of the Boost regulator with normal operations and provides protection functions like UVLO, OCP, OVP, OTP. PWM comparator compares COMP signal and current feedback signal to initial PWM signal. I2C BASE OSC Digital logic and registers part. Generates 2MHz clock. Well Controller VREF Generates the reference voltage for Error-amp and other bias circuit. It compares VIN and VOUT, the higher one will be the big P-MOSFET well potential. EA Error amplifier generates COMP signal by the difference between FB and VREF. Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8540A-00 June 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8540A Absolute Maximum Ratings z z z z z z z z z z (Note 1) Supply Voltage, VIN ------------------------------------------------------------------------------------------------------Boost Output Voltage, VOUT -------------------------------------------------------------------------------------------Switching Voltage, SW --------------------------------------------------------------------------------------------------SCL, SDA, EN, GPIO/PGOOD, FB/NC, SELECT -----------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WQFN-20L 4x4 ------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WQFN-20L 4x4, θJA -------------------------------------------------------------------------------------------------------WQFN-20L 4x4, θJC ------------------------------------------------------------------------------------------------------Junction Temperature -----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ----------------------------------------------------------------------------------------------MM (Machine Model) -----------------------------------------------------------------------------------------------------CDM (Charge Device Model) --------------------------------------------------------------------------------------------- Recommended Operating Conditions z z z −0.3V to 6V −0.3V to 6.5V −0.3V to 6.5V −0.3V to 6V 3.57W 28°C/W 7°C/W 150°C 260°C −65°C to 150°C 2kV 200V 500V (Note 4) Input Voltage, VIN ---------------------------------------------------------------------------------------------------------- 2.8V to 5.5V Junction Temperature Range --------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range --------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 3.6V, CIN = 4.7μF, COUT = 10μF, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit 2.8 -- 5.5 V Power Supply Input Voltage Range V IN UVLO UV VIN Falling -- 2.4 -- V VIN Supply Current IQ IOUT = 0A -- 590 700 μA VIN Shutdown Current ISHDN VIN = 5V -- 1 5 μA Output Voltage Range V OUT I C Control, OV[3:0] = 0000 to 1111 3.825 -- 5.45 V Feedback Voltage V FB EN Control 0.9702 0.99 1.0098 V Output 2 Oscillator and Timer Operating Frequency fOSC 1.6 2 2.4 MHz Maximum Duty Cycle D MAX 70 -- -- % N-MOSFET Ron R DS(ON)_N VOUT = 3.6V -- 90 -- mΩ P-MOSFET Ron R DS(ON)_P VOUT = 3.6V -- 110 -- mΩ Leakage into SW ILKG_SW -- 0.3 4 μA Power Switch VOUT = 0V, EN = LOW Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS8540A-00 June 2013 RT8540A Parameter Symbol Test Conditions Min Typ Max Unit 3.6 4 4.4 A VOUT Rising, 0000 ≤ OV[3:0] ≤ 0100 4.464 4.65 4.836 V VOUT Rising, 0101 ≤ OV[3:0] ≤ 1111, 5.568 SELECT = LOW 5.8 6.032 V Protection Function N-MOSFET Current Limit IOCP VOUT = 5V Over Voltage Protection VOVP OVP Hysteresis VOVP_HYS VOUT Falling -- 150 -- mV Thermal Shutdown TSD -- 160 -- °C -- 20 -- °C Thermal Shutdown Hysteresis TSD_HYS Logic Control SELECT Logic High VSELH 1.4 -- -- V SELECT Logic Low VSELL -- -- 0.4 V EN Logic High VENLH 1.4 -- -- V EN Logic Low VENLL -- -- 0.4 V SCL Logic High VSCLH 1.4 -- -- V SCL Logic Low VSCLL -- -- 0.4 V SDA Logic High VSDAH 1.4 -- -- V SDA Logic Low VSDAL -- -- 0.4 V GPIO Output Voltage High VOH_GPIO DIR = 1, GPIOTYPE = 0, IOH = 8mA VIN − 0.4 -- -- V GPIO Output Voltage Low VOL_GPIO DIR = 1, IOL = 5mA -- -- 0.3 V EN Pull Low Resistance REN -- 400 -- kΩ SELECT Pull Low Resistance RSEL -- 400 -- kΩ Clock Frequency of SCL -- -- 400 kHz fSCL Note 1. Stresses beyond those listed “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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8540A-00 June 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8540A Typical Application Circuit L 2.2µH RT8540A 7, 8 C1 4.7µF 1 18 20 Enable 13 12 2, 3, 4, 16, 17 SW VOUT 9, 10 C2 10µF VIN SELECT GPIO/ 19 PGOOD EN SCL SDA PGND AGND 6 Figure 1. For I2C Control L 2.2µH C1 4.7µF 7, 8 1 RT8540A SW VOUT R1 FB Enable 20 18 13 12 2, 3, 4, 16, 17 9, 10 VIN 5 EN SELECT C2 10µF R2 GPIO/ 19 PGOOD SCL SDA PGND 6 AGND Figure 2. For EN Control Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS8540A-00 June 2013 RT8540A Typical Operating Characteristics Efficiency vs. Output Current 100 90 90 80 80 70 Efficiency (%) Efficiency (%) Efficiency vs. Output Current 100 VIN = 2.8V VIN = 3V VIN = 3.6V VIN = 4.2V 60 50 40 30 20 VIN = 4.2V VIN = 3.6V VIN = 3V VIN = 2.8V 70 60 50 40 30 20 10 10 VOUT = 3.825V 0 VOUT = 4.95V 0 0 250 500 750 1000 1250 1500 1750 2000 0 250 500 Output Current (mA) Output Voltage vs. Output Current Output Voltage vs. Output Current 5.2 4.0 5.1 Output Voltage (V) Output Voltage (V) 1000 1250 1500 1750 2000 Output Current (mA) 4.2 3.8 VIN = 2.8V VIN = 3V VIN = 3.6V VIN = 4.2V 3.6 750 3.4 3.2 5.0 4.9 VIN = 4.2V VIN = 3.6V VIN = 3V VIN = 2.8V 4.8 4.7 4.6 VOUT = 4.95V VOUT = 3.825V 3.0 4.5 0 250 500 750 1000 1250 1500 1750 2000 0 250 500 Output Current (mA) 750 1000 1250 1500 1750 2000 Output Current (mA) Quiescent Current vs. Input Voltage Shutdown Current vs. Input Voltage 5.0 600 Shutdown Current (µA)1 Quiescent Current (µA) 4.5 500 400 300 200 100 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 2.8 3.1 3.4 3.7 4 4.3 4.6 4.9 5.2 Input Voltage (V) Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8540A-00 June 2013 5.5 2.8 3.1 3.4 3.7 4 4.3 4.6 4.9 5.2 5.5 Input Voltage (V) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8540A Output Voltage Ripple Power On EN (5V/Div) VOUT (100mV/Div) VOUT (5V/Div) VLX (5V/Div) VLX (5mA/Div) VIN = 3.6V, VOUT = 4.95V, IOUT = 500mA I IN (500mA/Div) VIN = 3.6V, VOUT = 4.95V Time (250ns/Div) Time (250μs/Div) Voltage Mode Load Transient Response Voltage Mode Load Transient Response VOUT (200mV/Div) VOUT (200mV/Div) IOUT (200mA/Div) IOUT (200mA/Div) VIN = 3.2V, VOUT = 3.825V, IOUT = 50mA to 500mA Time (100μs/Div) Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 VIN = 3.6V, VOUT = 4.95V, IOUT = 50mA to 500mA Time (100μs/Div) is a registered trademark of Richtek Technology Corporation. DS8540A-00 June 2013 RT8540A Application Information The RT8540A is a high-efficiency, high-current Boost converter in all single-cell Lithium-ion/polymer battery operated products. The RT8450A provides the ability to regulate the input voltage that is higher than the designed output voltage with its down-conversion mode. The RT8450A turns off its down-conversion mode automatically once the input voltage falls to approximately 200mV below the output voltage. Inductor Selection The RT8540A adopts fixed frequency PWM control architecture. For stable operation and the 2MHz high switching frequency, it is recommended to use a 2.2μH inductor. Small size and high efficiency are the major concerns for portable device, so the inductor should have low core loss at 2MHz and low DCR for better efficiency. Capacitor Selection Soft-Start The RT8540A employs a soft-start feature to limit the inrush current. The soft-start circuit prevents the excessive inrush current and input voltage droop. The soft-start clamps the input inrush current for a typical period of 400μs. Input UVLO The input operating voltage range is from 2.8V to 5.5V. The RT8540A provides an Under Voltage Lockout (UVLO) function to prevent it from unstable issue when startup. The UVLO threshold of input rising voltage is set at 2.3V typically with a hysteresis of 200mV. Over Voltage Protection (Open Circuit) The RT8540A provides an internal over voltage protection to limit its output voltage. The OVP function prevents the RT8540A from damaging while open circuit condition is occurred. Over Current Protection The RT8540A provides an internal over current protection to limit its output current. The typical value of the maximum current is 4A. Over Temperature Protection The RT8540A provides an over temperature protection to prevent the IC from overheating. When the junction temperature of the RT8540A rises above 160°C, the OTP function will be triggered and then the regulator will be shutdown. The OTP comes with a hysteresis of 20°C. Once the temperature is reduced below the over temperature protection threshold by 20°C, the output will soft-start again. Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8540A-00 June 2013 Input and output ceramic capacitors of 10μF are recommended for RT8540A applications. For better voltage filtering, ceramic capacitors with low ESR are recommended. The best performance of the RT8540A can be achieved by using the capacitor of large capacitance. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Enable Selection Function There is a SELECT pin on the RT8450A which provides the selection of I2C enable or non-I2C enable. By setting the SELECT pin “Low”, the IC enters non-I2C control operation. The IC will be enable when the EN pin is set “High”, and the output is regulated by connecting the FB pin to VOUT with the dividing resistors. The VOUT is set between 3.825V and 5.45V. Setting the SELECT pin “High”, the IC enters I2C control operation. The RT8450A provides an integrated software control bit ENVM bit to force the converter to enter normal operation. Under this condition, the output will be regulated by integrated software control bits OV[3:0]. SELECT EN ENVM Operation description 0 0 0 Shutdown 0 1 0 Enable 1 x 0 Shutdown 1 x 1 Enable is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8540A Register Map Table 1. 0x04 Error Flag Description PG FREE OTP FREE FREE Vout Short Bits D7 D6 D5 D4 D3 D2 D1 D0 Memory R/W R R R R R R R Default 0 0 0 0 0 0 0 0 PG Power Good bit. In write mode, this bit selects the functionality of the GPIO/PG output. 0 : PG signal is routed to the GPIO port. 1 : GPIO PORT VALUE bit is routed to the GPIO port. In read mode, this bit indicates the output voltage conditions. 0 : The converter is not operating within the voltage regulation limits. 1 : The output voltage is within it nominal value. OTP Thermal shutdown tripped Indicator flag reset after readout. FREE VOUT Short VOUT Short error flag reset after readout. Table 2. 0x05 Description RESET ENPSM DIR GPIO GPIOTYPE Bits D7 D6 D5 D4 D3 D2 D1 D0 Memory R/W R/W R/W R/W R/W R R R Default 0 1 1 0 1 0 0 0 RESET Register Reset bit. 0 : Normal operation. 1 : Default values are set to all internal registers. ENPSM Enable/Disable Power-Save Mode bit. 0 : Power-save mode disabled. 1 : Power-save mode enabled. DIR GPIO GPIOTYPE FREE GPIO Direction bit. 0 : GPIO configured as input. 1 : GPIO configured as output. GPIO Port Value. This bit contains the GPIO port Value. GPIO Port Type. 0 : GPIO is configured as push-pull output. 1 : GPIO is configured as open-drain output. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 is a registered trademark of Richtek Technology Corporation. DS8540A-00 June 2013 RT8540A Table 3. 0x06 Output Voltage Description ENVM FREE OV [3:0] Bits D7 D6 D5 D4 D3 D2 D1 D0 Memory R/W R R R R/W R/W R/W R/W Default 0 0 0 0 1 0 0 1 2 OV[3:0] Output Voltage Selection bits for I C Control : 0000 : 3.825V 0001 : 3.95V 0010 : 4.075V 0011 : 4.2V 0100 : 4.325V 0101 : 4.45V 0110 : 4.575V 0111 : 4.7V 1000 : 4.825V 1001 : 4.95V 1010 : 5.075V 1011 : 5.2V 1100 : 5.325V 1101 to 1111 : 5.45V ENVM Enable Voltage Mode bit. 0 : Shutdown mode. 1 : Normal operation. Register Summary Address : 0110011x Bit3 Vout Short Bit2 Bit1 Bit0 R R R R R 0 0 0 0 0 0 ENPSM DIR GPIO GPIOTYPE Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Memory 0 1 1 0 1 0 0 0 Default R/W R/W R/W R/W R/W R R R Description ENVM Bits Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Memory R/W R R R R/W R/W R/W R/W Default 0 0 0 0 1 0 0 1 Register Description 0x04 0x05 0x06 PG FREE OTP FREE FREE Bits Bit7 Bit6 Bit5 Bit4 Memory R/W R R Default 0 0 Description RESET Bits FREE Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8540A-00 June 2013 FREE FREE OV [3:0] is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT8540A Thermal Considerations Layout Consideration For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : For the best performance of the RT8540A, following PCB layout guidelines should be strictly followed. PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For WQFN-20L 4x4 package, the thermal resistance, θJA, is 28°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : ` The PGND of the IC should be connected to the ground plane of the PCB ` The output bypass capacitor should be placed as close to the IC as possible ` The trace lengths from the IC to the inductor, input capacitor and the output capacitor must be kept as short, direct and wide as possible. ` CIN and COUT of the RT8540A should be placed as close as possible and connected to PGND of the IC. ` It is recommended to add additional PCB exposed pad area for the flash LEDs for maximized heat-sinking ability. This is necessary for high current application and long flash duration application. P D(MAX) = (125°C − 25°C) / (28°C/W) = 3.57W for WQFN-20L 4x4 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 3 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Maximum Power Dissipation (W)1 4.0 Four-Layer PCB 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 3. Derating Curve of Maximum Power Dissipation Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 is a registered trademark of Richtek Technology Corporation. DS8540A-00 June 2013 RT8540A Outline Dimension 1 1 2 2 DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated. Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.150 0.300 0.006 0.012 D 3.900 4.100 0.154 0.161 Option 1 2.650 2.750 0.104 0.108 Option 2 2.100 2.200 0.083 0.087 E 3.900 4.100 0.154 0.161 Option 1 2.650 2.750 0.104 0.108 Option 2 2.100 2.200 0.083 0.087 D2 E2 e 0.500 L 0.350 0.020 0.450 0.014 0.018 W-Type 20L QFN 4x4 Package Richtek Technology Corporation 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. DS8540A-00 June 2013 www.richtek.com 13