RT9363A 3 Channels 90mA x1/x2 Charge Pump White LED Driver General Description Features The RT9363A is a compact, high efficient and highly integrated charge pump white LED driver. It maintains the highest efficiency by utilizing a x1/x2 fractional charge pump and low dropout current regulators. The RT9363A supports up to 3 white LEDs and regulates a constant current for uniform intensity. The part implements a 4-bit DAC for brightness control. Users can select external RSET z Over 80% Average Efficiency Over Battery Life z or internal RSET by ISET pin. The dimming of white LEDs' current can be achieved by applying a pulse signal to the EN pin. There are totally 16 steps of current could be set by users. The part can support 15mA to 30mA for the 100% current setting. Users also can use the internal RSET for 100% current setting of 20mA just by connecting the ISET pin to VIN. The operating voltage range is from 2.8V to 5.5V. Internal soft start circuitry effectively reduces the inrush current while both start-up and mode transition. The load is disconnected from VIN while shutdown and the shutdown current is less than 1uA. z Support Up to 3 White LEDs 80mV Typical Current Source Dropout Support Up to 90mA Output Current 1% Typical LED Current Accuracy 0.7% Typical LED Current Matching Soft Start Function Automatic Charge Pump Mode Selection 1MHz Random Frequency Oscillator Over Voltage Protection 16-Step Brightness Control Low Input Noise and EMI Low 1uA Shutdown Current Flexible Current Setting RoHS Compliant and 100% Lead (Pb)-Free RT9363A is available in a WDFN -10L 3x3 package. z z z z z z z z z z z z z Applications z z Mobile Phone, DSC, MP3 White LED Backlighting LCD Display Supply Ordering Information RT9363A Pin Configurations Package Type QW : WDFN-10L 3x3 (W-Type) Note : Richtek products are : ` LED3 LED2 LED1 CN CP 1 2 3 4 5 GND 11 10 9 8 7 9 Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) (TOP VIEW) EN ISET VOUT VIN GND WDFN-10L 3x3 RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. Marking Information For marking information, contact our sales representative directly or through a Richtek distributor located in your area. DS9363A-03 April 2011 www.richtek.com 1 RT9363A Typical Application Circuit Li-ion Battery 4 RT9363A CP 5 C IN 2.2uF + CN 7 VIN 9 ISET 10 EN GPIO 6 GND LED1 C FLY 1uF 3 LED2 2 1 LED3 8 VOUT C OUT 2.2uF Figure 1. Internal RSET(MAX) = 20mA, for 3-WLEDs Application Circuit Li-ion Battery + CN 7 VIN 4 RT9363A CP 5 C IN 2.2uF 9 ISET 10 EN GPIO 6 GND LED1 C FLY 1uF 3 LED2 2 1 LED3 8 VOUT C OUT 2.2uF Figure 2. Internal RSET(MAX) = 20mA, for 2-WLEDs Application Circuit Li-ion Battery + CN 7 VIN C IN 2.2uF 4 RT9363A CP 5 R SET 9 ISET 10 EN 6 GND GPIO LED1 C FLY 1uF 3 LED2 2 1 LED3 8 VOUT C OUT 2.2uF Figure 3. External RSET(MAX) = 15 to 30mA, for 3-WLEDs Application Circuit Li-ion Battery + CN 7 VIN C IN 2.2uF GPIO 4 RT9363A CP 5 R SET 9 ISET 10 EN 6 GND LED1 C FLY 1uF 3 LED2 2 1 LED3 8 VOUT C OUT 2.2uF Figure 4. External RSET(MAX) = 15 to 30mA, for 2-WLEDs Application Circuit www.richtek.com 2 DS9363A-03 April 2011 RT9363A Timing Diagram 30us < TREADY 0.5us < THI EN Shutdown 0 1 2 3 100% 15/16 14/16 13/16 2ms < TSHDN 0.5us < TLO < 500us 4 5 14 15 0 1 100% 12/16 ILEDX 15/16 2/16 1/16 Shutdown Figure 5. Pulse Dimming Waveform Functional Pin Description Pin No. Pin Name Pin Function 1 LED3 Current Sink for LED3. (If not in use, this pin must be connected to V IN). 2 LED2 Current Sink for LED2. (If not in use, this pin must be connected to V IN). 3 LED1 Current Sink for LED1. (If not in use, this pin must be connected to V IN). 4 CN Negative Terminal of Bucket Capacitor. 5 CP Positive Terminal of Bucket Capacitor. 6, GND 11 (Exposed Pad) Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 7 VIN Input Voltage. 8 VOUT Output Voltage Source for LED1~3. 9 ISET LED Current Adjust Input. 10 EN Chip Enable (Active High). DS9363A-03 April 2011 www.richtek.com 3 RT9363A Function Block Diagram CP CN VOUT VIN OVP Soft Start Circuit + Gate Driver Mode Decision 1MHz OSC Current Bias Vr1 - Min VDS UVLO LED1 LED2 LED3 16 Steps Pulse Dimming Controller EN Shutdown Delay Current Source ISET RSET GND RSET Selection www.richtek.com 4 DS9363A-03 April 2011 RT9363A Absolute Maximum Ratings z z z z z z z z (Note 1) Supply Input Voltage -----------------------------------------------------------------------------------------------------Output Voltages ----------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C WDFN 10L 3x3 ------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) WDFN 10L 3x3, θJA ------------------------------------------------------------------------------------------------------WDFN 10L 3x3, θJC ------------------------------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions z z −0.3V to 6V −0.3V to 6V 1.538W 60°C/W 8.2°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 3.6V, CIN = COUT = 2.2uF, CFLY = 1uF, VF = 3.5V, ILED1 = ILED2 = ILED3 = 20mA, ESR = 0.03Ω, TA = 25°C, unless otherwise specified). Parameter Input Power Supply Input Supply Voltage Under Voltage Lockout Threshold Symbol Test Conditions Min Typ Max Unit 2.8 -- 5.5 V VUVLO_R -- -- 2.4 V VUVLO_F 1.8 -- -- mV VIN Quiescent Current of x1 Mode IQx1 x1 Mode(LED1~3 connect to VIN) -- 1 -- mA Quiescent Current of x2 Mode IQx2 X2 Mode No Load -- 3 -- mA Shutdown Current ISHDN EN = 0V, VIN = 5V -- 1 11 uA ILED Accuracy ILED-ERR 100% Setting −8 -- +8 % Current Matching ILED-LED-ERR 100% Setting −5 -- +5 % Oscillator Frequency FOSC -- 1000 -- kHz x1 mode to x2 mode Transition Voltage VTS VF = 3.5V, IOUT = 60mA VIN Falling -- 3.6 -- V VOVP Open Circuit at any LED Pin -- 5.5 -- V LED Current Charge Pump Protection Over Voltage Protection To be continued DS9363A-03 April 2011 www.richtek.com 5 RT9363A Parameter Symbol Test Conditions Min Typ Max Logic-High VEN_H 1.5 -- -- Logic-Low VEN_L -- -- 0.4 Unit Digital Input EN Threshold Voltage EN Current Logic-High IEN_H VEN = VIN -- 1 7 Logic-Low IEN_L VEN = 0V -- 0.1 -- V uA EN Low to Shutdown Delay TSHDN Refer to Figure 5 2 -- -- ms EN High Time for Dimming T HI Refer to Figure 5 0.5 -- -- us EN High Time for Holding T LO Refer to Figure 5 0.5 -- 500 us Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. 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 for extended periods may remain possibility to affect device reliability. Note 2. θJA is measured in the natural convection at TA = 25°C on the high effective thermal conductivity four layers thermal test board of JEDEC 51-7 thermal measurement standard. The case point of θJC is on the expose pad. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. www.richtek.com 6 DS9363A-03 April 2011 RT9363A Typical Operating Characteristics Efficiency vs. Input Voltage LED Current vs. Input Voltage 100 26 90 24 LED Current (mA) 80 Efficiency (%) 70 60 50 40 30 20 22 20 LED3 LED1 LED2 18 16 14 12 10 LED Vf = 3.2V LED Vf = 3.2V 0 10 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 2.8 3.2 3.6 Input Voltage (V) 23 23 22 22 LED2 LED1 LED3 19 18 17 5.6 20 19 18 LED2 LED1 LED3 17 VIN = 3.2V 16 16 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 -40 -30 -20 -10 0 x2 Mode Quiescent Current vs. Temperature x1 Mode Quiescent Current vs. Temperature 1.6 5.0 1.5 4.5 Quiescent Current (mA) 1.4 1.3 1.2 1.1 1.0 0.9 0.8 10 20 30 40 50 60 70 80 90 Temperature (°C) Temperature (°C) Quiescent Current (mA) 5.2 21 VIN = 4.0V 0.7 4.8 x2 Mode LED Current vs. Temperature 24 LED Current (mA) LED Current (mA) x1 Mode LED Current vs. Temperature 20 4.4 Input Voltage (V) 24 21 4 4.0 3.5 3.0 2.5 2.0 1.5 VIN = 3.5V VIN = 3.5V 1.0 0.6 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 Temperature (°C) DS9363A-03 April 2011 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 Temperature (°C) www.richtek.com 7 RT9363A Shutdown Current vs. Temperature Frequency vs. Temperature 1.0 1200 1000 0.8 Frequency (kHz) Shutdown Current (uA) 0.9 0.7 0.6 0.5 0.4 0.3 0.2 800 600 400 200 0.1 VIN = 3.5V VIN = 3.5V 0.0 0 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 Temperature (°C) Temperature (°C) x1 Mode Inrush Current Response x2 Mode Inrush Current Response EN (5V/Div) EN (5V/Div) VOUT (1V/Div) VOUT (1V/Div) CN (2V/Div) CN (2V/Div) IIN (100mA/Div) IIN (100mA/Div) VIN = 3.3V VIN = 3.7V Time (250us/Div) Time (250us/Div) x1 Mode Dimming Operation x2 Mode Ripple Voltage VIN (50mV/Div) EN (2V/Div) VOUT (50mV/Div) CN (2V/Div) I LED (10mA/Div) VIN = 3.7V Time (5ms/Div) www.richtek.com 8 I LED (20mA/Div) VIN = 3.3V Time (2.5us/Div) DS9363A-03 April 2011 RT9363A Application information The RT9363A uses a fractional switched capacitor charge pump to power up to three white LEDs with a programmable current. The part integrates current sources and automatic mode selection charge pump. It maintains the high efficiency by utilizing an x1/x2 fractional charge pump and current sources. The small equivalent x1 mode open loop resistance and ultra-low dropout voltage of current source extend the operating time of x1 mode and optimize the efficiency in white LED applications. The operating voltage range is from 2.8V to 5.5V. Internal soft start circuitry effectively reduces the in-rush current while both start-up and mode transition. The load is disconnected from VIN while shutdown and the shutdown current is less than 1uA. High Efficiency x1/x2 Charge Pump Before the discussion of efficiency in RT9363A, two things need to be illustrated. One is the Li-ion battery life time, the other is the forward voltage of white LED. The Li-ion battery energy is not linearly proportion to battery voltage. In the Figure 6, It shows the 80% battery life of Li-ion is arranged from 3.65V to 4.0V. The other voltage range occupies less than 20% battery energy and is insignificant. In the backlight application, the forward voltage of white LEDs most likely falls in 3.2 to 3.5V @ILED = 20mA. The developing concept of RT9363 is based on the backlight application with Li-ion battery. RT9363A is very cost-effective product for white LEDs backlight driving. It extends the 80% battery life by the reduction of open loop resistance at x1 mode and current source drop out voltage. Figure 7 is the efficiency diagram of RT9363 and 80% battery life is marked by red rectangle. The RT9363A maximize the x1 mode operating range in the 80% battery life. Therefore, the efficiency is not significant different to that without x1.5 mode charge pump. The peak efficiency of RT9363A is 93% and the average is 84%. Comparing to the LED drivers with x1.5 mode, only 1 to 2% efficiency loss by x2 mode. (Assume 5% battery life in charge pump mode and the efficiency difference of x1.5 and x2 modes is 25%, the efficiency loss thus is 5%x25% = 1.25%). DS9363A-03 April 2011 Protection The RT9363A includes a soft start circuit to limit the inrush current at power on and mode transition. Soft start circuit holds the input current level long enough for output capacitor COUT reaching a desired voltage level. When the soft start off, the RT9363A won't sink spike current from VIN. An over voltage protection function protect the output voltage from dangerous high voltage. The OVP turns off charge pump when the voltage difference between VIN and VOUT is over the designed target. LED Current Setting In Backlighting part, an internal RSET is used to set the initial current (20mA) of white LED and implements a 4-bit DAC for brightness control. Users can easily configure the LED current by a serial pulse. The dimming of white LEDs' current can be achieved by applying a pulse signal to the EN pin. There are totally 16 steps of current could be set by users. An automatic RSET selection is implemented in this part. RT9363A can automatically select the internal or external RSETs by the connection of ISET pin. The LED current can be calculated by the following equation. ILED = 276 ⎛⎜ VSET ⎞⎟ ⎝ RSET ⎠ where VSET = 1.1V (typ.) and RSET is the external resistor connected from ISET pin to GND. LED Current Setting Table RSET LED current (m A) 10k 30.3 12.1k 25.1 15k 20.2 20k 15.2 30.1k 10.1 www.richtek.com 9 RT9363A Typical Operation Battery Voltage (V) As shown in the typical application circuit, the power of the RT9363A is provided from the external adapter or battery. When EN pin is low, the white LED for backlighting is turned off and draws a very low current from battery supply. To get the better performance of RT9363A, the selection of peripherally appropriate capacitor and value is very important. These capacitors determine some parameters such as input and output ripple, power efficiency, maximum supply current by charge pump, and start-up time. To reduce the input and output ripple effectively, the low ESR ceramic capacitors are recommended. Generally, to reduce the output ripple, increasing the output capacitance COUT is necessary. However, this will increase the start-up time of output voltage. For LED driver applications, the input voltage ripple is more important than the output ripple. Input ripple is controlled by input capacitor CIN, increasing the value of input capacitance can further reduce the ripple. Practically, the input voltage ripple depends on the power supply's impedance. Tantalum capacitors are not recommended for the RT9363A. If tantalum must capacitors are needed, CIN and CFLY must larger than 10μF and 1μF. Because tantalum capacitors' values are less than normal when using for high frequency applications. So tantalum capacitor values and ceramic capacitor values can't be the same. But COUT can't use tantalum capacitor, because during the x2 mode charge pump the VOUT is negative voltage. www.richtek.com 10 Capacity (mAH) 650 50 Figure 6. Li-ion Battery Energy Capacity Versus Battery Voltage. LED Efficiency vs. VIN 100 90 Efficiency (%) Capacitors Selection 3.65 80 70 60 50 40 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 VIN (V) Figure 7. Efficiency of RT9363A. (ILED = 60mA, VF = 3.5V) PCB Board Layout All the traces of LED and VIN running from chip to LEDs should be wide and short to reduce the parasitic connection resistance and shielded, isolated by ground plane. The Anodes of LEDs Output capacitor must be placed close to must connect to CIN, not battery the VOUT and connect to GND plane. directly. CFLY RSET LED3 1 10 EN LED2 LED1 2 9 ISET 8 CN 4 7 VOUT COUT VIN CP 5 9 When EN pin is high, RT9363A provides a twice mode load switch (x1) and high efficiency (x2) charge pump device intended for white LED backlight applications. To maximize the power conversion efficiency, an internal sensing circuit monitors the voltage required on each constant sink input and sets the load switch and charge pump modes based on the input battery voltage and the current sink input voltage. RT9363A provides the option to control the 16-steps brightness of white LEDs with a digital pulse signal applied to EN pin and the detailed timing of pulse dimming is shown in Figure 5. 80% Battery Life 4.2 4.0 GND 3 The traces running from pins to flying capacitor should be short and wide to reduce parasitic resistance and prevent noise radiation. GND The exposed pad, GND pad should be connected to a strong ground plane for heat sinking and noise prevention. CIN Input capacitor must be placed close to the VIN and connect to GND plane. Figure 8. PCB Layout Guide DS9363A-03 April 2011 RT9363A Outline Dimension D2 D L E E2 1 e SEE DETAIL A b 2 1 2 1 A A1 A3 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 0.180 0.300 0.007 0.012 D 2.950 3.050 0.116 0.120 D2 2.300 2.650 0.091 0.104 E 2.950 3.050 0.116 0.120 E2 1.500 1.750 0.059 0.069 e L 0.500 0.350 0.020 0.450 0.014 0.018 W-Type 10L DFN 3x3 Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: [email protected] Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9363A-03 April 2011 www.richtek.com 11