® RT8468 500V Power MOSFET Integrated High Efficiency Constant Current LED Driver General Description Features The RT8468 integrates a 500V power MOSFET and a PWM controller. It is used for step-down converters by well controlling the internal MOSFET and regulating a constant output current. The output duty cycle of the RT8468 can be up to 100% for wider input voltage applications, such as E27 and PAR30 off-line LED lighting products. z The RT8468 also features a 47kHz fixed frequency oscillator, an internal 220mV precision reference, and a PWM comparator with latching logic. The accurate output LED current is achieved by an averaging current feedback loop and the LED current dimming can be easily controlled via the ACTL pin. The RT8468 also has multiple features to protect the controller from fault conditions, including Under Voltage Lockout (UVLO), Over Current Protection (OCP) and Over Voltage Protection (OVP). Additionally, to ensure the system reliability, the RT8468 is built with the thermal protection function. z z z z z z z z z z Built-In 500V/1A Power MOSFET Low Cost and Efficient Buck Converter Solution Universal Input Voltage Range with Off-Line Topology Adjustable Constant LED Current Dimmable LED Current by ACTL Output LED String Open Protection Output LED String Short Protection Output LED String Over Current Protection Built-in Thermal Protection SOP-7 Package RoHS Compliant and Halogen Free Applications z E27, PAR30, Offline LED Lights Marking Information RT8468GS : Product Number The RT8468 is housed in a SOP-7 package. Thus, the components in the whole LED driver system can be made very compact. RT8468 GSYMDNN YMDNN : Date Code Simplified Application Circuit 500V CIN R1 RD RT8468 VCC C1 VC DRAIN R3 ACTL SENSE RVC SGND CVC SOURCE RS DF Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 D1 L1 LED+ COUT LED- is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8468 Ordering Information Pin Configurations RT8468 Package Type S : SOP-7 Lead Plating System G : Green (Halogen Free and Pb Free) (TOP VIEW) SOURCE Note : 7 DRAIN SGND 2 VCC 3 6 ACTL SENSE 4 5 VC Richtek products are : ` SOP-7 RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. Functional Pin Description Pin No. Pin Name Pin Function 1 SOURCE Internal Power MOSFET Source Connection. 2 SGND Ground. 3 VCC Power Supply Input. For good bypass, a ceramic capacitor near the VCC pin is required. 4 SENSE LED Current Sense Input. Typical sensing threshold is 220mV. 5 VC PWM Loop Compensation Node. 6 ACTL Analog Dimming Control. The typical effective dimming range is between 0.1V to 1.2V. 7 DRAIN Internal Power MOSFET Drain Connection. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8468-00 April 2013 RT8468 Function Block Diagram + + - Chip Enable 12V 17V/8V OSC OVP + VCC 35V DRAIN S R SOURCE R + - Control Circuit VC Dimming ACTL - SENSE + SGND Operation The RT8468 is a high voltage Buck PWM current mode driver with an integrated 500V power MOSFET. The start up voltage of RT8468 is around 17V. Once VCC is above 17V, RT8468 will maintain operation until VCC drops below 8V. The RT8468's main control loop consists of a 47kHz fixed frequency oscillator, an internal 220mV precision current sense threshold OPAMP (OP1), and a PWM comparator (CCOMP) with latching logic. In normal operation, the GATE turns high when the gate driver is set by the oscillator (OSC). The lower the average of the sensed current is below the loop-regulated 220mV threshold, the higher the VC pin voltage (OP1 output) will go high. Higher the VC voltage means longer the GATE turn-on period. The GATE of RT8468 can turn on more than 100% duty. It Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 is not always that the GATE turns low in each OSC cycle. The GATE turns low until the current comparator (CCOMP) resets the gate driver. The GATE will be set high again by OSC and the next switching cycle repeats. The ACTL voltage of RT8468 is internally biased to 0.6V. The adjustment of the regulated sense current threshold (dimming) can be achieved by varying ACTL pin voltage. The typical range of ACTL voltage adjustment is between 0.1V and 1.2V. The RT8468 is equipped with protection from several fault conditions, including input voltage Under Voltage Lockout (UVLO), Over Current Protection (OCP) and VIN/VOUT Over Voltage Protection (OVP). Additionally, to ensure the system reliability, the RT8468 is built with internal thermal protection function. is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8468 Absolute Maximum Ratings z z z z z z z z z z z z z (Note 1) Supply Input Voltage, VCC to SGND --------------------------------------------------------------------------------ACTL Voltage to SGND -------------------------------------------------------------------------------------------------VC Voltage to SGND ----------------------------------------------------------------------------------------------------SENSE Voltage to SGND ----------------------------------------------------------------------------------------------DRAIN to SOURCE Voltage, VDS -------------------------------------------------------------------------------------DRAIN Current, ID @ TC = 25°C ---------------------------------------------------------------------------------------DRAIN Current, ID @ TC = 100°C -------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOP-7 -----------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOP-7, θJA -----------------------------------------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility, Except DRAIN & SOURCE Pin (Note 3) HBM (Human Body Model) ---------------------------------------------------------------------------------------------MM (Machine Model) ----------------------------------------------------------------------------------------------------- Recommended Operating Conditions z z −0.3V to 40V −0.3V to 8V −0.3V to 6V −1V to 0.3V −0.3V to 550V 1.4A 0.9A 0.5W 200.2°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage, VCC ---------------------------------------------------------------------------------------------- 16V to 31V Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Electrical Characteristics (VCC = 24VDC, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Supply Voltage Input Start-Up Voltage VST -- 16 19 V Under Voltage Lockout Threshold Hysteresis ΔVUVLO -- 8 9 V Maximum Startup Current IST(MAX) -- 250 300 μA Input Supply Current ICC After Start-Up, VCC = 24V -- 2 5 mA Input Quiescent Current IQC Before Start-Up, VCC = 15V -- -- 2 μA 213 220 227 mV Current Sense Amplifier Current Sense Voltage VSENSE Sense Input Current ISENSE VSENSE = 0.2V -- 20 -- μA VC Sourcing Current IVC_Sr VSENSE = −150mV -- 18.5 -- μA VC Sinking Current IVC_Sk VSENSE = −230mV, VVC = 3.5V -- 165 -- μA VC Threshold for PWM Switch Off VVC 1.15 1.25 1.35 V Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS8468-00 April 2013 RT8468 Parameter Symbol Test Conditions Min Typ Max Unit Oscillator Switching Frequency fSW 38 47 56 kHz Oscillator Maximum Duty Cycle D MAX -- -- 100 % Maximum Duty in Transient Operation D MAX(TR) -- -- 100 % Maximum Duty in Steady State Operation D MAX -- 97 -- % Blanking Time tBLANK -- 300 -- ns -- 650 -- ns -- 1 20 μA LED Current On Threshold at ACTL VACTL_ON -- 1.2 -- V LED Current Off Threshold at ACTL VACTL_OFF -- 0.1 0.2 V Minimum Off-Time VC = 3V (Note 5) LED Dimming Analog Dimming ACTL Pin Input Current IACTL Internal MOSFET Static Drain-Source On-Resistance R DS(ON) VVC = 3V, ID = 0.6A -- 12 -- Ω Drain-Source Leakage Current IDSS VVC = 0V, VDS = 500V -- -- 10 μA Output Capacitance C OSS VCC = 0V, VDS = 25V, f = 1MHz -- 14 40 pF VOVP VCC pin 32 35 38 V -- 150 -- °C OVP and Soft-Start Over Voltage Protection Thermal Protection Thermal Shutdown Temperature TSD 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. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Guaranteed by design, not subjected to production test. Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8468 Typical Application Circuit AC In ~ CIN 10µF R1 1M R2 1M RD 10 RT8468 C1 4.7µF RVC 3.3k CVC 3.3nF 3 VCC 5 VC R3 1M DRAIN 7 ACTL 6 ZD1 SENSE 4 2 SGND SOURCE 1 Optional RS 2 DF Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 D1 L1 1m COUT LED+ ZD2 48V Optional 100mA LED- is a registered trademark of Richtek Technology Corporation. DS8468-00 April 2013 RT8468 Typical Operating Characteristics 55 Switching Frequency (kHz)1 Switching Frequency (kHz)1 Switching Frequency vs. Temperature Switching Frequency vs. VCC 55 51 47 43 39 35 51 47 43 39 35 0 4 8 12 16 20 24 28 32 36 -50 -25 0 VCC (V) Efficiency vs. VIN 75 100 125 Efficiency vs. Number of LEDs 90 90% 100% 100 17LED 15LED 12LED 10LED 9LED 8LED 95% 95 Efficiency (%) 7LED 6LED 5LED 4LED 3LED 95% 95 Efficiency (%) 50 Temperature (°C) 100% 100 85 85% 80 80% 75 75% 85% 85 80% 80 70 70% 75 75% VIN_AC = 110V to 220V, IOUT = 100mA 65 65% 110 130 150 170 190 70 70% 210 110VAC 180VAC 220VAC 90% 90 VIN_AC = 110V to 220V, IOUT = 100mA 3 230 5 VIN (V) 7 9 11 13 15 17 Number of LEDs (pcs) LED Current vs. VACTL LED Current vs. Output Voltage 115 120 100 110 LED Current (mA) LED Current (mA) 25 80 60 40 105 100 95 20 VIN_AC = 110V, IOUT = 100mA, LED 17 pcs, L = 1mH, VACTL = 0 to 2.5V VIN_AC = 110V, IOUT = 100mA, LED 17 pcs, L = 1mH 90 0 0.5 0.75 1 1.25 1.5 1.75 2 2.25 VACTL (V) Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 2.5 8 13 18 23 28 33 38 43 48 Output Voltage (V) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8468 SENSE Voltage vs. Input Voltage 230 115 220 SENSE Voltage (mV) LED Current (mA) LED Current vs. Input Voltage 120 110 105 100 VIN_AC = 85V to 110V, IOUT = 100mA, LED 17 pcs, L = 1mH 95 85 110 135 160 185 210 235 IOUT = 200mA (L = 0.68mH) 210 IOUT = 100mA (L = 1mH) 200 IOUT = 60mA (L = 1.5mH) 190 VIN_AC = 85V to 110V, LED 17 pcs 180 260 90 120 150 Input Voltage (V) 210 240 270 Input Voltage (V) SENSE Threshold vs. Temperature SENSE Voltage vs. VACTL 220 220 200 210 180 SENSE Threshold (mV) SENSE Voltage (mV) 180 160 140 120 100 80 60 40 VIN_AC = 110V, IOUT = 100mA, LED 17 pcs, L = 1mH, VACTL = 0 to 2.5V 20 200 190 180 170 160 150 IOUT = 100mA 140 0 0 0.52 1.04 1.56 2.08 2.6 -50 -25 0 25 50 VACTL (V) Temperature (°C) GATE Voltage and Inductor Current Power On 75 100 125 VIN (200V/Div) VDrain_Source (100V/Div) VOUT (50V/Div) IL (200mA/Div) IOUT (50mA/Div) VIN_AC = 110V, IOUT = 100mA, 17 LEDs, L = 1mH Time (5μs/Div) Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 VIN_AC = 110V, IOUT = 100mA, 17 LEDs, L = 1mH Time (100ms/Div) is a registered trademark of Richtek Technology Corporation. DS8468-00 April 2013 RT8468 Power Off VIN (200V/Div) VOUT (50V/Div) IOUT (50mA/Div) VIN_AC = 110V, IOUT = 100mA, 17 LEDs, L = 1mH Time (100ms/Div) Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8468 Application Information The RT8468 is a high efficiency PWM Buck LED driver for high brightness LED application. Its high side floating gate driver is used to control the Buck converter with internal MOSFET and regulate the constant output current. The RT8468 can achieve high accuracy LED output current via the average current feedback loop control. The internal sense voltage (220mV typ.) is used to set the average output current. The oscillator frequency is fixed at 47kHz to get better switching performance. Once the average current is set by the external resistor, RS, the output LED current can be dimmed by varying the ACTL voltage. Under Voltage Lockout (UVLO) The RT8468 includes a UVLO feature with 9V hysteresis. The GATE terminal turns on when VIN rises over 17V (typ.). The GATE terminal turns off when VIN falls below 8V (typ.). Setting Average Output Current The output current that flows through the LED string is set by an external resistor, RS, which is connected between the GND and SENSE terminal. The relationship between output current, IOUT, and RS is shown below : 0.22 IOUT = (A) RS Analog Dimming Control The ACTL terminal is driven by an external voltage, VACTL, to adjust the output current to an average value set by RS. The voltage range for VACTL to adjust the output current is from 0.2V to 1.3V. If VACTL becomes larger than 1.3V, the output current value will just be determined by the external resistor, RS. IOUTavg = (0.22V/RS ) × VACTL − 0.2 1.1 Component Selection For component selection, an example is shown below for a typical RT8468 application, where VIN = 110 to 90VAC/ 60Hz, LED output voltage = 30V, and output current = 200mA. The user can follow this procedure to design applications with wider AC voltage input and DC output voltage as well. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 Start-up Resistor Start-up resistor should be chosen not to exceed the maximum start-up current. Otherwise, the RT8468 may latch low and will never start. Start-up current = 130V/R1 for 110VAC regions, 260V/R1 for 220VAC regions. The typical start-up current is 250μA. Input Diode Bridge Rectifier Selection The current rating of the input bridge rectifier is dependent on the VOUT /VIN transformation ratio. The voltage rating of the input bridge rectifier, VBR, on the other hand, is only dependent on the input voltage. Thus, the VBR rating is calculated as below : VBR = 1.2 × ( 2 × VAC(MAX) ) where VAC(MAX) is the maximum input voltage (RMS) and the parameter 1.2 is used for safety margin. For this example : VBR = 1.2 × ( 2 × VAC(MAX) ) = (1.2 × 2 × 110) = 187V If the input source is universal, VBR will reach 466V. In this case, a 500V, 0.5A bridge rectifier can be chosen. Input Capacitor Selection The input capacitor supplies the peak current to the inductor and flattens the current ripple on the input. The low ESR condition is required to avoid increasing power loss. The ceramic capacitor is recommended due to its excellent high frequency characteristic and low ESR. For maximum stability over the entire operating temperature range, capacitors with better dielectric are suggested. The minimum capacitor is given by : VOUT(MAX) × IOUT(MAX) CIN ≥ ⎡( 2 × VAC(MIN) )2 − V 2DC(MIN) ⎤ ×η × fAC ⎣ ⎦ where fAC is the AC input source frequency and η is the efficiency of whole system. Notice that VDC(MIN) is the minimum voltage at bridge rectifier, output and VDC(MIN) should be larger than 2 x VOUT(MAX). For a 90 to 264VAC universal input range, the VDC(MIN) is 90V, therefore the LED string voltage VOUT(MAX) should be less than 45V. is a registered trademark of Richtek Technology Corporation. DS8468-00 April 2013 RT8468 For this particular example : 30 × 0.2 CIN ≥ = 13.7μF 2 ⎡( 2 × 90) − 902 ⎤ × 0.9 × 60 ⎣ ⎦ In addition, the voltage rating of the input filter capacitor, VCIN, should be large enough to handle the input voltage. VCIN ≥ (1.2 × 2 × VAC(MAX) ) = (1.2 × 2 × 110) = 187V Thus, a 22μF / 250V electrolytic capacitor can be chosen in this case. Due to its large ESR, the electrolytic capacitor is not suggested for high current ripple applications. Inductor Selection The inductor value and operating frequency determine the ripple current according to a specific input and output voltage. The ripple current, ΔIL, increases with higher VIN and decreases with higher inductance, as shown in equation below : ⎤ ⎡V ⎤ ⎡ V ΔIL = ⎢ OUT ⎥ × ⎢1− OUT ⎥ f x L V ⎣ ⎦ ⎣ IN ⎦ To optimize the ripple current, the RT8468 operates the Buck converter in BCM (Boundary-Condition Mode). The largest ripple current will occur at the highest VIN. To guarantee that the ripple current stays below the specified value, the inductor value should be chosen according to the following equation : L= = VOUT × TS × (1− D) 2 × IOUT 30 × 20.83μs × (1− 0.333) = 1.04mH 2 × 0.2 where D is the duty cycle and TS is the switching period. Forward Diode Selection When the power switch turns off, the path for the current is through the diode connected between the switch output and ground. This forward biased diode must have minimum voltage drop and recovery time. The reverse voltage rating of the diode should be greater than the maximum input voltage and the current rating should be greater than the maximum load current. In reality, the peak current through the diode is more than the maximum output current. This component current Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 rating should be greater than 1.2 times the maximum load current and the diode reverse voltage rating should be greater than 1.2 times the maximum input voltage, assuming a ± 20% output current ripple. The peak voltage stress of diode is : VD = 1.2 × ( 2 × VAC(MAX) ) = 1.2 × ( 2 × 110) = 187V The current rating of diode is : ID = 1.2 × IOUT,PK = 1.2 × 1.2 × 0.2 = 0.288A If the input source is universal (VIN = 90V to 264V), VD will reach 466V. A 500V, 2A ultra-fast diode can be used in this example. Output Capacitor Selection The selection of COUT is determined by the required ESR to minimize output voltage ripple. Moreover, the amount of bulk capacitance is also a key for COUT selection to ensure that the control loop is stable. Loop stability can be checked by viewing the load transient response. The output voltage ripple, ΔVOUT, is determined by : ΔVOUT = VO × (1− D) 8 × L × COUT × fOSC2 where fOSC is the switching frequency. Multiple capacitors placed in parallel may be needed to meet the ESR and RMS current handling requirement. Dry tantalum, special polymer, aluminum electrolytic and ceramic capacitors are all common selections and available in surface mount packages. Tantalum capacitors have the highest capacitance density, but it is important to only use ones that pass the surge test for use in switching power supplies. Special polymer capacitors offer very low ESR value, but with the trade-off of lower capacitance density. Aluminum electrolytic capacitors have significantly higher ESR, but still can be used in cost-sensitive applications for ripple current rating and long term reliability considerations. Thermal Protection A thermal protection feature is included to protect the RT8468 from excessive heat damage. When the junction temperature exceeds a threshold of 150°C, the thermal protection will turn off the GATE terminal. is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 Soldering Process of Pb-free Package Plating To meet the current RoHS requirements, pure tin is selected to provide forward and backward compatibility with both the current industry standard SnPb-based soldering processes and higher temperature Pb-free processes. In the whole Pb-free soldering processes pure tin is required with a maximum 260°C (<10s) for proper soldering on board, referring to J-STD-020 for more information. Thermal Considerations Maximum Power Dissipation (W)1 RT8468 0.6 Four-Layer PCB 0.5 0.4 0.3 0.2 0.1 0.0 0 25 50 75 100 125 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 Layout Considerations maximum power dissipation can be calculated by the following formula : For best performance of the RT8468, the following 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. The hold up capacitor, C1, must be placed as close as possible to the VCC pin. ` The output capacitor, COUT, must be placed as close as possible to the LED terminal. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For SOP-7 package, the thermal resistance, θJA, is 200.2°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 power ground (PGND) should be connected to a strong ground plane. ` Place the sense resistor RS as close to the SOURCE pin as possible. ` Keep the main current traces as short and wide as possible. PD(MAX) = (125°C − 25°C) / (200.2°C/W) = 0.5W for SOP-7 package ` Place L1, RS, and DF as close to each other as possible. Ambient Temperature (°C) Figure 1. Derating Curve of Maximum Power Dissipation The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 1 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 is a registered trademark of Richtek Technology Corporation. DS8468-00 April 2013 RT8468 Place the Input Capacitor CIN to the DRAIN pin as close as possible CIN VC ACTL RVCC2 VCC CVC COUT CS LED- PGND 3 VCC 4 2 SGND SENSE RS L1 SOURCE RB SENSE LED+ 6 7 D2 RVCC1 RVC 5 DRAIN VIN RACTL C1 DF Place the capacitor C1 as close as possible to the VCC. Place the Output capacitor COUT as close as possible to LED terminal Figure 2. PCB Layout Guide Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8468-00 April 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT8468 Outline Dimension Symbol Dimensions In Millimeters Dimensions In Inches Min. Max. Min. Max. A 4.801 5.004 0.189 0.197 B 3.810 3.988 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.510 0.013 0.020 F 1.194 1.346 0.047 0.053 F1 2.464 2.616 0.097 0.103 H 0.100 0.254 0.004 0.010 I 0.050 0.254 0.002 0.010 J 5.791 6.200 0.228 0.244 M 0.400 1.270 0.016 0.050 7-Lead SOP Plastic 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. www.richtek.com 14 DS8468-00 April 2013