® RT8286 2A, 21V 500kHz Synchronous Step-Down Converter General Description Features The RT8286 is a synchronous step-down regulator with integrated power MOSFETs. It achieves 2A of continuous output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. z 2A Output Current The RT8286 is available in a small SOP-8 (Exposed Pad) package for a compact solution. Internal Soft-Start z 150mΩ Ω/60mΩ Ω Internal Power MOSFET Switch z Internal Compensation Minimizes External Parts Count z Fixed 500kHz Frequency z Thermal Shutdown Protection z Cycle-by-Cycle Over Current Protection z Wide 4.5V to 21V Operating Input Range z Adjustable Output from 0.808V to 15V z Available in an SOP-8 (Exposed Pad) Package z RoHS Compliant and Halogen Free Ordering Information Applications Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. An internal soft-start minimizes external parts count and internal compensation circuitry. RT8286 Package Type SP : SOP-8 (Exposed Pad-Option 2) z z z z Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) z Distributive Power Systems Battery Charger DSL Modems Pre-Regulator for Linear Regulators Pin Configurations Note : Richtek products are : ` ments of IPC/JEDEC J-STD-020. ` (TOP VIEW) RoHS compliant and compatible with the current requireSuitable for use in SnPb or Pb-free soldering processes. Marking Information VIN 8 SW 2 SW 3 BOOT 4 GND GND 7 VCC 6 FB 5 EN 9 SOP-8 (Exposed Pad) RT8286ZSP : Product Number RT8286 ZSPYMDNN YMDNN : Date Code Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8286-02 June 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8286 Typical Application Circuit 1 VIN CIN 22µF Chip Enable BOOT VIN 4 RT8286 SW 5 EN 8, 9 (Exposed Pad) GND 2, 3 CBOOT 100nF L VOUT 6 FB RT VCC 7 R2 R1 COUT CC 0.1µF Table 1. Recommended Components Selection VOUT (V) 5 3.3 2.5 1.8 1.5 1.2 1.05 R1 (kΩ) 75 75 75 5 5 5 5 R2 (kΩ) 14.46 24.32 35.82 4.07 5.84 10.31 16.69 RT (kΩ) 0 0 0 30 39 47 47 L (μH) 4.7 3.6 3.6 2 2 2 1.5 COUT (μF) 22 x 2 22 x 2 22 x 2 22 x 2 22 x 2 22 x 2 22 x 2 Functional Pin Description Pin No. Pin Name 1 VIN 2, 3 SW 4 BOOT 5 EN 6 FB 7 VCC 8, GND 9 (Exposed Pad) Pin Function Supply Input. VIN supplies the power to the IC, as well as the step-down converter switches. Drive VIN with a 4.5V to 21V power source. Bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC. Switch Node. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BOOT to power the high side switch. High Side Gate Drive Boost Input. BOOT supplies the drive for the high side N-MOSFET switch. Connect a 100nF or greater capacitor from SW to BOOT to power the high side switch. Chip Enable (Active High). For automatic start up, connect the EN pin to VIN with a 100kΩ resistor. Feedback Input. FB senses the output voltage to regulate said voltage. Drive FB with a resistive voltage divider from the output voltage. The feedback threshold is 0.808V. Bias Supply. Decouple with 0.1μF to 0.22μF capacitor. The capacitance should be no more than 0.22μF. Ground. The Exposed Pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8286-02 June 2012 RT8286 Function Block Diagram VIN 1.2V Shutdown Comparator + - 5k 1µA 3V + Regulator BOOT - EN Current Sense Amplifier - Ramp Generator Oscillator 500kHz + Lockout Comparator S Q + 1.7V PWM Comparator VCC Reference FB Error + Amplifier Driver R SW GND - 30pF 400k 1pF Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8286-02 June 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8286 Absolute Maximum Ratings z z z z z z z z z z (Note 1) Supply Voltage, VIN ------------------------------------------------------------------------------------------- −0.3V to 26V Switch Voltage, SW ------------------------------------------------------------------------------------------- −0.3V to (VIN + 0.3V) Boot Voltage, BOOT ------------------------------------------------------------------------------------------- (SW − 0.3V) to (SW + 6V) Other Pins -------------------------------------------------------------------------------------------------------- −0.3V to 6V Power Dissipation, PD @ TA = 25°C SOP-8 (Exposed Pad) ---------------------------------------------------------------------------------------- 1.333W Package Thermal Resistance (Note 2) SOP-8 (Exposed Pad), θJA ----------------------------------------------------------------------------------- 75°C/W SOP-8 (Exposed Pad), θJC ---------------------------------------------------------------------------------------------------------------------- 15°C/W Junction Temperature ------------------------------------------------------------------------------------------ 150°C Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------- 260°C Storage Temperature Range --------------------------------------------------------------------------------- −65°C to 150°C ESD Susceptibility (Note 3) HBM (Human Body Model) ----------------------------------------------------------------------------------- 2kV Recommended Operating Conditions z z z (Note 4) Supply Input Voltage Range, VIN --------------------------------------------------------------------------- 4.5V to 21V Junction Temperature Range --------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range --------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 5V, TA = 25°C, unless otherwise specified) Parameter Shutdown Current Quiescent Current Min --- Typ 0 0.7 Max 1 -- Unit μA mA ISHDN IQ Upper Switch On Resistance R DS(ON)1 -- 150 -- mΩ Lower Switch On Resistance R DS(ON)2 -- 60 -- mΩ Switch Leakage Current Limit ILEAK ILIM V EN = 0V, VSW = 0V or 12V V BOOT − VSW = 4.8V -3.9 0 5 10 -- μA A Oscillator Frequency Short Circuit Frequency f SW V FB = 0.75V V FB = 0V 425 -- 500 150 575 -- kHz kHz Maximum Duty Cycle D MAX V FB = 0.8V -- 90 -- % Minimum On Time tON -- 100 -- ns Feedback Voltage V FB 0.796 0.808 0.82 V nA Feedback Current EN Input Threshold Voltage Symbol 4.5V ≤ VIN ≤ 21V Logic-High IFB V IH -2 10 -- 50 5.5 Logic-Low V IL V EN = 2V --- -1 0.4 -- V EN = 0V -- 0 -- V IN Rising 3.8 4 4.2 V -- 400 -- mV Enable Current Under Voltage Lockout Threshold Under Voltage Lockout Threshold Hysteresis V UVLO ΔVUVLO Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 Test Conditions V EN = 0 V EN = 2V, VFB = 1V V μA is a registered trademark of Richtek Technology Corporation. DS8286-02 June 2012 RT8286 Parameter Symbol Test Conditions VCC Regulator VCC Load Regulation ICC = 5mA Min Typ Max Unit -- 5 -- V -- 5 -- % ms Soft-Start Period tSS -- 2 -- Thermal Shutdown TSD -- 150 -- Thermal Shutdown Hysteresis ΔTSD -- 30 -- °C 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 © 2012 Richtek Technology Corporation. All rights reserved. DS8286-02 June 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8286 Typical Operating Characteristics Reference Voltage vs. Input Voltage Efficiency vs. Output Current 100 0.830 90 VIN = 12V 0.825 70 Reference Voltage (V) Efficiency (%) 80 VIN = 21V 60 50 40 30 20 0.820 0.815 0.810 0.805 0.800 0.795 10 VOUT = 1.22V, IOUT = 0A to 2A 0 0.790 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 4 6 8 10 Output Current (A) 14 16 18 20 22 Input Voltage (V) Reference Voltage vs. Temperature Output Voltage vs. Output Current 0.84 1.240 0.83 1.235 0.82 1.230 Output Voltage (V) Reference Voltage (V) 12 0.81 0.80 0.79 0.78 1.225 1.220 1.215 1.210 0.77 1.205 0.76 1.200 VIN = 12V, VOUT = 1.22V, IOUT = 0A to 2A -50 -25 0 25 50 75 100 125 0 0.25 0.5 1 1.25 1.5 1.75 2 Switching Frequency vs. Temperature Switching Frequency vs. Input Voltage 550 550 525 525 Switching Frequency (kHz)1 Switching Frequency (kHz)1 0.75 Output Current (A) Temperature (°C) 500 475 450 425 400 375 500 475 450 425 400 375 VIN = 12V, VOUT = 1.22V, IOUT = 1A VOUT = 1.22V, IOUT = 0.8A 350 350 4 6 8 10 12 14 16 18 20 Input Voltage (V) Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 22 -50 -25 0 25 50 75 100 125 Temperature (°C) is a registered trademark of Richtek Technology Corporation. DS8286-02 June 2012 RT8286 Current Limit vs. Temperature 10 8 8 Current Limit (A) Current Limit (A) Current Limit vs. Input Voltage 10 6 4 6 4 2 2 0 0 VIN = 12V, VOUT = 1.22V 4 6 8 10 12 14 16 18 20 -50 22 0 25 50 75 100 Input Voltage (V) Temperature (°C) Load Transient Response Load Transient Response VOUT (200mV/Div) VOUT (200mV/Div) IOUT (1A/Div) IOUT (1A/Div) VIN = 12V, VOUT = 1.22V, IOUT = 0A to 2A Time (100μs/Div) Output Voltage Ripple Output Voltage Ripple VOUT (50mV/Div) VLX (10V/Div) VLX (10V/Div) IL (2A/Div) IL (2A/Div) VIN = 12V, IOUT = 1A Time (1μs/Div) Copyright © 2012 Richtek Technology Corporation. All rights reserved. June 2012 125 VIN = 12V, VOUT = 1.22V, IOUT = 1A to 2A Time (100μs/Div) VOUT (50mV/Div) DS8286-02 -25 VIN = 12V, IOUT = 2A Time (1μs/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8286 Power On from VIN Power Off from VIN VIN (10V/Div) VIN (10V/Div) VOUT (1V/Div) VOUT (1V/Div) IL (2A/Div) IL (2A/Div) VIN = 12V, VOUT = 1.22V, IOUT = 2A VIN = 12V, VOUT = 1.22V, IOUT = 2A Time (5ms/Div) Time (50ms/Div) Power On from EN Power Off from EN VEN (5V/Div) VEN (5V/Div) VOUT (1V/Div) VOUT (1V/Div) VLX (10V/Div) VLX (10V/Div) IL (2A/Div) VIN = 12V, VOUT = 1.22V, IOUT = 2A Time (2.5ms/Div) Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 IL (2A/Div) VIN = 12V, VOUT = 1.22V, IOUT = 2A Time (50μs/Div) is a registered trademark of Richtek Technology Corporation. DS8286-02 June 2012 RT8286 Application Information The IC is a synchronous high voltage buck converter that can support the input voltage range from 4.5V to 21V and the output current can be up to 2A. Output Voltage Setting The output voltage is set by an external resistive divider according to the following equation : VOUT = VFB ⎛⎜ 1+ R1 ⎞⎟ ⎝ R2 ⎠ where VFB is the feedback reference voltage 0.808V (typical). The resistive divider allows the FB pin to sense a fraction of the output voltage as shown in Figure 1. Soft-Start The IC contains an internal soft-start function to prevent large inrush current and output voltage overshoot when the converter starts up. Soft-start automatically begins once the chip is enabled. During soft-start, the internal soft-start capacitor becomes charged and generates a linear ramping up voltage across the capacitor. This voltage clamps the voltage at the internal reference, causing the duty pulse width to increase slowly and in turn reduce the output surge current. Finally, the internal 1V reference takes over the loop control once the internal ramping-up voltage becomes higher than 1V. The typical soft-start time for this IC is set at 2ms. VOUT Under Voltage Lockout Threshold R1 FB RT8286 R2 GND Figure 1. Output Voltage Setting External Bootstrap Diode Connect a 100nF low ESR ceramic capacitor between the BOOT pin and SW pin as shown in Figure 2. This capacitor provides the gate driver voltage for the high side MOSFET. It is recommended to add an external bootstrap diode between an external 5V and BOOT pin for efficiency improvement when input voltage is lower than 5.5V or duty ratio is higher than 65% .The bootstrap diode can be a low cost one such as IN4148 or BAT54. The external 5V can be a 5V fixed input from system or a 5V output of the IC. Note that the external boot voltage must be lower than 5.5V. 5V BOOT RT8286 100nF The IC includes an input Under Voltage Lockout Protection (UVLO). If the input voltage exceeds the UVLO rising threshold voltage (4.2V), the converter resets and prepares the PWM for operation. If the input voltage falls below the UVLO falling threshold voltage (3.8V) during normal operation, the device stops switching. The UVLO rising and falling threshold voltage includes a hysteresis to prevent noise caused reset. Chip Enable Operation The EN pin is the chip enable input. Pulling the EN pin low (<0.4V) will shut down the device. During shutdown mode, the IC quiescent current drops to lower than 1μA. Driving the EN pin high (>2V, < 5.5V) will turn on the device again. For external timing control (e.g.RC), the EN pin can also be externally pulled high by adding a REN* resistor and CEN* capacitor from the VIN pin, as can be seen from the Figure 5. An external MOSFET can be added to implement digital control on the EN pin when front age system voltage below 2.5V is available, as shown in Figure 3. In this case, a 100kΩ pull-up resistor, REN, is connected between VIN and the EN pin. MOSFET Q1 will be under logic control to pull down the EN pin. SW Figure 2. External Bootstrap Diode Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8286-02 June 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8286 1 VIN REN 100k BOOT VIN CIN 4 CBOOT RT8286 SW 2, 3 L VOUT 5 EN R1 Chip Enable FB 6 Q1 7 VCC COUT RT R2 GND 8, 9 (Exposed Pad) CC Figure 3. Enable Control Circuit for Logic Control with Low Voltage 1 VIN REN 100k BOOT VIN CIN 4 CBOOT RT8286 SW 2, 3 VOUT 5 EN REN2 7 R1 FB 6 VCC CC L COUT RT GND 8, 9 (Exposed Pad) R2 Figure 4. The Resistors can be Selected to Set IC Lockout Threshold To prevent enabling circuit when VIN is smaller than the VOUT target value, a resistive voltage divider can be placed between the input voltage and ground and connected to the EN pin to adjust IC lockout threshold, as shown in Figure 4. For example, if an 8V output voltage is regulated from a 12V input voltage, the resistor REN2 can be selected to set input lockout threshold larger than 8V. Under Output Voltage Protection-Hiccup Mode For the IC, Hiccup Mode of Under Voltage Protection (UVP) is provided. When the FB voltage drops below half of the feedback reference voltage, VFB, the UVP function will be triggered and the IC will shut down for a period of time and then recover automatically. The Hiccup Mode of UVP can reduce input current in short-circuit conditions. Inductor Selection For a given input and output voltage, the inductor value and operating frequency determine the ripple current. The ripple current ΔIL increases with higher VIN and decreases with higher inductance. V V ΔIL = ⎡⎢ OUT ⎤⎥ × ⎡⎢1− OUT ⎤⎥ f × L VIN ⎦ ⎣ ⎦ ⎣ Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 Having a lower ripple current reduces not only the ESR losses in the output capacitors but also the output voltage ripple. Highest efficiency operation is achieved by reducing ripple current at low frequency, but it requires a large inductor to attain this goal. For the ripple current selection, the value of ΔIL = 0.24(IMAX) will be a reasonable starting point. The largest ripple current occurs at the highest VIN. To guarantee that the ripple current stays below a specified maximum, the inductor value should be chosen according to the following equation : ⎡ VOUT ⎤ ⎡ VOUT ⎤ L =⎢ ⎥ × ⎢1 − ⎥ ⎣ f × ΔIL(MAX) ⎦ ⎣ VIN(MAX) ⎦ The inductor's current rating (caused a 40°C temperature rising from 25°C ambient) should be greater than the maximum load current and its saturation current should be greater than the short circuit peak current limit. Please see Table 2 for the inductor selection reference and it is highly recommended to keep inductor value as close as possible to the recommended inductor values for each Vout as shown in Table 1. is a registered trademark of Richtek Technology Corporation. DS8286-02 June 2012 RT8286 Table 2. Suggested Inductors for Typical Application Circuit Component Supplier Series Dimensions (mm) TDK VLF10045 10 x 9.7 x 4.5 TDK SLF12565 12.5 x 12.5 x 6.5 TAIYO YUDEN NR8040 8x8x4 Input and Output Capacitors Selection The input capacitance, C IN, is needed to filter the trapezoidal current at the source of the high side MOSFET. To prevent large ripple current, a low ESR input capacitor sized for the maximum RMS current should be used. The RMS current is given by : V IRMS = IOUT(MAX) OUT VIN This formula has a maximum at VIN = 2VOUT, where IRMS = IOUT / 2. This simple worst case condition is commonly used for design because even significant deviations do not offer much relief. Choose a capacitor rated at a higher temperature than required. Several capacitors may also be paralleled to meet size or height requirements in the design. For the input capacitor, one 22μF low ESR ceramic capacitors are recommended. For the recommended capacitor, please refer to Table 3 for more detail. VIN −1 VOUT Table 3. Suggested Capacitors for CIN and COUT Location Component Supplier Part No. Capacitance (μF) Case Size CIN MURATA GRM32ER71C226M 22 1210 CIN TDK C3225X5R1C226M 22 1210 COUT MURATA GRM31CR60J476M 47 1206 COUT TDK C3225X5R0J476M 47 1210 COUT MURATA GRM32ER71C226M 22 1210 COUT TDK C3225X5R1C226M 22 1210 The selection of COUT is determined by the required ESR to minimize 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 ripple, ΔVOUT, is determined by : 1 ⎤ ΔVOUT ≤ ΔIL ⎡⎢ESR + 8fCOUT ⎦⎥ ⎣ Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. However, care must be taken when these capacitors are used at input and output. When a ceramic capacitor is used at the input Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8286-02 June 2012 and the power is supplied by a wall adapter through long wires, a load step at the output can induce ringing at the input, VIN. At best, this ringing can couple to the output and be mistaken as loop instability. At worst, a sudden inrush of current through the long wires can potentially cause a voltage spike at VIN large enough to damage the part. Thermal Shutdown Thermal shutdown is implemented to prevent the chip from operating at excessively high temperatures. When the junction temperature is higher than 150°C, the whole chip is shutdown. The chip is automatically re-enable when the junction temperature cools down by approximately 30 degrees. is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT8286 EMI Consideration Figure 5. Another method is by adding a resistor in series with the bootstrap capacitor, CBOOT, but this method will decrease the driving capability to the high side MOSFET. It is strongly recommended to reserve the R-C snubber during PCB layout for EMI improvement. Moreover, reducing the SW trace area and keeping the main power in a small loop will be helpful on EMI performance. For detailed PCB layout guide, please refer to the section Layout Considerations. Since parasitic inductance and capacitance effects in PCB circuitry would cause a spike voltage on SW pin when high side MOSFET is turned-on/off, this spike voltage on SW may impact on EMI performance in the system. In order to enhance EMI performance, there are two methods to suppress the spike voltage. One way is by placing an R-C snubber (RS*, CS*) between SW and GND and locating them as close as possible to the SW pin, as shown in 1 VIN REN* BOOT VIN CIN CBOOT RT8286 SW 5 4 L 2, 3 VOUT CS* EN COUT R1 RS * CEN* 7 VCC CC RT FB 6 GND 8, 9 (Exposed Pad) R2 * : Optional Figure 5. Reference Circuit with Snubber and Enable Timing Control 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 : 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 SOP-8 (Exposed Pad) packages, the thermal resistance, θJA, is 75°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 maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 6 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. 1.4 Maximum Power Dissipation (W) Thermal Considerations Four-Layer PCB 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 6. Derating Curve of Maximum Power Dissipation PD(MAX) = (125°C − 25°C) / (75°C/W) = 1.333W for SOP-8 (Exposed Pad) package Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 is a registered trademark of Richtek Technology Corporation. DS8286-02 June 2012 RT8286 Layout Considerations ` Connect feedback network behind the output capacitors. Keep the loop area small. Place the feedback components near the IC. ` Connect all analog grounds to a common node and then connect the common node to the power ground behind the output capacitors. ` An example of PCB layout guide is shown in Figure 7. for reference. Follow the PCB layout guidelines for optimal performance of the IC. ` Keep the traces of the main current paths as short and wide as possible. ` Put the input capacitor as close as possible to the device pins (VIN and GND). ` SW node is with high frequency voltage swing and should be kept at small area. Keep analog components away from the SW node to prevent stray capacitive noise pickup. Place the input and output capacitors as close to the IC as possible. GND CIN SW should be connected to inductor by wide and short trace and keep sensitive components away from this trace. L CBOOT VIN 8 SW 2 SW 3 BOOT 4 VOUT GND GND 7 VCC 6 FB 5 EN 9 RT R2 R1 Place the feedback as close to the IC as possible. VOUT COUT GND Figure 7. PCB Layout Guide Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS8286-02 June 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT8286 Outline Dimension H A M EXPOSED THERMAL PAD (Bottom of Package) Y J X B F C I D Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 4.000 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 H 0.170 0.254 0.007 0.010 I 0.000 0.152 0.000 0.006 J 5.791 6.200 0.228 0.244 M 0.406 1.270 0.016 0.050 X 2.000 2.300 0.079 0.091 Y 2.000 2.300 0.079 0.091 X 2.100 2.500 0.083 0.098 Y 3.000 3.500 0.118 0.138 Option 1 Option 2 8-Lead SOP (Exposed Pad) 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 DS8286-02 June 2012