® RT2805A 5A, 36V, 500kHz Current Mode Asynchronous Step-Down Converter General Description Features The RT2805A is a current mode asynchronous step-down converter that achieves excellent load and line regulation. Over a wide input voltage range from 5.5V to 36V and supports output current up to 5A. The Current mode operation provides fast transient response and eases loop stabilization. An adjustable soft-start reduces the stress on the input source at startup. In shutdown mode, the regulator draws only 25μA of supply current. The RT2805A requires a minimum number of readily available external components, providing a compact solution. The RT2805A provides protection functions inducing input under voltage lockout, cycle-by-cycle current limit, short circuit protection and thermal shutdown protection. The RT2805A is available in the SOP-8 (Exposed Pad) package. Applications Ordering Information RT2805A Package Type SP : SOP-8 (Exposed Pad-Option 2) Distributive Power Systems Battery Charger DSL Modems Pre-regulator for Linear Regulators Marking Information Lead Plating System G : Green (Halogen Free and Pb Free) RT2805AGSP : Product Number RT2805A GSPYMDNN Note : Richtek products are : 5A Output Current Wide Operating Input Range 5.5V to 36V Adjustable Output Voltage from 1.222V to 26V High Efficiency up to 90% Internal Compensation Minimizes External Parts Count Internal Soft-Start 110mΩ Ω Internal Power MOSFET Switch 25μ μA Shutdown Mode Fixed 500kHz Frequency Thermal Shutdown Cycle-by-Cycle Current Limit Available In an SOP-8 (Exposed Pad) Package RoHS Compliant and Halogen Free YMDNN : Date Code RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit VIN VIN CIN BOOT RT2805A L1 SW D1 Chip Enable EN VOUT R1 COUT FB GND Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 CBOOT R2 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT2805A Pin Configurations (TOP VIEW) BOOT NC 2 NC 3 FB 4 GND 9 8 SW 7 VIN 6 GND 5 EN SOP-8 (Exposed Pad) Functional Pin Description Pin No. Pin Name Pin Function BOOT Bootstrap Input for High Side Gate Driver. Connect a 10nF or greater capacitor from SW to BOOT to power the high side switch. 2, 3 NC No Internal Connection. 4 FB Feedback Input. The feedback threshold is 1.222V. 5 EN Enable Input. EN is a digital input that turns the regulator on or off. Drive EN higher than 1.4V to turn on the regulator, lower than 0.4V to turn it off. For automatic startup, leave EN unconnected. 6, 9 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 7 VIN Power Input. A suitable large capacitor should be connected from the VIN to GND to eliminate noise on the input to the IC. 8 SW Switch Node. Note that a capacitor is required from SW to BOOT to power the high side switch. 1 Function Block Diagram VIN Current Sense Amplifier - Ramp Generator + BOOT EN Regulator Oscillator 500kHz S + Reference FB 12k Error + Amplifier - 400k 30pF Q Driver R Current Comparator SW Bootstrap Control GND 13pF Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A Operation The RT2805A is a constant frequency, current mode asynchronous step-down converter. In normal operation, the high side N-MOSFET is turned on when the S-R latch is set by the oscillator and is turned off when the current comparator resets the S-R latch. While the N-MOSFET is turned off, the inductor current conducts through the external diode. Error Amplifier The error amplifier adjusts its output voltage by comparing the feedback signal (V FB) with the internal 1.222V reference. When the load current increases, it causes a drop in the feedback voltage relative to the reference, the error amplifier's output voltage then rises to allow higher inductor current to match the load current. Oscillator The internal oscillator runs at fixed frequency 500kHz. In short circuit condition, the frequency is reduced to 150kHz for low power consumption. Enable The converter is turned on when the EN pin is higher than 1.4V and turned off when the EN pin is lower than 0.4V. When the EN pin is open, it will be pulled up to logic-high by 1μA current internally. Soft-Start (SS) An internal current source charges an internal capacitor to build a soft-start ramp voltage. The FB voltage will track the internal ramp voltage during soft-start interval. The typical soft-start time is 5ms. Thermal Shutdown The over temperature protection function will shut down the switching operation when the junction temperature exceeds 150°C. Once the junction temperature cools down by approximately 30°C, the converter will automatically resume switching. Internal Regulator The regulator provides low voltage power to supply the internal control circuits and the bootstrap power for high side gate driver. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT2805A Absolute Maximum Ratings (Note 1) Supply Voltage, VIN ----------------------------------------------------------------------------------------Switching Voltage, SW ------------------------------------------------------------------------------------BOOT Voltage ------------------------------------------------------------------------------------------------Other Pins -----------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOP-8 (Exposed Pad), θJA --------------------------------------------------------------------------------SOP-8 (Exposed Pad), θJC -------------------------------------------------------------------------------Junction Temperature ---------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------Storage Temperature Range ------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) --------------------------------------------------------------------------------- Recommended Operating Conditions −0.3V to 40V −0.3V to (VIN + 0.3V) (VSW − 0.3V) to (VSW + 6V) −0.3V to 6V 2.04W 49°C/W 15°C/W 150°C 260°C −65°C to 150°C 2kV (Note 4) Supply Voltage, VIN ----------------------------------------------------------------------------------------- 5.5V to 36V Junction Temperature Range ------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 12V, TA = −40°C to 85°C unless otherwise specified) Parameter Symbol Reference Voltage VREF High Side Switch-On Resistance RDS(ON)1 Low Side Switch-On Resistance Current Limit Oscillator Frequency Short Circuit Frequency Maximum Duty Cycle Minimum On-Time Under Voltage Lockout Threshold Rising Under Voltage Lockout Threshold Hysteresis Logic-High EN Threshold Voltage Logic-Low Enable Pull Up Current Test Conditions Typ Max T A = 25°C 1.202 1.222 1.239 I OUT = 0A to 5A 1.196 1.222 1.245 Bias Gate Driver at VIN = 5.5V -- RDS(ON)2 Bias Gate Driver at VIN = 5.5V I LIM f OSC Voltage Mode Test VFB = 0.8V VFB = 0V DMAX t ON Unit V 110 230 m -- 10 15 6 400 -- 7.5 500 150 9 600 -- A kHz kHz VFB = 0.8V Come from Maximum Duty Cycle 85 -- 90 100 95 150 % ns VIN Rising, Check Switching -- 5.2 5.5 V VIN Falling, Check Switching -- 700 -- mV 1.4 --- --1 -0.4 -- A --3 25 0.6 5 -1 10 A mA ms -- 160 -- C VIH VIL Let EN = 1.4V, Check I Q Let EN = 0.4V, Check I Q Shutdown Current Quiescent Current Soft-Start Period I SHDN IQ VEN = 0V VEN = 2V, VFB = 1.5V Thermal Shutdown T SD Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 Min V is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A 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. The EVB board copper area is 70mm2. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT2805A Typical Application Circuit VIN 5.5V to 36V Chip Enable 7 CIN 4.7µF/ 50V x 2 BOOT VIN RT2805A 5 EN 1 SW 8 D1 B550A Open = Automatic Startup 6, 9 (Exposed Pad) CBOOT 10nF L1 VOUT CFF R1 COUT FB 4 GND R2 Table 1. Recommended Component Selection VOUT (V) R1 (k) R2 (k) CFF (pF) L (H) COUT (F) 2.5 100 100 82 6.8 22 x 2 3.3 100 58.6 82 10 22 x 2 5 100 31.6 82 15 22 x 2 8 100 18 82 22 22 x 2 Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A Typical Operating Characteristics Efficiency vs. Output Current Reference Voltage vs. Input Voltage 100 1.230 90 VIN = 12V VIN = 32V VIN = 36V 70 Reference Voltage (V) Efficiency (%) 80 60 50 40 30 20 10 VOUT = 5V 0 0 1 2 3 4 1.226 1.222 1.218 1.214 VOUT = 5V, IOUT = 0A 1.210 4 5 8 12 16 Output Current (A) 24 28 32 36 Output Voltage vs. Output Current 5.008 1.228 5.004 5.000 1.226 Output Voltage (V) Reference Voltage (V) Reference Voltage vs. Temperature 1.230 1.224 1.222 VIN = 12V VIN = 24V VIN = 36V 1.220 1.218 1.216 1.214 VIN = 36V VIN = 24V VIN = 12V 4.996 4.992 4.988 4.984 4.980 4.976 4.972 4.968 1.212 IOUT = 0A 1.210 -50 -25 0 25 50 75 100 4.964 VOUT = 5V 4.960 0 125 1 2 3 4 Frequency vs. Input Voltage Frequency vs. Temperature 540 530 530 520 520 Frequency (kHz) 540 510 500 490 480 470 510 500 490 480 VIN = 12V VIN = 24V VIN = 36V 470 460 460 450 450 VOUT = 5V, IOUT = 0A 440 4 8 12 16 20 24 28 32 Input Voltage (V) Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 5 Output Current (A) Temperature (°C) Frequency (kHz) 20 Input Voltage (V) VOUT = 5V 440 36 -50 -25 0 25 50 75 100 125 Temperature (°C) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT2805A Shutdown Current vs. Input Voltage 60 11 50 Shutdown Current (μA) Current Limit (A) Current Limit vs. Temperature 12 10 9 8 7 6 VIN = 12V 5 -50 -25 0 25 50 75 100 40 30 20 10 VEN = 0V 0 4 125 8 12 16 20 24 28 Temperature (°C) Input Voltage (V) Quiescent Current vs. Temperature Load Transient Response 32 36 1 Quiescent Current (mA) 0.9 VOUT (200mV/Div) 0.8 0.7 0.6 VIN = 36V VIN = 24V VIN = 12V 0.5 0.4 0.3 0.2 IOUT (2A/Div) 0.1 VIN = 12V, VOUT = 5V, IOUT = 0.2A to 5A 0 -50 -25 0 25 50 75 100 Time (100μs/Div) 125 Temperature (°C) Switching Load Transient Response VOUT (200mV/Div) VOUT (10mV/Div) VSW (10V/Div) IOUT (2A/Div) VIN = 12V, VOUT = 5V, IOUT = 2.5A to 5A Time (100μs/Div) Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 IL (5A/Div) VIN = 12V, VOUT = 5V, IOUT = 5A Time (1μs/Div) is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A Power On from EN Power Off from EN VEN (5V/Div) VEN (5V/Div) VOUT (5V/Div) VOUT (5V/Div) IL (5A/Div) IL (5A/Div) VIN = 12V, VOUT = 5V, IOUT = 5A Time (2.5ms/Div) Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 VIN = 12V, VOUT = 5V, IOUT = 5A Time (2.5ms/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT2805A Application Information The RT2805A is an asynchronous high voltage buck converter that can support the input voltage range from 5.5V to 32V and the output current can be up to 5A. Output Voltage Setting The resistive divider allows the FB pin to sense the output voltage as shown in Figure 1. VOUT R1 FB RT2805A R2 GND Figure 1. Output Voltage Setting The output voltage is set by an external resistive divider according to the following equation : VOUT = VREF 1 R1 R2 Where VREF is the reference voltage (1.222V typ.). Soft-Start The RT2805A contains an internal soft-start clamp that gradually raises the output voltage. The typical soft-start time is 5ms. Chip Enable Operation The EN pin is the chip enable input. Pull the EN pin low (<0.4V) will shutdown the device. During shutdown mode, the RT2805A quiescent current drops to lower than 25μA. Drive the EN pin to high (>1.4V, <5.5V) will turn on the device again. If the EN pin is open, it will be pulled to high by internal circuit. For external timing control (e.g.RC), the EN pin can also be externally pulled to High by adding a 100kΩ or greater resistor from the VIN pin (see Figure 3). 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. Where R1 = 100kΩ. V V IL = OUT 1 OUT VIN f L External Bootstrap Diode Having a lower ripple current reduces not only the ESR losses in the output capacitors but also the output voltage ripple. High frequency with small ripple current can achieve highest efficiency operation. However, it requires a large inductor to achieve this goal. Connect a 10nF low ESR ceramic capacitor between the BOOT pin and SW pin. 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 RT2805A. 5V VOUT VOUT L = 1 VIN(MAX) f I L(MAX) BOOT RT2805A 10nF SW Figure 2. External Bootstrap Diode Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 For the ripple current selection, the value of ΔIL = 0.2(IMAX) will be a reasonable starting point. The largest ripple current occurs at the highest VIN. To guarantee that the ripple current stays below the specified maximum, the inductor value should be chosen according to the following equation : 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. is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A Table 2. Suggested Inductors for Typical Application Circuit Component Dimensions Series Supplier (mm) TAIYO NR10050 10 x 9.8 x 5 YUDEN TDK SLF12565 12.5 x 12.5 x 6.5 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 a minimum voltage drop and recovery times. Schottky diode is recommended and it should be able to handle those current. The reverse voltage rating of the diode should be greater than the maximum input voltage, and current rating should be greater than the maximum load current. For more detail please refer to Table 4. CIN and COUT 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 VIN IRMS = IOUT(MAX) OUT 1 VIN VOUT This formula has a maximum at VIN = 2VOUT, where IRMS = I OUT / 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, two 4.7μF low ESR ceramic capacitors are recommended. For the recommended capacitor, please refer to table 3 for more detail. 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 as described in a later section. Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 The output ripple, ΔVOUT , is determined by : 1 VOUT IL ESR 8fCOUT The output ripple will be highest at the maximum input voltage since ΔIL increases with input voltage. 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 available in surface mount packages. Special polymer capacitors offer very low ESR value. However, it provides lower capacitance density than other types. Although Tantalum capacitors have the highest capacitance density, it is important to only use types that pass the surge test for use in switching power supplies. Aluminum electrolytic capacitors have significantly higher ESR. However, it can be used in cost-sensitive applications for ripple current rating and long term reliability considerations. Ceramic capacitors have excellent low ESR characteristics but can have a high voltage coefficient and audible piezoelectric effects. The high Q of ceramic capacitors with trace inductance can also lead to significant ringing. 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 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. A sudden inrush of current through the long wires can potentially cause a voltage spike at VIN large enough to damage the part. Checking Transient Response The regulator loop response can be checked by looking at the load transient response. Switching regulators take several cycles to respond to a step in load current. When a load step occurs, VOUT immediately shifts by an amount equal to ΔILOAD (ESR) also begins to charge or discharge COUT generating a feedback error signal for the regulator to return VOUT to its steady-state value. During this recovery time, VOUT can be monitored for overshoot or ringing that would indicate a stability problem. is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT2805A is to add a resistor in series with the bootstrap capacitor, CBOOT. But this method will decrease the driving EMI Consideration 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 is to place an R-C snubber between SW and GND and make them as close as possible to the SW pin (see Figure 3). Another method 7 VIN REN* BOOT VIN CIN RT2805A 5 EN 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 of Layout Consideration. 1 CBOOT L SW 8 VOUT RS* CEN* 6, 9 (Exposed Pad) RBOOT* CS* GND D B550C R1 COUT FB 4 R2 * : Optional Figure 3. Reference Circuit with Snubber and Enable Timing Control Thermal Considerations For continuous operation, do not exceed the maximum operation junction temperature. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula : PD(MAX) = (TJ(MAX) − TA ) / θJA Where T J(MAX) is the maximum operation junction temperature , TA is the ambient temperature and the 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 PSOP-8 package, the thermal resistance θJA is 75°C/W on the standard JEDEC 51-7 four-layers thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following formula : P D(MAX) = (125°C − 25°C) / (75°C/W) = 1.333W (min.copper area PCB layout) PD(MAX) = (125°C − 25°C) / (49°C/W) = 2.04W (70mm2 copper area PCB layout) Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 12 The thermal resistance θJA of SOP-8 (Exposed Pad) is determined by the package architecture design and the PCB layout design. However, the package architecture design had been designed. If possible, it's useful to increase thermal performance by the PCB layout copper design. The thermal resistance θJA can be decreased by adding copper area under the exposed pad of SOP-8 (Exposed Pad) package. As shown in Figure 4, the amount of copper area to which the SOP-8 (Exposed Pad) is mounted affects thermal performance. When mounted to the standard SOP-8 (Exposed Pad) pad (Figure 4a), θJA is 75°C/W. Adding copper area of pad under the SOP-8 (Exposed Pad) (Figure 4.b) reduces the θJA to 64°C/W. Even further, increasing the copper area of pad to 70mm2 (Figure 4.e) reduces the θJA to 49°C/W. The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 5 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power dissipation allowed. is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A 2.2 Four Layer PCB Power Dissipation (W) 2.0 1.8 Copper Area 70mm2 50mm2 30mm2 10mm2 Min.Layout 1.6 1.4 1.2 1.0 0.8 (d) Copper Area = 50mm2, θJA = 51°C/W 0.6 0.4 0.2 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 5. Derating Curve of Maximum Power Dissipation (e) Copper Area = 70mm2, θJA = 49°C/W Figure 4. Thermal Resistance vs. Copper Area Layout Design Layout Consideration (a) Copper Area = (2.3 x 2.3) mm2, θJA = 75°C/W Follow the PCB layout guidelines for optimal performance of the RT2805A. 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 (b) Copper Area = 10mm2, θJA = 64°C/W be kept at small area. Keep analog components away from the SW node to prevent stray capacitive noise pickup. Connect feedback network behind the output capacitors. Keep the loop area small. Place the feedback components near the RT2805A. Connect all analog grounds to a common node and then connect the common node to the power ground behind the output capacitors. (c) Copper Area = 30mm2, θJA = 54°C/W Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS2805A-03 August 2015 An example of PCB layout guide is shown in Figure 6 for reference. is a registered trademark of Richtek Technology Corporation. www.richtek.com 13 RT2805A SW should be connected to inductor by wide and short trace. Keep sensitive components away from this trace. SW VOUT CBOOT R1 COUT L1 BOOT VOUT COUT SW 8 NC 2 NC 3 FB 4 GND 9 7 VIN 6 GND 5 EN R2 The feedback components should be connected as close to the device as possible. D1 CIN CIN Input capacitor should be placed as close to the IC as possible. GND Figure 6. PCB Layout Guide Table 3. Suggested Capacitors for CIN and COUT Location Component Supplier Part No. Capacitance (F) Case Size CIN MURATA GRM32ER71H475K 4.7 1206 CIN TAIYO YUDEN UMK325BJ475MM-T 4.7 1206 Table 4. Suggested Diode Component Supplier Series VRRM (V) IOUT (A) Package DIODES B550C 50 5 SMC PANJIT SK55 50 5 SMC Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 14 is a registered trademark of Richtek Technology Corporation. DS2805A-03 August 2015 RT2805A 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 14F, No. 8, Tai Yuen 1st 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. DS2805A-03 August 2015 www.richtek.com 15