® RT9715CA 90mΩ Ω, 1.5A High-Side Power Switches with Flag General Description Features The RT9715CA is a cost-effective, low-voltage, single N-MOSFET high-side Power Switch IC for USB application. Low switch-on resistance (typ. 90mΩ) and low supply current (typ. 50μA) are realized in this IC. The RT9715CA integrates an over-current protection circuit, a short fold back circuit, a thermal shutdown circuit and an under-voltage lockout circuit for overall protection. Besides, a flag output is available to indicate fault conditions to the local USB controller. Furthermore, the chip also integrates an embedded delay function to prevent miss-operation from happening due to inrush-current. The RT9715CA is an ideal solution for USB power supply and can support in package SOT-23-5. Applications Ordering Information RT9715CA Package Type B : SOT-23-5 Lead Plating System G : Green (Halogen Free and Pb Free) Note : Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 90mΩ Ω (typ.) N-MOSFET Switch Operating Range : 2.7V to 5.5V Reverse Blocking Current Under Voltage Lockout Deglitched Fault Report (FLG) Thermal Protection with Foldback Over Current Protection Short Circuit Protection UL Approved−E219878 Nemko Approved−NO49621 RoHS Compliant and Halogen Free USB Peripherals Notebook PCs Pin Configurations (TOP VIEW) VIN EN 5 4 2 3 VOUT GND FLG SOT-23-5 Marking Information 4R= : Product Code 4R=DNN DNN : Date Code Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS9715CA-00 April 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT9715CA Typical Application Circuit Pull-Up Resistor (10k to 100k) USB Controller Supply Voltage 2.7V to 5.5V CIN 1µF RT9715CA VOUT EN VBUS + Enable Over -Current FLG VIN COUT 10µF GND D+ DGND 150µF Ferrite Beads Data μF aluminum electrolytic or tantalum between VOUT and GND is strongly recommended to meet the Note : A low-ESR 150μ 330mV maximum droop requirement in the hub VBUS. (see Application Information Section for further details) Functional Pin Description Pin No. Pin Name Pin Function 1 VOUT Output Voltage. 2 GND Ground. 3 FLG Fault FLAG Output. 4 EN Chip Enable (Active High). 5 VIN Power Input Voltage. Function Block Diagram VIN EN Bias UVLO Oscillator Charge Pump Thermal Protection Current Limiting Gate Control Output Voltage Detection VOUT FLG Delay GND Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS9715CA-00 April 2015 RT9715CA Absolute Maximum Ratings (Note 1) Supply Input Voltage, VIN -------------------------------------------------------------------------------------------- 6V EN Voltage -------------------------------------------------------------------------------------------------------------- −0.3V to 6V FLAG Voltage ---------------------------------------------------------------------------------------------------------- 6V Power Dissipation, PD @ TA = 25°C SOT-23-5 ---------------------------------------------------------------------------------------------------------------- 0.3W Package Thermal Resistance (Note 2) SOT-23-5, θJA ----------------------------------------------------------------------------------------------------------- 250°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 Mode) ------------------------------------------------------------------------------------------ 2kV MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V Recommended Operating Conditions (Note 4) Supply Input Voltage, VIN -------------------------------------------------------------------------------------------- 2.7V to 5.5V EN Voltage -------------------------------------------------------------------------------------------------------------- 0V to 5.5V Junction Temperature Range ---------------------------------------------------------------------------------------- −40°C to 100°C Ambient Temperature Range ---------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 5V, CIN = 1μF, COUT = 10μF, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Input Quiescent Current IQ Switch On, VOUT = Open -- 50 70 Input Shutdown Current ISHDN Switch Off, V OUT = Open -- 0.1 1 VIN = 5V, IOUT = 1.3A -- 90 110 m 1.5 2 2.8 A A Switch On Resistance A Current Limit ILIM VOUT = 4V Short Current ISC_FB VOUT = 0V, Measured Prior to Thermal Shutdown -- 1.4 -- Logic_High Voltage VIH VIN = 2.7V to 5.5V 2 -- -- Logic_Low Voltage VIL VIN = 2.7V to 5.5V -- -- 0.8 EN Input Current IEN VEN = 5V -- 0.01 0.1 A Output Leakage Current ILEAKAGE VEN = 0V, RLOAD = 0 -- 0.5 1 A Output Turn-On Rise Time TON_RISE 10% to 90% of VOUT Rising -- 200 -- s FLG Output Resistance RFLG I SINK = 1mA -- 20 -- FLG Off Current IFLG_OFF VFLG = 5V -- 0.01 1 A FLG Delay Time TD From fault condition to FLG assertion 5 12 20 ms EN Threshold Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS9715CA-00 April 2015 V is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT9715CA Parameter Symbol Test Conditions Min Typ Max Unit 1.3 1.7 -- V Under-Voltage Lockout VUVLO VIN Rising Under-Voltage Hysteresis VUVLO VIN Decreasing -- 0.1 -- V Thermal Shutdown Protection TSD VOUT > 1V -- 120 -- °C VOUT = 0V -- 100 -- °C VOUT = 0V -- 20 -- °C Thermal Shutdown Hysteresis 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 low effective thermal conductivity single-layer test board per JEDEC 51-3. 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. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS9715CA-00 April 2015 RT9715CA Typical Operating Characteristics On Resistance vs. Temperature On Resistance vs. Input Voltage 108 125 IOUT = 2A 120 104 On Resistance (mΩ) On Resistance (mΩ) 106 102 100 98 96 94 VIN = 5V, IOUT = 2A 115 110 105 100 95 90 85 80 92 75 70 90 2.7 3.1 3.5 3.9 4.3 4.7 5.1 -40 5.5 -25 -10 5 No Load 59 Quiescent Current (µA) Quiescent Current (µA) 60 56 54 52 50 48 46 44 42 VIN = 5V, No Load 58 57 56 55 54 53 52 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -40 -25 -10 5 20 35 50 65 80 95 110 Temperature (°C) Input Voltage (V) Shutdown Current vs. Temperature Shutdown Current vs. Input Voltage 1.0 No Load 0.9 Shutdown Current (µA)1 Shutdown Current (µA)1 80 50 2.7 0.9 65 51 40 1.0 50 Quiescent Current vs. Temperature Quiescent Current vs. Input Voltage 58 35 Temperature (°C) Input Voltage (V) 60 20 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 VIN = 5V 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 Input Voltage (V) Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS9715CA-00 April 2015 5.5 -40 -25 -10 5 20 35 50 65 80 95 110 Temperature (°C) is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT9715CA Output Voltage vs. Output Current UVLO Threshold vs. Temperature 6.0 2.2 5.5 VIN = 5V 2.0 UVLO Threshold (V) Output Voltage (V) 5.0 4.5 4.0 VIN = 3.3V 3.5 3.0 2.5 2.0 1.5 1.8 Rising 1.6 Falling 1.4 1.0 1.2 0.5 0.0 1.0 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 -40 -25 -10 5 2.4 2.40 2.3 2.35 2.2 2.30 Current Limit (A) Current Limit (A) 35 50 65 80 95 110 Current Limit vs. Temperature Current Limit vs. Input Voltage 2.1 2.0 1.9 1.8 1.7 VIN = 5V 2.25 2.20 2.15 2.10 2.05 1.6 2.00 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -40 -25 -10 5 20 35 50 65 80 95 110 Temperature (°C) Input Voltage (V) Short Current vs. Input Voltage Short Current vs. Temperature 2.0 2.0 1.9 1.9 1.8 1.8 Short Current (A) Short Current (A) 20 Temperature (°C) Output Current (A) 1.7 1.6 1.5 1.4 1.3 1.7 1.6 1.5 1.4 1.3 1.2 1.2 1.1 1.1 1.0 VIN = 5V 1.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 Input Voltage (V) Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 5.5 -40 -25 -10 5 20 35 50 65 80 95 110 Temperature (°C) is a registered trademark of Richtek Technology Corporation. DS9715CA-00 April 2015 RT9715CA FLG Delay Time vs. Temperature 12.0 11 11.5 FLG Delay Time (ms) FLG Delay Time (ms) FLG Delay Time vs. Input Voltage 12 10 9 8 7 6 5 VIN = 5V 11.0 10.5 10.0 9.5 9.0 8.5 4 8.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -40 -25 -10 5 20 35 50 65 Input Voltage (V) Temperature (°C) Power On from VIN Power Off from VIN EN = 5V, No Load VIN (2V/Div) VOUT (2V/Div) VOUT (2V/Div) Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS9715CA-00 April 2015 95 110 EN = 5V, No Load VIN (2V/Div) Time (25ms/Div) 80 Time (25ms/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT9715CA Applications Information The RT9715CA is a single N-MOSFET high-side power switches with enable input, optimized for self-powered and bus-powered Universal Serial Bus (USB) applications. The RT9715CA is equipped with a charge pump circuitry to drive the internal N-MOSFET switch; the switch's low RDS(ON), 90mΩ, meets USB voltage drop requirements; and a flag output is available to indicate fault conditions to the local USB controller. Input and Output VIN (input) is the power source connection to the internal circuitry and the drain of the MOSFET. VOUT (output) is the source of the MOSFET. In a typical application, current flows through the switch from VIN to VOUT toward the load. If VOUT is greater than VIN, current will flow from VOUT to VIN since the MOSFET is bidirectional when on. Unlike a normal MOSFET, there is no parasitic body diode between drain and source of the MOSFET, the RT9715CA prevents reverse current flow if VOUT is externally forced to a higher voltage than VIN when the chip is disabled (VEN < 0.8V). S D S D G RT9715CA Chip Enable Input The switch will be disabled when the EN pin is in a logic low condition. During this condition, the internal circuitry and MOSFET will be turned off, reducing the supply current to 0.1μA typical. Floating the EN may cause unpredictable operation. EN should not be allowed to go negative with respect to GND. The EN pin may be directly tied to VIN (GND) to keep the part on. Soft-Start for Hot Plug-In Applications In order to eliminate the upstream voltage droop caused by the large inrush current during hot-plug events, the Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 Fault Flag The RT9715CA series provides a FLG signal pin which is an N-Channel open drain MOSFET output. This open drain output goes low when current limit or the die temperature exceeds 120°C approximately. The FLG output is capable of sinking a 10mA load to typically 200mV above ground. The FLG pin requires a pull-up resistor, this resistor should be large in value to reduce energy drain. A 100kΩ pull-up resistor works well for most applications. In the case of an over-current condition, FLG will be asserted only after the flag response delay time, tD, has elapsed. This ensures that FLG is asserted only upon valid over-current conditions and that erroneous error reporting is eliminated. For example, false over-current conditions may occur during hot-plug events when extremely large capacitive loads are connected and causes a high transient inrush current that exceeds the current limit threshold. The FLG response delay time tD is typically 12ms. Under-Voltage Lockout Under-voltage lockout (UVLO) prevents the MOSFET switch from turning on until input the voltage exceeds G Normal MOSFET “soft-start” feature effectively isolates the power source from extremely large capacitive loads, satisfying the USB voltage droop requirements. approximately 1.7V. If input voltage drops below approximately 1.3V, UVLO turns off the MOSFET switch. Under-voltage detection functions only when the switch is enabled. Current Limiting and Short-Circuit Protection The current limit circuitry prevents damage to the MOSFET switch and the hub downstream port but can deliver load current up to the current limit threshold of typically 1.5A through the switch for RT9715CA. When a heavy load or short circuit is applied to an enabled switch, a large transient current may flow until the current limit circuitry responds. Once this current limit threshold is exceeded, the device enters constant current mode until the thermal shutdown occurs or the fault is removed. is a registered trademark of Richtek Technology Corporation. DS9715CA-00 April 2015 RT9715CA Thermal Shutdown Thermal protection limits the power dissipation in RT9715CA. When the operation junction temperature exceeds 120°C, the OTP circuit starts the thermal shutdown function and turns the pass element off. The pass element turn on again after the junction temperature cools to 80°C. The RT9715CA lowers its OTP trip level from 120°C to 100°C when output short circuit occurs (VOUT < 1V) as shown in Figure 1. 1V V OUT IOUT Thermal Shutdown IC Temperature 100 C 80 C Figure 1. Short Circuit Thermal Folded Back Protection when Output Short Circuit Occurs (Patent) Power Dissipation The junction temperature of the RT9715CA series depend on several factors such as the load, PCB layout, ambient temperature and package type. The output pin of the RT9715CA can deliver the current of up to 1.5A (RT9715CA) over the full operating junction temperature range. However, the maximum output current must be decreased at higher ambient temperature to ensure the junction temperature does not exceed 100°C. With all possible conditions, the junction temperature must be within the range specified under operating conditions. Power dissipation can be calculated based on the output current and the RDS(ON) of the switch as below. PD = RDS(ON) x IOUT2 Although the device is rated for 1.5A of output current, but the application may limit the amount of output current based on the total power dissipation and the ambient temperature. The final operating junction temperature for Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS9715CA-00 April 2015 PD (MAX) = ( TJ (MAX) − TA ) / θJA Where TJ (MAX) is the maximum junction temperature of the die (100°C) and TA is the maximum ambient temperature. The junction to ambient thermal resistance (θJA) for SOT-23-5 package at recommended minimum footprint are 250°C/W (θJA is layout dependent). Universal Serial Bus (USB) & Power Distribution V OUT Short to GND 120 C 100 C OTP Trip Point any set of conditions can be estimated by the following thermal equation : The goal of USB is to enable device from different vendors to interoperate in an open architecture. USB features include ease of use for the end user, a wide range of workloads and applications, robustness, synergy with the PC industry, and low-cost implementation. Benefits include self-identifying peripherals, dynamically attachable and reconfigurable peripherals, multiple connections (support for concurrent operation of many devices), support for as many as 127 physical devices, and compatibility with PC Plug-and-Play architecture. The Universal Serial Bus connects USB devices with a USB host: each USB system has one USB host. USB devices are classified either as hubs, which provide additional attachment points to the USB, or as functions, which provide capabilities to the system (for example, a digital joystick). Hub devices are then classified as either Bus-Power Hubs or Self-Powered Hubs. A Bus-Powered Hub draws all of the power to any internal functions and downstream ports from the USB connector power pins. The hub may draw up to 500mA from the upstream device. External ports in a Bus-Powered Hub can supply up to 100mA per port, with a maximum of four external ports. Self-Powered Hub power for the internal functions and downstream ports does not come from the USB, although the USB interface may draw up to 100mA from its upstream connect, to allow the interface to function when the remainder of the hub is powered down. The hub must be able to supply up to 500mA on all of its external downstream ports. Please refer to Universal Serial Specification Revision 2.0 for more details on designing compliant USB hub and host systems. is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT9715CA Over-Current protection devices such as fuses and PTC resistors (also called polyfuse or polyswitch) have slow trip times, high on-resistance, and lack the necessary circuitry for USB-required fault reporting. The faster trip time of the RT9715CA power distribution allows designers to design hubs that can operate through faults. The RT9715CA provides low on-resistance and internal fault-reporting circuitry to meet voltage regulation and fault notification requirements. Because the devices are also power switches, the designer of self-powered hubs has the flexibility to turn off power to output ports. Unlike a normal MOSFET, the devices have controlled rise and fall times to provide the needed inrush current limiting required for the bus-powered hub power switch. Voltage Drop The USB specification states a minimum port-output voltage in two locations on the bus, 4.75V out of a SelfPowered Hub port and 4.40V out of a Bus-Powered Hub port. As with the Self-Powered Hub, all resistive voltage drops for the Bus-Powered Hub must be accounted for to guarantee voltage regulation (see Figure 7-47 of Universal Serial Specification Revision 2.0). The following calculation determines VOUT (MIN) for multiple ports (NPORTS) ganged together through one switch (if using one switch per port, NPORTS is equal to 1) : VOUT (MIN) = 4.75V − [ II x ( 4 x RCONN + 2 x RCABLE ) ] − (0.1A x NPORTS x RSWITCH ) − VPCB Where RCONN = Resistance of connector contacts Supply Filter/Bypass Capacitor A 1μF low-ESR ceramic capacitor from VIN to GND, located at the device is strongly recommended to prevent the input voltage drooping during hot-plug events. However, higher capacitor values will further reduce the voltage droop on the input. Furthermore, without the bypass capacitor, an output short may cause sufficient ringing on the input (from source lead inductance) to destroy the internal control circuitry. The input transient must not exceed 6V of the absolute maximum supply voltage even for a short duration. Output Filter Capacitor A low-ESR 150μF aluminum electrolytic or tantalum between VOUT and GND is strongly recommended to meet the 330mV maximum droop requirement in the hub VBUS (Per USB 2.0, output ports must have a minimum 120μF of low-ESR bulk capacitance per hub). Standard bypass methods should be used to minimize inductance and resistance between the bypass capacitor and the downstream connector to reduce EMI and decouple voltage droop caused when downstream cables are hot-insertion transients. Ferrite beads in series with VBUS, the ground line and the 0.1μF bypass capacitors at the power connector pins are recommended for EMI and ESD protection. The bypass capacitor itself should have a low dissipation factor to allow decoupling at higher frequencies. Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 (two contacts per connector) RCABLE = Resistance of upstream cable wires (one 5V and one GND) RSWITCH = Resistance of power switch (90mΩ typical for RT9715CA) VPCB = PCB voltage drop The USB specification defines the maximum resistance per contact (RCONN) of the USB connector to be 30mΩ and the drop across the PCB and switch to be 100mV. This basically leaves two variables in the equation: the resistance of the switch and the resistance of the cable. If the hub consumes the maximum current (II) of 500mA, the maximum resistance of the cable is 90mΩ. The resistance of the switch is defined as follows : RSWITCH = { 4.75V − 4.4V − [ 0.5A x ( 4 x 30mΩ + 2 x 90mΩ) ] − VPCB } ( 0.1A x NPORTS ) = (200mV − VPCB ) ( 0.1A x NPORTS ) If the voltage drop across the PCB is limited to 100mV, the maximum resistance for the switch is 250mΩ for four ports ganged together. The RT9715CA, with its maximum 110mΩ on-resistance over temperature, can fit the demand of this requirement. is a registered trademark of Richtek Technology Corporation. DS9715CA-00 April 2015 RT9715CA Thermal Considerations Layout Consideration For continuous operation, do not exceed absolute 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 : In order to meet the voltage drop, droop, and EMI requirements, careful PCB layout is necessary. The following guidelines must be followed : Locate the ceramic bypass capacitors as close as possible to the VIN pins of the RT9715CA. Place a ground plane under all circuitry to lower both resistance and inductance and improve DC and transient performance (Use a separate ground and power plans if possible). Keep all VBUS traces as short as possible and use at least 50-mil, 2 ounce copper for all VBUS traces. Avoid vias as much as possible. If vias are necessary, make them as large as feasible. Place cuts in the ground plane between ports to help reduce the coupling of transients between ports. the thermal resistance θJA is 250°C/W on the standard JEDEC 51-3 single-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following formula : Locate the output capacitor and ferrite beads as close to the USB connectors as possible to lower impedance (mainly inductance) between the port and the capacitor and improve transient load performance. P D(MAX) = (100°C − 25°C) / (250°C/W) = 0.3W for SOT-23-5 package Locate the RT9715CA as close as possible to the output port to limit switching noise. PD(MAX) = (TJ(MAX) − TA) / θJA Where T J(MAX) is the maximum operation junction temperature 100°C, TA is the ambient temperature and the θJA is the junction to ambient thermal resistance. For recommended operating conditions specification of RT9715CA, where TJ(MAX) is the maximum junction temperature of the die (100°C) and TA is the maximum ambient temperature. The junction to ambient thermal resistance θJA is layout dependent. For SOT-23-5 package, The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 2 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. V BUS The input capacitor should be placed as close as possible to the IC. V OUT V IN Maximum Power Dissipation (W)1 0.5 Single Layer PCB GND 0.4 0.3 GND_BUS FLG EN V IN 0.2 Figure 3 0.1 0.0 0 10 20 30 40 50 60 70 80 90 100 Ambient Temperature (°C) Figure 2. Derating Curve of Maximum Power Dissipation Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS9715CA-00 April 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT9715CA Outline Dimension H D L B C b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.889 1.295 0.035 0.051 A1 0.000 0.152 0.000 0.006 B 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 C 2.591 2.997 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 H 0.080 0.254 0.003 0.010 L 0.300 0.610 0.012 0.024 SOT-23-5 Surface Mount 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. www.richtek.com 12 DS9715CA-00 April 2015