RT9721A/B 80mΩ Ω, 500mA High-Side Power Switches with Flag General Description Features The RT9721A/B are low voltage, single N-MOSFET highside power switches, optimized for self-powered and buspowered Universal Serial Bus (USB) applications. The RT9721A/B series provides a charge pump circuitry to drive the internal MOSFET switch; the switch's low RDS(ON), 80mΩ, meets USB voltage drop requirements; and a flag output is available to indicate fault conditions to the local USB controller. z Compliant to USB Specifications z Built-In N-MOSFET Ω ` Typical RDS(ON) : 80mΩ Output Can Be Forced to Higher Than Input (OffState) Low Supply Current : ` 50μ μA Typical at Switch On State ` 0.1μ μA Typical at Switch Off State Guaranteed 500mA Continuous Load Current Wide Input Voltage Ranges : 2.5V to 5.5V Open-Drain Fault Flag Output Hot Plug-In Application (Soft-Start) 2.15V Typical Under-Voltage Lockout (UVLO) Current Limiting Protection Thermal Shutdown Protection Reverse Current Flow Blocking (no body diode) UL Approved−E219878 RoHS Compliant and Halogen Free z z z Additional features include soft-start to limit inrush current during plug-in, thermal shutdown to prevent catastrophic switch failure from high-current loads, under-voltage lockout (UVLO) to ensure that the device remains off unless there is a valid input voltage present. The maximum current is limited to typically 750mA in dual ports in accordance with the USB power requirements, lower quiescent current as 50uA making this device ideal for portable battery-operated equipment. The RT9721A is designed without output auto-discharge function and RT9721B is designed with output autodischarge function. z z z z z z z z z Applications z z The RT9721A/B are available in SOT-23-5 package requiring minimum board space and smallest components. Ordering Information RT9721 Package Type B : SOT-23-5 Lead Plating System G : Green (Halogen Free and Pb Free) Output Discharge Function A : Without Auto-Discharge Function B : With Auto-Discharge Function 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. DS9721A/B-02 April 2011 z USB Bus/Self Powered Hubs USB Peripherals Notebook, Motherboard PCs Pin Configurations (TOP VIEW) VOUT FLG 5 4 2 3 VIN GND EN SOT-23-5 Marking Information For marking information, contact our sales representative directly or through a Richtek distributor located in your area. www.richtek.com 1 RT9721A/B Typical Application Circuit Pull-Up Resistor (10k to 100k) USB Controller Supply Voltage 5V 1 FLG VIN C IN 1µF 4 Over -Current RT9721A/B 3 VOUT EN 5 V BUS + Chip Enable C OUT 10µF GND 2 D+ DGND 150µF Ferrite Beads Data Functional Pin Description Pin No. Pin Name Pin Function 1 VIN Switch Input Voltage. 2 GND Ground. 3 EN Chip Enable (Active High). 4 FLG Open-Drain Fault Flag Output. 5 VOUT Switch Output Voltage. Function Block Diagram VIN EN Bias UVLO Oscillator Charge Pump Current Limiting Gate Control Output Voltage Detection VOUT Thermal Protection Auto Discharge RT9721B Only FLG Delay GND www.richtek.com 2 DS9721A/B-02 April 2011 RT9721A/B Absolute Maximum Ratings z z z z z z z z z (Note 1) Supply Input Voltage, VIN -----------------------------------------------------------------------------------------------EN Input Voltage ----------------------------------------------------------------------------------------------------------Flag Voltage ---------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOT-23-5 -------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOT-23-5, θJA --------------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM -------------------------------------------------------------------------------------------------------------------------MM ---------------------------------------------------------------------------------------------------------------------------- Recommended Operating Conditions z z z z 6V −0.3V to 6V 6V 0.4W 250°C/W 260°C 150°C −65°C to 150°C 4kV 400V (Note 4) Supply Input Voltage Range, VIN --------------------------------------------------------------------------------------EN Input Voltage Range -------------------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Ambient Temperature Range -------------------------------------------------------------------------------------------- 2.5V to 5.5V 0V to 5.5V −40°C to 125°C −40°C to 85°C Electrical Characteristics (VIN = 5V, CIN = 1μF, COUT = 10μF, TA = 25°C, unless otherwise specified) Parameter Switch On Resistance Symbol Test Conditions Min Typ Max Unit mΩ RDS(ON) VIN = 5V, IOUT = 100mA -- 80 100 ISW_ON Switch On, VOUT = Open -- 50 70 ISW_OFF Switch Off, VOUT = Open -- 0.1 1 Logic-Low Voltage VIL VIN = 2.5V to 5.5V, Switch Off -- -- 0.8 V Logic-High Voltage VIH VIN = 2.5V to 5.5V, Switch On 2 -- -- V EN Input Current IEN VEN = 5V -- 0.01 0.1 μA Output Leakage Current ILEAKAGE VEN = 0V, RLOAD = 0Ω -- 0.5 1 μA Output Turn-On Rise Time T ON_RISE 10% to 90% of V OUT Rising -- 200 -- μs Current Limit Detect Threshold ILIM_THRES IOUT Rising -- -- 1 A Current Limit ILIM VOUT = 4V 500 -- 900 mA FLG Output Resistance RFLG ISINK = 1mA -- 10 -- Ω FLG Off Current IFLG_OFF VFLG = 5V -- 0.01 1 μA tD From fault condition to FLG assertion 5 12 20 ms RDischarge VEN = 0V -- 100 150 Ω Supply Current EN Threshold FLG Delay Time (Note 5) Shutdown Auto-Discharge Resistance HOLD μA To be continued DS9721A/B-02 April 2011 www.richtek.com 3 RT9721A/B Parameter Symbol Test Conditions Min Typ Max Unit Under-Voltage Lockout VUVLO VIN Increasing 1.9 2.15 2.4 V Under-Voltage Hysteresis ΔVUVLO VIN Decreasing -- 0.1 -- V Thermal Shutdown Protection T SD -- 150 -- °C Thermal Shutdown Hysteresis ΔTSD -- 25 -- °C Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. 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. The FLAG delay time is input voltage dependent, see “Typical Operating Characteristics” graph for further details. www.richtek.com 4 DS9721A/B-02 April 2011 RT9721A/B Typical Operating Characteristics On Resistance vs. Temperature On Resistance vs. Input Voltage 110 150 IOUT = 100mA On Resistance (mΩ) On Resistance (mΩ) 105 100 95 90 85 VIN = 5V, IOUT = 100mA 130 110 90 70 50 80 2.5 3 3.5 4 4.5 5 -50 5.5 -25 0 Switch On Supply Current vs. Input Voltage Switch On Supply Current (uA) Switch On Supply Current (uA)1 75 100 125 Switch On Supply Current vs. Temperature 45.0 No Load 42.5 40 37.5 35 32.5 30 27.5 25 VIN = 5V, No Load 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 2.5 3 3.5 4 4.5 5 5.5 -50 -25 0 Input Voltage (V) 25 50 75 100 125 Tmeperature (°C) Switch Off Supply Current vs. Input Voltage 0.30 Switch Off Supply Current vs. Temperature 0.8 No Load Switch Off Supply Current (uA) Switch Off Supply Current (uA) 50 Temperature (°C) Input Voltage (V) 45 25 0.25 0.20 0.15 0.10 0.05 VIN = 5V, No Load 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.00 2.5 3 3.5 4 4.5 Input Voltage (V) DS9721A/B-02 April 2011 5 5.5 -50 -25 0 25 50 75 100 125 Temperature (°C) www.richtek.com 5 RT9721A/B UVLO Threshold vs. Temperature Output Voltage vs. Output Current 6 2.5 VIN = 5V UVLO Threshold (V) Output Volttage (V) 5 4 3 2 1 0 2.3 Rising 2.1 Falling 1.9 1.7 1.5 0 100 200 300 400 500 600 700 800 900 1000 100 0 -50 -25 0 Output Turn-On Rise Time vs. Input Voltage No Load 200 180 160 140 120 100 75 100 125 Output Turn-On Rise Time vs. Temperature VIN = 5V, No Load 230 210 190 170 150 80 2.5 3 3.5 4 4.5 5 -50 5.5 -25 0 Current Limit Detect Threshold vs. Input Voltage 900 800 700 600 500 3 3.5 4 4.5 Input Voltage (V) www.richtek.com 6 50 75 100 125 Current Limit Detect Threshold vs. Temperature Current Limit Detect Threshold (mA) 1000 2.5 25 Temperature (°C) Input Voltage (V) Current Limit Detect Threshold (mA) 50 250 Output Turn-On Rise Time (us) Output Turn-On Rise Time (us)1 220 25 Temperature (°C) Output Current (mA) 5 5.5 1000 VIN = 5V 900 800 700 600 500 -50 -25 0 25 50 75 100 125 Temperature (°C) DS9721A/B-02 April 2011 RT9721A/B Current Limit vs. Input Voltage Current Limit vs. Temperature 900 VIN − VOUT = 1V 850 850 800 800 Current Limit (mA) Current Limit (mA) 900 750 700 650 600 550 VIN = 5V, VOUT = 4V 750 700 650 600 550 500 500 2.5 3 3.5 4 4.5 5 5.5 -50 -25 0 Input Voltage (V) 75 100 125 VIN = 5V, RLOAD = 0Ω 13.5 12 FLAG Delay Time (ms) FLAG Delay Time (ms) 14.0 RLOAD = 0Ω 10 8 6 4 13.0 12.5 12.0 11.5 11.0 10.5 2 10.0 2.5 3 3.5 4 4.5 5 5.5 -50 Input Voltage (V) -25 0 25 50 75 100 125 Temperature (°C) EN Threshold Volatge vs. Input Voltage Power On from VIN 2.0 EN Threshold Voltage (V) 50 FLAG Delay Time vs. Temperature FLAG Delay Time vs. Input Voltage 14 25 Temperature (°C) 1.8 Rising 1.6 VIN (2V/Div) 1.4 Falling 1.2 VOUT (2V/Div) 1.0 RLOAD = 200Ω 0.8 2.5 3 3.5 4 4.5 5 5.5 Time (2ms/Div) Input Voltage (V) DS9721A/B-02 April 2011 www.richtek.com 7 RT9721A/B Power Off from VIN Turn On from EN VEN (5V/Div) VIN (2V/Div) VOUT (2V/Div) VOUT (2V/Div) I IN (500mA/Div) RLOAD = 200Ω COUT = 10μF, RLOAD = 10Ω Time (2ms/Div) Time (100μs/Div) Turn Off from EN Current Limit Response COUT = 10μF, RLOAD = 10Ω VIN = 5V, COUT = 10μF, RLOAD = 4Ω VEN (5V/Div) VOUT (2V/Div) VOUT (2V/Div) IOUT (500mA/Div) I IN (500mA/Div) Time (100μs/Div) Time (100μs/Div) FLAG Response Thermal Shutdown Response VIN = 5V, RLOAD = 4Ω VIN = 5V, RLOAD = 0Ω VOUT (5V/Div) VOUT (5V/Div) VFLG (5V/Div) VFLG (5V/Div) IOUT (500mA/Div) IOUT (1A/Div) Time (2ms/Div) www.richtek.com 8 Time (400ms/Div) DS9721A/B-02 April 2011 RT9721A/B Applications Information The RT9721A/B are single N-MOSFET high-side power switch with active-high enable input, optimized for selfpowered and bus-powered Universal Serial Bus (USB) applications. The RT9721A/B series equipped with a charge pump circuitry to drive the internal N-MOSFET switch; the switch's low RDS(ON), 80mΩ, 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 a parasitic body diode between drain and source of the MOSFET, the RT9721A/B prevent reverse current flow if VOUT being externally forced to a higher voltage than VIN when the chip is disabled (VEN < 0.8V). D S start” feature effectively isolates the power source from extremely large capacitive loads, satisfying the USB voltage droop requirements. Fault Flag The RT9721A/B series provides a FLG signal pin which is an N-Channel open drain MOSFET output. This open drain output goes low when VOUT < VIN − 1V, current limit or the die temperature exceeds 150°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 overcurrent 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. S D Under-Voltage Lockout G G Normal MOSFET RT9721A/B 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 are turned off, reducing the supply current to 0.1μA typical. The maximum guaranteed voltage for a logic low at the EN pin is 0.8V. A minimum guaranteed voltage of 2V at the EN pin will turn the RT9721A/B on. Floating the input may cause unpredictable operation. EN should not be allowed to go negative with respect to GND. 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 “softDS9721A/B-02 April 2011 Under-voltage lockout (UVLO) prevents the MOSFET switch from turning on until input voltage exceeds approximately 2.15V. If input voltage drops below approximately 2.05V, UVLO turns off the MOSFET switch, FLG will be asserted accordingly. Under-voltage detection functions only when the switch is enabled. Current Limiting 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 700mA through the switch of RT9721A/B series. 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. www.richtek.com 9 RT9721A/B Thermal Shutdown Thermal shutdown is employed to protect the device from damage if the die temperature exceeds approximately 150°C. The power switch will auto-recover when the IC is cooling down. The thermal hysteresis temperature is about 25°C. Universal Serial Bus (USB) & Power Distribution The goal of USB is to enable devices 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. www.richtek.com 10 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 RT9721A/B power distribution allow designers to design hubs that can operate through faults. The RT9721A/B have low on-resistance and internal fault-reporting circuitry that help the designer 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. Supply Filter/Bypass Capacitor A 1uF 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 6.5V of the absolute maximum supply voltage even for a short duration. Output Filter Capacitor A low-ESR 150uF 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 120uF 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. DS9721A/B-02 April 2011 RT9721A/B Voltage Drop Thermal Considerations The USB specification states a minimum port-output voltage in two locations on the bus, 4.75V output of a Self-Powered Hub port and 4.4V output 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 ). 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 : 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) : PD(MAX) = (TJ(MAX) − TA) / θJA 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 (two contacts per connector) 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 conditions specification of RT9721A/B, the maximum junction temperature is 125°C. The junction to ambient thermal resistance θJA is layout RCABLE : Resistance of upstream cable wires (one 5V and one GND) dependent. For SOT-23-5 package, 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 : RSWITCH : Resistance of power switch (80mΩ typical for RT9721A/B) P D(MAX) = (125°C - 25°C) / (250°C/W) = 0.4W for SOT-23-5 package VPCB : PCB voltage drop The maximum power dissipation depends on operating ambient temperature for fixed TJ(MAX) and thermal resistance θJA. For the RT9721A/B, Figure 1 shows the maximum power dissipation allowed under various ambient temperatures. 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)] − V PCB } / (0.1A x N PORTS ) = (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 RT9721A/B, with its maximum 110mΩ on-resistance over temperature, easily meets this requirement. DS9721A/B-02 April 2011 0.50 Maximum Power Dissipation (W) 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. Single Layers PCB 0.45 0.40 0.35 SOT-23-5 0.30 0.25 0.20 0.15 0.10 0.05 0.00 0 25 50 75 100 125 Ambient Temperature (°C) Figure 1. Maximum Power Dissipation Derating Curve www.richtek.com 11 RT9721A/B Layout Considerations For best performance of the RT9721A/B series, the following guidelines must be strictly followed. ` Input and output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. ` The GND should be connected to a strong ground plane for heat sink. ` Keep the main current traces as possible as short and wide. V OUT GND V IN FLG EN V IN GND Figure 2 www.richtek.com 12 DS9721A/B-02 April 2011 RT9721A/B 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 Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: [email protected] Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9721A/B-02 April 2011 www.richtek.com 13