US202

UNISONIC TECHNOLOGIES CO., LTD US202 Preliminary CMOS IC 100mΩ POWER DISTRIBUTION SWITCHES DESCRIPTION The US202 is a power distribution switch. It is particularly suitable for self-powered and bus-powered USB (Universal Series bus) applications. It has 23μA low quiescent supply current that meets the requirements of battery-powered portable equipments. A built-in charge pump is used to drive the N-channel N-MOSFET that is free of parasitic body diode to eliminate any reversed current flow across the switch when it is powered off. The US202 incorporates some protection circuits such as current limit and short protection circuits, soft start circuit, thermal shutdown and UVLO (Under-voltage Lockout) protection circuits. The thermal shutdown circuits protect this device from damage when over current occurs, and the soft start circuits are used to prevent inrush current when plug-in event occurs. The US202 can be used in such applications such as battery-powered equipments, motherboard USB power switchs, USB device power switchs, hot-plug power supplies, battery-charger circuits and so on. FEATURES * Input Voltage Varies From 2.2V to 6V * Guaranteed Continuous Current: 1.1A * High-Side NMOSFET: 100mΩ (TYP) * Soft Start * Current Limit:1.5A * Thermal Protection * Low Supply Current: 23μA ORDERING INFORMATION Ordering Number Lead Free US202XL-AF5-R Halogen Free US202XG-AF5-R Package SOT-25 Packing Tape Reel www.unisonic.com.tw Copyright © 2011 Unisonic Technologies Co., Ltd 1 of 7 QW-R502-445.b US202 MARKING Preliminary CMOS IC PIN CONFIGURATION PIN DESCRIPTION PIN NO. 1, 5 2 3 4 PIN NAME VOUT GND VIN EN DESCRIPTION Output Voltage Ground Power Input Chip Enable (Active High) UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 7 QW-R502-445.b US202 BLOCK DIAGRAM Preliminary CMOS IC UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 7 QW-R502-445.b US202 ABSOLUTE MAXIMUM RATING Preliminary CMOS IC PARAMETER SYMBOL RATINGS UNIT Supply Voltage VIN 7 V Chip Enable VEN -0.3~7 V Power Dissipation (TA = 25°C) PD 0.25 W Junction Temperature TJ -20~100 °C Storage Temperature TSTG -65~150 °C Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. ELECTRICAL CHARACTERISTICS (VIN = 5V, CIN = COUT = 1μF, TA = 25°C, unless otherwise specified) PARAMETER SYMBOL TEST CONDITIONS Input Voltage Range VIN Output NMOSFET RDS(ON) RDS(ON) IL = 1A VIN= 3V Supply Current VIN= 5V Output Turn-On Rising Time TR RL= 10Ω, 90% Settling Current Limit Threshold ILIMIT VOUT = 0V, measured prior to Short-Circuit Fold Back Current IOS thermal shutdown CE Input High Threshold VIH CE Input Low Threshold VIL Shutdown Supply Current IOFF CE = “0” Output Leakage Current II(LEAK) CE = “0”, VOUT = 0V VIN Under Voltage Lockout UVLO VIN Under Voltage Hysteresis Thermal Limit TSD Thermal Limit Hysteresis ∆TSD MIN 2.2 TYP 85 19 23 400 1.5 1.0 2.0 0.1 0.5 1.8 100 130 20 0.8 1 10 MAX UNIT 6 V 100 mΩ 40 µA 45 µS 2 A A V V µA µA V mV °C °C 1.1 1.3 UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 7 QW-R502-445.b US202 TEST CIRCUIT Preliminary CMOS IC VIN IOUT VIN VCE CE GND On Off VOUT VOUT CL 1µF + VOUT CIN 1µF + RL IL Test Circuit 2 Test Circuit 1 is performed by charging an external tank of bulk capacitor to the input then applying this voltage to the input of the unit. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 7 QW-R502-445.b US202 APPLICATION INFORMATION Preliminary CMOS IC The UTC US202 is a high-side single N-Channel MOSFET switch with active-high enable input. Input and Output VIN pin (input) is the power supply connection to the circuitry and the drain of the output MOSFET. VOUT pin (output) is the source of the output MOSFET. In a typical circuit, current flows through the switch from VIN to VOUT toward the load. Both VOUT pins must be short on the board and connected to the load and so do both VIN pins but connected to the power source. Thermal Shutdown Thermal shutdown is used to turn off the output MOSFET when the if the temperature is higher than130°C, 20°C of hysteresis prevents the switch turn on until the die temperature drops to 110°C. Soft Start When hot-plug events occur, the soft start is used to eliminate the upstream voltage droop due to the inrush current. The soft-start protects power supplies from damage caused by highly capacitive loads. Under-Voltage Lockout UVLO (Under voltage Lockout) turn off the MOSFET switch once the input voltage falls below 1.8V (TYP.) and if the input voltage exceeds 1.8V, the switch will be turned on. Current Limiting and Short Protection The current limit threshold is preset internally. The minimum value is 1.1A. The current limit circuit protects this device from damage resulting from undesired excess inrush current, which is encountered during hot plug-in events. The output current is limited to approximately 1.5A (TYP). When the output is short to ground, it will limit to a constant current 1A until thermal shutdown or short condition removed. VIN CIN 1µF VCE VIN CE GND On Off VOUT VOUT COUT 1µF VOUT Figure 1. High Side Power Switch with Chip Enable Control Filtering During the hot-plug events, in order to limit the input voltage drop, a 1μF ceramic capacitor is recommended to be placed between VIN to GND. However special care must be taken to the values of the capacitor, because higher capacitor values will further reduce the voltage drop at the input. In order to prevent inductive parasitic from pulling VOUT negative during turn-off or EMI damage to other components during the hot detachment, it’s better to connect a sufficient capacitor from VOUT to GND. This capacitor is also necessary for meeting the USB specification during hot plug-in operation. If the UTC US202 is implanted in device and application, minimum 1μF capacitor from VOUT to GND is recommended and higher capacitor values are also preferred. Choosing these capacitors properly is critical. A lower ESR on the capacitor can get a lower IR drop during the operation, so the Effective Series Resistance (ESR) of the capacitors must be considered. For ferrite beads, if they are in series with all power and ground lines, the EMI will be eliminated or reduced. The DC resistance of the wire kept to a minimum to reduce the voltage drop should be considered in choosing ferrite beads. Reverse Current Preventing Since the UTC US202’s MOSFET is bi-directional, it allows the voltage on VOUT pin is higher than that on VIN pin. In order to avoid reverse current occur, turn off this switch or connect VIN to a fixed voltage less than 1.3V. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 7 QW-R502-445.b US202 Preliminary CMOS IC APPLICATION INFORMATION (Cont.) Layout and Thermal Dissipation The switch should be placed as close to the USB connector as possible and all traces should be as short as possible to reduce the effect of undesirable parasitic inductance. Also, place the output capacitor and ferrite beads to the USB connector as close to as possible. If ferrite beads are used, use wires kept to a minimum resistance and large solder pads to minimize connection resistance. If the package is with dual VOUT or VIN pins, short both the same function pins as Fig.1 or Fig.2 to reduce the internal turn-on resistance. If the output power is delivered to two individual ports, it is specially necessary to short both VOUT pin at the switch output side in order to protect the switch when each port are plug-in separately. Under normal operating conditions, the package can dissipate the channel heat away. Wide power bus planes connected to VIN and VOUT and a ground plane in contact with the device will help dissipate additional heat. TYPICAL APPLICATION CIRCUIT VIN VIN CE GND VOUT VOUT VOUT CIN 1µF COUT (Note) 470µF Note: 470µF, Low ESR Electrolytic UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 7 QW-R502-445.b