unisonic technologies co., ltd us202 preliminary cmos ic www.unisonic.com.tw 1 of 6 copyright ? 2011 unisonic technologies co., ltd qw-r502-445.c 100m ? 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 23 a 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 w hen 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: 100m ? (typ) * soft start * current limit:1.5a * thermal protection * low supply current: 23 a ? ordering information ordering number package packing lead free halogen free US202XL-AF5-R us202xg-af5-r sot-25 tape reel
us202 preliminary cmos ic unisonic technologies co., ltd 2 of 6 www.unisonic.com.tw qw-r502-445.c ? marking ? pin configuration 4 5 3 1 2 v out gnd v in en v out ? pin description pin no. pin name description 1, 5 v out output voltage 2 gnd ground 3 v in power input 4 en chip enable (active high) ? block diagram
us202 preliminary cmos ic unisonic technologies co., ltd 3 of 6 www.unisonic.com.tw qw-r502-445.c ? absolute maximum rating parameter symbol ratings unit supply voltage v in 7 v chip enable v en -0.3~7 v power dissipation (t a = 25c) p d 0.25 w junction temperature t j -20~100 c storage temperature t stg -65~150 c note: absolute maximum ratings are those values be yond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? electrical characteristics (v in = 5v, c in = c out = 1 f, t a = 25c, unless otherwise specified) parameter symbol test conditions min typ max unit input voltage range v in 2.2 6 v output nmosfet r ds ( on ) r ds ( on ) i l = 1a 85 100 m ? supply current v in = 3v 19 40 a v in = 5v 23 45 output turn-on rising time t r r l = 10 ? , 90% settling 400 s current limit threshold i limit 1.1 1.5 2 a short-circuit fold back current i os v out = 0v, measured prior to thermal shutdown 1.0 a ce input high threshold v ih 2.0 v ce input low threshold v il 0.8 v shutdown supply current i off ce = ?0? 0.1 1 a output leakage current i i ( leak ) ce = ?0?, v out = 0v 0.5 10 a v in under voltage lockout uvlo 1.3 1.8 v v in under voltage hysteresis 100 mv thermal limit t sd 130 c thermal limit hysteresis ? t sd 20 c
us202 preliminary cmos ic unisonic technologies co., ltd 4 of 6 www.unisonic.com.tw qw-r502-445.c ? test circuit gnd c in c l ce v in test circuit 2 + v out r l + i l i out v ce on off v out v out v in 1f 1f 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.
us202 preliminary cmos ic unisonic technologies co., ltd 5 of 6 www.unisonic.com.tw qw-r502-445.c ? application information the utc us202 is a high-side single n-chann el mosfet switch with active-high enable input. input and output v in pin (input) is the power supply conn ection to the circuitry and t he drain of the output mosfet. v out pin (output) is the source of the out put mosfet. in a typical circuit, current flows through the switch from v in to v out toward the load. both v out pins must be short on the board and co nnected to the load and so do both v in 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 than130c, 20c of hysteresis prevents the switch turn on until the die temperature drops to 110c. 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 swit ch 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 minimu m 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 approxim ately 1.5a (typ). when the output is short to ground, it will limit to a constant current 1a until thermal shut down or short condition removed. gnd c in ce v in v out on off v ce figure 1. high side power switch with chip enable control v out v out v in c out 1f 1f filtering during the hot-plug events, in order to limit the input voltage drop, a 1 f ceramic capacitor is recommended to be placed between v in to gnd. however special care must be taken to the values of the capacitor, because higher capacitor values will further reduc e the voltage drop at the input. in order to prevent inductive parasitic from pulling v out negative during turn-off or emi damage to other components during the hot detachment, it?s bette r to connect a sufficient capacitor from v out to gnd. this capacitor is also necessary for meeting the usb spec ification during hot plug-in operation. if the utc us202 is implanted in device and application, minimum 1 f capacitor from v out 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 v out pin is higher than that on v in pin. in order to avoid reverse current occu r, turn off this switch or connect v in to a fixed voltage less than 1.3v.
us202 preliminary cmos ic unisonic technologies co., ltd 6 of 6 www.unisonic.com.tw qw-r502-445.c ? application information (cont.) layout and thermal dissipation the switch should be placed as close to the usb connec tor 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 re sistance and large solder pads to minimize connection resistance. if the package is with dual v out or v in pins, short both the same function pi ns 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 v out pin at the switch output side in order to protec t the switch when each port are plug-in separately. under normal operating conditions, the package can dissi pate the channel heat away. wide power bus planes connected to vin and v out and a ground plane in contact with the device will help dissipate additional heat . ? typical application circuit gnd c in 1f c out (note) 470f ce v out v out v in v out note: 470f, low esr electrolytic v in 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.
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