unisonic technologies co., ltd us1528 preliminary cmos ic www.unisonic.com.tw 1 of 8 copyright ? 2010 unisonic technologies co., ltd qw-r502-457.b usb high-side power switch advance information ? description the utc us1528 is an integrated high-side power switch. it is designed particularly for self-powered and bus-powered usb (universal serial bus) applications. the utc us1528 meets the requirements of the usb. the low on-resistance of the switch meet s usb voltage drop requirements. when the output load becomes higher than the current-limit threshold, the utc us1528 switches into constant - current mode and limits the output current at 1.4a (typ). an open-drain flag, playing a role as the mosfet output, is included to indicate error conditions to the local usb controller. a thermal shutdown circuit protects this devic e from catastrophic switch failure, which is caused by increasing power dissipation when continuous heavy loads or short circuit occurs. in addition, soft start is used to avoid the momentary voltage drop generated on t he upstream port that may occur when the switch is enabled in bus-powered applications. a uvlo (under-voltage lockout) circuit is us ed to keep the device off unless there is a valid input voltage present, and an enable input that is compatible with both 3.3v and 5v logic. the utc us1528 can be used for high-side power protection switch, usb power management, usb host and self-powered hubs, hot plug-in power supplies and battery-charger circuits. ? features * open-drain fault flag * low on-resistance mosfet: typical 110m ? (at 5.0v) * operating voltage varying from 3.0v to 5.5v * output can be forced higher than input when o perating in off state. * slow turn-on (soft-start) and fast turn-off * on-state supply cu rrent: 100 a (typ) * standby supply current: 1a (typ) * current limit: 1.4a (typ) * thermal shutdown protection circuit * uvlo (under-voltage lockout): 2.4v (typ) * logic level enable pin, available with active-high/low version ? ordering information ordering number package packing US1528XG-S08-R sop-8 tape reel
us1528 preliminary cmos ic unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r502-457.b ? pin configuration ? pin description pin no. pin name description 1 gnd ground. 2, 3 in input supply: output mosfet source, which also supplies ic's internal circuitry. connect to positive supply. en active-high switch enable input. a logic low turns on the switch. 4 en active-low switch enable input. a logic low turns on the switch. 5 flg open-drain fault flag (output): active-low , open-drain output. indicates overcurrent, thermal shutdown and uvlo. 6, 7, 8 out switch output: output mosfet drai n. typically connect to switched side of load.
us1528 preliminary cmos ic unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r502-457.b ? block diagram
us1528 preliminary cmos ic unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r502-457.b ? absolute maximum rating parameter symbol ratings unit supply voltage v in +6.0 v fault flag voltage v flg +6.0 v fault flag current i flg 50 ma output voltage v out +6.0 v output current i out internally limited enable input v en -0.3~6 v storage temperature t stg -65~+150 c notes: absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? operating ratings parameter symbol ratings unit supply voltage v in +3~+5.5 v ambient operating temperature t opr -40~85 c ? thermal data parameter symbol ratings unit junction to ambient ja 160 c/w ? electrical characteristics (v in =+5v, t a =25c) parameter symbol test conditions min typ max unit i s(off) switch off, out = open 1 5 a in supply current (note) i s(on ) switch on, out = open 100 160 a v ih low to high transition 2.5 v en/ en enable threshold v il high to low transition(note) 0.8 v i en(h) v en = v oh(min) = 2.5v 0.01 1 a en/ en input current i en(l) v en = v ol(max) = 1.0v 0.01 1 a en/ en input capacitance 1 pf v in = 5v, i out =500ma 110 140 m ? switch resistance r on v in = 3.3v, i out =500ma 130 180 m ? out turn-on delay t on r l =10 ? 0.03 ms out turn-on rise time t r r l =10 ? , c l =100f 0.5 ms out turn-off delay t off r l =10 ? 1 20 s out turn-off fall time t f r l =10 ? 1 20 s out leakage current i o(leak) 1 10 a short circuit current limit i short enable into load 1.0 1.4 2.0 a circuit limit threshold ramped load a pplied to enabled output 2.0 2.7 3.5 a t j increasing 135 c overtemperature shutdown threshold ot threshold t j decreasing 125 c v in =5v, i l =10ma 10 25 ? flg output resistance r on(flag) v in =3.3v, i l =10ma 15 40 ? flg off current i flag v flag =5v 0.01 1 a v in =increasing 2.5 v uvlo threshold v uvlo v in =decreasing 2.3 v note:for the utc us1528 , off is 2.5v and on is 0.8v. the enable input, en has approximately 200mv of hysteresis.
us1528 preliminary cmos ic unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r502-457.b ? functional description the utc us1528 is high-side single channel power switch; it has an enable input in active low. fault conditions turn off or inhibit turn-on of the output transistors. input and output in pin (input) is the power supply connection to the lo gic circuitry and the source of the output mosfet. out pin (output) is the output mosf et?s drain. current flows thr ough the switch from in pin to out pin toward the load in many applications. all out pins mu st be connected together to the load. the output mosfet and driving circuit are also designed to allow the mosfet drain to be externally forced to a higher voltage than the source (v out > v in ) when the switch is off. this avoi ds undesirable drai n-to-body diode current flow by connecting the body to the most positive voltage. if v out >v in when switch is enabled, current will flow from v out to v in . thermal shutdown thermal shutdown is designed to prevent this devic e from being damaged due to excessive power dissipation. it is used to turn off the output mosfet if the temperat ure is higher than135c, 10c of hysteresis prevents the switch from turning on until the die temperature drops to 125c. thermal shutdown circuit functions only when the switch is enabled. undervoltage lockout uvlo (undervoltage lockout) turns off the mosfet swit ch once the input voltage falls below 2.3v (typ) and if the input voltage exceeds 2.5v (typ), the switch will be turned on. uvlo detection functions only when the switch is enabled. current sensing and limiting the current limit threshold is fixed internally, allowing a 0.5a minimum current to flow through the output mosfet. however, the current limit threshold can prevent the output mosfet and external load from being damage. a current sense circuit protects the mosfet switch?s output current. if output current becomes higher than the current limit threshold, the output mosfet switch is turned off. the reacti on to an overcurrent is measured with the following scenarios: switch enabled into heavy load if the switch is powered on or enabled into a heavy load or short-circuit, the switch enters a constant-current mode immediately, reducing the output voltage. heavy load applied to enabled switch when a heavy load is applied, a large-undesired transient current occurs which may damage the switch. then the current limit circuit may turn off the swit ch, folding back into constant-current mode. fault flag fault flag is an open-drained output of an n-channel mosfet. it drops low to indicate error conditions as follows: current limiting, uvlo, or thermal shutdown. the flag output mosfet is capable of sinking a 10ma load to typically 100mv above ground.
us1528 preliminary cmos ic unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r502-457.b ? applications information supply filtering in order to control supply transients, a bypass capacitor is located nearly between in to gnd. 0.1f ~ 1f is suitable (see figure 1). without a bypa ss capacitor, an output short may cause sufficient ringing on the input (from supply lead inductance) to damage internal control circuitry. input transients must not exceed t he absolute maximum supply voltage (v in max = 6v) even for a short duration. en / en , the active-high/low enable input for a clearly defined input, the en/ en pin, with 0.2v hysteresis, must be driven logic high or logic low. floating the input may cause unpredictable operation. en/ en should not be allowed to go negative with respect to gnd. soft start the utc us1528 is high impedance when off and slowly becomes a low impedance as it turns on. this reduces inrush current and related volt age drop that results from charging a capacitive load, satisfying the usb voltage drop requirements, for bus-powered applications as shown in figure 2.
us1528 preliminary cmos ic unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r502-457.b ? applications information (cont.) in figure 3, the soft start circuit is shown, and the so ft start circuit can be utilized to meet usb transient regulation specifications with large load capacitances (c bulk >10f). the device will provide inrush current limiting for these applications. when hot-plug events occur, the soft start is used to e liminate the upstream voltage droop due to the inrush current. the soft-start protects power supplies from damage caused by highly capacitive loads.
us1528 preliminary cmos ic unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r502-457.b ? typical application circuit upstream v bus 100ma max. v bus d+ d- gnd gnd in out data 1 f 3.3v ldo 10k 1 f vin on/off oc gnd v cc 5.0v 3.3v usb controller 100k utc us1528l en flg out in gnd 0.1 f v bus d+ d- gnd usb port1 ferrite beads 150 f + data single-port self-powered usb hub application ferrite beads 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.
|
