unisonic technologies co., ltd us2076b preliminary cmos ic www.unisonic.com.tw 1 of 8 copyright ? 2010 unisonic technologies co., ltd qw-r502-447.a dual usb high-side power switch ? description the utc u2076b is a dual integrated high-side power switch particularly designed for self-powered and bus-powered universal serial bus (usb) applications. the utc u2076b meets the requirements of the usb. the low on-resistance of the switch sati sfies usb voltage drop requirements. fault current is limited to typically 750ma, well below the ul 25va safety requirement. flag outputs are available to indicate fault conditions to the local usb contro ller. in addition, soft start can eliminate the momentary voltage drop which is generated on the upstream port that may occur when the switch is enabled in bus-powered applications. this device has independent functi ons enable and flag, and an enable input is compatible with both 3.3v and 5v logic. the utc u2076b includes protection circuits. thermal shutdown circuit is designed to protect the device from being damaged when high-current loads exist. uvlo (under-voltage lockout) is used to keep the device off unless there is a valid input voltage present. the utc u2076b is used in application such as usb host and self-powered hubs, bus-powered hu bs, hot plug-in power supplies and battery-charger circuits. ? features * mosfet with low on-resistance: 140m ? max.@5.0v per channel * continuous load current: 500ma (min.) per channel * off-state supply current: 1a (typ.) * output can be forced high er than input (off-state) * current limit up to 1.25a (max.) * input supply voltage: 3.0v ~ 5.5v * on-state supply current: 110a (typ.) * thermal shutdown protection circuit * uvlo (undervoltage lockout): 2.4v (typ.) * open-drain fault flag * 1ms turn-on (soft-start) and fast turn-off * compliant to usb specifications * available with active-high enable sop-8 ? ordering information ordering number package packing US2076BG-S08-R sop-8 tape reel
us2076b preliminary cmos ic unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r502-447.a ? pin configuration ? pin description pin no. pin name description 1, 4 en(a/b) enable (input): logic-compatible enable input. active ? high; do not float. 2, 3 flg(a/b) fault flag (output): active-low, open-drai n output. indicates overcurrent, uvlo, and thermal shutdown. 6 gnd ground: supply return. 7 in supply input: output mosfet source. also s upplies ic's internal ci rcuitry. connect to positive supply. 5, 8 out(a/b) switch output: output mosfet dr ain. typically connect to switched side of load.
us2076b preliminary cmos ic unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r502-447.a ? block diagram
us2076b preliminary cmos ic unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r502-447.a ? absolute maximum rating parameter symbol ratings unit output current i out internally limited fault flag current i flg 50 ma fault flag voltage v flg +6.0 v supply voltage v in +6.0 v output voltage v out +6.0 v control input v en -0.3 ~ 6 v 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. ? 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, unless otherwise specified.) parameter symbol test conditions min typ max unit i s(off) switch off, out = open 25 a supply current i s(on) switch on, out = open 110 a v ih low to high transition 2.4 2.5 v enable input threshold v il high to low transition 1.0 2.2 v v en = v oh(min) = 2.4v 0.01 1 a enable input current i en v en = v ol(max) = 0.8v 0.01 1 a enable input capacitance 1 pf v in = 5v 100 m ? switch resistance r on v in = 3v 140 m ? output turn-on delay t on(dly) r l = 10 ? each output 1 ms output turn-on rise time t rise rl = 10 ? each output 0.5 ms output turn-off delay t off(dly) r l = 10 ? each output 1 20 s output turn-off fall time t off r l = 10 ? each output 1 20 s output leakage current i o(leak) each output 10 a short circuit current limit i short each output 0.5 0.75 1.25 a t j increasing 135 c overtemperature shutdown threshold ot threshold t j decreasing 125 c v in = 5v, i l =10ma 10 ? error flag output resistance v in = 3.3v, i l =10ma 15 ? error flag off current v flag = 5v 0.01 1 a v in = increasing 2.5 v uvlo threshold v uvlo v in = decreasing 2.3 v
us2076b preliminary cmos ic unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r502-447.a ? functional description the utc us2076b is dual high-side switch with active-high enable inputs. fault conditions turn off or inhibit turn-on one or both of the output transistors, controlling by the type of fa ult, and the flg pin is pulled to ground by being activated the open-drain error flag transistors. input and output in (input) is the power supply connection to the logic circuitry and the source of the output mosfet. outx (output) is the drain of t he output a or b mosfet. 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 driver 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 and signals the fault flag pin once the input voltage falls below 2.3v (typ.) and if the input voltage exceeds 2.5v (typ.), the swit ch 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 and a f ault flag is pulled low. the reaction to an overcurrent is measured with the following scenarios: switch enable into heavy load if a switch is powered-on or enabled into a heavy load or short-circuit, the switch immediately goes into a constant-current mode, redu cing output voltage. the fault flag goes lo w until the load is reduced or thermal shutdown occurs. 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 volt age. the fault flag drops low until ther mal shutdown occurs or the load is reduced. heavy load applied suddenly 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 switch, folding back into constant-current mode. in that case, the fault flag falls until the load is reduced. fault flag fault flag is an open-drained output of an n-channel mo sfet. it drops low to indicate error conditions as follows: current limiting, uvlo, or thermal shutdown. t he flag output mosfet is capable of sinking a 10ma load to typically 100mv above ground. both flag pins may be "wire-nored" to a common pullup resistor.
us2076b preliminary cmos ic unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r502-447.a ? 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. enable input for a clearly defined input, the en pin must be driven logic high or logic low. floating the input may cause unpredictable operation. en should not be allo wed to go negative with respect to gnd. soft start the utc us2076b 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. capactive load downstream usb device cable c bulk bus powered hub usb controller ena enb flga flgb outa outb gnd in 8 7 6 5 1 2 3 4 4.7 f cable gnd v bus usb host figure 2. soft start (single channel) utc us2076b
us2076b preliminary cmos ic unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r502-447.a ? applications information (cont.) in figure 3, the soft start circuit is shown, and the soft 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. usb controller usb function usb function c bulk c bulk cable gnd usb hub v bus ena enb flga flgb gnd outa outb in 1 2 3 4 8 7 6 5 usb peripheral figure 3. inrush curre nt-limit application us2076b 4.7 f if an inrush current which is from the connection of a heavy capacitive load, the inrush current may cause the fault flag to fall for a short duration, while the switch is in a constant-current mode, or charging the capacitance. in that case, to protect this circuit from damage due to erro neous overcurrent reporting, the fault flag circuit can be in series with a simple 1ms rc low-pass filter (see figure 4) ena enb flga flgb outa outb gnd in 1 2 3 4 5 6 7 8 10k 10k v + usb controller figure 4. transient filter transient overcurrent filter utc us2076b 0.1f oc
us2076b preliminary cmos ic unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r502-447.a ? typical application circuit 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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