? 2000 imp, inc. 408-432-9100/www.impweb.com 1 imp2525 imp2525 p ower m anagement applications usb power management usb hosts and self-powered hubs battery-charger circuits and power supplies meets or exceeds usb rev. 1.1 and 2.0 specification low mosfet r on (0.14 ? at 3v) 2.7v to 5.5v input operation current limiting soft-start turn-on (1ms) prevents turn-on glitches 500ma continuous load current mosfet short-circuit current limit (1.25a max) low supply current 110a on state current, 1a off state current active-low or active-high enable input 3.3v or 5v logic compatibility fault flag indicates three fault conditions: undervoltage current limit thermal shutdown open-drain fault flag output 2.4v undervoltage lockout (uvlo) pin compatible with the micrel mic2525 block diagrams usb high-side p usb high-side p o o w w er switc er switc h h C sing C sing le switc le switc h h C 0. C 0. 1 1 4 4 ? ? "on" r "on" r esis esis t t ance at 3v ance at 3v C mic2525 pin com C mic2525 pin com patible patible the imp2525 high-side power switch ic is designed for self-powered and bus-powered universal serial bus (usb) power supply and power management applications. the imp2525 conforms to usb standards with a low output switch on-resistance (r on ) and minimal voltage drop across the switch. the fault current is limited to 750ma typically, and a flag output conveys fault conditions to the local usb controller. the imp2525 provides a soft-start function that ramps up the on- current to eliminate any excessive voltage drop on the input side that could occur due to charging a capacitive load in bus-powered applica- tions. self-monitoring features include thermal shutdown to prevent catastrophic switch failure from high-current loads and undervoltage lockout (uvlo) that insures that the device remains off unless there is a valid supply voltage present. the enable input logic can be interfaced with both 3.3v and 5v logic. both active-high and active-low enable logic versions are available. the imp2525 devices are available in 8-pin dip and 8-pin so packages. imp offers a complete family of usb power management products. for dual-switch applications see the imp2526 data sheet and for quad-switch application, see the imp2524. the single-switch imp2525a features a 50% lower switch resistance, 0.07 ? . 2525_01.eps out nc/out 8 6 flg 2 gnd 3 imp2525 power switch gate control current limit 1.2v reference uvlo thermal shutdown oscillator en 1 in 7 charge pump key features
imp2525 imp2525 2 408-432-9100/www.impweb.com ? 2000 imp, inc. 6 pin descriptions ordering information 4 nc 3 gnd 2 flg 1 en 5nc 6 nc/out *connect pins 6 and 8 for mic2525 compatibility 7in * 8 out 2525_02.eps imp2525 so/dip 2525_03.eps out 8 6 in gnd 7 3 flg 2 en 1 logic, charge pump pin number name function 1 en enable input. this pin is the mosfet switch driver logic input. both active-high (-1 suffix) and active-low (-2 suffix) logic devices are available. 2 flg fault flag output. this open-drain output goes into an active-low state in response to undervoltage, current limit or thermal shutdown conditions. 3 gnd ground. power supply return for the internal circuitry of the ic. 4, 5 nc no connection. these pins have no internal connections to the device. 6 nc/out no connection. this pin has no internal connection to the device. connect pins 6 and 8 to maintain pin-compatibility with the mic2525. 7 in positive power supply voltage input. this is the switching mosfet drain connection as well as the positive supply for the ic. 8 out mosfet source. the output pin supplies power to the load. part number enable logic temperature range pins-package IMP2525-1BM active high 40 c to +85 c 8-so imp2525-2bm active low 40 c to +85 c 8-so imp2525-1bn active high 40 c to +85 c 8-dip imp2525-2bn active low 40 c to +85 c 8-dip pin configuration
imp2525 imp2525 ? 2000 imp, inc. usb high-side power switches 3 electrical characteristics supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . +6.0v fault flag voltage . . . . . . . . . . . . . . . . . . . . . . +6.0v fault flag current . . . . . . . . . . . . . . . . . . . . . . 50ma output voltage . . . . . . . . . . . . . . . . . . . . . . . . . +6.0v output current . . . . . . . . . . . . . . . . . . . . . . . . . internally limited enable input . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3v to 12v storage temperature . . . . . . . . . . . . . . . . . . . . . 65 c to +150 c lead temperature (soldering, 5 sec.) . . . . . . . 260 c package thermal resistance so ( ja ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 c/w dip( ja ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 c/w note: all voltages are referenced to gnd. these are stress ratings only and functional operation is not implied. exposure to absolute maximum ratings for prolonged time periods may affect device reliability. parameter symbol conditionsmin typ max units supply voltage range v in t a = 40 c to +85 c 2.7 5.5 v operating temperature range t a 40 85 c supply current i in off switch off, no load 0.75 5 a switch off v enoff 0.8v, v enon 2.4v imp2525-1 v enon 0.8v, v enoff 2.4v imp2525-2 supply current i in on switch on, no load 110 160 a switch on v enoff 0.8v, v enon 2.4v imp2525-1 v enon 0.8v, v enoff 2.4v imp2525-2 enable input threshold v enh low to high ( 0 to 1 ) enable voltage, note 1, 2 2.1 2.4 v v enl high to low ( 1 to 0 ) enable voltage, note 1, 2 0.8 1.9 enable input current i en v en = 0v to 5.5v 1 0.01 1 a enable input capacitance c en 1pf switch on resistance r on v in = 5v, i out = 500ma 0.1 0.14 ? v in = 3.3v, i out = 500ma 0.14 0.18 output turn-on delay t don r l = 10 ? 0.25 ms output turn-on rise time t ron r l = 10 ? 1ms output turn-off delay t doff r l = 10 ? , note 2 1 20 s output turn-off fall time t foff r l = 10 ? , note 2 1 20 s output leakage current i off 10 a short-circuit current limit i sc 0.50 0.75 1.25 a overtemperature shutdown t j increasing 135 c threshold t j decreasing 125 error flag output resistance r flag v in = 5v, i l = 10ma 10 25 ? v in = 3.3v, i l = 10ma 15 40 error flag output current i flag v flag = 5v 0.01 1 a uvlo threshold v uvlo v in increasing 2.5 v v in decreasing 2.3 unless otherwise noted, v in = 5v and t a = 25 c. notes 1. switch off is v en 0.8v and switch on is v en 2.4v for the imp2525-1. switch off is v en 2.4v and switch on is v en 0.8v for the imp2525-2. the enable input has approximately 200mv of hysteresis. 2. over operating temperature range, ?0 c t a 85 c. absolute maximum ratings
imp2525 imp2525 4 408-432-9100/www.impweb.com ? 2000 imp, inc. 6 detailed descriptions the imp2525 is a high-side n-channel mosfet switch that inter- faces with a usb controller by means of a switch-enable input and a fault-flag output. the enable input turns on the power mosfet with either a logic 1 for the imp2525-1 or logic 0 for the imp2525-2. any one of three fault conditions will activate the open-drain fault-flag output to alert the controller that the power mosfet has been turned off. input and output the in (input) pin is the power supply connection to the logic cir- cuitry and the high-side of the switch (the drain of the power mosfet). the out (output) pin is the low-side of the switch (the source of the power mosfet). in a typical circuit, current flows through the switch from in to out toward the load. the switch is referred to as a high-side switch since it drives the positive (or high) side of the load. the output mosfet source can be forced to a higher voltage than the drain (v out > v in ) when the output is off with little leakage current. if, however, v in drops below 2.3v, reverse current may flow out the in pin regard- less of the enable state. when the power switch is on, current can flow in either direction. fault flag - flg pin the fault flag pin, flg, connects to an n-channel, open-drain mosfet and goes low ( 0 ) for an occurrence of one or more of three conditions: undervoltage, current limit, or thermal shut- down. the flg output mosfet is capable of sinking a 10ma load to typically 100mv above ground. table 1 gives the states of the flg and out pins when a fault condition is detected. thermal shutdown thermal shutdown is active when the output switch is enabled (turned on). thermal shutdown shuts off the output mosfet and sets the fault flag if the on-chip temperature sensor exceeds 135 c. the switch is held off until the die temperature drops to 125 c or below. this 10 c of hysteresis will result in on-off short-circuit cycling if the short-circuit condition is not removed or the bus-controller does turn off the switch with the enable input. over temperature detection is active only if the chip is enabled. undervoltage lockout the undervoltage lockout (uvlo) prevents the output mosfet from being put into the on state until the positive sup- ply voltage, v in , exceeds 2.5v. when the output switch is in the on state and the positive supply voltage drops below 2.3v, the uvlo circuitry will assert the fault flag, flg, and shut off the output mosfet. the flg output will only assert an active low state when the mosfet switch is in the on state. undervoltage detection is active only if the chip is enabled. current limiting current limiting is achieved by sensing the voltage drop from drain-to-source of the power mosfet. when the internal thresh- old is exceeded the power mosfet is turned off. table 1. fault flag conditions - switch enabled condition cause flg pin 0 until switch state (flg = 0) thermal shutdown t j > 135 ct j 125 c turns off undervoltage lockout (uvlo) v in < 2.3v v in > 2.5v turns off current limiting i o > 0.5a (step load) enable off or stays on i o > 0.63a (ramped load) thermal shutdown
imp2525 imp2525 ? 2000 imp, inc. usb high-side power switches 5 application information supply filtering imp strongly recommends the use of a 0.1 f to 1 f bypass capac- itor to control transients on the power supply pin. this capacitor, connected from in to gnd, should be in close proximity to the imp2525 for maximum transient suppression. the lack of suitable bypassing can result in ringing on the in input when transients occur. this ringing, due to supply lead inductance, could damage imp2525 control circuitry if the 8v maximum input rating is exceeded. figure 1. supply bypassing 2525_04.eps 4.0v to 5.5v 0.1 f to 1 f in gnd imp2525 3 7 enable input as with any logic input, the enable pin, en, must be driven to a definitive logic state at all times. floating the input can result in spurious operation. do not drive en below gnd. fault flag output soft start the imp2525 provides a soft-start function that ramps up the on-current to eliminate any excessive voltage drop that could occur due to charging a capacitive load in bus-powered applica- tions. the "soft-start" results from a switch on resistance, r on , that is ramped down from a high impedance to 0.14 ? in millisec- onds. this r on ramping reduces the inrush current and related transients occur when charging capacitive loads; a requirement for meeting the usb voltage drop standards for bus-powered applications (see figure 2 ). in circuits with large load capacitances, c bulk , exceeding 10 f, the soft-start circuit shown in figure 3 can be used to limit the inrush start-up current to usb transient spec- ifications. the current limiting feature of the imp2525 provides this high-load, soft-start operation. 2525_06.eps en v bus gnd cable bus powered hub cable downstream usb device usb host 1 0.1 f capacitive load c bulk 4.7 f out flg 2 in gnd imp2525-xbm usb controller 3 out nc 4 8 7 6 5 nc figure 2. soft-start application
imp2525 imp2525 6 408-432-9100/www.impweb.com ? 2000 imp, inc. 6 2525_05.eps v+ 10k 10k 0.1 f flg 2 imp2525 overcurrent usb controller figure 4. transient filter 2525_07.eps en v bus gnd cable usb peripheral usb hub 1 c bulk 4.7 f out flg 2 in gnd imp2525-2 usb controller 3 out nc 4 8 7 6 5 nc usb function figure 3. inrush current-limit application 2525_08.eps en 1 out flg 2 in gnd data data 100k v cc 5.0v ferrite beads imp2525-2 3.3v usb controller 3 out 8 7 6 v in on/off overcurrent gnd 10k ldo in out gnd 150 f usb port 1 f 1 f 0.1 f gnd d d+ v bus upstream v bus 100ma max gnd d d+ v bus + figure 5. single-port self-powered hub application transient overcurrent filter if a heavy capacitive load is suddenly connected to the output, the switch current-limiting function may cause the fault-flag to go low for 10 s to 200 s as the switch, in a constant current mode, charges the capacitance. if this transient over-current fault report- ing is not wanted, a simple 1ms rc low-pass filter in series with the fault flag circuit will prevent this momentary flag ( figure 4 ). application information
imp2525 imp2525 ? 2000 imp, inc. usb high-side power switches 7 e e1 d1 d ea eb c 0 15 a e b2 b a2 l a1 plastic dip (8-pin)a.eps plastic dip (8-pin) b 8 c h e e d b a1 a so (8-pin).eps inchesmillimeters min max min max plastic dip (8-pin)* a 0.210 5.33 a1 0.015 0.38 a2 0.115 0.195 2.92 4.95 b 0.014 0.022 0.36 0.56 b2 0.045 0.070 1.14 1.78 b3 0.030 0.045 0.80 1.14 d 0.355 0.400 9.02 10.16 d1 0.005 0.13 e 0.300 0.325 7.62 8.26 e1 0.240 0.280 6.10 7.11 e 0.100 2.54 ea 0.300 7.62 eb 0.430 10.92 ec 0.060 l 0.115 0.150 2.92 3.81 so (8-pin)** a 0.053 0.069 1.35 1.75 a1 0.004 0.010 0.10 0.25 b 0.013 0.020 0.33 0.51 c 0.007 0.010 0.19 0.25 e 0.050 1.27 e 0.150 0.157 3.80 4.00 h 0.228 0.244 5.80 6.20 l 0.016 0.050 0.40 1.27 d 0.189 0.197 4.80 5.00 so (8-pin) * jedec drawing ms-001ba ** jedec drawing ms-012aa package dimensions
8 408-432-9100/www.impweb.com ? 2000 imp, inc. 6 notes project
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