2013. 2. 05 1/8 semiconductor technical data kic6971f/mf analog cmos integrated circuits revision no : 2 1.5a 2-channel current limited power switch the kic6971f/mf is integrated power switches optimized for usb and other hot-swap applications.the family of devices complies with usb 2.0 and is available with high polarity of enable input. they offer current and thermal limiting and short circuit protection as well as controlled rise time and under-voltage lockout functionality. features h single usb port power switches with discharge h operating input voltage range 2.7v to 5.5v h up to 1.5a maximum load current h internal short circuit current limiting(2.1a) h reverse current blocking h fault report with blanking time(7ms) h 90m ? power mosfet flp-8 0.20+0.1/-0.05 p t 1.27 u max 0.1 millimeters 0.4 0.1 0.15+0.1/-0.05 4.85 0.2 b2 gh l d a b1 dim 6.02 0.31.63 0.2 0.65 0.2 3.94 0.2 + _ + _ + _ + _ + _ + _ g h b1 b2 1 4 5 8 a p d l t u maximum ratings (ta=25 ? ) recommended operating conditions characteristic symbol min max unit input voltage v in 2.7 5.5 v output current i out 0 1.5 a msop-8 p t 0.65 millimeters 0.29~0.38 0.05~0.150.15~0.20 0.4~0.7 1.10 max 3.00 0.1 b2 gh l d a b1 dim 4.90 0.2 3.00 0.1 + _ + _ + _ g h b1 b2 a p d l t characteristic symbol rating unit input voltage v in 6.5 v output voltage v out 6.5 v thermal resistancejunction-to-ambient flp 129 ? /w msop 132 operating junction temperature tj -40~125 ? storage temperature t stg -55 q 150 kic6971f KIC6971MF note) device mounted on fr-4 substrate 2layer pcb. device name marking lot no. kic 6971 c 6971 downloaded from: http:///
2013. 2. 05 2/8 kic6971f/mf revision no : 2 block diagram the two current limit power switchs are the same function and each channel is as below. pin descriptions pin name pin number descriptions gnd 1 ground v in 2 voltage input pin v en1 3 s/w 1 enable input (active high) v en2 4 s/w 2 enable input (active high) v flg2 5 s/w 2 over-current and over-temperature fault report pin (open drain) v out1 6 s/w 2 voltage output pin v out2 7 s/w 1 voltage output pin v flg1 8 s/w 1 over-current and over temperature fault report pin (open drain) v in v out flg v en gnd uvlo reverse blocking driver thermal protection short circuit protection current sense current limit discharge control deglitch typical application circuit gnd v out1 v in v flg2 v en2 10k 10k on off power supply 2.7v to 5.5v 10 t + 0.1 t 0.1 t load 68 t + active high + 0.1 t load 68 t v out2 v en1 v flg1 2 8 5 3 4 6 7 1 downloaded from: http:///
2013. 2. 05 3/8 kic6971f/mf revision no : 2 electrical characteristics (v in =5v, ta=25 ? , unless otherwise stated) characteristic symbol test conditions min typ max units input uvlo v uvlo 2.0 2.2 2.4 v hysteresis 50 100 150 mv input shutdown current i shdn disabled, i out = 0 0.2 0.5 1 u input quiescent current i q enabled, i out = 0 20 45 70 u input leakage current i leak disabled, v out grounded - 0.1 1 u reverse leakage current i rev disabled, v in = 0v, v out = 5v, i rev at v in - 0.1 1 u switch on-resistance r ds(on) v in = 5v, i out = 1.5a, ta=25 ? 70 90 115 m ? v in = 5v, i out = 1.5a, -40 ? ? ta ? 85 ? - - 140 m ? short-circuit current limit i limit v in = 5v, v out = 4v, c l =120 ? , -40 ?! ta ! 85 ? 1.6 2.1 2.6 a current limiting trigger threshold i trig output current slew rate(<100a/s), c l =120 ? - 2.6 - a en input logic low voltagve v il v in = 2.7v to 5.5v - - 0.8 v en input logic high voltagve v ih v in = 2.7v to 5.5v 2 - - v en input leakage i sink v en =5v - - 1 u output turn-on delay time t d(on) c l =1 ? , rload=10 ? - 0.05 0.1 ms output turn-off delay time t d(off) c l =1 ? , rload=10 ? - 0.05 0.1 ms output turn-on rise time t r c l =1 ? , rload=10 ? - 0.6 1.5 ms output turn-on fall time t f c l =1 ? , rload=10 ? - 0.2 0.4 ms discharge time t dis c l =120 ? , rload=10 ? disabled to v out < 0.5v 1 3 6 ms flg blanking time t blank c in = 10 ? , c l = 22 ? 4 7 15 ms thermal shutdown threshold t shdn enabled, rload = 1 ? 130 150 170 ? thermal shutdown hysteresis t hys disabled, v out grounded - 25 - ? downloaded from: http:///
2013. 2. 05 4/8 kic6971f/mf revision no : 2 l trig =2.6a v en v en v out i out v flg i out v flg 7ms 7ms 7ms output short output short 7ms inormal=1a 7ms inormal=1a llimit=2.1a 7ms llimit=2.1a [figure 1. over current protection on power switch] [figure 2. short circuit protection on power switch] [figure 3. delay time] v en v out t d(off) t d(off) t f 50% 50% 10% 10% 90% 90% t r downloaded from: http:///
2013. 2. 05 5/8 kic6971f/mf revision no : 2 [over load] [short circuit] 200ms/div 200ms/div ? flg response condition condition flg remark over - load v in - v out ! 1.0v active l short circuit v out = 0 active l downloaded from: http:///
2013. 2. 05 6/8 kic6971f/mf revision no : 2 supply current, output enabled vs ambient temerature supply current, output enabled (ua) 01 0 0 -60 -40 -20 20 40 60 80 22 27 32 37 42 47 v in =5.0v v in =3.3v v in =2.7v ambient temperature ( ) undervoltage lockout vs ambient temperature undervoltage lockout (v) 01 0 0 -60 -40 -20 20 40 60 80 1.90 1.95 2.00 2.05 2.10 2.15 2.20 2.25 2.30 uvlo rising uvlo falling ambient temperature ( ) static drain-source on-state resistance vs ambient temerature static drain-source on-state resistance (m ) 01 0 0 -60 -40 -20 20 40 60 80 50 100 9080 70 60 110 120 130 140 150 160 170 180 v in =2.7v v in =3.3v v in =5v ambient temperature ( ) supply current, output disabled vs ambient temerature supply current, output disabled (ua) 01 0 0 -60 -40 -20 20 40 60 80 0 0.50.4 0.3 0.2 0.1 0.6 0.7 0.8 0.9 v in =5.0v v in =2.7v v in =3.3v ambient temperature ( ) short-circuit output current vs ambient temerature 01 0 0 -60 -40 -20 20 40 60 80 2.00 2.05 2.10 2.15 2.20 2.25 2.30 v in =5.0v v in =3.3v v in =2.7v c l =120uf ambient temperature ( ) short-circuit output current (a) typical characteristics (continued) downloaded from: http:///
2013. 2. 05 7/8 kic6971f/mf revision no : 2 functional description1. over-current and short circuit protection an internal sensing fet is employed to check for over-current conditions. unlike current-sense resistors, sense fets do notincrease the series resistance of the current path. when an over-current condition is detected, the device maintains a constant output current and reduces the output voltage accordingly. complete shutdown occurs only if the fault stays long enough to activate thermal limiting. 2. thermal protection thermal protection prevents the ic from damage when the die temperature exceeds safe margins. this mainly occurs whenheavy-overload or short-circuit faults are present for extended periods of time. the kic6981f/mf implements a thermal sensing to monitor the operating junction temperature of the power distribution switch. once the die temperature rises to approximately 150 ? c, the thermal protection feature gets activated as follows: the internal thermal sense circuitry turns the power switch off and the flg output is asserted thus preventing the power switch from damage. hysteresis in the thermal sensecircuit allows the device to cool down to approximately 25 ? c before the output is turned back on. this built-in thermal hysteresis feature is an excellent feature, as it avoids undesirable oscillations of the thermal protection circuit. the switchcontinues to cycle in this manner until the load fault is removed, resulting in a pulsed output. the flg open-drain output is asserted when an over-current occurs with 7-ms deglitch. 3. under-voltage lockout (uvlo) under-voltage lockout function (uvlo) guarantees that the internal power switch is initially off during start-up. the uvlofunctions only when the switch is enabled. even if the switch is enabled, the switch is not turned on until the power supply ha s reached at least 2.2v. whenever the input voltage falls below approximately 2.2v, the power switch is turned off. thisfacilitates the design of hot-insertion systems where it is not possible to turn off the power switch before input power is removed. 4. reverse current protection in a normal mosfet switch, current can flow in reverse direction (from the output side to the input side) when the output sidevoltage is higher than the input side, even when the switch is turned off. a reverse-current blocking feature is implemented in the kic6981f/mf to prevent such back currents. this circuit is activated by the difference between the output voltage and the input voltage. when the switch is disabled, this feature blocks reverse current flow from the output back to the input. 5. discharge function when enable is de-asserted, the discharge function is active. the output capacitor is discharged through an internal nmos thathas a discharge resistance of 100 ? . hence, the output voltage drops down to zero. the time taken for discharge is dependent on the rc time constant of the resistance and the output capacitor. 6. flg response the flg open-drain output goes active low for any of the two conditions: over-current or over-temperature. the time from when a fault condition is encountered to when the flg output goes low is 7-ms (typ). the flg output remains low until bothover-current and over-temperature conditions are removed. connecting a heavy capacitive load to the output of the device can cause a momentary over-current condition, which does not trigger the flg due to the 7-ms deglitch timeout. the kic6981f/mf is designed to eliminate erroneous over-current reporting without the need for external components, such as an rc delay network. downloaded from: http:///
2013. 2. 05 8/8 kic6971f/mf revision no : 2 applications information1. supply filtering a 0.01uf to 0.1 f bypass capacitor from in to gnd, located near the kic6981f/mf, is strongly recommended to control supply transients. without a bypass capacitor, an output short may cause sufficient ringing on the input (from supply leadinductance) to damage internal control circuitry. input transients must not exceed the absolute maximum supply voltage (vin max = 6.5v) even for a short duration. 2.en, the enable input en must be driven logic high for a clearly defined input. floating the input may cause unpredictable operation. en should not be allowed to go negative with respect to gnd. downloaded from: http:///
|
