View MIC209511_5406555.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

mic2095/mic2097/mic2098/mic2099 current-limiting power distribution switches mlf and micro leadframe are registered trademarks of amkor technology, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com general description the mic2095/97/98/99 family of switches are self- contained, current-limiting, hi gh-side power switches, ideal for power-control applications . these switches are useful for general purpose power distribution applications such as digital televisions (dtv), pr inters, set-top boxes (stb), pcs, pdas, and other peripheral devices. the current limiting switches feature either a fixed 0.5a/0.9a or resistor programmable output current limit. the family also has fault blanking to eliminate false noise- induced, over current conditi ons. after an over-current condition, these devices automa tically restart if the enable pin remains active. the mic2097 switch offers a unique new patented kickstart feature, which allows momentary high-current surges up to the secondary current limit (i limit_2nd ). this is useful for charging loads with high inrush currents, such as capacitors. the mic2095/97/98/99 family of switches provides under- voltage, over-temperature shutdown, and output fault status reporting. the family also provides either an active low or active high, logic level enable pin. the mic2095/97/98/99 family is offered in a space saving 1.6mm x 1.6mm thin mlf ? (tmlf) package. datasheets and support documentation can be found on micrel?s web site at: www.micrel.com . features ? mic2095: 0.5a fixed current limit ? mic2098: 0.9a fixed current limit ? mic2097/99: resistor programmable current limit ? 0.1a to 1.1a ? mic2097: kickstart for high peak current loads ? under voltage lock-out (uvlo) ? soft start prevents large current inrush ? automatic-on output after fault ? thermal protection ? enable active high or active low ? 170m ? typical on-resistance @ 5v ? 2.5v ? 5.5v operating range applications ? digital televisions (dtv) ? set top boxes ? pdas ? printers ? usb / ieee 1394 power distribution ? desktop and laptop pcs ? game consoles ? usb keyboard ? docking stations _________________________________________________________________________________________________________________________ typical application mic2095 usb power switch august 2011 m9999-080211-c
micrel, inc. mic2095/97/98/99 august 2011 2 m9999-080211-c ordering information part number marking enable logic kickstart ( ? ) ilimit fault/ output junction temperature range (1) package mic2095-1ymt j1k active high no 0.5a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2095-2ymt j2k active low no 0.5a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2097-1ymt k1k active high yes 0.1 a ? 1.1a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2097-2ymt k2k active low yes 0.1 a ? 1.1a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2098-1ymt h1k active high no 0.9a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2098-2ymt h2k active low no 0.9a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2099-1ymt g1k active high no 0.1 a ? 1.1a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf mic2099-2ymt g2k active low no 0.1 a ? 1.1a yes ?40c to +125c 6-pin 1.6mm x 1.6mm tmlf pin configuration 6-pin 1.6mm x 1.6mm tmlf (mt) (top view) mic2095-1ymt/mic2098-1ymt 6-pin 1.6mm x 1.6mm tmlf (mt) (top view) mic2095-2ymt/mic2098-2ymt 6-pin 1.6mm x 1.6mm tmlf (mt) (top view) mic2097-1ymt / mic2099-1ymt 6-pin 1.6mm x 1.6mm tmlf (mt) (top view) mic2097-2ymt / mic2099-2ymt
micrel, inc. mic2095/97/98/99 august 2011 3 m9999-080211-c pin description pin number pin name pin function 1 vout switch output (output): the load being driven by the switch is connected to this pin. 2 (mic2095/mic2098) nc no connect; pin not used. 2 (mic2097/mic2099) ilimit current limit (input): a resistor from this pin to ground sets the current limit value. see the ?setting i lmiit ? section for details on setting the resistor value. 3 fault/ fault status (output): a logic low on this pin i ndicates the switch is in current limiting, or has been shut down by the thermal protection circuit. this is an open-drain output allowing logical or?ing of fault/ outputs from multiple devices. 4 (mic2095-1/mic2097-1/ mic2098-1/mic2099-1) enable switch enable (input): logic high on this pin enables the switch. 4 (mic2095-2/mic2097-2/ mic2098-2/mic2099-2) enable/ switch enable (input): logic low on this pin enables the switch. 5 gnd ground. 6 vin power input (input): this pin provides power to both the output power switch and the internal control circuitry. ep ep used to remove heat from die. connect to ground. use multiple vias to the ground plane to minimize thermal impedance. see applications section for additional information.
micrel, inc. mic2095/97/98/99 august 2011 4 m9999-080211-c absolute maximum ratings (1) supply voltage (v in ) ....................................... ? 0.3v to 6.0v output voltage (v out ) ....................................... ? 0.3v to v in fault pin voltage (v fault ) .............................. ? 0.3v to v in enable pin voltage (v enable ).......................... ? 0.3v to v in ilimit pin voltage (v ilimit ) ................................ ? 0.3v to v in power dissipation (p d ) ..............................internally limited maximum junction temperature (t j )......................... 150c storage temper ature (ts)......................... ? 65c to +150c lead temperature (solde ring, 10sec .) ....................... 260c esd hbm rating (vout, gnd) (3) ................................. 4kv esd hbm rating (fault, enable, vin) (3) ................. 2kv operating ratings (2) supply voltage (v in )......................................... 2.5v to 5.5v enable pin voltage (v enable ) .............................. 0v to v in fault pin voltage (v fault ) ................................... 0v to v in ambient temperature range (t a ) .............. ?40c to +85c package thermal resistance (6) 1.6mm 1.6mm tmlf ( ja ) .............................. 93oc/w electrical characteristics (4) v in = 5v; c in = 1f t a = 25c unless noted, bold values indicate ?40c t a +85c. symbol parameter condition min. typ. max. units power input supply v in input voltage range 2.5 5.5 v quiescent supply current (5) switch = on active low enable, v en = 0v active high enable, v en = 1.5v 80 300 a switch = off active low enable, v en = 1.5v 8 15 a i in shutdown current switch = off active high enable, v en = 0.5v 0.1 5 a v in rising 2 2.25 2.5 v v in uvlo threshold v in falling 1.9 2.15 2.4 v uvlo threshold v in uvlo hysteresis 100 mv enable control enable logic level low (5) v il(max) 0.5 v v en enable logic level high (5) v ih(min) 1.5 v i en enable bias current 0v v en 5v 0.1 5 a t on_dly output turn-on delay r l = 43 ? , c l = 120f v en = 50% to v out = 10% 1000 1500 s t off_dly output turn-off delay r l = 43 ? , c l = 120f v en = 50% to v out = 90% 700 s t rise output turn-on rise time r l = 100 ? , c load = 1f v out = 10% to 90% 500 1000 1500 s thermal protection t j rising 145 c ot threshold over-temperature shutdown t j falling 135 c
micrel, inc. mic2095/97/98/99 august 2011 5 m9999-080211-c electrical characteristics (continued) v in = 5v; c in = 1f t a = 25c unless noted, bold values indicate ?40c t a +85c. symbol parameter condition min. typ. max. units internal switch 170 220 m ? r ds(on) on resistance v in = 5v, i out = 100ma 275 m? i leak output leakage current switch = off, v out = 0v active low enable, v en = 1.5v active high enable, v en = 0v 0.1 10 a output current limit (mic2095) i limit fixed current limit v out = 0.8 v in 0.5 0.7 0.9 a output current limit (mic2098) i limit fixed current limit v out = 0.8 v in 0.9 1.1 1.5 a output current limit (mic2097, mic2099) i out = 1.1a, v out = 0.8 v in ; v in =2.5v 175 215 263 v i out = 0.5a, v out = 0.8 v in ; v in =2.5v 152 206 263 v i out = 0.2a, v out = 0.8 v in ; v in =2.5v 138 200 263 v clf variable current limit factors i out = 0.1a, v out = 0.8 v in ; v in =2.5v 121 192 263 v kickstart tm current limit (mic2097) i limit_2nd secondary current limit v in = 2.5v; v out = 0v 1.5 a t d_limit duration of kickstart tm current limit v in = 2.5v 77 105 192 ms fault flag fault flag output voltage i ol = 10ma 0.25 0.4 v v fault/ fault flag off current v fault/ =5v 0.01 1 a fault delay (mic2095, mic2098, mic2099) t d_fault delay before asserting or releasing fault/ time from current limiting (v out = 0.4 x v in ) to fault/ state change 20 32 49 ms fault delay (mic2097) t d_fault delay before asserting or releasing fault/ time from current limiting (v out = 0.8 x v in ) to fault/ state change; v in = 2.5v 77 105 192 ms notes: 1. exceeding the absolute maximum rating may damage the device. 2. the device is not guaranteed to function outside its operating rating. 3. devices are esd sensitive. handli ng precautions recommended. human body mo del, 1.5k in series with 100pf. 4. specifications for packaged product only. 5. check the ordering information section to deter mine which parts are active high or active low. 6. requires proper thermal mounting to achieve this performance.
micrel, inc. mic2095/97/98/99 august 2011 6 m9999-080211-c timing diagrams 90% 10% 90% 10% t fall t rise rise and fall times enable vout 50% 90% 10% t on_dly t off_dly 50% switching delay times
micrel, inc. mic2095/97/98/99 august 2011 7 m9999-080211-c typical characteristics v in shutdown current vs. input voltage 0 2 4 6 8 10 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) supply current (a) -2 version v in shutdown current vs. input voltage -2 0 2 4 6 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) supply current (a) -1 version v in supply current vs. input voltage 0 20 40 60 80 100 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) supply current (a) current limit vs. input voltage mic2097/mic2099 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2.53.03.54.04.55.05.5 input voltage (v) current limit (a) r set = 200 ? , i set = 1.08a r set = 298 ? , i set = 0.7a r set = 508 ? , i set = 0.4a r set = 1920 ? , i set =0.1a v out =0.8*v in current limit vs. input voltage mic2095 0.0 0.2 0.4 0.6 0.8 1.0 2.53.03.54.04.55.05.5 input voltage (v) current limit (a) i limit i sc v out = 0.8*v in current limit vs. input voltage mic2098 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) current limit (a) i limit i sc v out = 0.8*v in current limit vs. input voltage mic2097/mic2099 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2.53.03.54.04.55.05.5 input voltage (v) current limit (a) i limit i sc r set =195 ? i set = 1.1a v out = 0.8*v in switch on resistance vs. input voltage 100 120 140 160 180 200 220 240 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) resistance (m ? ) i out = 100ma fault delay vs. input voltage mic2095/mic2098/mic2099 0 5 10 15 20 25 30 35 40 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) delay (ms) c load = 1 f r load = 100 ? fault delay vs. input voltage mic2097 0 20 40 60 80 100 120 140 2.5 3.0 3.5 4.0 4.5 5.0 5.5 input voltage (v) delay (ms) c load = 1 f r load = 100 ? kickstart current vs. input voltage mic2097 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.53.03.54.04.55.05.5 input voltage (v) peak current (a) r set = 195 ? i set = 1.1a v out = 0.8*v in kickstart period vs. input voltage mic2097 0 20 40 60 80 100 120 140 2.53.03.54.04.55.05.5 input voltage (v) time (ms)
micrel, inc. mic2095/97/98/99 august 2011 8 m9999-080211-c typical characteristics (continued) v in shutdowncurrent vs. temperature 0.0 0.2 0.4 0.6 0.8 1.0 -40 -15 10 35 60 85 temperature (c) shutdown current (a) v in = 5v v in = 3v -1 version v in shutdowncurrent vs. temperature 0.0 2.0 4.0 6.0 8.0 10.0 -40 -15 10 35 60 85 temperature (c) supply current (a) v in = 5v v in = 3v -2 version v in supply current vs.temperature 0 20 40 60 80 100 -40 -15 10 35 60 85 temperature (c) supply current (a) v in = 5v v in = 3v current limit vs. temperature mic2095 0.0 0.2 0.4 0.6 0.8 1.0 -40 -15 10 35 60 85 temperature (c) current limit (a) v in = 5.0v v out = 4v i limit i sc current limit vs. temperature mic2098 0.0 0.2 0.4 0.6 0.8 1.0 1.2 -40 -15 10 35 60 85 temperature (c) current limit (a) v in = 5.0v v out = 4v i threshold i sc current limit vs.temperature mic2097/mic2099 0.0 0.2 0.4 0.6 0.8 1.0 1.2 -40 -15 10 35 60 85 temperature (c) current limit (a) i limit v in = 5.0v v out = 4v r set =195 ? i set = 1.1a i sc r ds(on) vs. temperature 100 120 140 160 180 200 220 240 -40 -15 10 35 60 85 temperature (c) resistance (m ? ) v in = 5.0v v in = 3.3v output fall time vs. temperature 100 140 180 220 260 300 340 -40 -15 10 35 60 85 temperature (c) fall time ( s) v in = 3v v in = 5.0v c load = 1 f r load =100 ? output rise time vs. temperature 0 200 400 600 800 1000 1200 -40 -15 10 35 60 85 temperature (c) rise time ( s) v in = 3v v in = 5.0v c load = 1 f r load =100 ? v in uvlo thresholds vs. temperature 2.0 2.1 2.2 2.3 2.4 2.5 -40 -15 10 35 60 85 temperature (c) v in ulvo thresholds (v) v in rising v in falling fault delay vs. temperature mic2095/mic2099 0 5 10 15 20 25 30 35 40 -40 -15 10 35 60 85 temperature (c) delay (ms) c load = 1 f r load =100 ? v in = 3v v in = 5.0v kickstart current vs. temperature mic2097 1.20 1.25 1.30 1.35 1.40 1.45 1.50 1.55 1.60 -40 -15 10 35 60 85 temperature (c) peak current (a) v in = 3v v in = 5.0v v out = 4v r set =195 ? i set = 1.1a
micrel, inc. mic2095/97/98/99 august 2011 9 m9999-080211-c typical characteristics (continued) kickstart period vs. temperature mic2097 0 20 40 60 80 100 120 140 160 -40 -15 10 35 60 85 temperature (c) time (ms) v in = 3v v in = 5.0v i limit & i set vs. r set mic2097/mic2099 v in = 5v vo=4v t a = 25c 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 0 300 600 900 1200 1500 1800 2100 r set ( ? ) i set (a) i limit i set v in - v out (v in = 5.0v) vs. output current 0 50 100 150 200 250 0.0 0.2 0.4 0.6 0.8 1.0 1.2 output current (a) v in - v out (mv) v in = 5v 85oc 25oc -40oc v in - v out (v in = 3.0v) vs. output current 0 50 100 150 200 250 0.0 0.2 0.4 0.6 0.8 1.0 1.2 output current (a) v in - v out (mv) 85oc 25oc -40oc v in = 3v
micrel, inc. mic2095/97/98/99 august 2011 10 m9999-080211-c functional characteristics
micrel, inc. mic2095/97/98/99 august 2011 11 m9999-080211-c functional characteristics (continued)
micrel, inc. mic2095/97/98/99 august 2011 12 m9999-080211-c functional characteristics (continued)
micrel, inc. mic2095/97/98/99 august 2011 13 m9999-080211-c functional characteristics (continued)
micrel, inc. mic2095/97/98/99 august 2011 14 m9999-080211-c functional characteristics (continued)
micrel, inc. mic2095/97/98/99 august 2011 15 m9999-080211-c functional diagram mic2095/97/98/99 functional diagram
micrel, inc. mic2095/97/98/99 august 2011 16 m9999-080211-c functional description and application information v in and v out v in is both the power supply connection for the internal circuitry driving the switch and the input (source connection) of the power mosfet switch. v out is the drain connection of the power mosfet and supplies power to the load. in a typical circuit, current flows from v in to v out toward the load. since the switch is bi- directional when enabled, if v out is greater than v in , current will flow from v out to v in . when the switch is disabled, current will not flow to the load, except for a small unavoidable leakage current of a few micro amps. however, should v out exceed v in by more than a diode drop (~0.6v), while the switch is disabled, current will flow from output to input via the power mosfet?s body diode. when the switch is enabled, current can flow both ways, from v in to v out , or v out to v in . c in a minimum 1 f bypass capacitor positioned as close as possible to the v in and gnd pins of the switch is both good design practice and required for proper operation of the switch. this will c ontrol supply transients and ringing. without a sufficient bypass capacitor, large current surges or a short may cause sufficient ringing on v in (from supply lead inductance) to cause erratic operation of the switch?s control circuitry. for best performance a good quality, low-esr ceramic capacitor is recommended. an additional 22 f (or greater) capacitor, positioned close to the v in and gnd pins of the switch is necessary if the distance between a larger bulk capacitor and the switch is greater than 3 inches. this additional capacitor limits input voltage transients at the switch caused by fast changing input currents that occur during a fault condition, such as current limit and thermal shutdown. when bypassing with capacitors of 10 f and up, it is good practice to place a smaller value capacitor in parallel with the larger to handle the high frequency components of any line transients. values in the range of 0.1 f to 1 f are recommended. again, good quality, low-esr capacitors, preferably ceramic, should be chosen. c out an output capacitor is recommended to reduce ringing and voltage sag on the output during a transient condition. a value between 1f and 10f is recommended, however, larger values can be used. limitations on c out the part may enter current limit when turning on with a large output capacitance. this is an acceptable condition, however, if the part remains in current limit for a time greater than t d_fault , the fault pin will assert low. the maximum value of cout may be approximated by the following equation: max_in min_fault_dmin_limit max_out v t i c = eq. 1 where: i limit_min and t d_fault_min are the minimum specified values listed in the electrical characteristic table and v in_max is the maximum input voltage to the switch. current sensing and limiting the current limiting switches protect the system power supply and load from damage by continuously monitoring current through the on-chip power mosfet. load current is monitored by means of a current mirror in parallel with the power mosfet switch. current limiting is invoked when the load exceeds the over- current threshold. when current limiting is activated the output current is constrained to the limit value, and remains at this level until either the load/fault is removed, the load?s current requirement drops below the limiting value, or the switch goes into thermal shutdown. kickstart? the mic2097 has a kickstart feature that allows higher momentary current surges bef ore the onset of current limiting. this permits dynamic loads, such as small disk drives or portable printers to draw the inrush current needed to overcome inertial loads without sacrificing system safety. the kickstart parts differ from the non- kickstart parts which more rapidly limit load current, potentially starving a motor and causing the appliance to stall or stutter. during the kickstart delay period, (typically 105ms), a secondary current limit (nominally set at 1.5a), is in effect. if the load demands a current in excess the secondary limit, kickstart parts act immediately to restrict output current to the secondar y limit for the duration of the kickstart period. after th is time the kickstart parts revert to their normal current limit. an example of kickstart operation is in figure 1. kickstart may be over-ridden by the thermal protection circuit and if sufficient internal heating occurs, kickstart will be terminated and the output switch will be turned off. after the parts cools, if the load is still present i out ? i limit , not i limit_2nd .
micrel, inc. mic2095/97/98/99 august 2011 17 m9999-080211-c figure 1. mic2097 kickstart operation figure 1 label key: a. the mic2097 is enabled into an excessive load (slew-rate limiting not visible at this time scale) the initial current surge is limited by either the overall circuit resistance and power-supply compliance, or the secondary current lim it, whichever is less. b. r on of the power fet increases due to internal heating. c. kickstart period. d. current limiting initia ted. fault/ goes low. e. v out is non-zero (load is heavy, but not a dead short where v out = 0v. limiting response will be the same for dead shorts). f. thermal shutdown followe d by thermal cycling. g. excessive load released, normal load remains. mic2097 drops out of current limiting. h. fault/ delay period followed by fault/ going high. enable input the enable pin is a logic level compatible input which turns on or off the main mosfet switch. there are two versions of each device. the ? 1 version has an active high (enable) and the ? 2 version has an active low (enable/). fault output the fault/ is an n-channel open-drain output, which is asserted (low true) when the device either begins current limiting or enters thermal shutdown. the fault/ signal asserts after a brief delay period in order to filter out very brief over current conditions. after an over- current or over-temperature fault clears, the fault/ pin remains asserted (low) for the delay period. the fault/output is open-drain and must be pulled high with an external resistor. the fault/ signal may be wire-or?d with other similar outputs, sharing a single pull-up resistor. fault/ may be tied to a pull-up voltage source which is less than or equal to v in . soft-start control large capacitive loads can create significant inrush current surges when charged through the current limiting switch. when the switch is enabled, the built-in soft-start limits the initial inrush curr ent by slowly turning on the output. power dissipation and thermal shutdown thermal shutdown is used to protect the current limiting switch from damage should the die temperature exceed a safe operating temperature. thermal shutdown shuts off the output mosfet and asserts the fault/ output if the die temperature reaches 145c (typical). the switch will automatically resume operation when the die temperature cools down to 135c. if resumed operation results in reheat ing of the die, another shutdown cycle will occur and the switch will continue cycling between on and off states until the reason for the overcurrent condition has been resolved. depending on pcb layout, package type, ambient temperature, etc., hundreds of milliseconds may elapse from the time a fault occurs to the time the output mosfet will be shut off. this delay is caused because of the time it takes for the die to heat after the fault condition occurs. power dissipation depends on several factors such as the load, pcb layout, ambient temperature, and supply voltage. calculation of power dissipation can be accomplished by the following equation: ( ) 2 out ds(on) d irp = eq. 2 to relate this to junction temperature, the following equation can be used: aa)-(jdj trpt + = eq. 3 where t j = junction temperature, t a = ambient temperature, and r (j-a) is the thermal resistance of the package. in normal operation, excessive switch heating is most often caused by an output short circuit. if the output is shorted, when the switch is enabled, the switch limits the output current to the maximum value. the heat generated by the power diss ipation of the switch continuously limiting the current may exceed the package and pcb?s ability to cool the device and the switch will shut down and sign al a fault condition. please see the fault output description in the previous page for more details on the fault/ output. after the switch
micrel, inc. mic2095/97/98/99 august 2011 18 m9999-080211-c shuts down, and cools, it will re -start itself if the enable signal retains true (high on the enable parts, low on the enable/ parts). in figure 2, die temperature is plotted against i out assuming a constant ambient temperature of 85c. the plot also assumes the maximum specified switch resistance at high temperature. die temperature vs output current (ambient temperature = 85c) 70 80 90 100 110 120 130 0.0 0.2 0.4 0.6 0.8 1.0 1.2 i out (a) die temperature (c) tamb=85c figure 2. die temperature vs. i out setting i limit the current limit of the mic2097 and mic2099 parts are user programmable and controlled by a resistor connected between the i limit pin and ground. the value of the current limit resistor is determined by the following equations: limit limit r lf) itfactor(c currentlim i = eq. 4 or limit limit i lf) itfactor(c currentlim r = eq. 5 the current-limit factor (clf) is a number that is characteristic to the mic2097/9 switches. the clf is a product of the current-setting resistor value, and the desired current-limit value. please note that the clf varies with the current output current, so caution is necessary to use the correc t clf value for the current that you intend to use the part at. for example: if one wishes to set a i limit = 1.1a, looking in the electrical specifications we will find clf at i limit = 1.1 a, as noted in table 1. min. typ. max. units 175 215 263 v table 1. clf at i limit = 1.1a for the sake of this example, the typical value of clf at an i out of 1.1a is 215v. applying equation 5: == 195 1.1a 215v )(r limit eq. 6 choose r limit = 196 ? (the closest standard 1% value) designers should be aware that variations in the measured i limit for a given r limit resistor, will occur because of small differences between individual ics (inherent in silicon processing ) resulting in a spread of i limit values. in the example above we used the typical value of clf to calculate r limit . we can determine i limit ?s spread by using the minimum and maximum values of clf and the calculated value of r limit : a89.0 196 175v i limit_min = = eq. 7 a34.1 196 v263 i max_limit = = eq. 8 giving us a maximum i limit variation of: i limit_min i limit_typ i limit_max 0.89a (-19%) 1.1a 1.34a (+22%) for convenience, table 2 lists the resistance values for the r set pin, for various current limit values. nominal i limit r limit i limit_min i limit_max 0.1a 1920 0.063 0.137 0.2a 1000 0.138 0.263 0.3a 672 0.211 0.391 0.4a 508 0.288 0.517 0.5a 412 0.369 0.638 0.6a 344 0.448 0.764 0.7a 298 0.533 0.884 0.8a 263 0.620 1.002 0.9a 235 0.709 1.118 1.0a 213 0.801 1.233 1.1a 195 0.895 1.346 table 2. mic2097 and mic2099 r limit table
micrel, inc. mic2095/97/98/99 august 2011 19 m9999-080211-c when measuring i out it is important to remember voltage dependence, otherwise the measurement data may appear to indicate a problem when none really exists. this voltage dependence is illustrated in figures 5 and 6. i limit vs. i out measured when in current limit, the switches are designed to act as a constant-current source to the load. as the load tries to pull more than the maximum current, v out drops and the input-to-output voltage differential increases. as the (v in ? v out ) voltage differential increases, the ic internal temperature also increases. to limit the ic?s power dissipation, the current limit is reduced as a function of output voltage. in figure 5, output current is measured as v out is pulled below v in , with the test terminating when v out is 1v below v in . observe that once i limit is reached i out remains constant throughout the remainder of the test. in figure 6 this test is repeated but with (v in ? v out ) is 4v. this folding back of i limit can be generalized by plotting i limit as a function of v out , as shown in figures 3 and 4. the slope of v out between i out = 0v and i out = i limit (where i limit is a normalized 1a) is determined by r on of the switch and i limit . 0 0.2 0.4 0.6 0.8 1.0 1.2 0123456 normalized output current (a) output voltage (v) normalized output current vs. output voltage (5v) figure 5. i out in current limiting for v out = 4v figure 3. normalized output current vs. output voltage 0 0.2 0.4 0.6 0.8 1.0 1.2 0 0.5 1.0 1.5 2.0 2.5 3.0 normalized output current (a) output voltage (v) normalized output current vs. output voltage (2.5v) figure 6. i out in current limiting for v out = 1v under voltage lock out (uvlo) the switches have an under voltage lock out (uvlo) feature that will shut down t he switch in a reproducible manner when the input power supply voltage goes too low. the uvlo circuit disables the output until the supply voltage exceeds the uvlo threshold. hysteresis in the uvlo circuit prevents noise and finite circuit impedance from causing chatter during turn-on and turn- off. while disable by the uvlo circuit, the output switch (power mosfet) is off and no circuit functions, such as fault/ or enable, are considered to be valid or operative. figure 4. normalized output current vs. output voltage
micrel, inc. mic2095/97/98/99 august 2011 20 m9999-080211-c typical application schematics figure 7. mic2095-1 or mic2098-1 typical schematic note: mic2095-1 and mic2098-1; r5=nf; en pin uses r4 (pull-up resistor to v in ) to enable the output without an external enable signal. mic2095-2 and mic2098-2; r4=nf; en/ pin uses r5 (pull-down resistor to gnd) to enable the output without an external enable signal. figure 8. mic2097-1 typical schematic note: mic2097-1; r5=nf; en pin uses r4 (pull-up resistor to v in ) to enable the output without an external enable signal. mic2097-2; r4=nf; en/ pin uses r5 (pull-down resistor to gnd) to enable the output without an external enable signal. figure 9. mic2099-1 schematic note: mic2099-1; r5=nf; en pin uses r4 (pull-up resistor to v in ) to enable the output without an external enable signal. mic2099-2; r4=nf; en/ pin uses r5 (pull-down resistor to gnd) to enable the output without an external enable signal.
micrel, inc. mic2095/97/98/99 august 2011 21 m9999-080211-c evaluation board schematic figure 10. schematic of mic209x evaluation board notes: 1. evaluation board is used for all parts. 2. part numbering scheme is 209x-y where x is the place holder for the last number (i.e. mic209 5 , mic209 7, mic209 8 or mic2099 ) and y is the polarity of the enable signal (-1 indicates active high logic and -2 indicates active low logic). 3. mic209x-1 en pin only requires r4 (pull-up resistor to v in ) to enable the output without an external enable signal. 4. mic209x-2 en/ pin only requires r3 (pull-down resisto r-to-gnd) to enable the output without an external enable signal. 5. r1 is nf (no fill) with the mic2095 (fixed current limit).
micrel, inc. mic2095/97/98/99 august 2011 22 m9999-080211-c mic209x bill of materials item part number manufacturer description qty. c1 08056d106mat2a avx (1) ceramic capacitor, 10f, 6.3v, x5r 1 c2 06033d105mat2a avx (1) ceramic capacitor, 1f, 25v, x5r 1 c3 0805d226mat2a avx (1) ceramic capacitor, 22f, 6.3v, x5r 1 c4 120f (optional) 0 r1 (4) crcw06032000frt1 vishay dale (2) resistor, 200 (0603 size), 1% 1 r2, r3, r4 crcw06031002frt1 vishay dale (2) resistor, 10k (0603 size), 1% 3 u1 mic2095-1ymt micrel, inc. (3) current-limiting power distribution switch ? 0.5a fixed current limit ? active high enable 1 u1 mic2095-2ymt micrel, inc. (3) current-limiting power distribution switch ? 0.5a fixed current limit ? active low enable 0 u1 mic2097-1ymt micrel, inc. (3) current-limiting power distribution switch ? adjustable current limit with kickstart ? active high enable 0 u1 mic2097-2ymt micrel, inc. (3) current-limiting power distribution switch ? adjustable current limit with kickstart ? active low enable 0 u1 mic2098-1ymt micrel, inc. (3) current-limiting power distribution switch ? 0.9a fixed current limit ? active high enable 0 u1 mic2098-2ymt micrel, inc. (3) current-limiting power distribution switch ? 0.9a fixed current limit ? active low enable 0 u1 mic2099-1ymt micrel, inc. (3) current-limiting power distribution switch ? adjustable current limit ? active high enable 0 u1 mic2099-2ymt micrel, inc. (3) current-limiting power distribution switch ? adjustable current limit ? active low enable 0 notes: 1. avx: www.avx.com . 2. vishay: www.vishay.com . 3. micrel, inc.: www.micrel.com . 4. may be omitted when used with the mic2095 or mic2098 (fixed current limit).
micrel, inc. mic2095/97/98/99 august 2011 23 m9999-080211-c pcb layout recommendations figure 11. mic209x evaluation board top layer figure 12. mic209x evaluation board bottom layer
micrel, inc. mic2095/97/98/99 august 2011 24 m9999-080211-c package information 6-pin 1.6mm x 1.6mm tmlf (mt)
micrel, inc. mic2095/97/98/99 august 2011 25 m9999-080211-c recommended landing pattern 6-pin 1.6mm x 1.6mm tmlf (mt) micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944-0800 fax +1 (408) 474-1000 web http://www.micrel.com micrel makes no representations or warranties with respect to t he accuracy or completeness of the information furnished in this data sheet. this information is not intended as a warranty and micrel does not assume responsibility for it s use. micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. no license, whether expre ss, implied, arising by estoppel or other wise, to any intellectual property rights is granted by this document. except as provided in micrel?s terms and conditions of sale for such products, mi crel assumes no liability whatsoever, and micrel disclaims any express or implied warranty relating to the sale and/or use of micrel products including l iability or warranties relating to fitness for a particular purpose, merchantability, or infringement of an y patent, copyright or other intellectual p roperty right. micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended for surgical impla into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. can nt ? 2010 micrel, incorporated.

▲Up To Search▲

Price & Availability of MIC209511

	To Download MIC209511 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .