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february 2001 1 mic2026/2076 mic2026/2076 micrel mic2026/2076 dual-channel power distribution switch general description the mic2026 and mic2076 are high-side mosfet switches optimized for general-purpose power distribution requiring circuit protection. the mic2026/76 are internally current limited and have thermal shutdown that protects the device and load. the mic2076 offers ?mart?thermal shutdown that reduces current consumption in fault modes. when a thermal shut- down fault occurs, the output is latched off until the faulty load is removed. removing the load or toggling the enable input will reset the device output. both devices employ soft-start circuitry that minimizes inrush current in applications where highly capacitive loads are employed. a fault status output flag is asserted during overcurrent and thermal shutdown conditions. transient faults are internally filtered. the mic2026/76 are available in 8-pin dip or 8-lead sop. typical application ena outa flga in flgb gnd enb outb on/off overcurrent overcurrent on/off mic2026-2 logic controller v cc 2.7v to 5.5v 0.1f vin load load v cont. 10k 10k features 140m ? maximum on-resistance per channel 2.7v to 5.5v operating range 500ma minimum continuous current per channel short-circuit protection with thermal shutdown thermally isolated channels fault status flag with 3ms filter eliminates false assertions undervoltage lockout reverse current flow blocking (no body diode ) circuit breaker mode (mic2076) logic-compatible inputs soft-start circuit low quiescent current pin-compatible with mic2526 applications usb peripherals general purpose power switching acpi power distribution notebook pcs pdas pc card hot swap micrel, inc. ?1849 fortune drive ?san jose, ca 95131 ?usa ?tel + 1 (408) 944-0800 ?fax + 1 (408) 944-0970 ?http://www.mic rel.com
mic2026/2076 micrel mic2026/2076 2 february 2001 ordering information part number enable temperature range package mic2026-1bm active high 40 c to +85 c 8-lead sop mic2026-2bm active low 40 c to +85 c 8-lead sop mic2026-1bn active high 40 c to +85 c 8-pin dip mic2026-2bn active low 40 c to +85 c 8-pin dip mic2076-1bm active high 40 c to +85 c 8-lead sop mic2076-2bm active low 40 c to +85 c 8-lead sop mic2076-1bn active high 40 c to +85 c 8-pin dip mic2076-2bn active low 40 c to +85 c 8-pin dip pin description pin number pin name pin function 1 ena switch a enable (input): logic-compatible enable input. active high (-1) or active low (-2). 2 flga fault flag a (output): active-low, open-drain output. indicates overcurrent or thermal shutdown conditions. overcurrent conditions must last longer than t d in order to assert flga. 3 flgb fault flag b (output): active-low, open-drain output. low indicates overcurrent or thermal shutdown conditions.overcurrent conditions must last longer than t d in order to assert flgb. 4 enb switch b enable (input): logic-compatible enable input. active-high (-1) or active-low (-2). 5 outb switch b (output) 6 gnd ground 7 in input: switch and logic supply input. 8 outa switch a (output) pin configuration 1 2 3 4 8 7 6 5 outa in gnd outb ena flga flgb enb mic2026/76 8-lead sop (bm) 8-pin dip (bn)
february 2001 3 mic2026/2076 mic2026/2076 micrel electrical characteristics v in = +5v; t a = 25 c, bold values indicate 40 c t a +85 c; unless noted symbol parameter condition min typ max units i dd supply current mic20x6-1, v ena = v enb 0.8v 0.75 5 a (switch off), out = open mic20x6-2, v ena = v enb 2.4v 0.75 5 a (switch off), out = open mic20x6-1, v ena = v enb 2.4v 100 160 a (switch on), out = open mic20x6-2, v ena = v enb 0.8v 100 160 a (switch on), out = open v en enable input threshold low-to-high transition 1.7 2.4 v high-to-low transition 0.8 1.45 v enable input hysteresis 250 mv i en enable input current v en = 0v to 5.5v 1 0.01 1 a enable input capacitance 1 pf r ds(on) switch resistance v in = 5v, i out = 500ma 90 140 m ? v in = 3.3v, i out = 500ma 100 170 m ? output leakage current mic20x6-1, v enx 0.8v; 10 a mic20x6-1, v enx 2.4v, (output off) off current in mic2076 50 a latched thermal shutdown (during thermal shutdown state) t on output turn-on delay r l = 10 ? , c l = 1 f, see timing diagrams 1.3 5 ms t r output turn-on rise time r l = 10 ? , c l = 1 f, see timing diagrams 1.15 4.9 ms t off output turnoff delay r l = 10 ? , c l = 1 f, see timing diagrams 35 100 s t f output turnoff fall time r l = 10 ? , c l = 1 f, see timing diagrams 32 100 s i limit short-circuit output current v out = 0v, enabled into short-circuit 0.5 0.9 1.25 a current-limit threshold ramped load applied to output 1.0 1.25 a short-circuit response time v out = 0v to i out = i limit 20 s (short applied to output) t d overcurrent flag response v in = 5v, apply v out = 0v until flg low 1.5 3 7 ms delay v in = 3.3v, apply v out = 0v until flg low 3 ms undervoltage lockout v in rising 2.2 2.4 2.7 v threshold v in falling 2.0 2.15 2.5 v absolute maximum ratings (note 1) supply voltage (v in ) ...................................... 0.3v to +6v fault flag voltage (v flg ) .............................................. +6v fault flag current (i flg ) ............................................ 25ma output voltage (v out ) .................................................. +6v output current (i out ) ............................... internally limited enable input (i en ) .................................... 0.3v to v in + 3v storage temperature (t s ) ...................... 65 c to +150 c esd rating, note 3 operating ratings (note 2) supply voltage (v in ) ................................... +2.7v to +5.5v ambient temperature (t a ) ......................... 40 c to +85 c junction temperature range (t j ) ........... internally limited thermal resistance sop ( ja ) .......................................................... 160 c/w dip( ja ) ............................................................. 105 c/w
mic2026/2076 micrel mic2026/2076 4 february 2001 symbol parameter condition min typ max units error flag output i l = 10ma, v in = 5v 10 25 ? resistance i l = 10ma, v in = 3.3v 15 40 ? error flag off current v flag = 5v 10 a overtemperature threshold t j increasing, each switch 140 c note 4 t j decreasing, each switch 120 c t j increasing, both switches 160 c t j decreasing, both switches 150 c note 1. exceeding the absolute maximum rating may damage the device. note 2. the device is not guaranteed to function outside its operating rating. note 3. devices are esd sensitive. handling precautions recommended. note 4. if there is a fault on one channel, that channel will shut down when the die reaches approximately 140 c. if the die reaches approximately 160 c, both channels will shut down, even if neither channel is in current limit. test circuit device under test c l out r l v out timing diagrams 90% v out 10% 90% 10% t r t f output rise and fall times v en 50% 90% v out 10% t off t on active-low switch delay times (mic20x6-2) v en 50% 90% v out 10% t off t on active-high switch delay times (mic20x6-1)
february 2001 5 mic2026/2076 mic2026/2076 micrel 0 20 40 60 80 100 120 140 160 180 -40 -20 0 20 40 60 80 100 current ( a) temperature ( c) supply on-current vs. temperature 5v 3.3v 0 20 40 60 80 100 120 140 160 -40 -20 0 20 40 60 80 100 on-resistance (m ? ) temperature ( c) on-resistance vs. temperature 5v 3.3v i out = 500ma 0 1 2 3 4 5 -40 -20 0 20 40 60 80 100 rise time (ms) temperature ( c) turn-on rise time vs. temperature r l =10 ? c l =1 f v in = 5v v in = 3.3v 0 50 100 150 200 2.5 3.0 3.5 4.0 4.5 5.0 5.5 current ( a) input voltage (v) supply on-current vs. input voltage +85 c +25 c -40 c 0 50 100 150 200 2.5 3.0 3.5 4.0 4.5 5.0 5.5 resistance (m ? ) input voltage (v) on-resistance vs. input voltage i out = 500ma +85 c +25 c -40 c 0 0.5 1.0 1.5 2.0 2.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 rise time (ms) input voltage (v) turn-on rise time vs. input voltage r l =10 ? c l =1 f +85 c +25 c -40 c 0 200 400 600 800 1000 -40 -20 0 20 40 60 80 100 current limit (ma) temperature ( c) short-circuit current-limit vs. temperature v in = 3.3v v in = 5v 0 200 400 600 800 1000 1200 -40 -20 0 20 40 60 80 100 current limit threshold (ma) temperature ( c) current-limit threshold vs. temperature v in = 3.3v v in = 5v 0 100 200 300 400 -40 -20 0 20 40 60 80 100 fall time ( s) temperature ( c) fall time vs. temperature r l =10 ? c l =1 f v in = 3.3v 0 100 200 300 400 500 600 700 800 2.5 3.0 3.5 4.0 4.5 5.0 5.5 current limit (ma) input voltage (v) short-circuit current-limit vs. input voltage +85 c +25 c -40 c 0 200 400 600 800 1000 1200 2.5 3.0 3.5 4.0 4.5 5.0 5.5 current limit threshold (ma) input voltage (v) current-limit threshold vs. input voltage +85 c +25 c -40 c 0 50 100 150 200 250 300 2.5 3.0 3.5 4.0 4.5 5.0 5.5 rise time ( s) input voltage (v) fall time vs. input voltage t a = 25 c c l = 1 f r l = 10 ?
mic2026/2076 micrel mic2026/2076 6 february 2001 0 0.5 1.0 1.5 2.0 2.5 -40 -20 0 20 40 60 80 100 enable threshold (v) temperature ( c) enable threshold vs. temperature v in = 5v v en rising v en falling 0 1 2 3 4 5 -40 -20 0 20 40 60 80 100 delay time (ms) temperature ( c) flag delay vs. temperature v in = 3.3v v in = 5v 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 -40 -20 0 20 40 60 80 100 supply current ( a) temperature ( c) supply off current vs. temperature 5v 3.3v 0 0.5 1.0 1.5 2.0 2.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 enable threshold (v) input voltage (v) enable threshold vs. input voltage t a = 25 c v en falling v en rising 0 1 2 3 4 5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 delay time (ms) input voltage (v) flag delay vs. input voltage +85 c +25 c -40 c 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 2.5 3.0 3.5 4.0 4.5 5.0 5.5 supply current ( a) voltage (v) supply off current vs. input voltage +85 c +25 c -40 c 0 0.5 1.0 1.5 2.0 2.5 3.0 -40 -20 0 20 40 60 80 100 uvlo threshold (v) temperature ( c) uvlo threshold vs. temperature v in rising v in falling
february 2001 7 mic2026/2076 mic2026/2076 micrel functional characteristics uvlo v in rising (mic2026-1) time (10ms/div.) i out (100ma/div.) v in (2v/div.) v out (2v/div.) v flg (2v/div.) v en = v in c l = 57 f r l = 35 ? 2.4v uvlo v in falling (mic2026-1) time (100ms/div.) i out (100ma/div.) v in (2v/div.) v out (5v/div.) v flg (2v/div.) v en = v in c l = 57 f r l = 35 ? 2.2v turn-on/turnoff (mic2026-1) time (10ms/div.) i out (200ma/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v c l = 147 f r l = 35 ? 712ma (inrush current) 140ma turn-on (mic2026-1) time (500 s/div.) i out (200ma/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v c l = 147 f r l = 35 ? 140ma turnoff (mic2026-1) time (5ms/div.) i out (200ma/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v c l = 147 f r l = 35 ? 140ma enabled into short (mic2026-1) time (500 s/div.) i out (500ma/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v 3.1ms (t d ) 700ma
mic2026/2076 micrel mic2026/2076 8 february 2001 inrush current response (mic2026-1) time (1ms/div.) i out (200ma/div.) v en (10v/div.) v flg (5v/div.) v in = 5v r l = 31 ? c l = 10 f c l = 110 f c l = 210 f c l = 310 f current-limit response (ramped load mic2026-1) time (100ms/div.) i out (500ma/div.) v in (10v/div.) v out (5v/div.) v flg (10v/div.) v in = 5v c l = 47 f current-limit threshold (1a) thermal shutdown thermal shutdown hysteresis short removed short-circuit current (800ma) current-limit response (stepped short mic2026-1) time (1ms/div.) i out (2a/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v c l = 47 f r l = stepped short 800ma current-limit response (mic2026-1) time (50 s/div.) i out (5a/div.) v out (5v/div.) v in = 5v c l = 0 r l = stepped short short-circuit (800ma) independent thermal shutdown (mic2026-1) time (100ms/div.) i outb (500ma/div.) v enb (10v/div.) v flgb (5v/div.) v flga (5v/div.) v outa = no load (no thermal shutdown) thermal shutdown independent thermal shutdown (mic2026-1) time (100ms/div.) i outa (500ma/div.) v ena (10v/div.) v flgb (5v/div.) v flga (5v/div.) v outb = no load (no thermal shutdown) thermal shutdown
february 2001 9 mic2026/2076 mic2026/2076 micrel thermal shutdown (mic2076-2 output latched off) no load time (2.5s/div.) i outb (500mv/div.) v out (5v/div.) v flg (10v/div.) v in = 5v c l = 47 f v enb = 0v thermal shutdown load removed output reset r l = 0 thermal shutdown (output reset by toggling enable mic2076-2) time (100ms/div.) i out (500ma/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v enable reset thermal shutdown output reset ramp load to short c l = 57 f r l = 35 ? thermal shutdown (output reset by removing load mic2076-2) time (100ms/div.) i out (500ma/div.) v en (10v/div.) v out (5v/div.) v flg (5v/div.) v in = 5v c l = 47 f load removed (output reset) output latched off thermal shutdown ramp load to short independent thermal shutdown (mic2076-2) time (2.5s/div.) i outa (500ma/div.) v flga (5v/div.) v flgb (5v/div.) v in = 5v c l = 47 f v enb = 0v v ena = 0v output reset load removed no thermal shutdown on channel b thermal shutdown r l = 0 no load independent thermal shutdown (mic2076-2) time (2.5s/div.) i outb (500ma/div.) v flga (5v/div.) v flgb (10v/div.) v in = 5v c l = 47 f v enb = 0v v ena = 0v output reset load removed no thermal shutdown on channel a thermal shutdown r l = 0 no load
mic2026/2076 micrel mic2026/2076 10 february 2001 block diagram 1.2v reference thermal shutdown charge pump outb uvlo gate control in ena gate control outa flgb charge pump enb osc. flga current limit current limit gnd mic2026/2076 flag response delay flag response delay functional description input and output in is the power supply connection to the logic circuitry and the drain of the output mosfet. out is the source of the output mosfet. in a typical circuit, current flows from in to out toward the load. if v out is greater than v in , current will flow from out to in, since the switch is bidirectional when enabled. the output mosfet and driver circuitry are also designed to allow the mosfet source to be externally forced to a higher voltage than the drain (v out > v in ) when the switch is disabled. in this situation, the mic2026/76 prevents undesirable current flow from out to in. thermal shutdown thermal shutdown is employed to protect the device from damage should the die temperature exceed safe margins due mainly to short circuit faults. each channel employs its own thermal sensor. thermal shutdown shuts off the output mosfet and asserts the flg output if the die temperature reaches 140 c and the overheated channel is in current limit. the other channel is not effected. if however, the die tem- perature exceeds 160 c, both channels will be shut off. upon determining a thermal shutdown condition, the mic2076 will latch the output off. in this case, a pull-up current source is activated. this allows the output latch to automatically reset when the load (such as a usb device) is removed. the output can also be reset by toggling en. refer to figure 1 for timing details. the mic2026 will automatically reset its output when the die temperature cools down to 120 c. the mic2026 output and flg signal will continue to cycle on and off until the device is disabled or the fault is removed. figure 2 depicts typical timing. depending on pcb layout, package, ambient temperature, etc., it may take several hundred milliseconds from the incidence of the fault to the output mosfet being shut off. this time will be shortest in the case of a dead short on the output. power dissipation the device s junction temperature depends on several fac- tors such as the load, pcb layout, ambient temperature and package type. equations that can be used to calculate power dissipation of each channel and junction temperature are found below. p d = r ds(on) i out 2 total power dissipation of the device will be the summation of p d for both channels. to relate this to junction temperature, the following equation can be used: t j = p d ja + t a where: t j = junction temperature t a = ambient temperature ja = is the thermal resistance of the package
february 2001 11 mic2026/2076 mic2026/2076 micrel current sensing and limiting the current-limit threshold is preset internally. the preset level prevents damage to the device and external load but still allows a minimum current of 500ma to be delivered to the load. the current-limit circuit senses a portion of the output mos- fet switch current. the current-sense resistor shown in the block diagram is virtual and has no voltage drop. the reaction to an overcurrent condition varies with three scenarios: switch enabled into short-circuit if a switch is enabled into a heavy load or short-circuit, the switch immediately enters into a constant-current mode, reducing the output voltage. the flg signal is asserted indicating an overcurrent condition. short-circuit applied to enabled output when a heavy load or short-circuit is applied to an enabled switch, a large transient current may flow until the current- limit circuitry responds. once this occurs the device limits current to less than the short-circuit current limit specification. current-limit response ramped load the mic2026/76 current-limit profile exhibits a small foldback effect of about 200ma. once this current-limit threshold is exceeded the device switches into a constant current mode. it is important to note that the device will supply current up to the current-limit threshold. v en v out i out short-circuit fault thermal shutdown reached load and fault removed (output reset) v flg i limit i load 3ms typ. delay figure 1. mic2076-2 fault timing: output reset by removing load v en v out i out short-circuit fault thermal shutdown reached load/fault removed v flg i load i limit 3ms typ. delay figure 2. mic2026-2 fault timing fault flag the flg signal is an n-channel open-drain mosfet output. flg is asserted (active-low) when either an overcurrent or thermal shutdown condition occurs. in the case of an overcur- rent condition, flg will be asserted only after the flag response delay time, t d , has elapsed. this ensures that flg is asserted only upon valid overcurrent conditions and that erroneous error reporting is eliminated. for example, false overcurrent conditions can occur during hot-plug events when a highly capacitive load is connected and causes a high transient inrush current that exceeds the current-limit thresh- old for up to 1ms. the flg response delay time t d is typically 3ms. undervoltage lockout undervoltage lockout (uvlo) prevents the output mosfet from turning on until v in exceeds approximately 2.5v. under- voltage detection functions only when the switch is enabled.
mic2026/2076 micrel mic2026/2076 12 february 2001 applications information supply filtering a 0.1 f to 1 f bypass capacitor positioned close to v in and gnd of the device is strongly recommended to control supply transients. without a bypass capacitor, an output short may cause sufficient ringing on the input (from supply lead induc- tance) to damage internal control circuitry. printed circuit board hot-plug the mic2026/76 are ideal inrush current-limiters for hot-plug applications. due to the integrated charge pump, the mic2026/76 presents a high impedance when off and slowly becomes a low impedance as it turns on. this soft-start feature effectively isolates power supplies from highly ca- pacitive loads by reducing inrush current. figure 3 shows how the mic2076 may be used in a card hot-plug application. in cases of extremely large capacitive loads (>400 f), the length of the transient due to inrush current may exceed the delay provided by the integrated filter. since this inrush current exceeds the current-limit delay specification, flg will be asserted during this time. to prevent the logic controller from responding to flg being asserted, an external rc filter, as shown in figure 4, can be used to filter out transient flg assertion. the value of the rc time constant should be selected to match the length of the transient, less t d(min) of the mic2026/76. universal serial bus (usb) power distribution the mic2026/76 is ideally suited for usb (universal serial bus) power distribution applications. the usb specification defines power distribution for usb host systems such as pcs and usb hubs. hubs can either be self-powered or bus- powered (that is, powered from the bus). figure 5 shows a typical usb host application that may be suited for mobile pc applications employing usb. the requirement for usb host systems is that the port must supply a minimum of 500ma at an output voltage of 5v 5%. in addition, the output power delivered must be limited to below 25va. upon an overcurrent condition, the host must also be notified. to support hot-plug events, the hub must have a minimum of 120 f of bulk capacitance, preferably low esr electrolytic or tantulum. please refer to application note 17 for more details on designing compliant usb hub and host systems. for bus-powered hubs, usb requires that each downstream port be switched on or off under control by the host. up to four downstream ports each capable of supplying 100ma at 4.4v minimum are allowed. in addition, to reduce voltage droop on the upstream v bus , soft-start is necessary. although the hub can consume up to 500ma from the upstream bus, the hub must consume only 100ma max at start-up, until it enumer- ates with the host prior to requesting more power. the same requirements apply for bus-powered peripherals that have no downstream ports. figure 6 shows a bus-powered hub. ena outa flga flgb gnd outb in 18 27 36 5 usb controller enb 4 usb peripheral cable to "hot" receptacle c bulk gnd v bus 4.7 f usb function usb function c bulk mic2026-2bm figure 3. hot-plug application 10k v+ mic2026 en outa flga flgb gnd enb outb in 18 27 36 45 overcurrent logic controller r c figure 4. transient filter
february 2001 13 mic2026/2076 mic2026/2076 micrel ena outa flga in flgb gnd enb outb on/off overcurrent overcurrent on/off mic2026-2 3.3v usb controller v cc 5.0v 0.1f v bus d+ d gnd data (two pair) v bus d+ d gnd usb port 2 usb port 1 10k mic5207-3.3 in out gnd 47f 47f ferrite beads 4.50v to 5.25v upstream v bus 100ma max. v bus d+ d gnd data 1f 1f 10k vin to usb controller figure 5. usb two-port host application ena outa flga in flgb gnd enb outb on/off overcurrent overcurrent on/off mic2026-2 3.3v usb controller 0.1f v bus d+ d gnd data (two pair) v bus d+ d gnd usb port 2 usb port 1 10k mic5207-3.3 in out gnd 47f 47f ferrite beads 4.50v to 5.25v upstream v bus v bus d+ d gnd data 1f 1f 10k vin to usb controller 1.5k 2% figure 6. usb two-port bus-powered hub
mic2026/2076 micrel mic2026/2076 14 february 2001 package information 45 0 8 0.244 (6.20) 0.228 (5.79) 0.197 (5.0) 0.189 (4.8) seating plane 0.026 (0.65) max ) 0.010 (0.25) 0.007 (0.18) 0.064 (1.63) 0.045 (1.14) 0.0098 (0.249) 0.0040 (0.102) 0.020 (0.51) 0.013 (0.33) 0.157 (3.99) 0.150 (3.81) 0.050 (1.27) typ pin 1 dimensions: inches (mm) 0.050 (1.27) 0.016 (0.40) 8-lead sop (m) 0.380 (9.65) 0.370 (9.40) 0.135 (3.43) 0.125 (3.18) pin 1 dimensions: inch (mm) 0.018 (0.57) 0.100 (2.54) 0.013 (0.330) 0.010 (0.254) 0.300 (7.62) 0.255 (6.48) 0.245 (6.22) 0.380 (9.65) 0.320 (8.13) 0.0375 (0.952) 0.130 (3.30) 8-pin dip (n)
february 2001 15 mic2026/2076 mic2026/2076 micrel
mic2026/2076 micrel mic2026/2076 16 february 2001 micrel inc. 1849 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 web http://www.micrel.com this information is believed to be accurate and reliable, however no responsibility is assumed by micrel for its use nor for an y infringement of patents or other rights of third parties resulting from its use. no license is granted by implication or otherwise under any patent or pat ent right of micrel inc. ? 2001 micrel incorporated

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