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rt9711a/b/c/d 1 ds9711a/b/c/d-03 april 2011 www.richtek.com 80m , 1.5a/0.6a high-side power switches with flag marking information for marking information, contact our sales representative directly or through a richtek distributor located in your area. general description the rt9711a/b/c/d are cost-effective, low voltage, single n-mosfet high-side power switches, optimized for self- powered and bus-powered universal serial bus (usb) applications. the rt9711 series are equipped with a charge pump circuitry to drive the internal mosfet switch. the switch's low r ds(on) , 80m , meets usb voltage drop requirements. a flag output is available to indicate fault conditions to the local usb controller. additional features include soft-start to limit inrush current during plug-in, thermal shutdown to prevent catastrophic switch failure from high-current loads, under-voltage lockout (uvlo) to ensure that the device remains off unless there is a valid input voltage present, fault current is limited to typically 2.5a for rt9711a/b in dual ports and 1a for rt9711c/d in single port in accordance with the usb power requirements, lower quiescent current as 25 a making this device ideal for portable battery-operated equipment. the rt9711 series are available in sot-23-5, tsot-23-5, sop-8 and msop-8 packages fitting different aspect of broad applications. features z z z z z compliant to usb specifications z z z z z built-in n-mosfet ` ` ` ` ` typical r ds(on) : 80m (sot-23-5 & tsot-23-5) and 90m (sop-8 & msop-8) z z z z z output can be forced higher than input (off-state) z z z z z low supply current : 25 a typical at switch on state 1 a typical at switch off state z z z z z guaranteed 1.5a for rt9711a/b and 0.6a for rt9711c/d continuous load current z z z z z wide input voltage ranges : 2.5v to 5.5v z z z z z open-drain fault flag output z z z z z hot plug-in application (soft-start) z z z z z 1.7v typical under-voltage lockout (uvlo) z z z z z current limiting protection z z z z z thermal shutdown protection z z z z z reverse current flow blocking (no body diode) z z z z z smallest sot-23-5 and tsot-23-5 packages minimizes board space z z z z z ul approved ? ? ? ? ? e219878 z z z z z tuv iec60950-1 : 2005 certified z z z z z rohs compliant and 100% lead (pb)-free applications z usb bus/self powered hubs z usb peripherals z acpi power distribution z pc card hot swap z notebook, motherboard pcs z battery-powered equipment z hot-plug power supplies z battery-charger circuits note : richtek products are : ` rohs compliant and compatible with the current require- ments of ipc/jedec j-std-020. ` suitable for use in snpb or pb-free soldering processes. ordering information rt9711 package type b : sot-23-5 bg : sot-23-5 (g-type) j5 : tsot-23-5 s : sop-8 f : msop-8 lead plating system p : pb free g : green (halogen free and pb free) output current/en function a : 1.5a/active high b : 1.5a/active low c : 0.6a/active high d : 0.6a/active low
rt9711a/b/c/d 2 ds9711a/b/c/d-03 april 2011 www.richtek.com function block diagram functional pin description pin name pin function vin power input voltage vout output voltage gnd ground en/en chip enable. never let this pin floating. (active high for rt9711a/c, active low for rt9711b/d) flg open-drain fault flag output typical application circuit pin configurations (top view) note: a low-esr 150 f aluminum electrolytic or tantalum between v out and gnd is strongly recommended to meet the 330mv maximum droop requirement in the hub v bus . (see application information section for further details) sot-23-5 (g-type) sop-8/msop-8 sot-23-5/tsot-23-5 gate control output voltage detection delay oscillator uvlo charge pump bias thermal protection current limiting vout vin gnd en/en flg gnd vout vin 4 23 5 flg en/en vout gnd nc vin 4 23 5 en/en gnd vin vin vout vout vout 2 3 4 5 8 7 6 en/en flg vin vout gnd rt9711a/b/c/d + over -current v bus d+ d- gnd usb controller 1f 150f 10f supply voltage 5v pull-up resistor (10k to 100k) ferrite beads data rt9711a/c chip enable rt9711b/d chip enable flg en/en c in c out
rt9711a/b/c/d 3 ds9711a/b/c/d-03 april 2011 www.richtek.com absolute maximum ratings (note 1) z supply voltage --------------------------------------------------------------------------------------------------------- 6.5v z chip enable input v oltage ------------------------------------------------------------------------------------------- ? 0.3v to 6.5v z flag voltage ------------------------------------------------------------------------------------------------------------ 6.5v z power dissipation, p d @ t a = 25 c sot-23-5, tsot-23-5 ------------------------------------------------------------------------------------------------- 0.4w sop-8, msop-8 ------------------------------------------------------------------------------------------------------- 0.625w z package thermal resistance (note 2) sot-23-5, tsot-23-5, ja ------------------------------------------------------------------------------------------- 250 c/w sop-8, msop-8, ja ------------------------------------------------------------------------------------------------- 160 c/w z junction temperature ------------------------------------------------------------------------------------------------- 150 c z lead temperature (soldering, 10 se c.) --------------------------------------------------------------------------- 260 c z storage temperature range ---------------------------------------------------------------------------------------- ? 65 c to 150 c z esd susceptibility (note 3) hbm (human body mode) ------------------------------------------------------------------------------------------ 2kv mm (ma chine mode) -------------------------------------------------------------------------------------------------- 200v electrical characteristics recommended operating conditions (note 4) z supply input voltage -------------------------------------------------------------------------------------------------- 2.5v to 5 .5v z chip enable input v oltage ------------------------------------------------------------------------------------------- 0v to 5.5v z junction temperature range ---------------------------------------------------------------------------------------- ? 40 c to 125 c z ambient temperature range ---------------------------------------------------------------------------------------- ? 40 c to 85 c parameter symbol test conditions min typ max u nits switch on resistance (rt9711a/b) sot-23-5, tsot-23-5 r ds(on) i out = 1a, v in = 5v -- 80 100 m sop-8, msop-8 -- 90 110 switch on resistance (rt9711c/d) sot-23-5, tsot-23-5 i out = 0.5a, v in = 5 v -- 80 100 m s op-8, m sop -8 -- 90 11 0 supply c urrent i sw_on switch on, r load open -- 25 45 a i sw_off switch off, r load open -- 0.1 1 en /en threshold logic-low voltage v il v in = 2.5v to 5.5v -- -- 0. 8 v logic-high voltage v ih v in = 2.5v to 5.5v 2.0 -- -- v en /en input current i en/en v en/en = 0v to 5.5v -- 0.01 -- a output leakage c urrent i lea k v en = 0v, v en = 5 v, r load = 0 -- 0.5 10 a output turn-on rise time t on_rise 10% to 90% of v out ri s ing -- 400 -- us current limit rt9711a/b i lim current ramp (< 0.1a/ms) on v out 1.6 2.5 3. 2 a rt9711c/d 0.7 1 1. 4 a (v in = 5v, c in = c out = 1 f, t a = 25c, unless otherwise specified) to be continued
rt9711a/b/c/d 4 ds9711a/b/c/d-03 april 2011 www.richtek.com parameter symbol test conditions min typ max units sho rt circuit fold-back current rt9711a/b i sc_fb v out = 0v, measured prior to thermal shutdown -- 1 -- a rt9711c/d -- 0.8 -- flag out put r esistance r flg i sink = 1 ma -- 20 400 flag off current i flg_of f v flg = 5v -- 0.01 1 a flag delay time (note 5) t d from fault condition to flg assertion 5 12 20 ms shutdown pull-low resistance r ds v en = 0v, v en = 5v -- 75 150 under-voltage lockout v uvlo v in increasing 1.3 1.7 -- v under-voltage hysteresis v uvlo v in decreasing -- 0.1 -- v thermal shutdown protection t sd -- 130 -- c thermal shutdown hysteresis t sd -- 20 -- c note 1. stresses listed as the above "absolute maximum ratings" may cause permanent damage to the device. these are for stress ratings. functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. note 2. ja is measured in the natural convection at t a = 25 c on a low effective thermal conductivity single layer test board of jedec 51-3 thermal measurement standard. note 3. devices are esd sensitive. handling precaution is recommended. note 4. the device is not guaranteed to function outside its operating conditions. note 5. the flag delay time is input voltage dependent, see ? typical operating characteristics ? graph for further details.
rt9711a/b/c/d 5 ds9711a/b/c/d-03 april 2011 www.richtek.com typical operating characteristics supply current vs. input voltage 0 5 10 15 20 25 30 35 40 22.533.544.555.5 input voltage (v) supply current (ua) sot-23-5, r l = open c in = c out = 33 f/electrolytic switch on resistance vs. temperature 0 0.05 0.1 0.15 0.2 0.25 -40 -20 0 20 40 60 80 100 120 temperature switch on resistance ( ? ) ( c) sot-23-5, v in = 5v, i load = 1.5a c in = 1 f/x7r, c out = 10 f/x7r switch on resistance vs. temperature 0 0.05 0.1 0.15 0.2 0.25 -40 -20 0 20 40 60 80 100 120 temperature switch on resistance ( ? ) ( c) sop-8, v in = 5v, i load = 1.5a c in = 1 u f/x7r, c out = 10 f/x7r switch on resistance vs. input voltage 20 40 60 80 100 120 140 22.5 33.5 44.5 55.5 input voltage (v) switch on resistance (m ? ) sot-23-5, i load = 1.5a c in = c out = 33 f/electrolytic supply current vs. temperature 0 5 10 15 20 25 30 -40 -20 0 20 40 60 80 100 120 temperature (c) supply current (ua ) v in = 5v, switch on, r load open c in = c out = 33 f/electrolytic current limit vs. input voltage 1 1.2 1.4 1.6 1.8 2 22.533.544.555.5 input voltage (v) current limit (a) rt9711a/b, v in = v en = 5v c in = 1 f/x7r, c out = 10 f/x7r
rt9711a/b/c/d 6 ds9711a/b/c/d-03 april 2011 www.richtek.com en pin threshold voltage vs. temperature 0 0.4 0.8 1.2 1.6 2 2.4 -40 -20 0 20 40 60 80 100 120 temperature en pin threshold voltage (v) rt9711b, v in = 5v, i load = 100ma c in = c out = 33 f/electrolytic ( c) turn-off falling time vs. temperature 0 20 40 60 80 100 -40 -20 0 20 40 60 80 100 120 temperature turn-off falling time (us) v in = 5v, r load = 30 c in = 33 f/electrolytic c out = 1 f/electrolytic ( c) turn-off leakage current vs. temperature 0 0.5 1 1.5 2 2.5 3 3.5 4 -40 -20 0 20 40 60 80 100 120 temperature turn-off leakage current (ua) v in = 5v, r load = 0 c in = 33 f/electrolytic c out = 1 f/x7r ( c) turn-on rising time vs. temperature 0 100 200 300 400 500 600 700 -40 -20 0 20 40 60 80 100 120 temperature turn-on rising time (us) v in = 5v, r load = 30 c in = 33 f/electrolytic c out = 1 f/electrolytic ( c) en pinthreshold voltage vs. input voltage 0 0.4 0.8 1.2 1.6 2 22.5 33.544.5 55.5 input voltage (v) en threshold voltage (v) rt9711b, i load = 100ma c in = c out = 33 f/electrolytic current limit vs. temperature 1 1.2 1.4 1.6 1.8 2 -40 -20 0 20 40 60 80 100 120 temperature (c) current limit (a) rt9711a/b, v in = 5v c in = 1 f/x7r, c out = 10 f/x7r
rt9711a/b/c/d 7 ds9711a/b/c/d-03 april 2011 www.richtek.com flag delay time vs. input voltage 0 4 8 12 16 20 22.533.544.555.5 input voltage(v) flag delay time (ms) r load = 1 c in = c out = 33 f/electrolytic flag response with ramped load time (2.5ms/div) i out (1a/div) v out (5v/div) sot-23-5, v in = 5v c in = c out = 33 f/electrolytic v lag (5v/div) load transient response time (1ms/div) v out (1v/div) i out (1a/div) v in = 5v, c out = 1 f c in = 33 f/electrolytic r load = 1k to 2.2 4.8v 1.5a swith off supply current vs. temperature -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 -40 -20 0 20 40 60 80 100 120 temperature swith off supply current (ua) v in = 5v, r load = open c in = c out = 33 f/electrolytic ( c) flag delay time vs. temperature 7 8 9 10 11 12 13 14 15 16 -40 -20 0 20 40 60 80 100 120 temperature flag delay time (ms) r load = 1 , v in = 5v c in = c out = 33 f/electrolytic ( c) uvlo threshold vs. temperature 0 0.4 0.8 1.2 1.6 2 2.4 -40 -20 0 20 40 60 80 100 120 temperature uvlo threshold (v) v in increasing, i load = 15ma c in = c out = 33 f/electrolytic ( c)
rt9711a/b/c/d 8 ds9711a/b/c/d-03 april 2011 www.richtek.com turn off response time (100 s/div) v en (5v/div) v out (5v/div) rt9711b, v in = 5v, r load = 30 c in = 33 f/electrolytic c out = 1 f/electrolytic uvlo at rising v in (1v/div) v out (1v/div) sot-23-5, v in = 5v, r load = 30 , c out = 1 f c in = 33 f/electrolytic time (2.5ms/div) flag response during short circuit time (5ms/div) v flg (5v/div) i out (1a/div) v in = 5v, r load = 0 c in = c out = 33 f/electrolytic v en (5v/div) uvlo at falling time (5ms/div) v in (1v/div) v out (1v/div) v in = 5v, r load = 30 c out = 1 f c in = 33 f/electrolytic flag response during over load time (5ms/div) v flg (5v/div) i out (1a/div) v in = 5v, r load = 2 c in = c out = 33 f/electrolytic v out (5v/div) turn on response time (100 s/div) rt9711b, v in = 5v r load = 30 c in = 33 f/electrolytic c out = 1 f/electrolytic v en (5v/div) v out (5v/div)
rt9711a/b/c/d 9 ds9711a/b/c/d-03 april 2011 www.richtek.com output voltage vs. output current 0.6 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 4.6 5.0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 output current (a) output voltage (v) rt9711a, v in = 5v t a = 25 c t a = -45 c t a = 85 c output voltage vs. output current 0.6 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 4.6 5.0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 output current (a) output voltage (v) rt9711c, v in = 5v t a = 25 c t a = -45 c t a = 85 c current limit threshold vs. input voltage 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 2.533.544.555.5 input voltage (v) current limit threshold (a ) rt9711c, v in = 5v t a = 25 c t a = -45 c t a = 85 c current limit threshold vs. input voltage 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.5 3 3.5 4 4.5 5 5.5 input voltage (v) current limit threshold (a ) rt9711a, v in = 5v t a = 25 c t a = -45 c t a = 85 c
rt9711a/b/c/d 10 ds9711a/b/c/d-03 april 2011 www.richtek.com soft start for hot plug-in applications in order to eliminate the upstream voltage droop caused by the large inrush current during hot-plug events, the ? soft-start ? feature effectively isolates the power source from extremely large capacitive loads, satisfying the usb voltage droop requirements. fault flag the rt9711 series provides a flg signal pin which is an n-channel open drain mosfet output. this open drain output goes low when v out < v in ? 1v, current limit or the die temperature exceeds 130 c approximately. the flg output is capable of sinking a 10ma load to typically 200mv above ground. the flg pin requires a pull-up resistor, this resistor should be large in value to reduce energy drain. a 100k pull-up resistor works well for most applications. in the case of an over-current 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 over-current conditions and that erroneous error reporting is eliminated. for example, false over-current conditions may occur during hot-plug events when extremely large capacitive loads are connected and causes a high transient inrush current that exceeds the current limit threshold. the flg response delay time t d is typically 10ms. under-voltage lockout under-voltage lockout (uvlo) prevents the mosfet switch from turning on until input voltage exceeds approximately 1.7v. if input voltage drops below approximately 1.3v, uvlo turns off the mosfet switch, flg will be asserted accordingly. under-voltage detection functions only when the switch is enabled. current limiting and short-circuit protection the current limit circuitry prevents damage to the mosfet switch and the hub downstream port but can deliver load current up to the current limit threshold of typically 2.5a through the switch of rt9711a/b and 1a for rt9711c/d respectively. 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 current applications information the rt9711a/b/c/d are single n-mosfet high-side power switches with enable input, optimized for self- powered and bus-powered universal serial bus (usb) applications. the rt9711 series are equipped with a charge pump circuitry to drive the internal n-mosfet switch; the switch's low r ds(on) , 80m , meets usb voltage drop requirements; and a flag output is available to indicate fault conditions to the local usb controller. input and output v in (input) is the power source connection to the internal circuitry and the drain of the mosfet. v out (output) is the source of the mosfet. in a typical application, current flows through the switch from v in to v out toward the load. if v out is greater than v in , current will flow from v out to v in since the mosfet is bidirectional when on. unlike a normal mosfet, there is no a parasitic body diode between drain and source of the mosfet, the rt9711a/b/c/d prevents reverse current flow if v out being externally forced to a higher voltage than v in when the output disabled (v en < 0.8v or v en > 2v). d g s d g s normal mosfet rt9711a/b/c/d chip enable input the switch will be disabled when the en/en pin is in a logic low/high condition. during this condition, the internal circuitry and mosfet are turned off, reducing the supply current to 0.1 a typical. floating the en/en may cause unpredictable operation. en should not be allowed to go negative with respect to gnd. the en/en pin may be directly tied to v in (gnd) to keep the part on.
rt9711a/b/c/d 11 ds9711a/b/c/d-03 april 2011 www.richtek.com limit threshold is exceeded the device enters constant current mode until the thermal shutdown occurs or the fault is removed. and for sop-8 and msop-8 packages, the thermal resistance ja is 160 c/w. the maximum power dissipation at t a = 25 c can be calculated by following formula : p d(max) = (125 c ? 25 c) / 250 c/w = 0.4w for sot-23-5 and tsot-23-5 packages p d(max) = (125 c ? 25 c) / 160 c/w = 0.625w for sop-8 and msop-8 packages the maximum power dissipation depends on operating ambient temperature for fixed t j(max) and thermal resistance ja . for rt9711a/b/c/d packages, the figure 1 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. figure 1. derating curves for rt9711a/b/c/d package universal serial bus (usb) & power distribution the goal of usb is to be enabled device from different vendors to interoperate in an open architecture. usb features include ease of use for the end user, a wide range of workloads and applications, robustness, synergy with the pc industry, and low-cost implement- ation. benefits include self-identifying peripherals, dynamically attachable and reconfigurable peripherals, multiple connections (support for concurrent operation of many devices), support for as many as 127 physical devices, and compatibility with pc plug-and-play architecture. the universal serial bus connects usb devices with a usb host: each usb system has one usb host. usb devices are classified either as hubs, which provide 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 25 50 75 100 125 ambient temperature maximum power dissipation (w) single layer pcb ( c) sop-8, msop-8 sot-23-5, tsot-23-5 thermal shutdown thermal shutdown is employed to protect the device from damage if the die temperature exceeds approxi- mately 130 c. if enabled, the switch automatically restarts when the die temperature falls 20 c. the output and flg signal will continue to cycle on and off until the device is disabled or the fault is removed. power dissipation the junction temperature of the rt9711 series depend on several factors such as the load, pcb layout, ambient temperature and package type. the output pin of rt9711a/b/c/d can deliver the current of up to 1.5a (rt9711a/b), and 0.6a (rt9711c/d) respectively over the full operating junction temperature range. however, the maximum output current must be derated at higher ambient temperature to ensure the junction temperature does not exceed 100 c. with all possible conditions, the junction temperature must be within the range specified under operating conditions. power dissipation can be calculated based on the output current and the r ds(on) of switch as below. p d = r ds(on) x i out 2 although the devices are rated for 1.5a and 0.6a of output current, but the application may limit the amount of output current based on the total power dissipation and the ambient temperature. the final operating junction temperature for any set of conditions can be estimated by the following thermal equation : p d (max) = (t j (max) - t a ) / ja where t j(max) is the maximum operation junction temperature 125 c, t a is the ambient temperature and the ja is the junction to ambient thermal resistance. the junction to ambient thermal resistance ja is layout dependent. for sot-23-5 and tsot-23-5 packages, the thermal resistance ja is 250 c/w on the standard jedec 51-3 single-layer thermal test board.
rt9711a/b/c/d 12 ds9711a/b/c/d-03 april 2011 www.richtek.com additional attachment points to the usb, or as functions, which provide capabilities to the system (for example, a digital joystick). hub devices are then classified as either bus-power hubs or self-powered hubs. a bus-powered hub draws all of the power to any internal functions and downstream ports from the usb connector power pins. the hub may draw up to 500ma from the upstream device. external ports in a bus-powered hub can supply up to 100ma per port, with a maximum of four external ports. self-powered hub power for the internal functions and downstream ports does not come from the usb, although the usb interface may draw up to 100ma from its upstream connect, to allow the interface to function when the remainder of the hub is powered down. the hub must be able to supply up to 500ma on all of its external downstream ports. please refer to universal serial specification revision 2.0 for more details on designing compliant usb hub and host systems. over-current protection devices such as fuses and ptc resistors (also called polyfuse or polyswitch) have slow trip times, high on-resistance, and lack the necessary circuitry for usb-required fault reporting. the faster trip time of the rt9711a/b/c/d power distribution allow designers to design hubs that can operate through faults. the rt9711a/b/c/d have low on-resistance and internal fault-reporting circuitry that help the designer to meet voltage regulation and fault notification requirements. because the devices are also power switches, the designer of self-powered hubs has the flexibility to turn off power to output ports. unlike a normal mosfet, the devices have controlled rise and fall times to provide the needed inrush current limiting required for the bus-powered hub power switch. supply filter/bypass capacitor a 1 f low-esr ceramic capacitor from v in to gnd, located at the device is strongly recommended to prevent the input voltage drooping during hot-plug events. however, higher capacitor values will further reduce the voltage droop on the input. furthermore, without the bypass capacitor, an output short may cause sufficient ringing on the input (from source lead inductance) to destroy the internal control circuitry. the input transient must not exceed 6.5v of the absolute maximum supply voltage even for a short duration. output filter capacitor a low-esr 150 f aluminum electrolytic or tantalum between v out and gnd is strongly recommended to meet the 330mv maximum droop requirement in the hub v bus (per usb 2.0, output ports must have a minimum 120 f of low-esr bulk capacitance per hub). standard bypass methods should be used to minimize inductance and resistance between the bypass capacitor and the downstream connector to reduce emi and decouple voltage droop caused when downstream cables are hot-insertion transients. ferrite beads in series with v bus , the ground line and the 0.1 f bypass capacitors at the power connector pins are recommended for emi and esd protection. the bypass capacitor itself should have a low dissipation factor to allow decoupling at higher frequencies. voltage drop the usb specification states a minimum port-output voltage in two locations on the bus, 4.75v out of a self- powered hub port and 4.40v out of a bus-powered hub port. as with the self-powered hub, all resistive voltage drops for the bus-powered hub must be accounted for to guarantee voltage regulation (see figure 7-47 of universal serial specification revision 2.0 ). the following calculation determines v out (min) for multi- ple ports (n ports ) ganged together through one switch (if using one switch per port, n ports is equal to 1) : v out (min) = 4.75v ? [ i i x ( 4 x r conn + 2 x r cable ) ] ? (0.1a x n ports x r switch ) ? v pcb where r conn = resistance of connector contacts (two contacts per connector) r cable = resistance of upstream cable wires (one 5v and one gnd) r switch = resistance of power switch (80m typical for rt9711a/b/c/d)
rt9711a/b/c/d 13 ds9711a/b/c/d-03 april 2011 www.richtek.com v pcb = pcb voltage drop the usb specification defines the maximum resistance per contact ( r conn ) of the usb connector to be 30m and the drop across the pcb and switch to be 100mv. this basically leaves two variables in the equation: the resistance of the switch and the resistance of the cable. if the hub consumes the maximum current (i i ) of 500ma, the maximum resistance of the cable is 90m . the resistance of the switch is defined as follows : r switch = { 4.75v ? 4.4v ? [ 0.5a x ( 4 x 30m + 2 x 90m ) ] ? v pcb } ( 0.1a x n ports ) = (200mv ? v pcb ) ( 0.1a x n ports ) if the voltage drop across the pcb is limited to 100mv, the maximum resistance for the switch is 250m for four ports ganged together. the rt9711a/b/c/d, with its maximum 100m on-resistance over temperature, easily meets this requirement. layout considerations for best performance of the rt9711 series, the following guidelines muse be strictly followed : ` input and output capacitors should be placed close to the ic and connected to ground plane to reduce noise coupling. ` the gnd should be connected to a strong ground plane for heat sink. ` keep the main current traces as possible as short and wide. gnd en v in v out the input and output capacitors should be placed as close as possible to the ic. gnd flg v in figure 2. pcb layout guide
rt9711a/b/c/d 14 ds9711a/b/c/d-03 april 2011 www.richtek.com outline dimension a a1 e b b d c h l sot-23-5 surface mount package dimensions in millimeters dimensions in inches symbol min max min max a 0.889 1.295 0.035 0.051 a1 0.000 0.152 0.000 0.006 b 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 c 2.591 2.997 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.080 0.254 0.003 0.010 l 0.300 0.610 0.012 0.024
rt9711a/b/c/d 15 ds9711a/b/c/d-03 april 2011 www.richtek.com tsot-23-5 surface mount package dimensions in millimeters dimensions in inches symbol min max min max a 0.700 1.000 0.028 0.039 a1 0.000 0.100 0.000 0.004 b 1.397 1.803 0.055 0.071 b 0.300 0.559 0.012 0.022 c 2.591 3.000 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.080 0.254 0.003 0.010 l 0.300 0.610 0.012 0.024 a a1 e b b d c h l
rt9711a/b/c/d 16 ds9711a/b/c/d-03 april 2011 www.richtek.com a b j f h m c d i 8-lead sop plastic package dimensions in millimeters dimensions in inches symbol min max min max a 4.801 5.004 0.189 0.197 b 3.810 3.988 0.150 0.157 c 1.346 1.753 0.053 0.069 d 0.330 0.508 0.013 0.020 f 1.194 1.346 0.047 0.053 h 0.170 0.254 0.007 0.010 i 0.050 0.254 0.002 0.010 j 5.791 6.200 0.228 0.244 m 0.400 1.270 0.016 0.050
rt9711a/b/c/d 17 ds9711a/b/c/d-03 april 2011 www.richtek.com richtek technology corporation headquarter 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 fax: (8863)5526611 information that is provided by richtek technology corporation is believed to be accurate and reliable. richtek reserves the ri ght to make any change in circuit design, specification or other related things if necessary without notice at any time. no third party intellectual property inf ringement of the applications should be guaranteed by users when integrating richtek products into any application. no legal responsibility for any said applications i s assumed by richtek. richtek technology corporation taipei office (marketing) 5f, no. 95, minchiuan road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)86672399 fax: (8862)86672377 email: marketing@richtek.com l d e e1 e a b a1 a2 dimensions in millimeters dimensions in inches symbol min max min max a 0.810 1.100 0.032 0.043 a1 0.000 0.150 0.000 0.006 a2 0.750 0.950 0.030 0.037 b 0.220 0.380 0.009 0.015 d 2.900 3.100 0.114 0.122 e 0.650 0.026 e 4.800 5.000 0.189 0.197 e1 2.900 3.100 0.114 0.122 l 0.400 0.800 0.016 0.031 8-lead msop plastic package

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