sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 1 ordering information description usb power distribution switches are high-side n- channel mosfet switches with built-in overcurrent protection and low on-state resistance. the sc5826 switch is designed to meet the usb requirements for power switching and maintenance-free fault protection for self-powered & bus-powered hub applications. the sc5826 features low on-state resistance to meet the usb requirement for voltage drop and regulation. the switch is controlled by an enable input that is compatible with 3v and 5v logic. the enable input is available with an active high or active low input for maximum design flexibility. the device provides short circuit current limiting at a value of less than 1.6a, well below the usb limit of 5a. during an overcurrent condition the device provides a fault notification to signal the usb controller. an integrated thermal protection circuit automatically shuts the switch off when the junction temperature reaches its thermal limit. the switch remains off until the junction temperature drops approximately 10c. the switch will continue to cycle on and off until the fault is removed. inrush current limiting prevents the voltage drop on an upstream port when the switch is enabled. an undervoltage lockout circuit guarantees the switch is initially off during start-up. tel:805-498-2111 fax:805-498-3804 web:http:// www.semtech.com note: (1) add suffix ?tr? for tape and reel. device (1) enable package sc5826-1cs active high so-8 SC5826-2CS active low so-8 features ? designed to meet usb specification 1.1 power management requirements ? 500ma continuous load current ? high-side mosfet switch with low r ds(on) ? short-circuit current protection ? internal thermal shutdown ? undervoltage lockout ? logic overcurrent output ? soft start circuit with slow turn-on time applications ? universal serial bus (usb) power management ? self-powered or bus-powered usb hubs ? root hubs in desktop pcs & servers ? notebook pcs ? peripherals block diagram pin configuration top view (8-pin soic)
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 2 parameter symbol maximum units input voltage range v in -0.3 to +7 v output voltage range` v out -0.3 to +7 v enable input v en -0.3 to +7 v continuous output current i o internally limited ma operating ambient temperature range t a -40 to +85 c operating junction temperature range t j -40 to +125 c storage temperature range t stg -65 to +150 c lead temperature (soldering) 10 seconds t l 300 c absolute maximum ratings pin description pin # pin name pin function 1, 4 ena/enb enable input: ttl compatible switch enable input. 2, 3 flga/flgb error flag output: flg is asserted active low during fault condition. 6 gnd ground. 7 in input voltage: output mosfet drain. connect to supply voltage. 5, 8 outa/outb power switch output: output mosfet source. connect to switched side of load. pin configuration top view (8-pin soic)
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 3 electrical characteristics (1)(2) unless specified: t a = 25c, v in = 5v, i oa /i ob = 500ma (switches on). parameter symbol conditions min typ max units power switch on resistance r on 4.25v v in 5.50v 100 140 m ? output leakage current i l(off) v o = 5.5v, switches off 1 a output turn on rise time t r c o = 1f, r o = 10 ? 1ms output turn off fall time t f c o = 1f, r o = 10 ? 0.1 1 ms enable input high level input voltage v en(hi) 4.25v v in 5.50v 2.4 v low level input voltage v en(lo) 4.25v v in 5.50v 0.8 v input current i en en = v in , outa/b = open 0 1 a en = 0v, i oa /i ob = 0ma, outa/b = open 0 1 output turn on delay t d(on) 0.25 ms output turn off delay t d(off) 25 50 s current limit short circuit current limit i os v oa /v ob = gnd, switches on 0.65 0.90 1.60 a supply current outputs off i in(off) switches off 0.02 1 a outputs on i in(on) i oa /i ob = 0ma 130 200 a undervoltage lockout uvlo threshold v uvlo 2.2 2.7 v hysteresis v hyst 90 mv error flag output resistance r flg i flg = 10ma, v oa /v ob = gnd, switches on 10 50 ? leakage current (off) i flg v flg = 5.0v, switches off 0.01 1 a over temperature protection high trip level t hi 160 c hysteresis t hyst 10 c note: (1) for sc5826-1, switch off is v en 0.8v and switch on is v en 2.4v (?active high?). for sc5826-2, switch on is v en 0.8v and switch off is v en 2.4v (?active low?). for testing purposes en will be 0v or v in as applicable, unless otherwise specified. (2) this device is esd sensitive. use of standard esd handling precautions is required.
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 4 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 -50 -25 0 25 50 75 100 125 150 t j (c) i os (a) v in = 5v 2.000 2.100 2.200 2.300 2.400 2.500 2.600 2.700 2.800 2.900 3.000 -50 -25 0 25 50 75 100 125 150 t j (c) v uvlo (v) v in rising v in falling 0 25 50 75 100 125 150 175 200 -50 -25 0 25 50 75 100 125 150 t j (c) i in(on) (a) v in = 5v typical characteristics supply current (outputs on) vs. junction temperature short circuit output current vs. junction temperature uvlo threshold vs. junction temperature 50 60 70 80 90 100 110 120 130 140 150 -50 -25 0 25 50 75 100 125 150 t j (c) r on (m ? ? ? ? ) i o = 0.5a v in = 4.25v v in = 5.5v on resistance vs. junction temperature vs. input voltage
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 5 detailed description the sc5826 hotswitch? is a dual port, high-side switch optimized for power control & distribution in uni- versal serial bus (usb) applications. it features an n- channel power mosfet with a low on-state resistance for meeting usb voltage regulation requirements. it available with active high (sc5826-1) or active low (sc5826-2) inputs. in/out the input is the supply voltage connection to the drain of the power switch mosfet. the output is con- nected to the source of the mosfet. under normal operating conditions when the power switch is enabled, current flows from the input to the output towards the load. the power switch is designed to sustain a mini- mum load current of 500ma in accordance with usb specifications. charge pump an internal charge pump powers the mosfet gate drive circuit and provides the necessary voltage to pull the gate above the source. control logic the gate drive circuit controls the gate voltage of the mosfet power switch. the gate drive circuit also controls the rise & fall times of the power switch output voltage. the typical ?soft start? or output voltage rise time is 1ms. enable input a logic signal at the enable (en) pin activates the power mosfet switch. a logic 1 (sc5826-1) or logic 0 (sc5826-2) will bias the charge pump, gate drive, and control circuitry turning on the power switch. a logic signal of opposite polarity turns off the switch. if both outputs are off, the device powers down. the en- able input is compatible with 3v & 5v logic levels. error flag the error flag (flg) output is an n-channel, open drain mosfet. the flg pin is an active low during short circuit, undervoltage, or thermal shutdown conditions. the output remains low until the fault condition is re- moved. thermal sense an internal thermal shutdown circuit turns off the power switch output mosfet when the die junction tempera- ture exceeds 160c. the output flg pin is asserted to a logic low signaling a fault condition. a built in hys- teresis prevents the switch from turning on until the die temperature has cooled approximately 10c. the switch will continue to cycle on and off until the fault condition is removed. the thermal sense circuit func- tions only when the switch is enabled. undervoltage lockout an undervoltage lockout circuit monitors the input volt- age and prevents the power switch mosfet from turning on until the input voltage (in) exceeds 2.5v (typical). if the input voltage falls 90mv (typical) below that point after the switch has been turned on, the un- dervoltage lockout turns off the power switch output mosfet and asserts the flg output to logic low. the undervoltage lockout functions only when the switch is enabled.
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 6 typical applications figure 1 - self-powered hub with individual port power management self-powered hub, indidual port power management: a self-powered hub must supply a continuous 500ma of current to each downstream port. since an internal power supply is used to supply the power, self-powered hubs are required to implement overcurrent protection for safety. the self-powered hub must also have a method to detect and report fault conditions to the usb controller. the circuit below utilizes the sc5826 to pro- vide individual port overcurrent protection & power switching for maximum port protection. under fault conditions, the sc5826 provides the short-circuit cur- rent limiting function and has a fault flag logic output for notifying the hub controller. the usb hub can use the sc5826 to remove power from the faulty port, allowing the other ports to operate normally. since usb is a hot insertion and removal system, usb ports are subject to electrostatic discharge (esd). the srda05-4 provides esd protection on the down- stream data and power lines. each device will protect two usb ports. with proper layout the port is hard- ened to greater than 15kv, meeting the requirements of iec 1000-4-2. on the upstream port, the lcda05 provides esd protection to the above levels for one line pair. the sc5203 (or sc5205) ldo regulator is used to power the hub controller from the upstream bus.
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 7 typical applications figure 2 - bus-powered hub with ganged port power management bus-powered hub, ganged port power management: a bus-powered hub distributes power and data from an input port to downstream ports. it must supply a con- tinuous 100ma of current to each downstream port. a bus-powered hub must be able to switch power to downstream ports to prevent illegal device hook-up. inrush current limiting is also required to prevent power supply drooping. the circuit below utilizes the sc5826 to provide ganged port power switching, inrush current limiting and overcurrent protection for maximum port protection. in a ganged switch configuration, all ports are switched simultaneously. under fault conditions, the usb controller will remove power to all of the ganged ports. for individual port management, an ad- ditional sc5826 may be used. since usb is a hot insertion and removal system, usb ports are subject to electrostatic discharge (esd). the srda05-4 provides esd protection on the down- stream data and power lines. each device will protect two usb ports. with proper layout the port is hard- ened to greater than 15kv, meeting the requirements of iec 1000-4-2. on the upstream port, the lcda05 provides esd protection to the above levels for one line pair. the sc5203 (or sc5205) ldo regulator is used to power the hub controller from the upstream bus.
sc5826 ? 2000 semtech corp. hotswitch? usb power distribution switch preliminary - february 18, 2000 652 mitchell road newbury park ca 91320 8 outline drawing - so-8 jedec ref: ms-012aa land pattern - so-8 ecn00-886
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