1 datasheet high voltage synchronous rectified buck mosfet driver ISL95808 the ISL95808 is a high frequency, dual mosfet driver with low shutdown current, optimized to drive two n-channel power mosfets in a synchronous-rectified buck converter topology. it is especially suited for mobile computing applications that require high efficiency and excellent thermal performance. the driver, combined with an intersil multiphase buck pwm controller, forms a complete single-stage core-voltage regulator solution for advanced mobile microprocessors. the ISL95808 features a 4a typical sinking current for the lower gate driver. this current is capable of holding the lower mosfet gate off during the rising edge of the phase node. this prevents shoot-through power loss caused by the high dv/dt of phase voltages. the operating voltage matches the 30v breakdown voltage of the mosfet s commonly used in mobile computer power supplies. the ISL95808 also features a three-state pwm input. this pwm input, working together with intersil?s multiphase pwm controllers, will prevent negative voltage output during cpu shutdown. this feature eliminates a protective schottky diode usually seen in microprocessor power systems. mosfet gates can be efficiently switched up to 2mhz using the ISL95808. each driver is capable of driving a 3000pf load with propagation delays of 8n s and transition times under 10ns. bootstrapping is implemented with an internal schottky diode. this reduces system cost and complexity, while allowing for the use of higher performance mosfets. adaptive shoot--through protection is integrated to prevent both mosfets from conducti ng simultaneously. a diode emulation feat ure is integrated in the ISL95808 to enhance converter efficiency at light load conditions. this feature also allows for monotonic start-up into prebiased outputs. when diode emulation is enabled, the driver will allow discontinuous conduction mode by detecting when the inductor current reaches zero and subsequently turning off the low-side mosfet gate. the ISL95808 also features very low shutdown supply current (5v, 3a) to ensure the low power consumption. features ? dual mosfet drivers for synchronous rectified bridge ? adaptive shoot-through protection ?0.5 on-resistance and 4a sink current capability ? supports high switching frequency up to 2mhz - fast output rise and fall time - low propagation delay ? three-state pwm input for power stage shutdown ? internal bootstrap schottky diode ? low shutdown supply current (5v, 3a) ? diode emulation for enhanced light-load efficiency and prebiased start-up applications ? vcc por (power-on reset) feature integrated ? low three-state shutdown hold-off time (typical 160ns) ?dfn package ? pb-free (rohs compliant) applications ? core voltage supplies for intel? and amd? mobile microprocessors ? high frequency low profile dc/dc converters ? high current low output voltage dc/dc converters ? high input voltage dc/dc converters related literature ? tb389 , ?pcb land pattern design and surface mount guidelines for mlfp packages? ? tb447, ?guidelines for preventing boot-to-phase stress on half-bridge mosfet driver ics? vcc pwm 10k control logic shoot- through protection boot ugate phase lgate gnd vcc fccm thermal pad figure 1. block diagram caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | copyright intersil americas llc 2014, 2015, 2016. all rights reserved intersil (and design) is a trademark owned by intersil corporation or one of its subsidiaries. all other trademarks mentioned are the property of their respective owners. may 25, 2016 fn8689.2
ISL95808 2 fn8689.2 may 25, 2016 submit document feedback pin configuration ISL95808 (8 ld 2x2 dfn) top view ordering information part number ( notes 1 , 2 , 3 ) part marking temp. range (c) tape and reel (units) package (rohs compliant) pkg. dwg. # ISL95808hrz-t 08 -10 to +100 6k 8 ld 2x2 dfn l8.2x2d ISL95808irz-t 08i -40 to +100 6k 8 ld 2x2 dfn l8.2x2d notes: 1. please refer to tb347 for details on reel specifications. 2. these intersil pb-free plastic packaged products employ spec ial pb-free material sets, molding compounds/die attach materials , and 100% matte tin plate plus anneal (e3 termination finish , which is rohs compliant and compatible wi th both snpb and pb-free soldering opera tions). intersil pb- free products are msl classified at pb-free peak reflow temperat ures that meet or exceed the pb-free requirements of ipc/jedec j std-020. 3. for moisture sensitivity level (msl), please see product information page for ISL95808 . for more information on msl, please see tech brief tb363 . 1 6 vcc lgate pwm gnd 5 6 6 phase fccm 7 8 ugate boot 2 3 4 pin descriptions pin number pin name description 1 ugate the ugate pin is the upper gate drive output. conne ct to the gate of high-side power n-channel mosfet. 2 boot boot is the floating bootstrap supply pin for the upper gate drive. connect the bootstrap capacitor between this pin and the phase pin. the bootstrap capacitor provid es the charge to turn on the upper mosfet. see ? internal bootstrap diode ? on page 7 for guidance in choosing the appropriate capacitor value. 3 pwm the pwm signal is the control input for the driver. the pw m signal can enter three distinct states during operation. see ? three-state pwm input ? on page 6 for further details. connect this pin to the pwm output of the controller. 4 gnd gnd is the ground pin for the ic. 5 lgate lgate is the lower gate drive output. connect to gate of the low-side power n-channel mosfet. 6 vcc connect the vcc pin to a +5v bias supply. place a high quality bypass capacitor from this pin to gnd. the vcc pin of the driver(s) and related vcc or +5v bias supply pin of the intersil controller must share a common +5v supply. 7 fccm the fccm pin enables or disables diode emulation. when fccm is low, diode emulation is allowed. when fccm is high, continuous cond uction mode is forced. see ? diode emulation ? on page 6 for more detail. high impedance on the input of fccm will shut down ISL95808. 8 phase connect the phase pin to the source of the upper mosf et and the drain of the lower mosfet. this pin provides a return path for the upper gate driver.
ISL95808 3 fn8689.2 may 25, 2016 submit document feedback i absolute maximum rating s thermal information supply voltage (vcc) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 7v input voltage (v fccm , v pwm ) . . . . . . . . . . . . . . . . . . . . -0.3v to vcc + 0.3v boot voltage (v boot-gnd ) . . . . . . . . . . . . . . . -0.3v to 33v or 36v (<20ns) boot to phase voltage (v boot-phase ). . . . . . . . . . . . . . . . -0.3v to 7v (dc) -0.3v to 9v (<10ns) phase voltage ( note 4 ) . . . . . . . . . . . . . . . . . . . . . . . . . . (gnd - 0.3v) to 30v gnd - 8v (<20ns pulse width, 10j) ugate voltage. . . . . . . . . . . . . . . . . . . . . . . . . . v phase - 0.3v (dc) to v boot v phase - 5v (<20ns pulse width, 10j) to v boot lgate voltage . . . . . . . . . . . . . . . . . . . . . . . . .gnd - 0.3v (dc) to vcc + 0.3v gnd - 2.5v (<20ns pulse width, 5j) to vcc + 0.3v thermal resistance (typical) ? ja (c/w) ? jc (c/w) 8 ld 2x2 dfn package ( notes 5 , 6 ) . . . . . . 87 22 maximum storage temperature range . . . . . . . . . . . . . .-65c to +150c pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see tb493 recommended operating conditions ambient temperature hrz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-10c to +100c irz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40c to +100c maximum operating junction temperature . . . . . . . . . . . . . . . . . . +125c supply voltage, vcc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5v 10% caution: do not operate at or near the maximum ratings listed for extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. notes: 4. the phase voltage is capable of withstan ding -7v when the boot pin is at gnd. 5. ? ja is measured in free air with the componen t mounted on a high effective thermal conduc tivity test board with ?direct attach? fe atures. see tech brief tb379 . 6. for ? jc , the ?case temp? location is the center of the exposed metal pad on the package underside. electrical specifications recommended operating conditions, unless otherwise noted. boldface limits apply across the operating temperature range t a = -40c to +100c for industrial (irz) and t a = -10c to +100c for hi-temp commercial (hrz) . symbol parameter test conditions min ( note 8 )typ max ( note 8 )unit v cc supply current i vccsd shutdown bias supply current pw m and fccm pin floating - 3.3 4 a i vcc operating bias supply current pwm pin floating, v fccm = 5v - 80 - a pwm pin floating, v fccm = 0v - 120 - a por v cc rising -3.40 3.90 v hrz v cc falling 2.40 2.90 - v irz 2.39 2.90 - v hysteresis - 500 - mv bootstrap diode hrz forward voltage v vcc = 5v, forward bias current = 2ma 0.43 0.55 0.65 v irz v vcc = 5v, forward bias current = 2ma 0.43 0.55 0.70 v pwm input i pwm input current v pwm = 5v - 250 - a v pwm = 0v - -250 - a pwm three-state rising threshold v vcc = 5v 0.70 1.00 1.30 v pwm three-state falling threshold v vcc = 5v 3.5 3.8 4.1 v hrz three-state shutdown hold-off time v vcc = 5v, temperature = +25c 100 175 250 ns irz v vcc = 5v, temperature = +25c 85 175 250 ns fccm input i fccm input current v fccm = 5v - 50 - a v fccm = 0v - 50 - a fccm shutdown rising threshold v vcc = 5v 1.4 1.8 2.2 v
ISL95808 4 fn8689.2 may 25, 2016 submit document feedback fccm shutdown falling threshold v vcc = 5v 2.8 3.2 3.6 v t ps4exit ps4 exit latency v vcc = 5v - 15 s switching time t ru ugate rise time ( note 7 )v vcc = 5v, 3nf load - 8.0 - ns t rl lgate rise time ( note 7 )v vcc = 5v, 3nf load - 8.0 - ns t fu ugate fall time ( note 7 )v vcc = 5v, 3nf load - 8.0 - ns t fl lgate fall time ( note 7 )v vcc = 5v, 3nf load - 4.0 - ns t pdlu ugate turn-off propagation delay v vcc = 5v, outputs unloaded - 18 - ns t pdll lgate turn-off propagation delay v vcc = 5v, outputs unloaded - 25 - ns t pdhu ugate turn-on propagation delay v vcc = 5v, outputs unloaded - 20 - ns t pdhl lgate turn-on propagation delay v vcc = 5v, outputs unloaded - 20 - ns t pts ug/lg three-state propagation delay v vcc = 5v, outputs unloaded - 35 - ns t lgmin minimum lg on-time in dcm - 350 - ns output ( note 7 ) r u upper drive source resistance 500ma source current - 1 2.5 i u upper driver source current v ugate-phase = 2.5v - 2.00 - a r u upper drive sink resistance 500ma sink current - 1 2.5 i u upper driver sink current v ugate-phase = 2.5v - 2.00 - a r l lower drive source resistance 500ma source current - 1 2.5 i l lower driver source current v lgate = 2.5v - 2.00 - a r l lower drive sink resistance 500ma sink current - 0.5 1.0 i l lower driver sink current v lgate = 2.5v - 4.00 - a notes: 7. limits established by characteriza tion and are not production tested. 8. parameters with min and/or max limits are 100% tested at +25 c, unless otherwise specified. te mperature limits established by characterization and are not production tested. electrical specifications recommended operating conditions, unless otherwise noted. boldface limits apply across the operating temperature range t a = -40c to +100c for industrial (irz) and t a = -10c to +100c for hi-temp commercial (hrz) . (continued) symbol parameter test conditions min ( note 8 )typ max ( note 8 )unit
ISL95808 5 fn8689.2 may 25, 2016 submit document feedback typical application with 2-phase converter ps4 exit timing diagram +5v boot ugate phase lgate pwm fccm vcc drive v in +5v boot ugate phase lgate pwm v in +v core gnd isen2 isen1 pwm2 pwm1 main vcc +5v ISL95808 control vcc drive ISL95808 fccm fccm thermal pad thermal pad figure 2. typical application with 2-phase converter pwm ugate fccm t ps4exit 5v 5v 2.5v figure 3. ps4 exit timing diagram
ISL95808 6 fn8689.2 may 25, 2016 submit document feedback timing diagram description theory of operation designed for speed, the ISL95808 dual mosfet driver controls both high-side and low-side n-channel fets from one externally provided pwm signal. a rising edge on pwm initiates the turn-off of the lower mosfet (see ? timing diagram ?in figure 4 ). after a short propagation delay [t pdll ], the lower gate begins to fall. typical fall times [t fl ] are provided in the ?electrical specifications? table on page 4 . adaptive shoot-through circuitry monitors the lgate voltage. when lgate has fallen below 1v, ugate is allowed to turn on. this prevents both the lower and upper mosfets from conducting simultaneously, or shoot-through. a falling transition on pwm indicates the turn-off of the upper mosfet and the turn-on of the lower mosfet. a short propagation delay [t pdlu ] is encountered before the upper gate begins to fall [t fu ]. the upper mosfet gate -to-source voltage is monitored and the lower gate is allowed to rise after the upper mosfet gate-to-source voltage drops below 1v. the lower gate then rises [t rl ], turning on the lower mosfet. this driver is optimized for converters with large step-down compared to the upper mosfet because the lower mosfet conducts for a much longer time in a switching period. the lower gate driver is therefore sized much larger to meet this application requirement. the 0.5 on-resistance and 4a sink current capability enables the lower gate driver to absorb the current injected to the lower gate through the drain-to-gate capacitor of the lower mosfet. this prevents a shoot-through caused by the high dv/dt of the phase node. the pwm and fccm pins actively pull to mid-supply if left open. diode emulation diode emulation allows for higher converter efficiency under light load situations. with diode emulation active, the ISL95808 will detect the zero current crossing of the output inductor and turn off lgate. this ensures that discontinuous conduction mode (dcm) is achieved. diode emulation is asynchronous to the pwm signal. therefore, the ISL95808 w ill respond to the fccm input immediately after it changes state. note: intersil does not recommend diode emulation use with r ds(on) current sensing topologies. the turn-off of the low-side mosfet can cause gross current measurement inaccuracies. three-state pwm input a unique feature of the ISL95808 an d other intersil drivers is the addition of a shutdown window to the pwm input. if the pwm signal enters and remains within the shutdown window for a set hold-off time, the output driver s are disabled and both mosfet gates are pulled and held low. the shutdown state is removed when the pwm signal moves outside the shutdown window. otherwise, the pwm rising and fal ling thresholds outlined in the ?electrical specifications? table on page 3 determine when the lower and upper gates are enabled. the vcc pin of the driver(s) and related vcc or +5v bias supply pin of the intersil controller must share a common +5v supply. adaptive shoot-through protection both drivers incorporate adaptive shoot-through protection to prevent upper and lower mosfets from conducting simultaneously and shorting the input supply. this is accomplished by ensuring the falling gate has turned off one mosfet before the other is allowed to turn on. during turn-off of the lower mosfet, the lgate voltage is monitored until it reaches a 1v threshold, at which time the ugate is released to rise. adaptive shoot-through ci rcuitry monitors the upper mosfet gate-to-source voltage during ugate turn-off. once the upper pwm ugate lgate t pdll t fl t pdhu t ru t pdlu t fu t pdhl t rl 1v 2.5v t ru t fu t fl 1v t pts t tsshd t tsshd t pts figure 4. timing diagram
ISL95808 7 fn8689.2 may 25, 2016 submit document feedback mosfet gate-to-source voltage ha s dropped below a threshold of 1v, the lgate is allowed to rise. internal bootstrap diode this driver features an internal bootstrap schottky diode. simply adding an external capacitor across the boot and phase pins completes the bootstrap circuit. the bootstrap capacito r must have a maximum voltage rating above the maximum battery voltage plus 5v. the bootstrap capacitor can be derived from equation 1 : where q gate is the amount of gate charge required to fully charge the gate of the upper mosfet. the ? v boot term is defined as the allowable droop in the rail of the upper drive. as an example, suppose an up per mosfet has a gate charge, q gate , of 25nc at 5v and also assume the droop in the drive voltage over a pwm cycle is 200mv. one will find that a bootstrap capacitance of at leas t 0.125f is required. the next larger standard value capacitance is 0.15f. a good quality ceramic capacitor is recommended. power dissipation package power dissipation is mainly a function of the switching frequency and total gate charge of the selected mosfets. calculating the power dissipation in the driver for a desired application is critical to ensuring safe operation. exceeding the maximum allowable power dissipation level will push the ic beyond the maximum recommended operating junction temperature of +125c. when designing the driver into an application, it is recommended th at the following calculation be performed to ensure safe operation at the desired frequency for the selected mosfets. the powe r dissipated by the driver is approximated, as shown in equation 2 : where f sw is the switching frequenc y of the pwm signal. v u and v l represent the upper and lower gate rail voltage. q u and q l is the upper and lower gate charge determined by mosfet selection and any external capaci tance added to the gate pins. the lv cc v cc product is the quiescent power of the driver and is typically negligible. layout considerations reducing phase ring the parasitic inductances of the pcb and power devices (both upper and lower fets) could cause increased phase ringing, which may lead to voltages that exceed the absolute maximum rating of the devices. when phase rings below ground, the negative voltage could add charge to the bootstrap capacitor through the internal bootstrap diode. under worst-case conditions, the added charge could overstress the boot and/or phase pins. to prevent this from happening, the user should perform a careful layout inspection to reduce trace inductances, and select low lead inductance mosfets and drivers. d 2 pak and dpak packaged mosfets have high parasitic lead inductances. if higher inductance mosfets must be used, a schottky diode is recommended across the lower mosfet to clamp negative phase ring. a good layout would help reduce the ringing on the phase and gate nodes significantly: ? avoid using vias for decoupling components where possible, especially in the boot-to-phase path. little or no use of vias for vcc and gnd is also recommended. decoupling loops should be short. ? all power traces (ugate, phase, lgate, gnd and vcc) should be short and wide, and avoid using vias. if vias must be used, two or more vias per layer transition is recommended. ? keep the source of the upper fet as close as thermally possible to the drain of the lower fet. ? keep the connection in between the source of lower fet and power ground wide and short. ? input capacitors should be placed as close to the drain of the upper fet and the source of the lower fet as thermally possible. c boot q gate ? v boot ----------------------- - ? (eq. 1) figure 5. bootstrap capacitance vs boot ripple voltage ? v boot_cap (v) c boot_cap (f) 2.0 1.6 1.4 1.0 0.8 0.6 0.4 0.2 0.0 0.3 0.0 0.1 0.2 0.4 0.5 0.6 0.9 0.7 0.8 1.0 q gate = 100nc 1.2 1.8 50nc 20nc pf sw 1.5v u q u v l q l + ?? i vcc v cc + = (eq. 2) figure 6. power dissip ation vs frequency frequency (khz) 0 100 200 300 400 500 600 700 800 900 1000 0 200 400 600 800 1000 1200 1400 1600 1800 2000 power (mw) q u = 50nc q l = 50nc q u = 50nc q l = 100nc q u =100nc q l = 200nc q u = 20nc q l =50nc
ISL95808 8 intersil products are manufactured, assembled and tested utilizing iso9001 quality systems as noted in the quality certifications found at www.intersil.com/en/suppor t/qualandreliability.html intersil products are sold by description only. intersil corporat ion reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnished by intersil is believed to be accurate and reliable. however, no responsi bility is assumed by intersil or its subsid iaries for its use; nor for any infringem ents of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of i ntersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com fn8689.2 may 25, 2016 for additional products, see www.intersil.com/en/products.html submit document feedback refer to tech brief tb447 ?guidelines for preventing boot-to-phase stress on half-bridg e mosfet driver ics? for more information. fccm trace placement fccm trace should not be placed ne xt to digital signal traces or pwm/phase traces from other channels in multiphase designs. thermal management for maximum thermal performance in high current, high switching frequency applications , connecting the thermal pad of the dfn part to the power ground with multiple vias is recommended. this heat spreading allows the part to achieve its full thermal potential. about intersil intersil corporation is a leading provider of innovative power ma nagement and precision analog so lutions. the company's product s address some of the largest markets within the industrial and infrastr ucture, mobile computing and high-end consumer markets. for the most updated datasheet, application notes, related documentatio n and related parts, please see the respective product information page found at www.intersil.com . you may report errors or suggestions for improving this datasheet by visiting www.intersil.com/ask . reliability reports are also av ailable from our website at www.intersil.com/support . revision history the revision history provided is for in formational purposes only and is believed to be accurate, but not warranted. please go to web to make sure you have the latest revision. date revision change may 25, 2016 fn8689.2 additional information added on page 2 and page 6 relative to +5v supply being common between vcc of ISL95808 and intersil controllers. on page 3 added ac rating for the boot pin to existing dc rating. june 29, 2015 fn8689.1 removed additional information from dfn package bullet listed in features on page 1. ordering information table on page 2 changed to reflect addition of irz rated product and updated product markings. part marking updated for hrz version. electrical spec table beginning on page 3 updated to reflect irz addition. changed min value of ?forward voltage? on page 3 from 0.50 to 0.43 updated pod l8.2x2d with current version, changes are as follows: tiebar note 5 updated from: "tiebar shown (if presen t) is a non-functional feature." to: "tiebar shown (if present) is a non-functional feature and may be located on any of the 4 sides (or ends)." october 24, 2014 fn8689.0 initial release
ISL95808 9 fn8689.2 may 25, 2016 submit document feedback package outline drawing l8.2x2d 8 lead dual flat no-lead plastic package (dfn) with exposed pad rev 1, 3/15 bottom view detail "x" side view typical recommended land pattern top view pin #1 b 0.10 m a c c seating plane base plane 0.08 0.10 see detail "x" c c 0 . 00 min. 0 . 05 max. 0 . 2 ref c index area pin 1 6 (4x) 0.15 a b 1 package 2.00 2.00 1.550.10 0.900.10 0.22 ( 6x0.50 ) ( 8x0.22 ) 2.00 2.00 ( 8x0.30 ) ( 8x0.20 ) ( 8x0.30 ) 0.50 8 0.90 1.55 6x 0.900.10 index area outline located within the zone indicated. the pin #1 identifier may be unless otherwise specified, tolerance: decimal 0.05 the configuration of the pin #1 identifier is optional, but mus t be between 0.15mm and 0.30mm from the terminal tip. dimension applies to the metallized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to amse y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes: 6 4 tiebar shown (if present) is a non-functional feature and may be located on any of the 4 sides (or ends).
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