mp6910 fast turn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 1 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. the future of analog ic technology description the mp6910 is a fast turn-off intelligent rectifier for flyback converters that combines a 100v power switch that replaces diode rectifiers for high efficiency. the chip regulates the forward voltage drop of the internal power switch to about 70mv and turns it off before the voltage goes negative. features ? supports dcm and quasi-resonant flyback converter ? integrated 10m ? 100v power switch ? compatible with energy star, 1w standby requirements ? v dd range from 8v to 24v ? 70mv v ds regulation function (1) ? max 400khz switching frequency ? light load mode function (1) with <300ua quiescent current ? supports high-side and low-side rectification ? power savings of up to 1.5w in a typical notebook adapter applications ? industrial power systems ? distributed power systems ? battery powered systems ? flyback converters all mps parts are lead-free and adhere to the rohs directive. for mps green status, please visit mps website under products, quality assurance page. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. notes: 1) related issued patent: us patent us8,067,973; us8,400,790. cn patent zl201010504140.4; zl200910059751.x. othe r patents pending typical application mp6910 not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 2 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. ordering information part number* package top marking mp6910dz to220-3 mp6910dz * for rohs compliant packaging, add suffix ?lf; (e.g. mp6910dz?lf) package reference vddvd vs absolute maxi mum ratings (2) v dd to v s .......................................-0.3v to +27v v d to v s .......................................-0.7v to +100v maximum operating frequency............. 400khz continuous drain current (t c =25c) .......... 40a continuous drain current (t c =100c) ........ 15a maximum power dissipation (3) ................. 2.7w junction temperature ...............................150 c lead temperature (solder).......................260 c storage temperature .............. -55c to +150 c recommended operation conditions (4) v dd to v s .............................................8v to 24v operating junction temp. (t j ). -40c to +125c thermal resistance (5) ja jc to220-3..................................45 ....... 3 .... c/w notes: 2) exceeding these ratings may damage the device. 3) t a =+25 . the maximum allowable power dissipation is a function of the maximum junction temperature t j (max), the junction-to-ambient thermal resistance ja , and the ambient temperature t a . the maximum allowable continuous powe r dissipation at any ambient temperature is calculated by p d (max) = (t j (max)-t a )/ ja . exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. internal thermal shutdown circui try protects the device from permanent damage. 4) the device is not guaranteed to function outside of its operating conditions. 5) measured on jesd51-7, 4-layer pcb. not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 3 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. electrical characteristics v dd = 12v, t a = +25 c, unless otherwise noted. parameter symbol conditions min typ max units drain-to-source breakdown voltage v (br)dss 100 110 v v dd voltage range 8 24 v v dd uvlo rising 5.0 6.0 7.0 v v dd uvlo hysteresis 0.8 1.2 1.5 v operating current i cc f sw =100khz 4.5 8 ma light-load mode current 260 360 a control circuitry section v ss ?v d forward voltage v fwd 55 70 85 mv turn-on delay (6) t don 200 ns turn off threshold (v ss -v d ) (6) 30 mv turn-off delay (6) t doff v d =v ss 30 45 ns minimum on-time (6) t min 1.6 s light-load-enter delay t ll-delay 120 s light-load-enter pulse width t ll 2.2 s light-load-enter pulse width hysteresis t ll-h 0.2 s light-load mode exit pulse width threshold (v ds ) v ll-ds -400 -250 -150 mv power switch section single pulse avalanche current (7) i as 66 a single pulse avalanche energy (7) e as 597 mj drain-source on-state resistance r ds(on) v gs =10v, i d =20a 10.2 m ? input capacitance c iss v ds =40v, f=1mhz 5110 pf output capacitance c oss 334 pf reverse transfer capacitance c rss 150 pf drain-source diode characteristics reverse recovery time t rr 81 ns diode reverse change q rr 190 nc notes: 6) guaranteed by design and characterization. 7) starting t j =25c, l=0.3mh pin functions pin # name description 1 vdd supply voltage 2 vd fet drain 3 vs fet source, also used as reference for vdd not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 4 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. block diagram logic driver vdd vd vss control circuitry figure 1?function block diagram operation the mp6910 supports operation in dcm and quasi-resonant flyback converters. the control circuitry controls the gate in forward mode and will turn the gate off when the mosfet current is fairly low. blanking the control circuitry contains a blanking function. when it pulls the integrate mosfet on/off, it makes sure that the on/off state at least lasts for some time. the turn on blanking time is ~1.6us, which determines the minimum on-time. during the turn on blanking period, the turn off threshold is not totally blanked, but changes the threshold voltage to ~+50mv (instead of -30mv). this assures that the part can always be turned off even during the turn on blanking period. (albeit slower) under-voltage lockout (uvlo) when the vdd is below uvlo threshold, the part is in sleep mode and the integrated mosfet is never turned on. basic operation the basic operations of flyback converter with mp6910 are: z turn on phase the switch current will first flow through the body diode of the integrate mosfet, which generates a negative vds across it (<- 500mv). the voltage is much smaller than the turn on threshold of the control circuitry (- 70mv), which turns on the integrate mosfet after 200ns turn on delay (defined in fig.2). z conducting phase when the integrated mosfet is turned on, vds becomes to rise according to its on resistance, as soon as vds rises above the turn on threshold (-70mv), the control circuitry stops pulling up the gate driver, which leads the driver voltage of the integrate mosfet dropped to larger the on resistance to ease the rise of vds. by doing that, vds is adjusted to be around -70mv even when the current through the switch is not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 5 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. fairly small, this function can make the internal driver voltage fairly low when the mosfet is turned off to fast the turn off speed (this function is still active during turn on blanking period which means the integrate mosfet could still be turned off even with very small duty). fig.3 shows synchronous rectification operation at heavy load condition. due to the high current, the internal driver voltage will be saturated at first. after vds goes to above -70mv, driver voltage decreases to adjust the vds to typical -70mv. fig.4 shows synchronous rectification operation at light load condition. due to the low current, the driver voltage never saturates but begins to decrease as soon as the integrated mosfet is turned on and adjust the vds. z turn off phase when vds rises to trigger the turn off threshold (-30mv), the driver voltage of the switch is pulled to low after about 20ns turn off delay (defined in fig.2) by the control circuitry. similar with turn-on phase, a 200ns blanking time is added after the switch is turned off to avoid error trigger. light-load latch-off function the gate driver of integrate mosfet in mp6910 is latched to save the driver loss at light-load condition to improve efficiency. the light-load- enter pulse width t ll is internal fixed (~2.2 s). when synchronous power switch conducting period keeps lower than t ll for longer than the light-load-enter delay (t ll-delay ), mp6910 enters light-load mode and latches off the integrate mosfet (fig.5 for detail). during light-load mode, mp6910 monitors the integrate mosfet body diode conducting period by sensing v ds (when v ds exceeds the light-load mode exit pulse width threshold v ll-ds , mp6910 considers the integrate mosfet body diode conducting time finishes). if the mosfet body diode conduction time is longer than t ll +t ll-h (t ll-h , light-load-enter pulse width hysteresis), the light-load mode is finished and the integrate mosfet of mp6910 is unlatched to restart the synchronous rectification (fig.6 for detail). typical system implementations fig.7 shows the typical system implementation for the ic supply derived from output voltage, which is available in low-side rectification and the output voltage is recommended to be in the vdd range of mp6910 (from 8v to 24v). if output voltage is out of the v dd range of mp6910 or high-side rectification is used, it is recommended to use an auxiliary winding from the power transformer for the ic supply, which is shown in fig.8 and fig.9. there is another non-auxiliary winding solution for the ic supply, which uses an external ldo circuit from the secondary transformer winding. see fig.10 and fig.11, compared with using auxiliary winding for ic supply, this solution has a bit higher power loss which is dissipate on the ldo circuit especially when the secondary winding voltage is high. v ds internal dri ver voltage t do n t dof f -70mv -30mv 2v figure 2?turn on and turn off delay not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 6 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. -70mv -30mv v ds i sd internal driver voltage t0 t1 t2 figure 3?synchronous rectification operation at heavy load -70mv -30mv v ds i sd internal driver voltage t0 t1 t2 figure 4? synchronous rectification operation at light load switching current normal mode light load mode t ll 120 s t ll t ll sr gate load become light figure 5?enter light load mode sr gate switching current light load mode normal mode t ll +t ll- h t ll +t ll-h t ll +t ll-h t ll +t ll-h load become heavy figure 6?exit light load mode not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 7 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. 1 3 mp6910 c1 c2 vd vdd vss 2 figure 7?ic supply derived directly from output voltage figure 8?ic supply derived from auxiliary winding in low-side rectification figure 9?ic supply derived from auxiliary winding in high-side rectification not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 8 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. figure 10?ic supply derived from secondary winding in low-side rectification figure 11?ic supply derived from secondary winding in high-side rectification not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier mp6910 rev. 1.05 www.monolithicpower.com 9 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. package information not recommended for new designs refer to mp6910a
mp6910- fast t urn-off intelligent rectifier notice: the information in this document is subject to change wi thout notice. users should warra nt and guarantee that third party intellectual property rights are not infringed upon w hen integrating mps products into any application. mps will not assume any legal responsibility for any said applications. mp6910 rev. 1.05 www.monolithicpower.com 10 6/23/2014 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2014 mps. all rights reserved. not recommended for new designs refer to mp6910a
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