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1/14 www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. system power supply for tv series fet controller type 3ch system power supply ics bd8621efv description bd8621efv has realized the high performance and reliability required as a power supply for thin-screen tv. with built-in fet 1ch current mode cont rol, the dc/dc converter series has t he advantage of high-speed load response and wide phase margin. due to the high-speed load response, it is most suitable fo r tv-purpose processors with increasingly high performance, and due to the wide phase margin it leaves a good margin for board pattern & constant setting and so facilitates its application design. as a high-reliability design, it has various built-in protecti on circuits (overcurrent protection, output voltage abnormal protection, thermal protection, and off-latc h function at the time of abnormality etc. ), therefore as an advantage it does not easily damage in every possible abnormal condition such as all-pin short circuit test etc. and hence most suitable for thin-screen tv which requires the high reliability. features 1) 3a output current 2) low rds(on) internal switches (pchmos:75m ? nchmos:55m ? ) 3) 1% reference voltage accuracy 4) programmable frequency : 250khz-1mhz 5) (frequency in programmable by adjusting rt re sistance or synchronizing with synclk terminal.) 6) terminal rt open/short detecting function 7) over current protection function 8) output over voltage/low voltage pr otection function (over : fb > vref +60mv , low : fb < vref -60mv) 9) timer off latch function in abnormal circumstances 10) thermal shutdown function 11) under voltage protection 12) soft start/start delay circuit 13) soft start time out function 14) protecting bus function with terminal pdet 15) htssop-b20 package no.09034eat03
technical note 2/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. electrical characteristics (unless otherwise noted ta=25 ? ? ?
technical note 3/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. block diagram fig1 block diagram pin description no. symbol description explanation 1 sgnd signal gnd terminal small signal system gnd 2 fb feed back terminal output voltage detection 3 pdet off latch signal output protecting bus communication terminal 4 sw output terminal switching output 5 sw 6 pgnd power gnd terminal gnd for power mosfet 7 pgnd 8 pgnd 9 sw output terminal power mos output 10 sw 11 vin power supply input terminal power supply input. the decoupling is done to pgnd 12 vin 13 vin 14 vin 15 reg internal regulator synchronizable switching output terminal frequency with external clock 16 en enable input on/off control for device operation 17 test terminal for test sgnd short in the set. 18 ss/delay soft start adjustment capacity connection terminal the soft start time is adjusted with the connected capacitor 19 fc error amplifier output error amplifier phase compensation point 20 rt frequency adjustment resistance connection terminal the switching frequency is set by the connected resistance
technical note 4/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. pin equivalence circuit diagram no. symbol explanation terminal equivalent circuit diagram 1 sgnd gnd (connected 0v) 2 fb output voltage detection terminal vin sgnd 2 5 6 7 vin pgnd 4 5 9 vin pgnd 10
technical note 5/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. no. symbol explanation terminal equivalent circuit diagram 15 reg internal regulator output voltage 16 en enable terminal 17 test using at test mode
technical note 6/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. no. symbol explanation terminal equivalent circuit diagram 18 ss /delay soft start time adjustment terminal 19 fc error amplifier compensation terminal 20 rt oscillator frequency adjustment terminal
technical note 7/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. operation description enable control the device can be controlled on/off by en terminal (16 pin) voltage. an internal circuit starts when ven reaches 1.1v. fig.2 on/off transition wave form in en controlling en terminal voltage ss terminal voltage output setting voltage
technical note 8/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. soft start time set function as for bd8621efv, output can do soft start without overshoot by charging soft start capacity (css) connected between ss and sgnd terminal. also, soft start time (tss) can be set by se tting soft start capacity (css) arbitrarily. osc oscillation fre quency setting function the output oscillation frequency can be set by connecting resistance between terminal rt (20 pins) and sgnd (range = 250khz - 1mhz) the relation between rt terminal resistance and the oscillation frequency follows fig.3. 10 1000 10 100 1000 10000 rt terminal resistance[k] frequency[khz] fig.3 rt resistance-oscillation frequency switching frequency synchronization an internal transmitter of bd8621efv can be synchronized with the external clock signal connected with the terminal synclk (15 pins). the frequency of external clock can be set within the range of 250khz-1mhz. in this case, please set the rt resistance that may become about -20% value of the external clock frequency. * be short-circuited synclk terminal to sgnd when a frequency synchronous function is not used.
technical note 9/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. protection function protection circuit is effective for destruction prevention due to accident so that avoid usin g under continuous protection operation. low voltage protection function (lvp) the voltage of the terminal fb (2 pins) is compared with internal reference voltage vref. if fb terminal voltage falls below v lvp (= vref -60mv) and the state continues fo r 500us, output changes to low voltage and the state is fixed. in that case , pdet (3pin) output changes to l. table 1 output low voltage protection function en terminal ss terminal fb terminal low voltage protection function low voltage protection operation >v enh >1.4v(typ) v lvp effective on v lvp off <1.4v(typ) - invalidity off v enh >1.4v(typ) v ovp effective on v ovp off <1.4v(typ) - invalidity off technical note 10/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. under voltage lock out protection (uvlo) as for bd8621efv, the power-supply voltage decr ease detection protection circuit is built in. it the input voltage decrease below the uvlo voltage (2.5v typ) , the device state changes to the standby mode (moreover, to prevent the chattering of the output) hy steresis width of 100mv(typ) has been in stalled in the uvlo cancel voltage. rt terminal open/short protection function (rto/rts) rt terminal opening/short protection function pr event the clock from abnormal oscillation. if rt terminal open/short protection function is detected, output voltage changes to low level and is fixed. terminal rt opening/short protection function is available if the state continue for 500us ec, abnormal detection operates when the state continues about 500 sec(typ). soft start time-out function if vss doesn't exceed vssth within 64msec (typ) since a so ft start began, bd8621efv controls an off latch. vo is fixed in a low level. fig.5 soft start time-out thermal shut down function thermal shut down circuit (tsd circuit) is built into bd862 1efv. when the temperature of t he chip exceeds tjmax=175, the dc/dc converter is fixed in a low voltage. tsd function is aimed to shut down ic from thermal re ckless driving under an abnormal state to exceed tjmax=175. it aims at neither protection nor the guarantee of the set. therefore, please do not use this function to protect the set. over current protection function the over current protection function has been achieved by limiting the current that flows on high side mosfet. the current is controlled in every one cycle of the switching frequency. when an abnormal state continues for about 500 sec(typ), the output is fixed in a low level.
technical note 11/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. protecting bus function with terminal pdet the terminal pdet (3 pins) monitors whether ic is normal or not. when ic becomes abnormal, the pdet output is reduced at "l" level with the output voltage fixed ?l? level at the same ti me. moreover, it is possible to make the output fix in a low level by compulsorily reducing the terminal pdet at "l" level from the outside. when two or more bd8621efv is used in the application, this function prevents the ic from destroying, because one ic error transmits all other ics by pdet line in the co ndition that pdet terminals are connected each other. fig.6 protecting bus communication please give the terminal pdet as open when you do not use protecting bus function. error detection (off latch) release method bd8621efv enters the state of an off latc h when the protection function operates. to release the off latch state, en terminal vo ltage should be changed to low level once time.
technical note 12/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. each characteristic reference data fig.7 output load respons e fig.8 output ripple ? fig.9 efficiency fig.10 soft start fig.11 regulation 0.790 0.792 0.794 0.796 0.798 0.800 0.802 0.804 0.806 0.808 0.810 -25 0 25 50 75 100 ambie nt ? temperature ? : ? ta ? [ ] error ? amp ? reference ? vol tage ? : ?? vre f ? [v ] 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 -25 0 25 50 75 100 amb ie nt ? temperature ? : ? ta ? [ ] ss ? charge ? current ?? : ? is s ? [ a] fig.12 reference voltage - temperature characteristic fig.13 ss charging current - temperature characteristic 0 10 20 30 40 50 60 70 80 90 100 10 100 1000 10000 [%] load current [ma] efficienc y [ % ] vin = 3.3v vout = 1.2v 1.00 ? 1.10 ? 1.20 ? 1.30 ? 1.40 ? 1.50 ? 0.0000 0.5000 1.0000 1.5000 2.0000 2.5000 3.0000 load current [a] output voltage : vo[v] vin = 5v io = 3a vout : 20mv/div vin = 2v/div vout = 0.5v/div ss = 2v/div 1usec/div 10msec/div vin = 5.0v vin = 5v vout : 100mv/div io = 1a/div vin = 3.3v vin = 3.3v vin = 5.0v vout = 1.2v
technical note 13/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. 500.0 ? 510.0 ? 520.0 ? 530.0 ? 540.0 ? 550.0 ? 560.0 ? 570.0 ? 580.0 ? 590.0 ? 600.0 ? 2.533.544.555.5 frequency ? : ? fosc ? [khz] input ? voltage ? : ? vin ? [v] 500.0 510.0 520.0 530.0 540.0 550.0 560.0 570.0 580.0 590.0 600.0 -25 0 25 50 75 100 ambie nt ? temperature ? : ? ta ? [ ] frequency ? : ? fosc ? [k h z ] fig.14 switching frequency-power-supply voltage fig.15 switching frequency-temperature characteristic 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 2.533.544.555.5 inp ut ? vol tage ? : ? vin ? [v ] on \ resistance: ? ron ? [m ] 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 110.00 -25 0 25 50 75 100 ambie nt ? temperature ? : ? ta ? [ ] on \ resistance: ? ron ? [m ] fig.16 pmos on resistance-power-supply voltage fig.17 pmos on resistance-temperature characteristic 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 2.5 3 3.5 4 4.5 5 5.5 inp ut ? vol tage ? : ? vin ? [v ] on \ resistance: ? ron ? [m ] 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 -25 0 25 50 75 100 ambie nt ? temperature ? : ? ta ? [ ] on \ resistance: ? ron ? [m ] fig.18 nmos on resistance-power-supply voltage fig.19 nmos on resistance-temperature characteristic 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 -25 0 25 50 75 100 ambie nt ? temperature ? : ? ta ? [ ] en ? vol tage ? high: ? v enh ? [v ] 0.0 ? 50.0 ? 100.0 ? 150.0 ? 200.0 ? 250.0 ? 300.0 ? 350.0 ? 400.0 ? 2.5 3 3.5 4 4.5 5 5.5 circuit ? current: ? icc ? [ua] input ? voltage ? : ? vin ? [v] fig.20 terminal en h voltage-temperature characteristic fi g.21 circuit current-power-suppl y voltage characteristic ta = 25 ta = 25 vin = 3.3v ta = 25 vin = 3.3v vin = 3.3v vin = 3.3v ta = 25 v fb = 0.83v v fc = 1.0v sw = high
technical note 14/14 bd8621efv www.rohm.com 2009.05 - rev.a ? 2009 rohm co., ltd. all rights reserved. ordering part number b d 8 6 2 1 e f v - e 2 part no part no. package efv: htssop-b20 packaging and forming specification e2: embossed tape and reel ta p e quantit y direction of feed embossed carrier ta p e 2500 p cs e2 (the direction is the 1pin of product is at the upper left when you hold reel on the left hand and you pull out the tape on the right hand) unit:mm ) htssop-b20 1.0max. 10 1 20 11 0.17 1.0 0.2 0.5 0.15 0.65 s 0.08 +0.05 ?0.04 +0.05 ?0.03 0.2 6.4 0.2 0.85 0.05 0.08 0.05 4.4 0.1 0.325 6.5 0.1 s reel 1pin 1234 1234 1234 1234 1234 1234 1234 1234 when you order , please order in times the amount of package quantity. direction of feed
r0039 a www.rohm.com ? 2009 rohm co., ltd. all rights reserved. notice rohm customer support system http://www.rohm.com/contact/ thank you for your accessing to rohm product informations. more detail product informations and catalogs are available, please contact us. notes no copying or reproduction of this document, in part or in whole, is permitted without the consent of rohm co.,ltd. the content specied herein is subject to change for improvement without notice. the content specied herein is for the purpose of introducing rohm's products (hereinafter "products"). if you wish to use any such product, please be sure to refer to the specications, which can be obtained from rohm upon request. examples of application circuits, circuit constants and any other information contained herein illustrate the standard usage and operations of the products. the peripheral conditions must be taken into account when designing circuits for mass production. great care was taken in ensuring the accuracy of the information specied in this document. however, should you incur any damage arising from any inaccuracy or misprint of such information, rohm shall bear no responsibility for such damage. the technical information specied herein is intended only to show the typical functions of and examples of application circuits for the products. rohm does not grant you, explicitly or implicitly, any license to use or exercise intellectual property or other rights held by rohm and other parties. rohm shall bear no responsibility whatsoever for any dispute arising from the use of such technical information. the products specied in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, ofce-automation equipment, commu- nication devices, electronic appliances and amusement devices). the products specied in this document are not designed to be radiation tolerant. while rohm always makes efforts to enhance the quality and reliability of its products, a product may fail or malfunction for a variety of reasons. please be sure to implement in your equipment using the products safety measures to guard against the possibility of physical injury, re or any other damage caused in the event of the failure of any product, such as derating, redundancy, re control and fail-safe designs. rohm shall bear no responsibility whatsoever for your use of any product outside of the prescribed scope or not in accordance with the instruction manual. the products are not designed or manufactured to be used with any equipment, device or system which requires an extremely high level of reliability the failure or malfunction of which may result in a direct threat to human life or create a risk of human injury (such as a medical instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuel-controller or other safety device). rohm shall bear no responsibility in any way for use of any of the products for the above special purposes. if a product is intended to be used for any such special purpose, please contact a rohm sales representative before purchasing. if you intend to export or ship overseas any product or technology specied herein that may be controlled under the foreign exchange and the foreign trade law, you will be required to obtain a license or permit under the law.

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