????????? ??? ? ???? rm6 22x ? general description rm622x combines a dedicated current mode pwm controller with a high volt age powe r mosfet . it is o p timized for high performa n ce,low st andby power ,and cost ef fective of f- line flyback converte r app- lications in sub 20w ra ng e. rm622x of fers co mplete protection covera ge w i th automatic self-recovery feature inclu d ing c y cle- by-c ycle current limiting,over load pr otection,vdd over volt age clamp and und er volt age lockout. excellent emi performance is achieved with freque ncy shuf flin g technique tog- ether with sof t switching control at the totem pole gate drive out put. the tone energy at below 20khz is minimized in the design a nd au dio nosie is eliminated during ope r a tion.rm622 x is of fered in dip8 p a ckage. applica t ions of fline ac/dc flyback co nverte r for ? battery charger ? pda power s uppiles ? digit a l came ras and ca mcorder adapto r ? vcr,svr,s tb,dvd&dvcd player smps ? set-t op box powe r ? auxiliary power suppl y for pc and server ? open-fr ame smps fea t ures ? power on sof t st art reducing mosfet vds s t ress . ? freque ncy shuf fling for emi ? extended b u rst mode control fo r improve d e f ficiency and minimum st andby pow er design ? audio noise free op eratio n ? fixed 50khz switching frequency ? internal synchronized slo p compensation ? low vdd st art-up curre nt and low oper ationg curre nt ? leb and current sense input ? good protec tion coverag e with auto self-recov e ry ? vdd over volt age clamp and und er volt age lockout with hysteresis ? input compensated cycle-by-c ycle over -curre nt threshold setting for const ant output power li miting over unive rsal input volt age ra nge. ? overlo ad pr o t ection ? over volt age protection http://
????????? ??? ? ???? rm6 22x ? typical application l2 r16 r9 r10 - + d2 br 1 2 1 3 4 u2 l1 8 6 7 4 + c2 c3 d1 t1 1 2 3 4 5 6 r12 d4 + c7 + c8 r13 + + + r14 n l c9 f1 r15 pc817c 3 2 4 1 fb d3 + c4 +vout r20 c11 r18 u4 rm622x vddg 1 vdd 2 fb 3 sense 4 drain 5 dr a i n 6 gnd 7 gnd 8 fb c5 r11 ac 85v ~26 4v pin assignment(sop-8&dip8) u4 rm622x vddg 1 vdd 2 fb 3 sense 4 drain 5 d rai n 6 gnd 7 gn d 8 pin description s pin name description gnd ground fb feedback input pin.the pwm duty cycle is determined by voltage level into this pin and the current-sense signal at pin 4 vdd-g internal gate driver power supply sense current sense input vdd power supply input drain hv mosfet driver pin,the driver pin is connected to the primary lead of the transformer.
????????? ??? ? ???? rm6 22x ? block diagram absolute maximum ra tings parameter v a lue drain voltage(off state) -0.3v to 600v vdd voltage -0.3v to 30v vdd-g input voltage -0.3v to 30v vdd clamp continous curr ent 10ma fb input voltage -0.3v to 7v sense input voltage -0.3v to 7v min/max operating junction temperature tj -20 to150 min/max storage temper a t ure -55 to160 lead temperature(soldering 10sec) 260 note: s t esses be yo nd thos e l i sted un der ?a b s olut e ma ximu m ratings?ma y cause p e rma n ent dama ge to the device,e x p o sure to abso l ute maximum- rated con d itio n s for extend ed periods ma y af fect device relia bi lit y .
????????? ??? ? ???? rm6 22x ? symbol parameter test conditions min typ max unit supply voltage (vdd) i_startup vdd start up current vdd=14.1v,measure leakage current into vdd 4 20 ua i_vdd (operation) operation current vfb=3v 2 ma uvlo(on) vdd under voltage lockout enter 8.5 9 9.5 v uvlo(off) vdd under voltage lockout exit(recovery) 14.2 14.8 16 v ovp(on) over voltage protection voltage cs=0v, fb=3v ramp up vdd until gate clock is off 27.0 28.5 30.0 v vdd_clamp vdd zener clamp voltage idd=10ma 30 v feedback input section(fb pin) vfb_open vfb open loop voltage 5.4 5.6 6.0 v ifb_short fb pin short circuit current short fb pin to gnd and measure current 1.65 ma vth_od zero duty cycle fb threshold voltage 0.8 v vth_pl power limiting fb threshold voltage 3.7 v td_pl power limiting debounce time 50 ms zfb_in input impedance 4 k current sense input(sense pin) soft start time 4 ms t_blanking leading edge blanking 300 ns electrical characteristics (ta=25c un l ess ot herwis e note d , vd d = 16v) v2. 5 5 / 11
????????? ??? ? ???? rm6 22x ? z sense_in input impedance 40 k td_oc over current detection and control delay from over current occurs till the gate drive out p ut start to turn off 120 ns vth_oc internal current limiting threshold voltage fb=3.3v 0.82 0.9 0.98 v oscillator fosc normal oscillation 45 50 55 khz f_temp frequency temperature stability 5 % f_vdd frequency voltage 5 % d_max maximum duty cycle fb=3.3v, cs=0v 70 80 90 % f_hiccup hiccup mode base 22 khz power mosfet section bvdss mosfet drain source breakdown voltage vgs=0v, ids=250ua 600 v RM6221S 8.0 9.5 rds(on) static drain to source on resistance vgs=10v, ids=1a rm6222d 5.0 5.8 frequency jitting f_soc frequency modulation range base frequency -4 4 %
????????? ??? ? ???? rm6 22x ? operation desc ription the rm622 x is a low power off-line smps switcher optimized for off- line flyback converter a p p lications in sub 24w po wer rang e. the hiccup m ode control greatl y reduces the standby po w e r cons- umption and helps the design easily to meet th e internation a l powe r conservation requir e ments. startup current and start up control startup curre nt of rm622x is designed to be ver y low so that vdd could be char ged up abo ve uv lo threshold level and device starts up quickly. a large value startup resistor can therefore be used t o minimize the power loss yet achieve a reliable startup in applica t ion. for ac/dc adapto r with unive rsal input range desi gn, a 2 mohm , 1/8 w startup resistor could be used togethe r with a vdd capacitor to provi de a fast startup and yet low pow e r dissipation design solution. operation current the oper ation current of rm622x is lower than 2 ma. good efficiency is achieved with rm622 x low operati ng current together with the ?a dvanced hiccup mode? control features. soft start rm622x features an inter nal 4 ms soft start to softe n the electrical stress occurr- ing in the power supply d u ring startup. it is activated during t he power on sequenc e. as soon as vdd reache s uvlo(off), the peak current is gradually i n creased fro m nearl y zero to the maximum level. every restart up is followed b y a soft start. oscillator normal operation the normal switching frequency of rm622x is internally fixe d at 50 khz. no extern al freq uency setting component s are req u ire d for pcb design simplification. frequenc y jitting for emi improvement the freque n c y jitter (switching freque ncy modulation) i s implemented in rm622 x. the oscillatio n frequency i s modulated so that the tone ener gy is spread out. the spread spectrum minimizes the condu- ction band emi and therefore eases the system desig n. advanced h i ccup mode operation at light load or zero load condition, most of the powe r dissipation in a switching mode powe r suppl y is from switching loss on the mosfet, th e core loss o f the transfor m er and the loss on the snubb er circuit. the magnitude of powe r loss is in proportio n to the switching frequency. l o wer switching freque ncy leads to the reduction on the powe r loss a nd thus conserves the en ergy. the switching frequency i s internally ad justed at no load or ligh t load condition. the switch fr eque ncy red u ces at light/no load conditio n to improve the conversion efficiency. at light l oad or no load cond ition, the fb input drops belo w hiccup mode threshold level and de vice enters hiccup mode control . the gate drive outp u t switches only when vd d voltage d r op s below a pr eset level and fb input is active to output an on state to minimize the switching loss and reduce the standby powe r consumption to the greatest extend. the switching frequency control also eliminates th e audio nois e at any load ing conditions. current sen s ing and le ading edge blanking cycle-b y -c ycle current limiting is offe red in rm622x curre nt mode pwm control. the switch curre nt is dete c ted by sense resistor into the sense pin. an internal leading e dge blank ci rcuit chops off the sensed volta ge spike at initial internal powe r mosfet on stat e due to snubber
????????? ??? ? ???? rm6 22x ? diode re vers e recover y a nd surge gat e current of internal po wer mosfet so that the extern al rc filter ing on sense input is no longe r ne eded. the cu rrent limiting comparator i s disabled and cannot tur n off the internal p o wer mosfet during the blanking peri od. the pwm duty cycle is determined b y the current sense input voltage a nd the fb input voltage. internal slope compensation built-in slope compensat ion circuit ad ds voltage r a mp onto the current sense input voltage for pwm generati on. this greatly improves the close loop stability at ccm and pr eve n ts the sub-har monic oscillation and thus red u ces the output ripple vol t age. drive the internal powe r mosfet in rm6 22x is driven by a dedicated gate driver for powe r switch control. too weak the gate drive strengt h results in h i gher cond uction and switch loss of mosfet while too strong gate d r ive results the compromise of emi.a good trade-off is achieved thr ou- gh the built-in totem pole gate design with right output strength an d dead time control. the low idle loss and good emi syste m design is easier to achieve with this de d- icated control scheme .in addition to the gate drive control sc heme mentioned, the gate drive strength c an also be adjusted extern ally by a resistor connected bet w- een vdd and vddg, the falling edge of the drain out put can be well controlled. it provi des great flexibility for system emi design. protection controls good power supply syst em reliability is achieved wit h its rich protection features including cycle-by-c ycle current limiting (ocp); over load protection (olp); u nder voltage lockout on vdd ( u vlo); over voltage p r ote c tion (ovp) and vdd clamp function. the ocp is line voltage compen- sated to achieve c onstant output powe r limit over the univers al input voltage r ange. at overload condition wh e n fb input volt- age exce eds power limit threshold val ue for more tha n td_pl, control circuit reacts to shut down the switcher. switcher rest- arts when vdd voltag e d r ops below u v lo limit.vdd is supplied by t r ansformer a u xil- iary win d ing output. whe n vdd ramp up to ovp threshold voltage (2 8.5v), the output of rm622x will be shut down, when vdd drops belo w uvlo(on ) limit and switcher enters powe r on start-up seque nce ther e- after. when vdd is higher than vdd. clamp threshold voltage, the internal v dd clamp circuitry will clamp vdd to 30v, and the output of rm622x is shut down als o .
????????? ??? ? ???? rm6 22x ? p ackage dimensions dip-8
????????? ??? ? ???? rm6 22x ? sop-8
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