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curr ent mode pwm contr oller 1 ? pt 22 01_ds_en2.0 pt2201 general description pt2201 is a hig hly integrated current mode pwm controller, with the features of extreme low start up current, low operating current plus green mode operation and built-in protection functions allows the design of smps become easier to meet the high performance, high reliability and low standby power requirements. the start-up current is very small typically 3ua so that a large start up resistor can be used in the start-up circuit to minimize standby power. under the light lo ad or no load conditions the pt2201 automatically decrease s pwm frequency and enters burst mode operation thus the power loss on power mosfet is reduced. with a programmable oscillator the pwm frequency is easily set via an external resistor. synchronized slope compensati on has been implemented in the pt2201 to avoid potential sub harmonic oscillation caused by peak current control mode when operating under continuous conduct mode. moreove r, the internal leb on the current sense input removes the signal glitch due to snubber circuit diode reverse rec overy and greatly reduces the external component count and system cost in the design. the pt2201 also features multi-level protections to enhance smps reliability including cycle by cycle over current protection, over load protection, programmable over temperature protection, ov er voltage protection on vdd and vdd under voltage lock-out . the gate drive output is clamped at 18v to protect th e power mosfet. the burst mode frequency is lim ited above 20 khz thus the potential audible noise is avoid while th e system is under light or no load conditions. the pt2201 is available in sop8 and dip8 packages. fea t ures z frequency jittering for better emi performance z frequency automatically decrease to minimize standby power z noise free operation z programmable pwm frequency z current mode operation, bu ilt-in slope compensation z low start-up current z constant power limit for universal ac input z leading edge blanking on current sense z gate output 18v clamp z protection functions ? auto recovery programmable over temperature protection otp ? auto recovery over voltage protection on vdd (ovp) and uvlo ? line compensated cycle by cycle current limit (ocp) ? locked over load protection (olp) applica t ions z open-frame smps z fly - back switchi ng power supplier z power adaptor z battery charger orderi n g information p a ckage tempera t ure ra nge or deri ng part number transpor t medi a ma rki ng sop-8 -40 to 85 pt 2201bsoh t ape and reel pt2201 xxxxxx dip-8 -40 to 85 pt 2201bdih tube pt2201 xxxxxx note: xxxxx x a s sembly factory code lot number v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 2 ? pt 22 01_ds_en2.0 pt2201 typical applica t ion circuit emi fi lter pt 2 201 vdd gate sense gn d ri fb ac in tl 43 1 dc ou t vin rt ntc pin assignment pin descriptions pin no . pin na mes desc ripti on 1 gn d g round 2 fb feedb ack input pin. pwm duty cycle is determined by voltage level into this pin and sense pin voltage level. 3 vi n rectified line input for startup and line voltage sensing 4 ri in tern al oscillator frequency setting pin. a re sistor connected between ri and gnd sets the pwm frequency. 5 rt t emperature sensing input pin, connecting to an ntc resistor 6 sens e cu rr en t sen se input pin. connected to mosfet current sensing resistor node. 7 vdd d c power supply pin. 8 ga te t o t e m-pole gate drive output for power mosfet. o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 3 ? pt 22 01_ds_en2.0 pt2201 absol u te maximum ratings (note1) sym p arameter v a lue unit vin/v dd vin/vdd dc supply voltage 30 v vd d clamp vd dclam p voltage 33 v id d clamp vd d clamp continuous cuurrent 10 ma v fb fb in put voltage -0.3-7 v v sense sense inpu t voltage -0.3-7 v v rt r t input volatage -0.3-7 v v ri r i input voltage -0.3-7 v t opt m i n/max operating junction temp. -40 to 150 t s tg min/max storage temp. -55 to 150 hbm esd cap ability, hbm 2000(note2) v r ja sop -8 dip -8 150 90 /w recomm ended o perating range sym p arameter v aule unit vdd v dd supply voltage 10 30 v r i ri resistor value 100 kohm t a operating ambient temperature -20 85 no te 1 : absolute maximum ratings indicate limits beyond which damage to the device may occur. recommended operating range indicates conditions for which the device is functional, but do not guarantee specific performance limits. electrical characteristics state dc and ac electrical specifications und er particular test conditions which guarantee specific performance limits. this assumes that the device is within the operatin g range. specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. note 2: human body model, 100pf discharged through a 1.5k ? resistor. o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 4 ? pt 22 01_ds_en2.0 pt2201 electri cal chara cteristics ( t opt =25 , v dd=16v unl e ss specified otherwise ) sym bol p arameter test condit ion mi n typ ma x unit su ppl y voltage (vdd) v dd_on v dd s t art-up voltage v dd ri si ng 14.0 15.0 16.0 v v dd_min v dd mi nimum operating level v dd falling 6.5 7.5 8.5 v v dd_ovp v dd ov er v oltage protection level v dd ri si ng 24.5 26 27.5 v v dd_ovp_off v dd ove r voltage protection release level v dd fallin g 22.5 24 25.5 v v ovp_hys v dd ov er v oltage hysteresis v dd_ovp -v dd_ovp_off 2 v v zener v dd pin zen e r diode clamp voltage i(v dd )=5m a 33 v curr en t i n t o vdd i vdd_st ar t v dd s t art-up current v dd =1 5v measuring current into v dd 3 20 ua i vdd_oper v dd operating cu rrent v dd =16v, r i=100kohm v fb =3v , gate floating 1 ma feed back pin (fb) v ofb v fb op en lo op voltage v dd =1 6v , 6.0 v v pl fb over load protection level 4.4 v v gm gree n m ode fb threshold 1.7 v v bm bu rst mode en tering thre shold 0.9 v v zd zero duty cycle fb threshold v dd =16v, r i=100kohm 0.75 v t pl_dela y ov er lo ad protection delay time ri=100kohm 80 ms z fb fb pin input impendence 9.0 kohm i fb fb pin supply current fb short to gnd, measuring current flowing from fb pin 0.6 ma oscill a tor (osc) f osc oscillato r freque n cy ri=100kohm 60 65 70 khz f jit fosc/ fosc r i=100kohm -3 3 % t jittring fre quency modulation period ri=100kohm 32 ms f min m i nimum pwm frequency v dd =16v , r i=100kohm 22 khz ri accepta ble ri range 50 100 250 kohm o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 5 ? pt 22 01_ds_en2.0 pt2201 electri cal chara cteristics (continue) sym bol p arameter test condit ion mi n typ ma x unit f dt oscillato r freque n cy stability at different temperature v dd =16v, r i=100kohm -20 o c 10 0 o c 2 % f dv oscillator freq uency stability at different vdd input level v dd =12~25v , ri=1 00 kohm 2 % pwm secti on a v pwm input gain v fb / v cs 3.0 v/v t blk leadi n g edge blanking time 300 ns d max pw m maximum duty cycle 80 % d min pw m minimum duty cycle 0 % over temp protection (rt) i rt rt pin supply current vdd=16v ri=100kohm 70 ua v otp r t pin over t e mp protection threshold vdd=16v ri=100kohm 1.015 1.065 1.115 v v otp_hys r t pin over temp protection hysteresis 100 mv v r t_open r t pin floating voltage vdd=16v ri=100kohm 6 v current sense input (sense) z cs sens e input impendence 30 kohm v th_oc oc p threshold at ivin=0 fb=4v, i(vin)=0 0.85 0.90 0.95 v v oc / i vin ocp i vin co m pensation coefficient -0.87 mv/ua v th_oc_1 oc p th re shold with compensation fb=4v, i(vin)=150ua 0.77 v t oc_dela y delay t ime from ocp to gate output off v dd =16v, cs>v th _oc c ga te =100 0p f 100 ns ga te output v ol ga te output low level v dd =1 6v , io=-20ma 0.3 v v oh ga te output high level v dd =1 6v , io=20ma 11 v t_r ga te output rising time v dd =1 6v , cl=1000pf 120 ns t_f ga te output falling time v dd =1 6v , cl=1000pf 50 ns v gmax ga te o ut p ut clamp voltage 18 v o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 6 ? pt 22 01_ds_en2.0 pt2201 simplifi ed bl ock diagram opera t ion description w ith en hanced functions and extremely low start up current and low operating current together with optimized controlling mode, the pt2201 is easy to meet the high performance as well as low standby power requirement in the smps application. its detail features are described as below: startup and uvlo the start up of pt2201 is realized through the current provided by a resistor connecting to hv line charges the capacitor connectin g to vdd pin to the start up threshold voltage. as shown below, as long as the voltage on chold is below the start up threshold the pt2201 stays in uvlo status. the current supplied by rstart charges the chold through vdd pin thus the voltage on vdd increases. the pt2201 starts to operate when the voltage level on vdd reaches v dd_on st art up threshold. after startup the pt2201 begins to deliver drive signal on gate and the operating current is supplied by the auxiliary winding of the transformer. since the pt2201 sinks a few macro amperes of current before start up, a large start up resistor could be used in the start up circuit to mini mize standby power. as for the applications with general ac input range a 2mohm 1/8w resistor and a 10uf/50v capacitor compose a simple and reliable start up circuit. o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 7 ? pt 22 01_ds_en2.0 pt2201 opera t in g cu rrent the pt2201 is fabricated with bicmos process, the operating current has been reduced to less 1ma when gate is floating, thus the system efficiency is improved and at the same time, a smaller hold up capacitor can be used to speed up start up progress. feedback and pwm the pt2201 adopts current mode control scheme. the voltage feedback loop is closed by the tl431 and an opto-coupler connected between output node and fb pin, as shown below: a 2.5v reference voltage has been implemented in the tl431, if the divided voltage of r1 and r2 is less than 2.5v tl431will sink current from vo and the current is transferred to the fb pin by the opto-coupler. the transferred current is loaded by a resistor connected to the internal regulator output so fb pin voltage is determined and thus pwm signal is generated. rf b vcc rfb1 43 1 r1 r2 rc cc rf b2 vo - + pwm co mp energy save operation at light load: generally he smps switching loss is proportional to switching frequency of power mosfet. in order to achieve high conversion efficiency when the load decrease the pt2201 automatically debase pwm frequency to reduce switching loss. the reduction of the load current results in the decrease of voltage on fb pin, when the voltage on fb pin is lower than 1.7v the pwm frequency will linearly decrease with v fb un til t ouch bottom which is 1/3 normal operating frequency. if the fb pin voltage drops below the preset level the pt2201 enters burst mode operation, some pwm cycles is skipped to minimize switching loss. moreover if the fb pin voltage falls below zero-duty level which is set to be 0.75v the pwm is disabled immediately until it recovers to above zero-duty threshold. oscillator and frequency jittering the operating frequency can be easily set via a resistor connected to the ri pin and gnd. the relationship between operating frequen cy and ri follows the expression: fosc=6500/ri. which fosc represents normal operating frequency with unit in khz, and ri with unit in kohm. the frequency jittering is implemented in the pt2201. the oscillation frequency is modulated so that the tone energy is spread out. the spread spectrum minimizes the conduction band emi and th erefore reduces system design challenge. care should be considered that the pwm frequency will be reduced to one third of normal operating frequency so a large ri is not recommended because the audible noise maybe exists when the load is too light. cu r rent sense and leb: one function of the sense pin is sensing the current of the power mosfet to generate a current slope and the other function is providing cy cle by cycle current limit. pt2201 senses power mosfet?s current through a resistor connected between source terminal of the power mosfet and gnd. the voltage on sense and fb determines duty cycle of the pwm signal. as for cycle by cycle curren t limit, at each pwm cycle when the voltage of sense input excess the internal threshold the pwm signal is terminated after a short delay to protect the power mosfet. the relationship between the ocp threshold and the current of power mosfet follows below expression: i oc =v oc /rcs; ioc is t he current of power mosfet, voc is the threshold of ocp and rcs represents sensing resistor. the internal ocp threshold is modulated by the current into vin pin, o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 8 ? pt 22 01_ds_en2.0 pt2201 wi t h ze ro current flowing into vin the threshold is 0.9v. a spike is inevitable on the sensed signal on rcs at the instance when the power mosfet is turned on due to the recovery time of the secondary rectifier and the snubber circuit. the leb has been implemented in pt2201, during the leb time the ocp comparator is disabled so the pwm signal can not be terminated by the turn-on spike on the sensed signal so the external rc filter can be removed. internal slope compensa tion: to eliminate the potential sub-harmonic oscillation problem when the duty cycle excess 0.5, the slope compensation has been implemented in the pt2201. at each pwm duty cycle a constant slope is added to the sensed current ramp so that the system stability is improved. unive rsal input ocp compensation: because there is always a constant delay time td from ocp is triggered to the power mosfet is turned off, the actual current of the mosfet at the instance it is turned off is different from the setting value. taking the below figure as reference, considering the dela y time of td the actual current is: ipeak1=ipeak+islope1*td. islope1=vindc/lpri. with a higher input level the actual ocp current is ipeak2=ipeak+islope2*td, islope2=vindc2/lpri. which lpri represents primary winding inductance of transformer, td is a constant delay time and does no t vary with vin. from above equations it can be derived that the actual ocp threshold of the power mosfet is always larger than setting value due to the ocp delay time and the difference increases with the increase of vin. in order to compensate the difference at different input level the ocp threshold in pt2201 has been designed to vary with the current into vin pin, it means that a larger ivin results in a lower ocp threshold thus the actual ocp threshold of power mosfet maintains unchanged in the universal input range. over temperat ure protection the ambient temperature sense and protection is realized via a ntc resistor connected between the rt pin and gnd. the pt2201 pr ovides a temperature free constant current via the rt pin. when the ambient temperature rise the ntc resistor value gets small thus the voltage on rt pin decreases, when the voltage on the rt pin drops below the internal threshold the otp protection is trigged and pt2201 stops delivering pwm signal to mosfet. the current flowing out of the rt pin is determined by the following equation: i rt =6 . 5 1.065/ri. with the ri=100kohm the i rt =70ua . vdd ove r voltage protection: when open loop occurs the opto-coupler does not sink current thus the voltage on fb rise and current limit will be triggered. if the load is not large enough the output voltage will increase becaus e of redundant power is delivered to the load. under this condition if the olp is not triggered the output voltage will lost control so that the load is in danger of damaged of over voltage. because the voltage on auxiliary winding is proportional to the output voltage the vdd rises with the output. o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 9 ? pt 22 01_ds_en2.0 pt2201 whe n the voltage on vdd reaches the ovp threshold the pt2201 stops delivering pwm signal to the power mosfet, voltage on vdd begins to drop due to the internal power consumption, the pt2201 will recover from ovp state when voltage on vdd drops below the ovp release threshold. the ovp cycle will repeat after recovery until if the fault condition is removed. over load protection: the ove r load protection function (olp) provides another protection to the system from damage when load short circuit or over load occurs. in that condition the voltage on the fb rise, when the v fb excess e s 4.4v the pt2201 starts a timer, after a delay time t pl_dela y if th e fau lt condition still exists the pwm signal is blocked. vdd will then drops due to internal power consumption. when vdd drops below the v dd_min thresho ld, th e pt2201 will be totally shut down. when this happens, the start up sequence will kick in and vdd is charging up again. ga te output the out put drives the gate of the power mosfet. the optimized totem-pole type driver offers a good tradeoff between driving ability and emi. additionally the output high level is clamped to 18v by an internal clamp so that power mo sfet transistor can be protected against undesirable gate over voltage. a resistor between gate and gnd initials the gate voltage to zero at the off state. o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
curr ent mode pwm contr oller 10 ? pt 22 01_ds_en2.0 pt2201 typical performance chara c teristics v dd =16 v , ri=100kohm, t a =25 if no t otherwise noted i dd vs. v dd 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 16 v dd (v) i dd (ua) v dd_on vs.temperature 16.4 16.6 16.8 17.0 17.2 17.4 17.6 -20 0 25 45 65 85 105 125 temp(c) v dd_o n (v) i dd_s tart vs. tem perature 0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 -20 0 25 45 65 85 105 125 temp(c) i vdd _ st art ( ua) v d d_min vs temperature 10. 2 10.4 10.6 10.8 11.0 11.2 11.4 11.6 11.8 12.0 -20 0 25 45 65 85 105 125 temp(c) v dd_m in (v) fos c v s. temperature ri=100kohm 56.0 58.0 60.0 62.0 64.0 66.0 68.0 70.0 -20 0 20 4 0 60 80 100 120 te mp (c) fo sc (khz ) fosc vs . v fb ri= 100kohm 0 10 20 30 40 50 60 70 0.9 1 .1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 v fb (v ) fpwm (k hz) o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
current mode pwm controller 11 ? pt2201_d s_e n2.0 pt2201 fosc vs. ri 0 20 40 60 80 100 120 140 50 70 90 110 130 150 170 190 rikohm f osc khz d max vs. temperature ri=100kohm 78.00 78.50 79.00 79.50 8 0.00 80.50 81.00 - 2 0 - 1 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 2 0 temp(c) d max (%) v oc v s. te mp era ture ivin=0 0.860 0.870 0.880 0.890 0.900 0.910 0.920 0.930 0.940 0.950 -20 0 20 40 60 80 100 120 temp(c) v oc (v) i rt vs. tempera ture ri=100kohm 67.0 67.5 68.0 68.5 69.0 69.5 70.0 70.5 -20 0 20 40 60 80 100 120 tempc i rt (ua) fosc vs. vdd ri =100kohm 55 57 59 61 63 65 67 69 12 13 14 15 16 17 18 19 20 21 22 23 24 25 vdd(v) f osc (khz) v th_oc vs. ivin 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 0 40 80 120 160 200 240 280 i vin (ua) v th_oc (v) o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
current mode pwm controller 12 ? pt2201_d s_e n2.0 pt2201 packag e informa tion (1) sop8 l dimensions in millimeters dimension s in inch symbol min max min max a 1.350 1. 75 0 0.053 0.069 a1 0.100 0. 25 0 0.004 0.010 a2 1.350 1.55 0 0.053 0.061 b 0.330 0. 51 0 0.013 0.020 c 0.170 0. 25 0 0.006 0.010 d 4.700 5. 10 0 0.185 0.200 e 3.800 4. 00 0 0.150 0.157 e1 5.800 6. 20 0 0.228 0.244 e 1.270(bsc) 0 .050(bsc) l 0. 40 0 1. 27 0 0.016 0.050 0 8 0 8 o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
current mode pwm controller 13 ? pt2201_d s_e n2.0 pt2201 packag e informa tion (2) dip8 dimensions in millimeters dimensions in i nches symbol min max min max a 3. 71 0 4. 31 0 0.146 0.170 a1 0.510 0. 02 0 a2 3.200 3. 60 0 0.126 0.142 b 0.38 0 0. 570 0.015 0.022 b1 1.52 4 (b sc) 0.060 (bsc) c 0. 20 4 0. 360 0.008 0.014 d 9.000 9. 40 0 0.354 0.370 e 6.200 6.60 0 0.244 0.26 e1 7.320 7. 92 0 0.288 0.312 e 2.540(bsc) 0 .100(bsc) l 3.000 3. 60 0 0.118 0.142 e2 8.400 9. 00 0 0.331 0.354 o?^?uf?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com

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