2013/8/1 v3 page 1 SP6878 quasi-resonant pwm controller description applications the SP6878 is a low cost, quasi-resonant flyback controller where the maximum frequency is below 100khz. the internal valley detector ensures the converter operates at quasi-resonant operation over wide range of line voltage. the build-in advanced energy saving function would provide the users a superior ac/dc power application of higher efficiency, low external component counts, and lower cost solution for applications. the SP6878 features more protections or functions for the following characteristics: over voltage protection (ovp ) ; over temperature protection (otp); over load protection (olp). SP6878 is available by sop-8/ dip-8p packages. ? ac/dc switching power adaptor ? set-top box power supply ? open-frame switching power supply features pin configuration ? high-voltage bcd process ? under voltage lockout (uvlo ) ? quasi-resonant control ? internal 4ms soft start ? over temperature latch shutdown ? olp (over load protection) ? ovp (over voltage protection) on vcc pin ? 100khz maximum frequency ? 800ma driving capability sop-8/dip-8 part marking sop-8/dip-8p
2013/8/1 v3 page 2 SP6878 quasi-resonant pwm controller typical applcation circuit for high efficiency smps pin description pin symbol description 1 fr set the internal frequency and timer. 2 fb voltage feedback. it provides feedback to the internal pwm comparator to control the duty cycle. 3 cs current sense. 4 gnd ground 5 gate gate driver output to drive the external mosfet. 6 vcc supply voltage for the ic 7 dem core reset detection and ovp. 8 ot over temperature protection by connection through a ntc resistor to gnd.
2013/8/1 v3 page 3 SP6878 quasi-resonant pwm controller block diagram ordering information part number package part marking SP6878d8tgb dip-8 SP6878 SP6878s8rgb sop-8 SP6878 SP6878d8tgb : tube ; pb ? free ; halogen-free SP6878s8rgb : tape reel ; pb ? free ; halogen-free absoulte maximum ratings (t a =25 , unless otherwise specified.) the following ratings designate persistent limits beyond which damage to the device may occur . symbol parameter value unit v cc dc supply voltage 25 v v fr/fb/cs / dem /ot fr /fb / cs/dem/ot voltage -0.3 ~ 7.0 v esd human body model 4 kv machine model 300 v t o p e operating ambient temperature -40 ~ 85 t j operating junction temperature range -40 ~ 150 t stg storage temperature range -40 ~ 150 t lead pb-free lead soldering temperature for 5 sec. 260 r ? jc thermal resistance junction ? case (*) sop-8 150 /w dip-8 90 (*) the power dissipation and thermal resistance are evalua ted under copper board mounted with free air conditions.
2013/8/1 v3 page 4 SP6878 quasi-resonant pwm controller electrical characteristics (t a =25 , v cc =16v, r fr = 20k ohm unless otherwise specified.) symbol parameter conditions min. typ. max. unit supply voltage ( vcc pin ) i stt startup current vcc=uvlo-1.5v 5 15 ua i op operating current v fb = 3v 2.0 4.0 ma v fb = 3v, c l = 1nf 3.0 5.0 ma uvlo (off) min. operating voltage 7.5 v uvlo (on ) start threshold voltage 13.5 v ovp level over voltage protection 19 v vcc clamp clamping voltage i vcc = 5ma 20 v voltage feedback ( fb pin ) isc short circuit current 1.5 ma vop open loop voltage 5.3 v v th_bm_on burst mode on threshold 0.8 v v th_bm_off burst mode off threshold 0.7 v z fb input impedance 4 k tl olp olp trip level 4.4 v td olp olp delay time (note) 80 ms demagnetization ( dem pin ) v th(dem) demagnetization threshold voltage 75 mv vc h input clamp voltage high 6 v vc l input clamp voltage low -0.7 v tsupp suppression of the transformer ringing at start of secondary stoke 2.5 us t dem demag propagation delay 250 ns v th_ ovp output ovp trigger point 3.75 v current sensing ( cs pin ) v th_ duty_zero internal current limiting threshold zero duty cycle, v fb =3v 0.415 0.45 0.485 v v th_ duty_max internal current limiting threshold max duty cycle, v fb =3v 0.8 v v th_ cs_min burst mode cs threshold zero output, v fb =1v 0.3 v t leb leading edge blanking time 300 ns gate driver output ( gate pin ) v ol output low level v cc =15v, io=100ma 1 v v oh output high level v cc =15v, io=100ma 7.5 v vg_clamp output clamp voltage level vcc=18v 16.5 tr rising time c l = 1nf 80 ns tf falling time c l = 1nf 30 ns frequency setup (fr pin) r fr resistor range 20 k v_fr_open fr open voltage 2.0 v fburst burst mode switching frequency 22 khz fmax_qr_l frequency low clamp in qr mode 47 52 57 khz fmin_qr_h frequency high clamp in qr mode 82 90 98 khz g_pfm pfm mode frequency modulation slope 90 khz f(shiffle) /f fmin_qr_l frequency shuffling range -4 +4 % t on maximum on time r fr = 20 k 10 13 15 us
2013/8/1 v3 page 5 SP6878 quasi-resonant pwm controller t off maximum off time r fr = 20 k 40 55 75 us over temp protection ( ot pin ) v_ot_open ot pin open voltage 3.5 v v th(otp) otp threshold voltage 1.00 1.05 1.10 v i ot output current of ot pin r fr = 20k 100 ua soft start t_soft internal soft startup 4 ms note: the olp delay time is proportional to the period of switchi ng cycle. so that, the lower fr resistor value will set the higher switching frequency and the shorter olp delay time.
2013/8/1 v3 page 6 SP6878 quasi-resonant pwm controller dip- 8p package outline
2013/8/1 v3 page 7 SP6878 quasi-resonant pwm controller sop-8 package outline
2013/8/1 v3 page 8 SP6878 quasi-resonant pwm controller information provided is alleged to be exact and consistent. sync power corporation presumes no responsibility for the penalties of use of such information or for any violation of pa tents or other rights of third parties that may result from its use. no license is granted by allegation or otherwise under any pate nt or patent rights of sync power corporation. conditions mentioned in this publication ar e subject to change without notice. this p ublication surpasses and replaces all information previously supplied. sync power corporation products are not authorized for use as critical components in life support devices or systems without express written approval of sync power corporation. ?the sync power logo is a registered trademark of sync power corporation ?2011 sync power corporation ? printed in taiwan ? all rights reserved sync power corporation 7f-2, no.3-1, park street nankang district (nksp), taipei, taiwan, 115, r.o.c phone: 886-2-2655-8178 fax: 886-2-2655-8468 http://www.syncpower.com
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