march 2001 preliminary ml4804 power factor correction and pwm controller combo general description the ml4804 is a controller for power factor corrected, switched mode power supplies. power factor correction (pfc) allows the use of smaller, lower cost bulk capacitors, reduces power line loading and stress on the switching fets, and results in a power supply that fully complies with iec1000-3-2 specification. intended as a bicmos enhancement of the industry-standard ml4824, the ml4804 includes circuits for the implementation of leading edge, average current, ?oost?type power factor correction and a trailing edge, pulse width modulator (pwm). it also includes a trifault detect function to help ensure that no unsafe conditions will result from single component failure in the pfc. 1a gate-drive outputs minimize the need for external driver circuits. low power requirements improve efficiency and reduce component costs. an over voltage comparator shuts down the pfc section in the event of a sudden decrease in load. the pfc section also includes peak current limiting and input voltage brownout protection. the pwm section can be operated in current or voltage mode, at up to 250khz, and includes an accurate 50% duty cycle limit to prevent transformer saturation. features internally synchronized leading-edge modulated pfc and trailing-edge modulated pwm in one ic trifault detect tm for ul1950 compliance and enhanced safety v cc ovp provides additonal pfc fault protection slew rate enhanced transconductance error amplifier for ultra-fast pfc response low power: 200 a startup current, 5.5ma operating current low total harmonic distortion, high pf reduces ripple current in the storage capacitor between the pfc and pwm sections average current, continuous boost leading edge pfc pwm configurable for current-mode or voltage mode operation overvoltage and brown-out protection, uvlo, and soft start block diagram 15 veao ieao v fb i ac v rms i sense ramp 1 oscillator ovp v cc ovp tri-fault pfc i limit uvlo v ref pulse width modulator power factor corrector 2.5v + - - + 16 2 4 3 7.5v reference 14 v cc 13 v cc vea 7 iea 1 + - pfc out 12 s r q q s r q q 2.75v v cc -1v ramp 2 8 pwm out 11 s r q q v dc 6 ss 5 dc i limit 9 v cc duty cycle limit - + 1.0v - + 2.45v v fb - + v ref v in ok gain modulator v cc 1.6k ? 1.6k ? 1.25v 25a - + dc i limit + ? 16.4v 0.5v + ? + - - + 17v rev. 1.0.2 3/9/2001
ml4804 2 rev. 1.0.2 3/9/2001 pin configuration pin description pin name function 9 dc i limit pwm cycle-by-cycle current limit comparator input 10 gnd ground 11 pwm out pwm driver output 12 pfc out pfc driver output 13 v cc positive supply 14 v ref buffered output for the internal 7.5v reference 15 v fb pfc transconductance voltage error amplifier input 16 veao pfc transconductance voltage error amplifier output pin name function 1 ieao slew rate enhanced pfc transconductance error amplifier output 2i ac pfc ac line reference input to gain modulator 3i sense current sense input to the pfc gain modulator 4v rms pfc gain modulator rms line voltage compensation input 5 ss connection point for the pwm soft start capacitor 6v dc pwm voltage feedback input 7 ramp 1 oscillator timing node; timing set by r t c t 8 ramp 2 when in current mode, this pin functions as the current sense input; when in voltage mode, it is the pwm modulation ramp input. 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 ieao i ac i sense v rms ss v dc ramp 1 ramp 2 veao v fb v ref v cc pfc out pwm out gnd dc i limit top view ml4804 16-pin pdip (p16) 16-pin narrow soic (s16n)
ml4804 rev. 1.0.2 3/9/2001 3 electrical characteristics unless otherwise specified, v cc = 15v, r t = 52.3k ? , c t = 470pf, t a = operating temperature range (note 1) symbol parameter conditions min typ max units voltage error amplifier input voltage range 0 5 v transconductance v non inv = v inv , veao = 3.75v 30 65 90 feedback reference voltage 2.43 2.5 2.57 v input bias current note 2 -0.5 -1.0 a output high voltage 6.0 6.7 v output low voltage 0.1 0.4 v source current v in = 2.5v 0.5v, v out = 6v -40 -140 a sink current v in = 2.5v 0.5v , v out = 1.5v 40 140 a open loop gain 50 60 db power supply rejection ratio 11v < v cc < 16.5v 50 60 db current error amplifier input voltage range -1.5 2 v transconductance v non inv = v inv , veao = 3.75v 50 100 150 input offset voltage 0 4 15 mv input bias current -0.5 -1.0 a output high voltage 6.0 6.7 v output low voltage 0.65 1.0 v source current v in = 0.5v, v out = 6v -40 -104 a sink current v in = 0.5v, v out = 1.5v 40 160 a open loop gain 60 70 db power supply rejection ratio 11v < v cc < 16.5v 60 75 db ovp comparator threshold voltage 2.65 2.75 2.85 v hysteresis 180 280 350 mv absolute maximum ratings absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device operation is not implied. v cc .............................................................................................. 18v i sense voltage ............................................... -5v to 0.7v voltage on any other pin ..... gnd - 0.3v to v ccz + 0.3v i ref ........................................................................................... 10ma i ac input current ..................................................... 10ma peak pfc out current, source or sink ....................... 1a peak pwm out current, source or sink ..................... 1a pfc out, pwm out energy per cycle ................... 1.5 j junction temperature ............................................. 150 c storage temperature range ....................... -65 c to 150 c lead temperature (soldering, 10 sec) ..................... 260 c thermal resistance ( ja ) plastic dip ........................................................... 80 c/w plastic soic ...................................................... 105 c/w operating conditions temperature range ml4804cx .................................................... 0 c to 70 c ml4804ix .................................................. -40 c to 85 c ? ?
ml4804 4 rev. 1.0.2 3/9/2001 electrical characteristics symbol parameter conditions min typ max units tri-fault detect fault detect high 2.65 2.75 2.85 v time to fault detect high v fb = v fault detect low 24ms to v fb =open; 470pf from v fb to gnd fault detect low 0.4 0.5 0.6 v v cc ovp comparator threshold voltage t a = operation temp range 16.4 v hysteresis t a = operation temp range 1.7 2.0 2.3 v pfc i limit comparator threshold voltage -0.9 -1.0 -1.1 v (pfc i limit v th - gain modulator output) 120 220 mv delay to output 150 300 ns dc i limit comparator threshold voltage 0.95 1.0 1.05 v input bias current 0.3 1 a delay to output 150 300 ns v in ok comparator threshold voltage 2.35 2.45 2.55 v hysteresis 0.8 1.0 1.2 v gain modulator gain (note 3) i ac = 100 a, v rms = v fb = 0v 0.60 0.80 1.05 i ac = 50 a, v rms = 1.2v, v fb = 0v 1.8 2.0 2.40 i ac = 50 a, v rms = 1.8v, v fb = 0v 0.85 1.0 1.25 i ac = 100 a, v rms = 3.3v, v fb = 0v 0.20 0.30 0.40 bandwidth i ac = 100 a 10 mhz output voltage i ac = 350 a, v rms = 1v, 0.60 0.75 0.9 v v fb = 0v oscillator initial accuracy t a = 25 c 717681khz voltage stability 11v < v cc < 16.5v 1 % temperature stability 2% total variation line, temp 68 84 khz ramp valley to peak voltage 2.5 v pfc dead time 520 600 ns f osc = 250khz, r t = 75.0k ? , c t = 100pf 250 330 n s c t discharge current v ramp 2 = 0v, v ramp 1 = 2.5v 3.5 5.5 7.5 ma
ml4804 rev. 1.0.2 3/9/2001 5 electrical characteristics symbol parameter conditions min typ max units reference output voltage t a = 25 c, i(v ref ) = 1ma 7.4 7.5 7.6 v line regulation 11v < v cc < 16.5v 10 25 mv load regulation 0ma < i(v ref ) < 10ma; 10 20 mv ta = 0? to 70? 0ma |