 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| general description the ML4831 is a complete solution for a dimmable, high power factor, high efficiency electronic ballast. contained in the ML4831 are controllers for boost type power factor correction as well as for a dimming ballast. the power factor circuit uses the average current sensing method with a gain modulator and over-voltage protection. this system produces power factors of better than 0.99 with low input current thd at > 95% efficiency. special care has been taken in the design of the ML4831 to increase system noise immunity by using a high amplitude oscillator, and a current fed multiplier. an over-voltage protection comparator inhibits the pfc section in the event of a lamp out or lamp failure condition. the ballast section provides for programmable starting scenarios with programmable preheat and lamp out-of- socket interrupt times. the ic controls lamp output through either frequency modulation using lamp current feedback. the ML4831 is designed using micro linears semi- standard tile array technology. customized versions of this ic, optimized to specific ballast architectures can be made available. contact micro linear or an authorized representative for more information. * this product is end of life as of july 1, 2000 features n complete power factor correction and dimming ballast control on one ic n low distortion, high efficiency continuous boost, average current sensing pfc section n programmable start scenario for rapid or instant start lamps n lamp current feedback for dimming control n variable frequency dimming and starting n programmable restart for lamp out condition to reduce ballast heating n over-temperature shutdown replaces external heat sensor for safety n pfc over-voltage comparator eliminates output runaway due to load removal n large oscillator amplitude and gain modulator improves noise immunity block diagram ju l y 20 00 ML4831 * electronic ballast controller 1 7 r(set) oscillator 8 r(t)/c(t) 10 r(x)/c(x) pre-heat and interrupt timers control & gating logic 2 ia out 4 ia+ power factor controller under-voltage and thermal shutdown output drivers 3 i(sine) 1 ea out 18 ea?ovp v ref 17 pfc out 15 gnd 11 vcc 16 pgnd 12 out b 13 out a 14 lfb out 6 lamp f.b. 5 interrupt 9
ML4831 2 pin configuration pin# name function pin# name function 1 ea out pfc error amplifier output and compensation node 2 ia out output and compensation node of the pfc average current transconductance amplifier. 3 i(sine) pfc gain modulator input. 4 ia+ non-inverting input of the pfc average current transconductance amplifier and peak current sense point of the pfc cycle by cycle current limit comparator. 5 lamp f.b. inverting input of an error amplifier used to sense (and regulate) lamp arc current. also the input node for dimming control. 6 lfb out output from the lamp current error transconductance amplifier used for lamp current loop compensation 7 r(set) external resistor which sets oscillator f max , and r(x)/c(x) charging current pin description 8 r(t)c(t) oscillator timing components 9 interrupt input used for lamp-out detection and restart. a voltage greater than 7.5 volts resets the chip and causes a restart after a programmable interval. 10 r(x)/c(x) sets the timing for the preheat, dimming lockout, and interrupt 11 gnd ground 12 p gnd power ground for the ic 13 out b ballast mosfet drive output 14 out a ballast mosfet drive output 15 pfc out power factor mosfet drive output 16 vcc positive supply for the ic 17 v ref buffered output for the 7.5v voltage reference 18 eaC/ovp inverting input to pfc error amplifier and ovp comparator input ML4831 18-pin dip (p18) ea out ia out i(sine) ia+ lamp f.b. lfb out r(set) r(t)/c(t) interrupt ea?ovp v ref vcc pfc out out a out b p gnd gnd r(x)/c(x) 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 top view ML4831 3 electrical characteristics unless otherwise specified, r(set) = 31.6k w , r(t) = 16.2k w , c(t) = 1.5nf, t j = junction operating temperature range, i cc = 25ma parameter conditions min typ max units pfc current sense amplifier (pins 2, 4) small signal transconductance 130 200 270 m mhos input voltage range C0.3 3.5 v output low i sine = 0ma, v pin1 = 0v, v pin4 = C0.3v, r l = 0.2 0.4 v output high i sine = 1.5ma, v pin18/4 = 0v, r l = 5.2 5.6 6 v source current i sine = 1.5ma, v pin18/4 = 0v, v pin2 = 5v C0.3 ma sink current i sine = 0ma, v pin2 = 0.3v, v pin4 = C0.3v, v pin1 = 0v 0.3 ma pfc voltage feedback amplifier (pins 1, 18)/lamp current amplifier (pins 5, 6) input offset voltage 3.0 10.0 mv input bias current C0.3 C1.0 m a small signal transconductance 50 80 110 m mhos input voltage range C0.3 3.5 v output low v pin5/18 = 3v, r l = 0.2 0.4 v output high v pin5/18 = 2v, r l = 7.2 7.5 v source current v pin5/18 = 0v, v pin1/6 = 7v C0.2 ma sink current v pin5/18 = 5v, v pin1/6 = 0.3v 0.2 ma gain modulator output voltage i sine = 100 m a, v pin1 = 3v 40 mv i sine = 300 m a, v pin1 = 3v 130 mv i sine =100 m a, v pin1 = 6v 112 mv i sine = 300 m a, v pin1 = 6v 350 mv output voltage limit i sine = 1.5ma, v pin18 = 0v 865 mv offset voltage i sine = 0, v pin18 = 0v 15 mv i sine = 150 m a, v pin18 = 3v 15 mv i(sine) input voltage i sine = 200 m a 0.8 1.4 1.8 v 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. supply current (i cc ) ............................................... 75ma output current, source or sink (pins 13, 14, 15) dc ................................................................... 250ma output energy (capacitive load per cycle) .............. 1.5 mj gain modulator i(sine) input (pin 3) ..................... 10 ma analog inputs (pins 5, 9, 18) ............... C0.3v to vcc C2v pin 4 input voltage ........................................... C3v to 2v maximum forced voltage (pins 1, 6) .......... C0.3v to 7.7v maximum forced current (pins 1, 2, 6) ................ 20ma maximum forced voltage (pin 2) .................. C0.3v to 6v junction temperature ............................................. 150 c storage temperature range ..................... C65 c to 150 c lead temperature (soldering 10 sec.) ..................... 260 c thermal resistance ( q ja ) plastic dipCp ................................................... 70 c/w operating conditions temperature range ML4831c .................................................. 0 c to 85 c ML4831 4 electrical characteristics (continued) parameter conditions min typ max units oscillator initial accuracy t a = 25 c 727680khz voltage stability v ccz C 3v < v cc ML4831 6 average current and output voltage regulation the pwm regulator in the pfc control section will act to offset the positive voltage caused by the multiplier output by producing an offsetting negative voltage on the current sense resistor at pin 4. a cycle-by-cycle current limit is included to protect the mosfet from high speed current transients. when the voltage at pin 4 goes negative by more than 1v, the pwm cycle is terminated. for more information on compensating the average current and boost voltage error amplifier loops, see ml4821 data sheet. overvoltage protection and inhibit the ovp pin serves to protect the power circuit from being subjected to excessive voltages if the load should change suddenly (lamp removal). a divider from the high voltage dc bus sets the ovp trip level. when the voltage on pin 18 exceeds 2.75v, the pfc transistors are inhibited. the ballast section will continue to operate. the ovp threshold should be set to a level where the power components are safe to operate, but not so low as to interfere with the boost voltage regulation loop. figure 1. ML4831 block diagram transconductance amplifiers the pfc voltage feedback, pfc current sense, and the loop current amplifiers are all implemented as operational transconductance amplifiers. they are designed to have low small signal forward transconductance such that a large value of load resistor (r1) and a low value ceramic capacitor (<1 m f) can be used for ac coupling (c1) in the frequency compensation network. the compensation network shown in figure 2 will introduce a zero and a pole at: f rc f rc zp == 1 2 1 2 11 12 pp (2) + 18 2.5v r1 c1 c2 figure 2. compensation network 7 r(set) r(x)/c(x) vcc v ref gnd ia out ia + ? mul + 10 16 17 11 2 4 out b 13 + + + + 2.5v v ref ?v preheat timer osc under-voltage and thermal shutdown + s r q t q q p gnd 12 out a 14 pfc out 15 r(t)/c(t) 8 interrupt 9 lfb out 6 lamp f.b. 5 7k pwm (pfc) 7k i(sine) ea out ea ?ovp 3 1 18 + 2.5v + 2.75v ovp gain modulators ML4831 7 figure 3 shows the output configuration for the operational transconductance amplifiers. current mirror in out current mirror in out gmv in io = gmv in iq + 2 gmv in iq 2 figure 3. output configuration a dc path to ground or vcc at the output of the transconductance amplifiers will introduce an offset error. the magnitude of the offset voltage that will appear at the input is given by v os = io/gm. for a io of 1ua and a gm of 0.08 m mhos the input referred offset will be 12.5mv. capacitor c1 as shown in figure 2 is used to block the dc current to minimize the adverse effect of offsets. slew rate enhancement is incorporated into all of the operational transconductance amplifiers in the ML4831. this improves the recovery of the circuit in response to power up and transient conditions. the response to large signals will be somewhat non-linear as the transconductance amplifiers change from their low to high transconductance mode. this is illustrated in figure 4. v in differential linear slope region 0 i o figure 4. transconductance amplifier characteristics ballast output section the ic controls output power to the lamps via frequency modulation with non-overlapping conduction. this means that both ballast output drivers will be low during the discharging time t dis of the oscillator capacitor c t . oscillator the vco frequency ranges are controlled by the output of the lfb amplifier (pin 6). as lamp current decreases, pin 6 rises in voltage, causing the c(t) charging current to decrease, thereby causing the oscillator frequency to decrease. since the ballast output network attenuates high frequencies, the power to the lamp will be increased. 17 + 1.25/3.75 8 c(t) v ref i chg v ref control r(t)/c(t) r(t) 5 ma clock c(t) v th = 3.75v v tl = 1.25v t dis t chg figure 5. oscillator block diagram and timing the oscillator frequency is determined by the following equations: f tt osc chg dis = + 1 (3) and trcin virv virv chg t t ref ch t tl ref ch t th = +- +- ? ? ? ? (4) ML4831 8 the oscillators minimum frequency is set when i ch = 0 where: f rc osc tt @ 1 051 . (5) this assumes that t chg >> t dis . when lfb out is high, i ch = 0 and the minimum frequency occurs. the charging current varies according to two control inputs to the oscillator: 1. the output of the preheat timer 2. the voltage at pin 6 (lamp feedback amplifier output) in preheat condition, charging current is fixed at i r set chg preheat () . () = 25 (6) in running mode, charging current decreases as the v pin6 rises from 0v to v oh of the lamp fb amplifier. the highest frequency will be attained when i chg is highest, which is attained when v pin6 is at 0v: i r set chg( ) () 0 5 = (7) highest lamp power, and lowest output frequency are attained when v pin6 is at its maximum output voltage (v oh ). in this condition, the minimum operating frequency of the ballast is set per (5) above. for the ic to be used effectively in dimming ballasts with higher q output networks a larger c t value and lower r t value can be used, to yield a smaller frequency excursion over the control range (v pin6 ). the discharge current is set to 5ma. assuming that i dis >> i rt : tc dis vco t () @ 490 (8) ic bias, under-voltage lockout and thermal shutdown the ic includes a shunt regulator which will limit the voltage at v cc to 13.5 (v ccz ). the ic should be fed with a current limited source, typically derived from the ballast transformer auxiliary winding. when v cc is below v ccz C 0.7v, the ic draws less than 1.7ma of quiescent current and the outputs are off. this allows the ic to start using a bleed resistor from the rectified ac line. to help reduce ballast cost, the ML4831 includes a temperature sensor which will inhibit ballast operation if the ics junction temperature exceeds 120 c. in order to use this sensor in lieu of an external sensor, care should be taken when placing the ic to ensure that it is sensing temperature at the physically appropriate point in the ballast. the ML4831s die temperature can be estimated with the following equation: tt p cw jad @ 65 / (9) vccz v(on) v(off) 15ma 1.3ma v cc i cc t t figure 6. typical v cc and i cc waveforms when the ML4831 is started with a bleed resistor from the rectified ac line and bootstrapped from an auxiliary winding. starting, re-start, preheat and interrupt the lamp starting scenario implemented in the ML4831 is designed to maximize lamp life and minimize ballast heating during lamp out conditions. the circuit in figure 7 controls the lamp starting scenarios: filament preheat and lamp out interrupt. c(x) is charged with a current of i r(set) /4 and discharged through r(x). the voltage at c(x) is initialized to 0.7v (v be ) at power up. the time for c(x) to rise to 3.4v is the filament preheat time. during that time, the oscillator charging current (i chg ) is 2.5/r(set). this will produce a high frequency for filament preheat, but will not produce sufficient voltage to ignite the lamp. after cathode heating, the inverter frequency drops to f min causing a high voltage to appear to ignite the lamp. if the voltage does not drop when the lamp is supposed to have ignited, the lamp voltage feedback coming into pin 9 rises to above v ref , the c(x) charging current is shut off and the inverter is inhibited until c(x) is discharged by r(x) to the 1.2v threshold. shutting off the inverter in this manner prevents the inverter from generating excessive heat when the lamp fails to strike or is out of socket. typically this time is set to be fairly long by choosing a large value of r(x). ML4831 9 10 9 r(x) c(x) 6.8 + 1.2/3.4 heat inhibit 0.625 r(set) + 1.2/6.8 + v ref dimming lockout r(x)/c(x) int q r s figure 7. lamp preheat and interrupt timers lfb out is ignored by the oscillator until c(x) reaches 6.8v threshold. the lamps are therefore driven to full power and then dimmed. the c(x) pin is clamped to about 7.5v. a summary of the operating frequencies in the various operating modes is shown below. operating mode operating frequency [f(max) to f(min)] preheat 2 dimming lock-out f(min) dimming control f(min) to f(max) 6.8 3.4 1.2 .65 0 7.5 r(x)/c(x) heat dimming lockout int inhibit figure 8. lamp starting and restart timing ML4831 10 applications power factor corrected fluorescent dimming lamp ballast 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 ML4831 d1 d3 d2 d4 l g n f1 120v l1 l2 c2 c1 c3 d8 t1 4 1 32 r6 r14 c12 c5 d5 d6 r1 r4 r2 r3 r5 r24 c25 c26 c4 c6 c7 r16 r10 r17 c10 + r7 r11 q1 d7 c11 + r12 r13 r9 r8 c13 c14 c24 c15 c16 ++ r15 d11 d12 c22 q2 q3 t2 5 84 1 c17 r21 r22 t3 2 1 4 5 3 6 8 7 10 9 c20 c19 t4 1 4 8 5 41 8 5 t5 c23 y y r r b b d13 c21 r23 figure 9. typical application: 2-lamp isolated dimming ballast with active power factor correction for 120vac input ML4831 11 table 1: parts list for the ML4831eval evaluation kit capacitors qty. ref. description mfr. part number 2 c1, 2 3.3nf, 125vac, 10%, ceramic, y capacitor panasonic eck-dns332me 1 c3 0.33 m f, 250vac, x, capacitor panasonic ecq-u2a334mv 4 c4, 8, 9, 22 0.1 m f, 50v, 10%, ceramic capacitor avx sr215c104kaa 2 c5, 21 0.01 m f, 50v, 10%, ceramic capacitor avx sr211c103kaa 1 c6 1.5 m f, 50v, 2.5%, npo ceramic capacitor avx rpe121cog152 2 c7, 12 1 m f, 50v, 20%, ceramic capacitor avx sr305e105maa 1 c10 100 m f, 25v, 20%, electrolytic capacitor panasonic ece-a1efs101 1 c11 100 m f, 250v, 20%, electrolytic capacitor panasonic ece-s2eg101e 1 c13 4.7 m f, 50v, 20%, electrolytic capacitor panasonic ece-a50z4r7 3 c14, 15, 17 0.22 m f, 50v, 10%, ceramic capacitor avx sr305c224kaa 1 c16 1.5 m f, 50v, 10%, ceramic capacitor avx sr151v152kaa 1 c19 22nf, 630v, 5%, polypropylene capacitor wima mkp10, 22nf, 630v, 5% 1 c20 0.1 m f, 250v, 5%, polypropylene capacitor wima mkp10, 0.1 m f, 250v, 5% 1 c23 0.068 m f, 160v, 5%, polypropylene capacitor wima mkp4, 68nf, 160v, 5% 1 c24 220 m f, 16v, 20%, electrolytic capacitor panasonic ece-a16z220 1 c25 47nf, 50v, 10%, ceramic capacitor avx sr211c472kaa 1 c26 330pf, 50v, 10%, ceramic capacitor avx sr151a331jaa resistors: 1 r1 0.33 w , 5%, 1/2w, metal film resistor nte hwd33 1 r2 4.3k, 1/4w, 5%, carbon film resistor yageo 4.3k-q 1 r3 47k, 1/4w, 5%, carbon film resistor yageo 47k-q 1 r4 12k, 1/4w, 5%, carbon film resistor yageo 12k-q 1 r5 20k, 1/4w, 1%, metal film resistor dale sma4-20k-1 1 r6 360k, 1/4w, 5%, carbon film resistor yageo 360k-q 1 r7 36k, 1w, 5%, carbon film resistor yageo 36kw-1-nd 3 r8, 22, 11 22 w , 1/4w, 5%, carbon film resistor yageo 22-q 1 r9 402k, 1/4w, 1%, metal film resistor dale sma4-402k-1 1 r10 17.8k, 1/4w, 1%, metal film resistor dale sma4-17.8k-1 1 r12 475k, 1/4w, 1%, metal film resistor dale sma4-475k-1 1 r13 5.49k, 1/4w, 1%, metal film resistor dale sma4-5.49k-1 ML4831 12 table 1: parts list for ML4831eval evaluation kit (continued) resistors: (continued) qty. ref. description mfr. part number 4 r14, 17, 24, 25 100k, 1/4w, 5%, carbon film resistor yageo 100k-q 1 r15 681k, 1/4w, 5%, carbon film resistor yageo 681k-q 1 r16 10k, 1/4w, 1%, metal film resistor dale sma4-10k-1 1 r21 33 w , 1/4w, 5%, carbon film resistor yageo 33-q 1 r23 25k, pot (for dimming adjustment) bourns 3386p-253-nd diodes: 4 d1, 2, 3, 4 1a, 600v, 1n4007 diode motorola 1n4007tr (or 1n5061 as a substitute) 2 d5, 6 1a, 50v (or more), 1n4001 diodes motorola 1n4001tr 1 d7 3a, 400v, byv26c or byt03 400 fast recovery gi byv26c or mur440 motorola ultra fast diode 5 d8, 9, 11, 0.1a, 75v, 1n4148 signal diode motorola 1n4148tr 12, 13 ics: 1 ic1 ML4831, electronic ballast controller ic micro ML4831cp linear transistors: 3 q1, 2, 3 3.3a, 400v, irf720 power mosfet ir ir720 magnetics: 1 t1 t1 boost inductor, e24/25, 1mh, custom coils p/n 5039 or coiltronics p/n ctx05-12538-1 e24/25 core set, tdk pc40 material 8-pin vertical bobbin (cosmo #4564-3-419), wind as follows: 195 turns 25awg magnet wire, start pin #1, end pin #4 1 layer mylar tape 14 turns 26awg magnet wire, start pin #3, end pin #2 note: gap for 1mh 5% 1 t2 t2 gate drive xfmr, l pri = 3mh, custom coils p/n 5037 or coiltronics p/n ctx05-12539-1 toroid magnetics yw-41305-tc wind as follows: primary = 25 turns 30awg magnet wire, start pin #1, end pin #4 secondary = 50 turns 30awg magnet wire, start pin #5, end pin #8 ML4831 13 table 1: parts list for ML4831eval evaluation kit (continued) magnetics: (continued) qty. ref. description mfr. part number 1 t3 t3 inductor, l pri = 1.66mh, custom ciols p/n 5041 or coiltronics p/n ctx05-12547-1 e24/25 core set, tdk pc40 material 10 pin horizontal bobbin (plastron #0722b-31-80) wind as follows: 1st: 170t of 25awg magnet wire; start pin #10, end pin #9. 1 layer of mylar tape 2nd: 5t of #32 magnet wire; start pin #2, end pin #1 1 layer of mylar tape 3rd: 3t of #30 kynar coated wire; start pin #4, end pin #5 4th: 3t of #30 kynar coated wire; start pin #3, end pin #6 5th: 3t of #30 kynar coated wire; start pin #7, end pin #8 note: gap for 1.66mh 5% (pins 9 to 10) 1 t4 t4 power xfmr, l pri = 3.87mh, custom ciols p/n 5038 or coiltronics p/n ctx05-12545-1 e24/25 core set, tdk pc40 material 8 pin vertical bobbin (cosmo #4564-3-419) wind as follows: 1st: 200t of 30awg magnet wire; start pin #1, end pin #4. 1 layer of mylar tape 2nd: 300t of 32awg magnet wire; start pin #5, end pin #8 note: gap for inductance primary: (pins 1 to 4) @ 3.87mh 5% 1 t5 t5 current sense inductor, custom coils p/n 5040 or coiltronics p/n ctx05-12546-1 toroid magnetics yw-41305-tc wind as follows: primary = 3t 30awg magnet coated wire, start pin #1, end pin #4 secondary = 400t 35awg magnet wire, start pin #5, end pin #8 inductors: 2 l1, 2 emi/rfi inductor, 600 m h, dc resistance = 0.45 w prem. spe116a magnetics fuses: 1 f1 2a fuse, 5 x 20mm miniature littlefuse f948-nd 2 fuse clips, 5 x 20mm, pc mount f058-nd hardware: 1 single to-220 heatsink aavid eng. pb1st-69 2 double to-220 heatsink ierc pse1-2tc 3 mica insulators keystone 4673k-nd ML4831 1 4 ordering information part number temperature range package ML4831c p 0 c to 8 5 c molded pdip (p18) ( e nd o f l if e ) micro linear reserves the right to make changes to any product herein to improve reliability, function or design. micro linear does not assume any liability arising out of the application or use of any product described herein, neither does it convey any license under its patent right nor the rights of others. the circuits contained in this data sheet are offered as possible applications only. micro linear makes no warranties or representations as to whether the illustrated circuits infringe any intellectual property rights of others, and will accept no responsibility or liability for use of any application herein. the customer is urged to consult with appropriate legal counsel before deciding on a particular application. ds 48 31 -0 1 2092 concourse drive san jose, ca 95131 tel: 408/433-5200 fax: 408/432-0295 seating plane 0.240 - 0.260 (6.09 - 6.61) pin 1 id 0.295 - 0.325 (7.49 - 8.26) 0.890 - 0.910 (22.60 - 23.12) 0.016 - 0.022 (0.40 - 0.56) 0.100 bsc (2.54 bsc) 0.008 - 0.012 (0.20 - 0.31) 0.015 min (0.38 min) 18 0?- 15 1 0.050 - 0.065 (1.27 - 1.65) 0.170 max (4.32 max) 0.125 min (3.18 min) 0.045 min (1.14 min) (4 places) package: p18 18-pin pdip ? micro linear 1997 micro linear is a registered trademark of micro linear corporation products described in this document may be covered by one or more of the following patents, u.s.: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; japan: 2598946. other patents are pending. physical dimensions inches (millimeters) |
Price & Availability of ML4831
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |