GL494 1 GL494 pwm control circuit description the GL494 incorporates on a single monolithic chip all the functions required in the construction of a pulse - width - modulation control circuit. designed primarily for power supply control, the GL494 contains an on - ch ip 5 - volt regulator, two error amplifiers, adjustable oscillator, dead - time control comparator, pulse - steering flip - flop, and output - control circuitry. the uncommitted output transistors pro - vide either common - emitter or emitter - follower output capability. push - pull or single - ended output operation may be selected through the output - control function. the ar - chitecture of the GL494 prohibits the possibility of either output being pulsed twice during push - pull operation. features ? complete pwm power control circuitry ? uncommitted outputs for 200ma sink or source ? output control selects single - ended or push - pull operation ? internal circuitry prohibits double pulse at either output ? internal regulator provides a stable 5v reference supply ? variable dead - ti me provides control over total range pin configuration function table output control output function grounded single - ended or parallel output at ref v normal push - pull operation block diagram oscillator reference regulator noninv input inv. input feedback dead time control cr rr gnd c1 non inv input inv. input ref. out output control vcc c2 e2 e1 r t c t dead time control noninverting(1) input inverting (2) input noninverting(16) input inverting (15) input feedback error amp lifiers pwm comparator output control (see function table) pulse steering flip flop v cc ref out gnd e1(9) c1(8) e1(10) c2(11) (4) (3) (7) (12) (14) (13) t q q 0.1v + + - - error amp1 error amp2 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9
GL494 2 absolute maximum ratings supply voltage, cc v ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? . . 41 v amplifier input voltage ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? . . cc v +0.3 v collector output voltage ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 41 v continuous total dissipation at (or below) 25 c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? . 1000 mw operating free - air temperature range ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? - 20 to 85 c storage temperature range ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? . ? . . - 65 to 150 c collector output current ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? . . 250 ma recommended operation conditions parameter min max unit supp ly voltage, cc v 7 40 v amplifier input voltage, 1 v - 0.3 cc v - 2 v collector output voltage, vo 40 v collector output current (each transistor) 200 ma current into feed back terminal 0.3 ma timing capacitor, t c 0.47 10,000 nf timing resistor, t r 1.8 500 w k oscillator frequency 1 300 khz operating free - air temperature - 20 85 c electrical characteristics (t emperature c 85 ~ 20 - , cc v =15v, f=10khz) reference section parameter test conditions min typ(1) max unit output voltage ( ref v ) ma 1 i o = 4.75 5 5.25 v input regulation v 7 v cc = to 40v, c 25 t a = 2 25 mv output regulation 1 i o = to 10ma, c 25 t a = 1 15 mv output voltage change with temperature c 20 t a - = to c 85 0.2 1 % short - circuit output current (2) 0 v ref = 35 ma oscillator section parameter test conditions min typ(1) max unit frequency f 01 . 0 c t m = , w = k 12 r t 10 khz standard deviation of frequency (3) all values of cc v , a t t t , r , c constant 10 % frequency change with voltage v 7 v cc = to 40v, c 25 t a = 0.1 % frequency change with temperature f 01 . 0 c t m = , w = k 12 r t c 20 t a - = to c 85 2 %
GL494 3 dead time control section parameter test conditions min typ(1) max unit input bias current (pin 4) v i =0 to 5.25v - 2 - 10 a m maximum duty cycle, each output ) 4 pin ( i v =0v 45 % zer o duty cycle 3 3.3 v input threshold voltage (pin 4) maximum duty cycle 0 v error amp sections parameter test conditions min typ(1) max unit input offset voltage v 5 . 2 v ) 3 pin ( o = 2 10 mv input offset current v 5 . 2 v ) 3 pin ( o = 25 250 na input bias current v 5 . 2 v ) 3 pin ( o = 0.2 1 a m low - 0.3 common - mode input voltage range v 7 v cc = to 40v high 2 v cc - v open - loop voltage amplification 5 . 0 v , v 3 v o o = = d to3. 5v 70 95 db unity - gain bandwidth 8 00 khz common - mode rejection ratio v 40 v cc = , c 25 t a = 65 80 db output sink current (pin 3) mv 15 v id - = to ? 5v, v 7 . 0 v ) 3 pin ( o = 0.3 0.7 ma output source current (pin 3) mv 15 v id = to 5v, v 5 . 3 v ) 3 pin ( o = - 2 ma pwm comparaor section parameter test conditions min typ(1) max unit input threshold voltage (pin 3) zero duty cycle 4 4.5 v input sink current (pin 3) v 7 . 0 v ) 3 pin ( o = 0.3 0.7 ma switching characteristics parameter test conditions min typ(1) max unit output voltage rise time 100 200 ns output voltage fall time common - emitter configuration, see test circuit 3 25 100 ns output voltage rise time 100 200 ns outpu t voltage fall time emitter - follower configuration, see test circuit 4 40 100 ns
GL494 4 output section parameter test conditions min typ(1) max unit collector off - state current v 40 v , v 40 v cc ce = = 2 100 ma emitter off - state current 0 v , v 40 v v e c cc = = = - 100 ma common - emitter ma 200 i , 0 v c e = = 1.1 1.3 collector - emitter saturation voltage emitter - follower ma 200 i , v 15 v e c - = = 1.5 2.5 v output control input current ref i v v = 3.5 ma total device parameter test conditions min typ(1) max unit v 15 v cc = 6 10 ma standby supply current all o ther inputs & outputs open v 40 v cc = 9 15 ma average supply current v 2 v ) 4 pin ( = see test circuit 1 7.5 ma notes: (1) all typical values except for temperature coefficients are at c 25 t a = (2) duration of the short circuit should not exceed one second. (3) standard deviation is a measure of the statistical distribution about the mean as derived from the formula 1 n ) x x ( n 1 n 2 n - - = s ? =
GL494 5 parameter measurement information 1. dead time and feedback control 2. error amplifier characteristics 3. common - emitter configuration test circuit output voltage waveform dead time (4) (8) c1 feedback (3) (9) e1 re (6) cr (5) (11) c2 (+) (16) error (12) e2 ( - ) (15) amp (+) (1) error ( - ) (2) amp output control vcc=15v test inputs output 1 output 2 (14) ref out gnd (7) (13) 50k w 150 w 2w 150 w 2w 12k w 0.01 m f voltage at c1 voltage at c2 voltage at c t dead - time control intput feedback max duty cycle max threshold voltage threshold voltage vcc vcc 0 0 0% 0% 0v 0.7v v1 error amplifier under test feedback terminal other error amplifi er v ref ? ? + + (each output circuit) output 15v 68 w 2w c l =15pf (includes probe and jig capacitance) 90% 90% 10% 10% t f t r test circuit voltage waveforms
GL494 6 4. emitter - follower configuration test circuit output voltage waveform typical performance curves (each output eircuit) 15v 68 w 2w output c l =15pf (includes probe and jig capacitance) 90% 90% 10% 10% t f t r 300k 100k 10k 1k 100 30 100 90 80 70 60 50 40 30 20 10 0 1k 2k 5k 10k 20k 50k 100k 200k 500k 1m 1.0 10 100 1k 10k 100k 1m 20 0 - 20 - 40 - 60 - 80 - 100 - 120 - 140 - 160 - 80 a vol , open - loop voatage gain (db) 10 9 8 7 6 5 4 3 2 1 0 50 40 30 20 10 0 100 1k 10k 100k 0 1.0 2.0 3.0 3.5 %dt. percent deadtime, each output ach output figure 1 ? oscillator frequency versus timing resistance figure 2 ? open loop voltage gain and phase versus frequency figure 3 ? percent dead time versus oscillator frequency figure 4 ? percent duty cycle versus dead - time control voltage r t , timing resistance ( w ) f, frequency (hz) fo, oscillator frequency (hz) dead time control voltage (v) vcc=15v 0.001 m f ct=0.01 m f 0.1 m f 0.1 m f a vol 0.01 m f ct=0.01 m f vcc=15v vo=3v r l =2k w vcc=15v voc=vref v (pin4) =0v vcc=15v voc=vref 1) c t =0.01 r t =10k 2) c t =0.001 r t =30k 1 2 q
GL494 7 1. 9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 0 50 100 150 200 250 0 50 100 150 200 250 0 5.0 10 15 20 25 30 35 40 v ce(sat) , saturation voltage (v) i e , emitter current (ma) figure 5 ? emitter - follower configuration output - saturation voltage versus emitter current v ce(sat) , saturation voltage (v) icc, supply current (ma) i c , collector current (ma) vcc, supply voltage (v) figure 6 ? common - emitter configuration output - saturation voltage versus collector current fugure 7 ? standby - supply c urrent versus supply voltage vcc=15v vcc=15v
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