View SG6842BCVD_8343985.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 1 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 features linearly-decreasing pwm frequency burst-mode low start-up current (8ua) low operating current (3.7ma) internal latch circuit (otp, ovp) leading-edge blanking synchronized slope compensation totem pole output with soft driving improved emi constant power limit (full ac input range) current mode operation cycle-by-cycle current limiting under voltage lockout (uvlo) programmable pwm frequency gate output maximum voltage clamp (18v) vdd over voltage protection (ovp) programmable over temperature protection (otp) few external components required applications general-purpose switch mode power supplies and flyback power converters, including: power adapters open-frame smps battery-charger adapters description the highly integrated sg6842 series of pwm controllers provides several features to enhance the performance of flyback converters. to minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. under zero-load conditions, the power supply enters burst-mode. this completely shuts off pwm output. then, the output restarts just before the supply voltage, vdd, drops below the uvlo voltage. this green-mode function enables the power supply to easily meet international power conservation requirements. for improved power conversion efficiency, the sg6842 series is manufactured using the bicmos process. this allows the start-up current to be reduced to 8ua, and the operating current to be reduced to 3.7ma. for even higher power conversion efficiency, a large start-up resistance can be used. built-in synchronized slope compensation ensures the stability of peak current mode control. proprietary internal compensation ensures constant output power limiting over a universal range of ac input voltages, from 90vac to 264vac. sg6842 controllers provide many protection functions. pulse-by-pulse current limiting ensures a constant output current, even when short circuits occur. should an open circuit failure occur in the feedback loop, the internal protection circuit will disable pwm output. pwm output will be disabled as long as vdd ex ceeds a threshold. the gate output is clamped at 18v to protect the power mos from damage due to high voltage conditions. an external ntc thermistor can be applied to sense the ambient temperature for over temperature protection. when internal latch circuit is used to latch-off the controller, the latch will be reset when the power supply vdd is disabled. sg6842 series controllers are available in both 8-pin dip and so packages. typical application
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 2 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 marking diagrams pin configuration ordering information part number package sg6842blvs 8-pin sop sg6842blvd 8-pin dip sg6842blvsz 8-pin sop(lead free) sg6842blvdz 8-pin dip(lead free) sg6842bcvs 8-pin sop SG6842BCVD 8-pin dip sg6842bcvsz 8-pin sop(lead free) SG6842BCVDz 8-pin dip(lead free) pin descriptions pin no. symbol function description 1 gnd ground ground. 2 fb feedback the signal from the external compensation circuit is fed into this pin. the pwm duty cycle is determined in response to the signal from this pin and the current-sense signal from pin 6. 3 vin start-up input for start-up, this pin is pulled high to the rectified line input. this pin is pulled via a resistor. since the start-up current requirement of the sg6842 is very small, a large start-up resistance can be used to minimize power loss. under normal operation, this pin is also used to detect the line voltage. the line voltage is detected to compensate the output power limit, so that it can be kept constant over a universal ac input range 4 ri reference setting a resistor connected from the ri pin to ground will provide the sg6842 with a constant current source. this current charges an internal capacitor. this determines the switching frequency. increasing the resistance will decrease the amplitude of the current from the current source, and thereby reduce the switching frequency. using a 26k ? resistor r i results in a 50ua constant current i i and a 65khz switching frequency. 5 rt temperature detection for over-temperature protection. an external ntc thermistor is connected from this pin to ground. the impedance of the ntc will decrease at high temperatures. once the voltage of the rt pin drops below a fixed limit of 1.05v, pwm output will be disabled. sg6842 bfvtp xxxxxxxyywwv 8 1 b: b = linearly decreasing frequency + b urst-mode f: l = otp l atch: the pin is reset when ac is disconnected. c = hysteresis otp : th e pin is reset when the temperature c ools down. v: v = ov p latch t : d = dip, s = sop p : z =lead free + rohs compatible null=regular package xxxxxxx : wafer lot yy : year; ww : week v : assembly location ri vin gate vdd sense rt gnd fb 3 1 2 5 6 8 7 4
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 3 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 6 sense current sense current sense. the sensed voltage is used for current-mode control and pulse-by-pulse current limiting. 7 vdd power supply power supply. if an open circuit failure occurs in the feedback loop, the internal protection circuit will disable pwm output as long as vdd remains higher than 26v. 8 gate driver output the totem-pole output driver for the power mosfet. a soft driving waveform is implemented for improved emi.
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 4 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 block diagram vdd vin internal bias gate sense v dd fb sq r osc gnd rt uvlo 16.5v/10.5v 3 7 5 1 8 6 2 0.9v 1.065v i rt soft driver blanking circuit ovp 6v r1 r2 rb green mode controller vdd pwm latch slop e compensation 5.2v otp ri 4 current reference debounce 56ms vdd vin internal bias gate sense v dd fb sq r osc gnd rt uvlo 16.5v/10.5v 3 7 5 1 8 6 2 0.9v 1.065v i rt soft driver blanking circuit ovp 6v r1 r2 rb green mode controller vdd pwm latch slop e compensation 5.2v otp ri 4 current reference debounce 56ms vdd vin internal bias gate sense v dd fb sq r osc gnd rt uvlo 16.5v/10.5v 3 7 5 1 8 6 2 0.9v 1.065v i rt soft driver blanking circuit ovp 6v r1 r2 rb green mode controller vdd pwm latch slop e compensation 5.2v otp ri 4 current reference debounce 56ms vdd vin internal bias gate sense v dd fb sq r osc gnd rt uvlo 16.5v/10.5v 3 7 5 1 8 6 2 0.9v 1.065v i rt soft driver blanking circuit ovp 6v r1 r2 rb green mode controller vdd pwm latch slop e compensation 5.2v otp ri 4 current reference debounce 56ms
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 5 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 absolute maximum ratings symbol parameter test condition value unit v dd supply voltage low impedance source, 27 v i z zener current - 10 ma v in input terminal 28 v i sink error amplifier sink current - 10 ma v fb input voltage to fb pin - -0.3 to 7v v v sense input voltage to sense pin - -0.3 to 7v v v rt input voltage to rt pin - -0.3 to 7v v v ri input voltage to ri pin - -0.3 to 7v v p d power dissipation at t a < 50c dip sop 800 400 mw r j-a thermal resistance junction-air dip sop 82.5 141 c/w r j-c thermal resistance junction-case dip sop 67.1 41.2 c/w t j operating junction temperature - 150 c t a operating ambient temperature - -40 to 125 c t stg storage temperature range - -65 to +150 c t l lead temperature (soldering) 10 sec dip 10 sec sop 260 230 c esd capability, hbm model - 2.0 kv recommended operating conditions symbol parameter min. max. unit v dd supply voltage - 20 v t a operating ambient temperature -30 85 c electrical characteristics (vdd =15v, temp =27c) vdd section symbol parameter test condition min. typ. max. unit v th(on) on threshold voltage 15.5 16.5 17.5 v v th(off) off threshold voltage 9.5 10.5 11.5 v i dd st start-up current v dd = 15v 8 30 ua i dd op operating supply current fb=sense=0v, v dd =15v, gate open 3.7 5 ma blv version v dd-ovp v dd over voltage protection (latch off). 24.5 25.5 26.5 v bcv version v dd-ovp v dd over voltage protection (latch off). 22.6 23.6 24.6 v t d - vdd-ovp v dd over voltage protection debounce (disable pw m output) r i =26k 100 usec v dd-zener v dd zener crowbar i dd = 10ma 27 30 33 v v dd-th-g v dd low-threshold voltage to exit green-off mode v th(off) + 0.8 v th(off) + 1.25 v th(off) + 1.7 v
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 6 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 feedback input section symbol parameter test condition min. typ. max. unit a v input-voltage to current-sense attenuation 1/4.5 1/4 1/3.5 v/v z fb input impedance 4.5 k i fb bias current 2 ma v fbp protection level for limited power control 5.2 v t delay-lps the delay time for limited power control. v fb =5.2v r i =26k 56 msec v fb0 fb pin open voltage 6.75 v current sense section symbol parameter test condition min. typ. max. unit z cs input impedance 12 k t pd delay to output 100 200 nsec ? v th @ i in80ua threshold voltage change versus vin pin input current i in = 80 ua, r i =26k 0.77 0.82 0.87 v ? v th @ i in160ua threshold voltage change versus vin pin input current i in = 160 ua, r i =26k 0.72 0.77 0.82 v b nk leading edge blanking time 260 360 460 nsec oscillator section symbol parameter test condition min. typ. max. unit f osc normal mode frequency r i =26k 60 65 70 khz f osc-green green-on mode frequency r i =26k 20 22.5 25 khz v g green-off mode voltage at fb pin v dd =15v 1.4 1.6 1.8 v v n fb pin frequency reduction threshold v dd =15v 1.9 2.1 2.3 v s g green-mode modulation slope r i =26k 85 hz/mv f dv frequency variation versus v dd deviation v dd =11.5 to 20v 5 % f dt frequency variation versus temp. deviation t a =-30 to 85 : 1.5 5 % fre q uenc y v fb f osc-goff : 0khz v n : 2.1v pwm frequency v g : 1.6v s g : 85hz/mv f osc-green : 22.5khz f osc : 65khz
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 7 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 pwm output section symbol parameter test condition min. typ. max. unit dcy (max) maximum duty cycle 80 85 90 % v ol output voltage low v dd = 12v, i o = 50ma 1.5 v v oh output voltage high v dd = 12v, i o = 50ma 8v v t r rising time v dd =15v, c l =1nf 150 250 350 nsec t f falling time v dd =15v, c l =1nf 30 50 90 nsec v clamp gate output clamping voltage v dd =25v 18 v over temperature protection section symbol parameter test condition min. typ. max. unit i rt output current of rt pin r i =26k 64 70 76 ua v otp-off otp turn-off level 1.015 1.065 1.115 v bcv version v otp-reset-on otp release level v otp-off +0.06 v otp-off +0.1 v otp-off +0.14 v t dotp-latch over-temperature latch-off debounce r i =26k 60 100 140 usec ri section symbol parameter test condition min. typ. max. unit ri nor r i operating range 15.5 36 k ? ri max max. r i value for protection 216 k ? ri min min. r i value for protection 6 k ?
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 8 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 typical characteristics start-up current (i dd st ) vs vdd voltage 2.0 4.0 6.0 8.0 10.0 12.0 5 6 7 8 9 10 11 12 13 14 15 16 vdd voltage (v) start-up current (ua) frequency vs. fb voltage 28 33 38 43 48 53 58 63 68 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 2.05 2.10 2.15 2.20 2.25 2.30 fb voltage (v) frequency (khz) pwm oscillator frequency (fosc) vs temperature 65.2 65.3 65.4 65.5 65.6 65.7 65.8 65.9 66.0 66.1 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) fosc (khz) maximum duty cycle dc( max. )vs temperature 85.00 85.50 86.00 86.50 87.00 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) max. duty cycle (%) temperature=25 c start-up current (i dd st ) vs tem perature 18.5 19.0 19.5 20.0 20.5 21.0 21.5 -40 - 25 -10 5 20 35 50 65 80 95 110 125 t em pera t ure ( ) start-up current (ua) vdd=14.5v vdd enter burst mode voltage vs temperature 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12.0 12.1 12.2 12.3 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) vburst
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 9 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 min. operating voltage (v dd ( min )) vs temperature 9.80 10.00 10.20 10.40 10.60 10.80 11.00 11.20 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) vdd(min) (v) start threshold voltage (v th(on )) vs temperature 16.10 16.20 16.30 16.40 16.50 16.60 16.70 16.80 16.90 17.00 17.10 17.20 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) v th(on) (v) duty cycle vs fb voltage 10 20 30 40 50 60 70 80 90 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 fb voltage duty cycle output current of pin rt (i rt ) vs temperature 70.400 70.450 70.500 70.550 70.600 70.650 70.700 70.750 70.800 70.850 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) i rt (ua) v otp, stop vs temperature 1.015 1.025 1.035 1.045 1.055 1.065 1.075 1.085 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperature ( ) v otp, stop (v) v sense vs i vin 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 80 100 120 140 160 i vin (ua) v sense
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 10 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 operation description start-up current the typical start-up current is only 8ua. this allows a high resistance, low-wattage start-up resistor to be used, to minimize power loss. a 1.5 m , 0.25w, start-up resistor and a 10uf/25v vdd hold-up capacitor would be sufficient for an ac/dc adapter with a universal input range. operating current the required operating current has been reduced to 3.7ma. this results in higher efficiency and reduces the vdd hold-up capacitance requirement. green-mode operation the proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. on-time is limited to provide protection against abnormal conditions and brownouts. to further reduce power consumption under zero-load conditions, pwm output will be completely turned off, and the power supply will enter burst-mode. after the pwm oscillator is turned off, the ic?s supply voltage vdd w ill drop gradually. before the vdd voltage drops below the uvlo voltage, the pwm oscillator will be turned on again. this green-mode function dramatically reduces power consumption under light-load and zero-load conditions. power supplies using a sg6842 controller can easily meet even the most restrictive international regulations regarding standby power consumption. oscillator operation a resistor connected from the ri pin to ground generates a constant current source for the sg6842 controller. this current is used to charge an internal capacitor. the charge of the capacitor determines the internal clock period and the switching frequency. increasing the resistance will decrease the amplitude of the current source and reduce the switching frequency. using a 26k resistor r i results in a 50ua constant current i i , and a corresponding 65khz switching frequency. the relationship between r i and the switching frequency is: ) ( khz ) (k r 1690 i pwm f ? = ---------------------------- (1) leading edge blanking each time the power mosfet is switched on, a turn-on spike will inevitably occur at the sense-resistor. to avoid premature termination of the switching pulse, a 360nsec leading-edge blanking time is built in. conventional rc filtering is not n ecessary. during this blanking period, the current-limit comparator is disabled, and it cannot switch off the gate drive. under-voltage lockout (uvlo) the turn-on/turn-off thresholds are fixed internally at 16.5v/10.5v. to enable a sg6842 controller during start-up, the hold-up capacitor must first be charged to 16.5v through the start-up resistor. the hold-up capacitor will continue to supply vdd before energy can be delivered from the auxiliary winding of the main transformer. vdd must not drop below 10.5v during this start-up process. this uvlo hysteresis window ensures that the hold-up capacitor can adequately supply vdd during start-up. gate output / soft driving the sg6842 bicmos output stage is a fast totem pole gate driver. cross-conduction has been avoided to minimize heat dissipation, increase efficiency, and enhance reliability. the output driver is clamped by an internal 18v zener diode in order to protect the power mosfet transistors from any harmful over-voltage gate signals. a soft driving waveform is implemented to minimize emi. slope compensation the sensed voltage across the current sense resistor is used for current-mode control and pulse-by-pulse current limiting. the built-in slope compensation function improves power suppl y stability and prevents peak current-mode control from causing sub-harmonic
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 11 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 oscillations. with every sw itching cycle, the sg6842 controller produces a positively-sloped, synchronized ramp signal. constant output power limit when the sense voltage across the sense resistor r s reaches the threshold voltage (around 0.85v), the output gate drive will be turned off following a small propagation delay t d . this propagation delay will result in an additional current proportional to t d *v in /l p . the propagation delay is nearly constant regardless of the input line voltage v in . higher input line voltages will result in larger additional currents. thus, under high input-line voltages the output power limit will be higher than under low input-line voltages. the output power limit variation can be significant over a wide range of ac input voltages. to compensate for this, the threshold voltage is adjusted by the current i in . since the pin vin is connected to the rectified input line voltage through the start-up resistor, a higher line voltage will result in a higher current i in through the pin vin. the threshold voltage decreases if the current i in increases. a small threshold voltage will force the output gate drive to terminate earlier, thus reducing total pwm turn-on time, and making the output power equal to that of the low line input. this proprietary internal compensation feature ensures a constant output power limit over a wide range of ac input voltages (90vac to 264vac). vdd over-voltage protection vdd over-voltage protection has been built in to prevent damage due to over voltage conditions. when the voltage vdd exceeds 25.5v due to abnormal cond itions, pwm output will be turned off. over-voltage conditions are usually caused by open feedback loops. thermal protection an external ntc thermistor can be connected from the rt pin to ground. the impedance of the ntc will decrease at high temperatures. when the voltage of the rt pin drops below 1.065v , pwm output will be disabled. limited power control the fb voltage will increase every time the output of the power supply is shorted or over-loaded. if the fb voltage remains higher than a built-in threshold (5.2v) for longer than 56msec, pwm output will then be turned off. as pwm output is turned off, the supply voltage vdd will also begin decreasing. when vdd goes below the turn-off threshold (eg, 10.5v) the controller will be totally shut down. vdd will be charged up to the turn-on threshold voltage of 16.5v through the start-up resistor until pwm output is restarted. this protection feature will continue to be activated as long as the over-loading condition persists. this will prevent the power supply from overheating due to over loading conditions. protection latch circuit for the sg6842 family, the built-in latch function provides a versatile protection feature that does not require external components. see ordering information for a detailed description. to reset the latch circuit, it is necessary to remove the supply voltage from vdd pin noise immunity noise from the current sense or the control signal may cause significant pulse width jitter, particularly in continuous-conduction mode. slope compensation helps alleviate this problem. good placement and layout practices should be followed. the designer should avoiding long pcb traces and component leads. compensation and filter components should be located near the sg6842. finally, increasing the power-mos gate resistance is advised.
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 12 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 reference circuit circuit (12v/5a) bom reference component reference component f1 fuse 4a/250v c9 ec 1000uf/25v bd1 bd 4a/600v r1,r2 r 330k 1/4w cy1 yc 222p/250v r3,r4 r 47k 1/4w l1 uu10.5-10mh r5 r 47 1/4w u1 ic sg6842 r6 r 10 1/4w u2 ic pc-817 r7 r 1k 1/4w u3 ic tl431 r8 r 470k 1/8w t1 transformer pq2620 r9,r13 r 51 1/4w d1 byv95c r10 r 26k 1/8w 1% d2,d3,d4 fr103 r11 thermistor ntc 10k c1,c2 ec 56uf/400v r12 r 0.34 1w 1% c3 cc 103p/500v r14 r 220 1/4w c4 ec 10uf/50v r15 r 4.7k 1/8w c5 ec 4.7uf/50v r16 r 154k 1/8w 1% c6,c8 cc 102p/200v r17 r 39k 1/8w 1% c7,c10 cc 222p/50v q1 mos phx7nq60e l1 cy1 r13 c8 c9 q1 r9 r12 d2 r11 gate sense vin gnd fb vo gnd d6 d1 r4 c3 r3 r5 f1 bd1 c1 l n c2 r7 r17 r14 c10 r16 vo r15 u2 u3 u1 r10 t1 vdd ri rt r8 8,9 6,7 1,2 3 4 5 d3 d4 c4 c5 r1 r2 c7 c6 r6
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 13 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 package information dip-8 outline dimensions 4 1 85 d e1 e e b a1 a2 a b b1 l e dimensions millimeters inches symbol min. typ. max. min. typ. max. a 5.334 0.210 a1 0.381 0.015 a2 3.175 3.302 3.429 0.125 0.130 0.135 b 1.524 0.060 b1 0.457 0.018 d 9.017 9.271 10.160 0.355 0.365 0.400 e 7.620 0.300 e1 6.223 6.350 6.477 0.245 0.250 0.255 e 2.540 0.100 l 2.921 3.302 3.810 0.115 0.130 0.150 eb 8.509 9.017 9.525 0.335 0.355 0.375 ? 0 ? 7 ? 15 ? 0 ? 7 ? 15 ?
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 14 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 sop-8 outline dimensions 1 4 85 h e e b a a1 d c f l dimensions millimeter inch symbol min. t yp . max. min. t yp .max. a 1.346 1.752 0.053 0.069 a 1 0.101 0.254 0.004 0.010 b 0.406 0.016 c 0.203 0.008 d 4.648 4.978 0.183 0.196 e 3.810 3.987 0.150 0.157 e 1.016 1.270 1.524 0.040 0.050 0.060 f 0.381x45 ? 0.015x45 ? h 5.791 6.197 0.228 0.244 l 0.406 1.270 0.016 0.050 ? 0 ? 8 ? 0 ? 8 ?
product specification highly-integrated green-mode pwm controller sg6842 ? system general corp. - 15 - www.sg.com.tw version 1.3(iro33.0009.b4) jul.23, 2004 disclaimers life support system general?s products are not designed to be used as components in devices intended to support or sustain human life. use of system general?s products in components intended for surgical implant into the body, or other applications in which failure of system general?s products could create a situation where personal death or injury may occur, is not authorized without the express written approval of system general?s chief executive officer. system general will not be held liable for any damages or claims resulting from the use of its products in medical applications. military system general's products are not designed for use in military applications. use of system general?s products in military applications is not authorized without the express written approval of system general?s chief executive officer. system general will not be held liable for any damages or claims resulting from the use of its products in military applications. right to make changes system general reserves the right to change this document and/or this product without notice. customers are advised to consult their system general sales representative before ordering.

▲Up To Search▲

Price & Availability of SG6842BCVD

	To Download SG6842BCVD Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .