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1 www.semtech.com SC4910A/b high performance secondary side controller with synchronous rectifier power management revision: june 1, 2005 description features applications typical application circuit ? synchronous rectification with adaptive control ? programmable secondary side delay ? programmable switching frequency ? programmable max. duty cycle ? remote voltage sense capability ? close-loop soft start with active low shutdown ? 0.75v precision reference for low output applications ? oscillator sychronization ? undervoltage lockout ? operation to 1mhz ? current-mode or voltage-mode operation ? single stage power conversion with multiphase link capability (with sc4201) ? monotonic start-up with pre-biased output ? active current sharing capability ? 20 pin tssop package the SC4910A/b is an integrated, full featured, second- ary side controller designed for use in single ended and isolated switch mode power supplies with synchronous rectification where efficiency and fast transient response are of primary concern. the SC4910A/b has outputs for both primary fet and secondary synchronous rectifica- tion. the primary drive output is designed to drive a small and low cost pulse transformer to isolate the primary fet driver. the secondary control makes it much easier to monitor and control the system load with tight control loops and implement load current sharing and synchro- nous rectification. the SC4910A/b features synchronous rectification, multi- phase link capability, programmable secondary side delay, programmable switching frequency and program- mable maximum duty cycle. it is designed for either current mode or voltage mode operation. the SC4910A has a typical turn-on threshold of 9v and the sc4910b has a threshold of 4.5v. +12v c4 load c6 t3 r3 c5 c1 m1 sc1301 m2 r8 c10 r4 r7 t2 c2 r2 r6 l1 d2 sc4910 18 17 11 12 6 4 8 7 20 19 3 1 15 2 5 10 fb comp outb ishare phase cs outa pgnd rt1 rt2 ss -sense delay sync/en vref pvcc m3 sc1301 d3 c8 +vin r1 c9 sc1301 r9 c3 d1 r5 t1 16 13 14 pvcc avcc 9 pgnd agnd ? telecom isolated dc to dc converters ? isolated vrms ? networking power supplies ? industrial power supplies ? distributed power architectures ? high density power modules
2 ? 2005 semtech corp. www.semtech.com SC4910A/b power management absolute maximum ratings electrical characteristics r e t e m a r a ps n o i t i d n o c t s e tn i mp y tx a mt i n u y l p p u s r e w o p t n e r r u c g n i t a r e p ow o l = n e / c n y s0 15 1a m t u o k c o l e g a t l o v r e d n u d l o h s e r h t t r a t s a 0 1 9 4 c s7 . 80 . 93 . 9v b 0 1 9 4 c s5 3 . 40 5 . 45 7 . 4v s i s e r e t s y h o l v u a 0 1 9 4 c s0 0 40 5 50 0 7v m b 0 1 9 4 c s0 0 20 0 35 7 3v m e c n e r e f e r f e r v e g a t l o v t u p t u o a 0 1 9 4 c s5 7 . 40 . 55 2 . 5v b 0 1 9 4 c s7 9 . 20 3 . 33 6 . 3v n o i t a l u g e r e n i lv 5 1 < c c v < v 3 . 95 10 3v m n o i t a l u g e r d a o li < a m 0 f e r a m 5 <20 1v m t r a t s t f o s t u p t u o s s 5 7 . 0v y c a r u c c a e g a t l o v t a t = j c 5 2 =1 -1 + % 5 . 1 -5 . 1 + n o i t a l u g e r e n i lv 5 1 < c c v < v 3 . 95 -05 +v m e c n a d e p m i ) 2 ( k 7 ? r e t e m a r a pl o b m y sm u m i x a ms t i n u e g a t l o v y l p p u sc c v8 1v e g a t l o v t u p t u o c c vv e s a h p c c vv e r a h s i , n e / c n y s , p m o c , b f 7 o t 3 . 0 -v k n i s r o e c r u o s t n e r r u c b t u o & a t u o 0 5 1a m e g n a r e r u t a r e p m e t n o i t c n u jt j 0 5 1 + o t 0 4 -c e g n a r e r u t a r e p m e t e g a r o t st g t s 0 5 1 + o t 0 6 -c . c e s 0 1 ) g n i r e d l o s ( e r u t a r e p m e t d a e lt d a e l 0 6 2c unless specified: t a = t j = -40c to 125c , v cc = 12v, r t1 = r t2 = 50k, r delay = 50k, c ss = 0.1f. exceeding the specifications below may result in permanent damage to the device, or device malfunction. operation outside of th e parameters specified in the electrical characteristics section is not implied. exposure to absolute maximum rated conditions for extended periods of time may affect device reliability.
3 ? 2005 semtech corp. www.semtech.com SC4910A/b power management electrical characteristics (cont.) r e t e m a r a ps n o i t i d n o c t s e tn i mp y tx a mt i n u r e i f i l p m a r o r r e t n e r r u c s a i b t u p n i 1 . 05a e g a t l o v t e s f f o 27 v m n i a g p o o l n e p o 0 8 b d r r m c ) 1 ( 0 7 b d r r s p ) 1 ( 0 7 b d e g a t l o v h g i h t u p t u o i p m o c a m 0 . 1 =5 7 . 19 . 1 v e g a t l o v w o l t u p t u o i p m o c a m 0 . 1 =9 . 00 . 1 v h t d i w d n a b n i a g y t i n u ) 1 ( 0 . 5 z h m e t a r w e l s ) 1 ( 0 . 2 s / v r o t a l l i c s o e g n a r y c n e u q e r fr y c n e u q e r f . n i m 1 t r = 2 t k 0 0 5 =0 5z h k r y c n e u q e r f . x a m 1 t r = 2 t k 5 2 =0 0 0 1 y c n e u q e r f 0 5 40 0 50 5 5z h k e g a t l o v k a e p ) 1 ( 5 . 2v e g a t l o v y e l l a v ) 1 ( 0 . 1 v h g i h t u p n i e l b a n e 0 . 2 v w o l t u p n i e l b a n e 8 . 0 v e l c y c y t u d e l c y c y t u d m u m i x a m ) 2 ( 0 9 % e l c y c y t u d m u m i n i m 0 % e c n a r e l o t e l c y c y t u d 5 -5 + % t i m i l t n e r r u c d l o h s e r h t e l c y c y b e l c y c 5 7 9 . 05 2 0 . 15 7 0 . 1 v d l o h s e r h t n w o d t u h s 1 . 15 2 . 14 . 1 v t u p t u o o t y a l e d ) 2 ( 0 0 1 s n e c n a d e p m i t u p n i ) 2 ( 0 2 k ? unless specified: t a = t j = -40c to 125c , v cc = 12v, r t1 = r t2 = 50k, r delay = 50k, c ss = 0.1f.
4 ? 2005 semtech corp. www.semtech.com SC4910A/b power management r e t e m a r a ps n o i t i d n o c t s e tn i mp y tx a mt i n u b t u o d n a a t u o w o l t u p t u o i t u p t u o a m 0 0 1 =13 . 1 v h g i h t u p t u o i t u p t u o a m 0 0 1 =5 7 . 90 1 v e m i t e s i r ) 2 ( c t u o f p 0 0 1 =0 2 s n e m i t l l a f ) 2 ( c t u o f p 0 0 1 =0 2 s n y a l e d g n i s i r a t u o o t g n i l l a f b t u o ) 2 ( r y a l e d k 0 5 = ? 0 7 s n g n i s i r b t u o o t g n i l l a f a t u o ) 2 ( v 5 . 1 > e s a h p0 2 2 s n v 5 . 1 < e s a h p0 3 r e i f i l p m a r o r r e e r a h s t n e r r u c e c n a t c u d n o c s n a r t ) 1 ( 8 1 . 0 s m t n e r r u c k n i s r o e c r u o s t u p t u o ) 1 ( 0 1 a electrical characteristics (cont.) notes: (1) guaranteed by design. (2) guaranteed by characterization. (3) this device is esd sensitive. use of standard esd handling requirements are required. unless specified: t a = t j = -40c to 125c , v cc = 12v, r t1 = r t2 = 50k, r delay = 50k, c ss = 0.1f.
5 ? 2005 semtech corp. www.semtech.com SC4910A/b power management r e b m u n t r a pe g a k c a p t r t s t i a 0 1 9 4 c s ) 2 ( 0 2 - p o s s t ) 1 ( t r t s t i b 0 1 9 4 c s ) 2 ( notes: (1) only available in tape and reel packaging. a reel contains 2500 devices. (2) lead free product. this product is fully weee and rohs compliant. pin configurations ordering information 1 2 3 4 5 6 7 8 rt1 -sense top view (20 pin tssop) 13 14 15 16 rt2 sync/en fb ss comp cs ishare vref delay phase avcc agnd pvcc pgnd 9 10 12 pvcc pgnd outb outa 11 18 17 19 20 marking information part number (example: 1471) yyww = date code (example: 0012) xxxxx = semtech lot no. (example: p94a01) part number (example: 1471) yyww = date code (example: 0012) xxxxx = semtech lot no. (example: p94a01)
6 ? 2005 semtech corp. www.semtech.com SC4910A/b power management pin descriptions # n i pe m a n n i pn o i t c n u f n i p 1e s n e s -. n r u t e r e s n e s e g a t l o v e t o m e r 2n e / c n y s . e s n e s - o t d e c n e r e f e r . n i p e l b a s i d / e l b a n e d n a n o i t a z i n o r h c n y s l a n o i t c e r i d i b 3s s. t r a t s t f o s 4s c. t u p n i e s n e s t n e r r u c 5f e r v. t u p t u o e c n e r e f e r l a n r e t n i v 5 6e s a h p. n o i t a c i f i t c e r s u o n o r h c n y s r o f e d o n e s a h p 7d n g a. d n u o r g g o l a n a 8d n g p. a t u o r o f d n u o r g r e w o p 9d n g p. b t u o r o f d n u o r g r e w o p 0 1a t u o . o l v u g n i r u d w o l . t e f s o m d r a w r o f y r a d n o c e s d n a t e f s o m y r a m i r p r o f r e v i r d t u p t u o 1 1b t u o . o l v u g n i r u d w o l . r e i f i t c e r d r a w r o f r o f l a n g i s g n i v i r d t e f s o m e h t t u p t u o 2 1c c v p. b t u o r o f y l p p u s r e w o p 3 1c c v p. a t u o r o f y l p p u s r e w o p 4 1c c v a. e g a t l o v y l p p u s g o l a n a 5 1y a l e d g n i l e e h w e e r f e h t f o f f o - n r u t m o r f s i y a l e d e h t . b t u o d n a a t u o n e e w t e b y a l e d e v i t c i d e r p o t 0 2 s i e m i t y a l e d e h t . t e f s o m y r a m i r p d n a t e f s o m d r a w r o f e h t f o n o - n r u t o t t e f s o m . e l b a m m a r g o r p s n 0 0 2 6 1e r a h s i. s u b e r a h s t n e r r u c 7 1p m o c. n o i t a s n e p m o c k c a b d e e f 8 1b f. k c a b d e e f 9 12 t r . r o t a l l i c s o l a n r e t n i e h t f o p m a r e v i t a g e n e h t l o r t n o c o t 2 t r r o t s i s e r g n i m i t o t t c e n n o c 0 21 t r . r o t a l l i c s o l a n r e t n i e h t f o p m a r e v i t i s o p e h t l o r t n o c o t 1 t r r o t s i s e r g n i m i t o t t c e n n o c
7 ? 2005 semtech corp. www.semtech.com SC4910A/b power management block diagram figure. 1
8 ? 2005 semtech corp. www.semtech.com SC4910A/b power management applications information the SC4910A/b is a secondary side pwm controller work- ing either in current mode or voltage mode mainly for applications of forward converters with synchronous rec- tification. while the outa drives the primary mosfet through transformer and the secondary forward recti- fier, the outb drives the secondary freewheeling recti- fier. the switching frequency and maximum duty cycle can be programmable with two resistors. the delay time from the falling edge of outa to the rising edge of outb is adaptive by monitoring the phase node voltage. the delay time from the falling edge of outb to the rising edge of outa is determined by a programming resistor from the delay pin to ground. the ishare pin allows for current sharing among the parallel operating units to make current equally distribute load. the -sense pin separated from gnd pin provides true output voltage remote sense capability. other features include soft start, sychronization or enable/disable by user, provided 5v reference voltage. oscillator the frequency and duty cycle of the oscillator is controlled by placing two resistors from the rt1 and rt2 pins to ground. the resistor at rt1 controls the maximum ?on? duty cycle and the resistor at rt2 controls the ?off? portion of a cycle. when the resistor at rt1 is equal to that at rt2, the maximum duty cycle will be approximately 50%. the following formula is used to determine the time duration of the ?on? and ?off? portions: 12 10 20 ? = rt t current sense and current limit the cs pin has an input impedance of 20k ohms and swings from 1.0v to 2.5v. with a 5k ohm resistor from cs to ground, the device operates in voltage mode with a ramp that will swing from 0.2v to 0.5v. when the 5k resistor is connect to a voltage that is proportional to the primary side current, the device will operate in current mode. the cycle-by-cycle current limit is triggered when the cs pin voltage rises above 1v. if cs exceeds 1.25v, the faulty latch will be set and the outputs will be driven low. the soft start capacitor is then discharged by the internal current sink. no outputs are allowed until the soft start capacitor is fully discharged to 0.15v. at this point the fault latch will be reset and the sc4910 will begin a soft start process. this results in a hiccup current limit mode for continuous fault conditions. sync/en the enable function looks at the sync/en pin and an internal timing capacitor. if the sync/en pin is low and the internal timing capacitor voltage is high, then the sc4910 is disabled with outa, outb and ss pulled low. when the sync/en pin is held high, the device is enabled and runs off of the internal oscillator. when a rising signal is detected on the sync/en pin a one-shot is triggered and discharges the internal timing capacitor. as long as the internal timing capacitor is below an internal reference level, the device will synchronize with the external pulse. if the internal timing capacitor is allowed to charge up to the internal reference level before another sync pulse is detected, the device will switch back to the internal oscillator. soft start the ss pin is connected to the internal reference, 0.75v, through an internal 6k ohm resistor. the ss pin is also connected to the non-inverting input of the error amplifier. with an external capacitor connected to this pin, the soft start timing will be determined by this rc time constant. during start-up, the ss pin is held low until the undervoltage lockout threshold is reached. once the uvlo threshold is reach, the ss pin is released and the device will regulate to the voltage on this pin. undervoltage lockout when the supply voltage v cc is below the undervoltage lockout threshold, both outa and outb are held low. the ss pin and the comp pin are also held low. once the undervoltage lockout threshold has been surpassed, outa, outb, ss and comp are released for normal operation.
9 ? 2005 semtech corp. www.semtech.com SC4910A/b power management programmable delay sc4910 is for single ended topologies with secondary side synchronous rectification. it provides outputs to drive the primary mosfet through a small pulse transformer and the secondary synchronous rectifiers directly. to avoid cross conduction and optimize performance, adjustable delay is necessary between forwarding and freewheeling switches. the delay from falling edge of outb to rising edge of outa is determined by a resistor from the delay pin to ground. the following formula is used to calculate the delay time: ns 20 12 1 r t delay + ? ? = where, r is the delay time setting resistor. r should be between 20k and 200k. the delay time from falling edge of outa to rising edge of outb is adaptive and is triggered when the phase node falls below 1.5v. if after 220ns the phase node has still not fallen, the device will automatically switch. operation mode sc4910 could be configured either current mode or voltage mode operation. in current mode, the current sense signal comes to the cs pin while an external resistor could configure slope compensation. in voltage mode, an external resistor forms sawtooth with the internal 20k resistor for voltage mode operation while current limit signal comes to the same pin. in current mode, which is preferred for application of sc4910, current is sensed by a current transformer for current feedback and over current protection. the current in the primary switch is sensed and controlled by developing a voltage proportional to current across a sense resistor on the secondary. the sensed voltage is then fed into the cs pin of sc4910. the typical current limit threshold in the current sense pin of the sc4910 is 1.0v. the over current limit is assumed typical 120% of full load current. then the current sense resistor can be calculated by the following equation: ) pk ( i % 120 n n 0 . 1 rs o s ? ? ? = applications information (cont.) where n ? power transformer primary to secondary turns ratio n s ? secondary turns of current sense transformer io(pk) ? peak inductor current an example of choosing a current sense resistor is given below. assume the converter full load current is 20a and peak inductor current is 23a, the power transformer primary to secondary turns ratio is 6:1 and the current sense transformer primary to secondary turns ratio is 1:100, then, ? ? ? ? = 21 23 % 120 100 6 0 . 1 rs slope compensation slope compensation is needed to prevent sub-harmonic oscillation at duty cycle higher than 50% and to compensate the peak to average difference in peak current mode control. the following equation can be used to calculate the external slope. if negative se is obtained by the equation , no slope compensation is needed. s s o l in o in in o n n r n v i v ) n v v ( 2 v n v 2 se ? ? ? ? ? ? ? where se ? external slope magnitude vin ? low input line voltage vo ? output voltage n ? power transformer primary to secondary turns ratio n s ? secondary turns of current sense transformer ? i l - peak-to-peak inductor current ripple for example, if the low input line voltage is 36v, output voltage is 3.3v, power transformer primary to secondary turns ratio is 6:1; the peak-to-peak inductor current ripple is 6a, and current sense gain r s is 21w, then the external slope needed is: mv 85 100 6 21 6 3 . 3 6 36 ) 6 3 . 3 36 ( 2 36 6 3 . 3 2 se ? ? ? ? ? ? ? ? ? ?
10 ? 2005 semtech corp. www.semtech.com SC4910A/b power management this is the minimum external slope required to avoid sub- harmonic oscillation at low input line. with sc4910, the external slope is very easy to implement. referring to figure 2, r12 is the current sense resistor. r10 and the internal 20k ? resistor divide the internal slope 1.0v - 2.5v down to the required compensation slope. ) f n l r v se ( ) 0 . 1 5 . 2 ( 20 ) f n l r v se ( 10 r s s m s in s s m s in ? ? ? ? ? ? ? ? ? ? ? = where: lm - power transformer magnetizing inductance fs = switching frequency in the example, ? = ? ? ? ? ? ? ? ? ? ? ? ? ? = 240 ) 3 e 250 100 6 e 450 21 36 085 . 0 ( ) 0 . 1 5 . 2 ( 20 ) 3 e 250 100 6 e 450 21 36 085 . 0 ( 10 r r10 c36 r22 c22 c13 u5 sc4910 18 17 11 16 6 4 10 7 20 19 3 1 15 2 5 14 8 9 13 12 fb comp outb ishare phase cs outa agnd rt1 rt2 ss -sense delay sy nc/en vref avcc pgnd pgnd pvcc pvcc r21 r12 r25 figure 2 applications information (cont.) closed-loop compensation the simplified control-to-output transfer function for the forward converter with current mode control, for small value of external slope ( se sn, sn is on-time slope of sensed current waveform) is given by: p z vgo vg s 1 s 1 g g + + = where closed loop current with stage power of gain dc r i v nn g s o o s vgo = closed loop current with stage power of pole ant min do rc 1 p = stage power of zero esr c r 1 esr z = where r - load resistance c - output capacitance resr - output capacitors esr for the given example above, at low line and r = 0.165 ? , c = 2 x 680uf = 1360uf, r esr = 17m ? , therefore: db 13 71 . 4 21 20 3 . 3 100 6 g vgo = = ? ? ? = hz 6887 s / rad 43253 6 e 1360 x 3 e 17 1 hz 710 s / rad 4456 6 e 1360 x 165 . 0 1 z p = = ? ? = = = ? =
11 ? 2005 semtech corp. www.semtech.com SC4910A/b power management type 2 compensator (figure 3) is needed for the above current mode control. the compensation network gives the following characteristics: p z 1 comp s 1 s 1 s g + + = figure 3 where 3 1 3 1 2 pc 1 2 zc 3 1 1 1 c c c c r 1 c r 1 ) c c ( r 1 + = = + = the loop gain will be given by: o ref pc zc 1 p z vgo fb comp vg v v s 1 s 1 s s 1 s 1 g k g g t ? + + ? + + = = figure 4 applications information (cont.) the goal of the compensation design is to shape the loop with high dc gain, high bandwidth, enough phase margin, and high attenuation for high frequency noises. figure 4 gives the asymptotic diagrams of the power stage with current loop closed and its loop gain. one integrator is added to increase the dc gain. w zc is used to cancel the power stage pole w p so that the loop gain has ?20db rate when it reaches 0 db line. w pc is placed at output capacitor esr or half switching frequency, whichever is lower. arbitrarily choose r2, then ) c c ( 1 r , 1 c c , r c 3 1 i 1 zc pc 1 3 p 2 1 1 + = ? = = i is adjusted for satisfactory phase margin and crossover frequency. synchronization synchronization of oscillators in multiphase operation allows for reduced size of filtering components and improved dynamic response. sc4910 provides single stage conversion where sc4201 provides the multiphase function. sc4910 and sc4201 are placed on the secondary side, outputs a and c of the sc4201 are fed into the sync pins of 2 separate sc4910?s. both power supplies operate 180 degrees apart. sc4201 can be configured up to 4 phase operation. r2 c3 c1 r1 vref - + c pc z p loop gain t(s) power stage compensator zc fs
12 ? 2005 semtech corp. www.semtech.com SC4910A/b power management load remote sensing dedicated -sense pin provides true remote sensing of the regulated supply?s output terminal voltage for high current applications. as shown in figure 5, the bandgap reference ?ground ? is brought out as ?sense, which is connected to the ?load ground? and to the local analog ground by the resistor r10. with this way combined with upper side r1, the voltage drop on power line is offset and the load voltage is truly sensed. r7 r8 load r10 c5 sc4910 18 17 11 16 6 4 10 7 20 19 3 1 15 2 5 12 8 9 13 14 fb comp outb ishare phase cs outa agnd rt1 rt2 ss -sense delay sync/en vref pvcc pgnd pgnd pvcc avcc c6 r1 r6 figure 5 load current sharing a single wire connected between the ishare pins will force current sharing between parallel units for paralleling or n+1 redundant operation. the ishare pin allows for current sharing between several parallel units. the ishare pin connects internally to the non-inverting input of ishare amplifier. an internal 4k ? resistor is between the inverting and non-inverting inputs of this amplifier, with the inverting input also connected to the comp pin. the output of the amplifier connects to the ss (0.75v ref) pin. during normal operation, when all devices are sharing the load current equally, the comp pin voltages on each units should be approximately equal. if one of the devices begins to take on too much or too little of the load, the difference in comp pin voltage will cause the ishare amplifier to adjust the ss (0.75v ref) voltage accordingly. in the event of ishare pulled down below 1v, the ishare amplifier is disabled to prevent output voltage of the unit lower than specification. applications information (cont.)
13 ? 2005 semtech corp. www.semtech.com SC4910A/b power management typical characteristics icc vs vcc 8.00 10.00 12.00 14.00 16.00 18.00 4.5 6.5 8.5 10.5 12.5 14.5 vcc (v) icc (ma) ta = 25c sync/en = high sync/en = low icc vs temperature 0.00 5.00 10.00 15.00 20.00 25.00 -40 -20 0 20 40 60 80 100 120 temperature (c) icc (ma) vcc = 12v syn/en = high syn/en = low (SC4910A) uvlo hysteresis vs temperature 550.00 555.00 560.00 565.00 570.00 575.00 580.00 -40 -20 0 20 40 60 80 100 120 temperature (c) uvlo hysteresis (mv) (SC4910A) uvlo high threshold vs temperature 8.90 8.91 8.92 8.93 8.94 8.95 8.96 8.97 8.98 -40 -20 0 20 40 60 80 100 120 temperature (c) uvlo high thre shold (v) (sc4910b) uvlo hysteresis vs temperature 284.00 286.00 288.00 290.00 292.00 294.00 296.00 298.00 300.00 302.00 -40 -20 0 20 40 60 80 100 120 temperature (c) uvlo hysteresis (mv) (sc4910b) uvlo high threshold vs temperature 4.52 4.52 4.53 4.53 4.54 4.54 4.55 4.55 4.56 -40 -20 0 20 40 60 80 100 120 temperature (c) uvlo high thre shold (v)
14 ? 2005 semtech corp. www.semtech.com SC4910A/b power management typical characteristics (cont.) error amp input bias current vs vcc 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 4.5 6.5 8.5 10.5 12.5 14.5 vcc (v) error amp input bias current (na) t a = 25c vfb = 5v vfb = 0v error amp input bias current vs temperature -200.00 -100.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 -40 -20 0 20 40 60 80 100 120 temperature (c) error amp input bias current (na) vcc = 12v vfb = 5v vfb = 0v error amp offset voltage vs vcc -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 4.5 6.5 8.5 10.5 12.5 14.5 vcc (v) error amp offse t voltage (mv) t a = 25c error amp offset voltage vs temperature 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 -40 -20 0 20 40 60 80 100 120 temperature (c) error amp offse t voltage (mv) vcc = 12v bandgap voltage vs vcc 0.745 0.747 0.749 0.751 0.753 0.755 9 101112131415 vcc (v) bandgap voltage (v) t a = 25c iout = 0ma bandgap voltage vs temperature 0.7475 0.7480 0.7485 0.7490 0.7495 0.7500 0.7505 -40 -20 0 20 40 60 80 100 120 temperature (c) bandgap voltage (v) vcc = 12v
15 ? 2005 semtech corp. www.semtech.com SC4910A/b power management error amp output voltage vs temperature 0.50 1.00 1.50 2.00 2.50 3.00 -40 -20 0 20 40 60 80 100 120 temperature (c) error amp output voltage (v) vcc = 12v icomp = 1ma high low oscillator frequency vs temperature 475 480 485 490 495 500 505 510 515 520 525 -40 -20 0 20 40 60 80 100 120 temperature (c) oscillator frequency (khz) rt1 = rt2 = 50kohm enable voltage vs temperature 0.50 1.00 1.50 2.00 2.50 3.00 -40 -20 0 20 40 60 80 100 120 temperature (c) enable voltage (v) vcc = 12v high low max duty cycle vs temperature 89.00 89.20 89.40 89.60 89.80 90.00 90.20 90.40 90.60 90.80 91.00 -40 -20 0 20 40 60 80 100 120 te mpe rature (c) max duty cycle (%) output a progammable delay vs temperature 60.00 65.00 70.00 75.00 80.00 85.00 90.00 -40 -20 0 20 40 60 80 100 120 temperature (c) progammable delay (ns) rdelay = 50kohm typical characteristics (cont.)
16 ? 2005 semtech corp. www.semtech.com SC4910A/b power management evaluation board schematics d5 1n4148ws q2 fmmt718 d6 1n4148ws c1 2.2nf +12v r3 5.1 2 7 6 3 1 8 4 5 u4 sc 1302a d1 es1d +12pri +vin c17 0.1uf fb 18 comp 17 outb 11 ishare 16 ph ase 6 cs 4 outa 10 agnd 7 rt1 20 rt2 19 ss 3 -sense 1 delay 15 sync/en 2 vr ef 5 avcc 14 pgnd 8 pgnd 9 pvcc 13 pvcc 12 u5 sc 4910 1 3 4 6 t3 pe68386 d10 1n4148ws r14 37.4k r15 18.2k r25 62k d12 1n4148ws r12 22 r11 10k r37 5.1 ilim=24a 3.3v/20a r27 100k d11 1n4148ws r1 39k +vin c11 0.1uf d15 smaz20 4 5 3 2 1 6 7 8 m6 si4490dy 4 5 3 2 1 6 7 8 m7 not populat ed c16 0.1uf c32 2.2nf c12 0.1uf c26 0.47uf 1u,100v c33 1u,100v c34 4 5 3 2 1 6 7 8 m3 si4842dy r26 10.0 4 5 3 2 1 6 7 8 m2si4842dy r18 10k r38 10k fs=250khz r13 10.0k vin+ vin- con1 c18 0.1uf c28 100pf c19 0.1uf c13 150pf r5 4.7 c22 0.1uf luvlo 1 rt 2 fb 3 comp 4 ilim 5 gnd 6 out 7 vc c 8 u6 sc4911 r6 10k c20 100pf c21 1.0nf r50 10 8 7 1 3 t2 p8208t 3 4 5 8 2 1 t4 pb2090 2 5 8 10 t1 pa0168a d14 b130l c23 47uf r8 4.7 r4 10k c30 47nf c24 47uf c31 1000pf c29 150pf c2 0.1uf,100v c36 0.1uf c25 47uf l1 1.3uh c8 680uf +12v * : optional r28 2.7meg r30 100k r35 20k r31 470k 1 2 4 5 vr ef u3 sc4431 r33 100k r36 100k r34 1.00 r29 68 r32 51 q3 fmmt718 q4 not populated +12v c14 0.1uf c37 470pf q1 si2320ds d9 1n4148ws d20* 1n5819hw c50 22nf 1u,100v c5 r17 1k d22* 1n5819hw d21* 1n5819hw q5 fmmt718 d2 1n4148ws c27 10uf r51 10 1u,100v c4 1u,100v c3 +12v 4 5 3 2 1 6 7 8 m1 s i4842dy 4 5 3 2 1 6 7 8 m4 si4842dy +12v d3 1n4148ws 2 7 6 3 1 8 4 5 u2 sc1302a r53 0 r21 124k vout- 7 sens e 4 ishar e 5 sens e 3 vout+ 1 en 6 con2 c6 100uf r22 75k r23 43k r10 1.5k 4 5 3 2 1 6 7 8 m5 si4490dy r52 1k c51 10uf c7 100uf r24 2.0k r19 6.8k c9 680uf r2 10.0
17 ? 2005 semtech corp. www.semtech.com SC4910A/b power management m e t iy t i t n a u qe c n e r e f e rt r a p# r e r u t c a f u n a mt n i r p t o o f 32 2 3 c , 1 cf n 2 . 25 0 8 0 _ c / m s 412 cv 0 0 1 , f u 1 . 0m 4 0 1 a 2 r 7 x 6 1 2 3 c , k d t6 0 2 1 _ c / m s 55 4 3 c , 3 3 c , 5 c , 4 c , 3 cv 0 0 1 , f u 1, a t a r u m b 1 0 a k 5 0 1 a 2 7 r r 5 5 m r g 0 2 2 2 _ c / m s 64 9 c , 8 c , 7 c , 6 cv 4 , f u 0 8 60 8 6 b p t 4 , o y n a s3 4 3 7 _ t c / m s 70 1, 9 1 c , 8 1 c , 7 1 c , 6 1 c , 4 1 c , 2 1 c , 1 1 c 1 5 c , 6 3 c , 2 2 c f u 1 . 05 0 8 0 _ c / m s 82 9 2 c , 3 1 cf p 0 5 15 0 8 0 _ c / m s 91 0 2 cf p 0 6 55 0 8 0 _ c / m s 0 111 2 cf n 5 . 15 0 8 0 _ c / m s 1 13 5 2 c , 4 2 c , 3 2 cv 6 1 , f u 7 47 4 b p t 6 1 , o y n a s3 4 3 7 _ t c / m s 2 116 2 cf u 7 4 . 06 0 2 1 _ c / m s 3 117 2 cv 0 1 , f u 0 1, a t a r u m l 1 3 c k 6 0 1 c 1 6 r e 2 3 m r g 0 1 2 1 _ c / m s 4 118 2 cf p 0 0 15 0 8 0 _ c / m s 5 110 3 cf n 7 45 0 8 0 _ c / m s 6 111 3 cf p 0 0 0 15 0 8 0 _ c / m s 7 117 3 cf p 0 7 45 0 8 0 _ c / m s 8 110 5 cf n 2 25 0 8 0 _ c / m s 9 111 dd 1 s e3 1 - d 1 s e . c n i s e d o i da m s _ / m s 0 20 1, 9 d , 6 d , 5 d , 2 d 2 2 d , 1 2 d , 0 2 d , 2 1 d , 1 1 d , 0 1 d w h 9 1 8 5 n 17 - w h 9 1 8 5 n 1 . c n i s e d o i d3 2 1 d o s 1 214 1 dl 0 3 1 b3 1 - l 0 3 1 b . c n i s e d o i da m s 2 215 1 da 0 2 j a m s3 1 - a 0 2 1 j a m s . c n i s e d o i da m s 3 211 lh u 3 . 1e 3 r 1 f a p q t e , c i n o s a n a p1 s - c c p 4 24 4 m , 3 m , 2 m , 1 my d 2 4 8 4 i sy a h s i v8 - o s 5 22 6 m , 5 my d 0 9 4 4 i sy a h s i v8 - o s 6 211 qs d 0 2 3 2 i sy a h s i v3 2 1 _ 3 2 t o s / m s 7 211 rk 9 35 0 8 0 _ r / m s 8 22 6 2 r , 2 r0 15 0 8 0 _ r / m s 9 22 7 3 r , 3 r1 . 55 0 8 0 _ r / m s 0 36 8 3 r , 8 1 r , 7 1 r , 1 1 r , 6 r , 4 rk 0 15 0 8 0 _ r / m s 1 32 8 r , 5 r7 . 45 0 8 0 _ r / m s evaluation board bill of materials
18 ? 2005 semtech corp. www.semtech.com SC4910A/b power management evaluation board bill of materials m e t iy t i t n a u qe c n e r e f e rt r a p# r e r u t c a f u n a mt n i r p t o o f 2 310 1 r2 1 45 0 8 0 _ r / m s 3 312 1 r2 25 0 8 0 _ r / m s 4 313 1 rk 0 . 0 15 0 8 0 _ r / m s 5 314 1 rk 4 . 7 35 0 8 0 _ r / m s 6 315 1 rk 2 . 8 15 0 8 0 _ r / m s 7 319 1 rk 5 . 1 25 0 8 0 _ r / m s 8 311 2 rk 0 6 15 0 8 0 _ r / m s 9 312 2 rk 2 . 0 45 0 8 0 _ r / m s 0 413 2 rk 3 45 0 8 0 _ r / m s 1 414 2 rk 9 1 . 65 0 8 0 _ r / m s 2 415 2 rk 0 1 15 0 8 0 _ r / m s 3 43 3 3 r , 0 3 r , 7 2 rk 0 0 15 0 8 0 _ r / m s 4 418 2 rg e m 7 . 25 0 8 0 _ r / m s 5 439 2 r8 65 0 8 0 _ r / m s 6 411 3 rk 3 8 35 0 8 0 _ r / m s 7 412 3 r1 55 0 8 0 _ r / m s 8 414 3 r15 0 8 0 _ r / m s 9 415 3 rk 7 . 45 0 8 0 _ r / m s 0 516 3 rk 0 3 15 0 8 0 _ r / m s 1 52 1 5 r , 0 5 r0 15 0 8 0 _ r / m s 2 512 5 rk 0 . 15 0 8 0 _ r / m s 3 511 t8 6 1 0 a pe s l u p4 p x 4 512 tt 8 0 2 8 pe s l u p8 0 2 8 p 5 513 t6 8 3 8 6 e pe s l u p6 8 3 8 6 e p 6 514 tr 4 1 4 1 3m o c d i m 7 52 4 u , 2 ua 2 0 3 1 c sh c e t m e sn i p 5 _ 3 2 t o s 8 513 u1 3 4 4 c sh c e t m e sn i p 5 _ 3 2 t o s 9 515 u0 1 9 4 c sh c e t m e s0 2 - p o s s t 0 616 u1 1 9 4 c sh c e t m e s8 - p o s m
19 ? 2005 semtech corp. www.semtech.com SC4910A/b power management outline drawing - tssop-20 semtech corporation power management products division 200 flynn road, camarillo, ca 93012 phone: (805)498-2111 fax (805)498-3804 contact information land pattern - tssop-20 this land pattern is for reference purposes only. consult your manufacturing group to ensure your company's manufacturing guidelines are met. notes: 1. f x h inches dimensions z p y x dim c g millimeters h .126 3.20 f .157 4.00 (.222) (5.65) z g y p (c) 4.10 .161 0.65 .026 0.40 .016 1.55 .061 7.20 .283 l (l1) c 01 gage plane see detail detail a a 0.25 .026 bsc .252 bsc 20 .004 .169 .251 .173 .255 .007 - 20 0.10 0.65 bsc 6.40 bsc 4.40 6.50 - .177 .259 4.30 6.40 .012 0.19 4.50 6.60 0.30 bxn 2x n/2 tips seating aaa c e/2 indicator pin 1 2x 1 3 2 n e1 bbb c a-b d ccc c dimensions "e1" and "d" do not include mold flash, protrusions 3. or gate burrs. datums and to be determined at datum plane controlling dimensions are in millimeters (angles in degrees). -b- notes: 1. 2. -a- -h- side view (.039) .004 .008 - .024 - - - - 0 .018 .003 .031 .002 - 8 0 0.20 0.10 - 8 0.45 0.09 0.80 0.05 .030 .007 .047 .042 .006 - (1.0) 0.60 - 0.75 0.20 - - - 1.20 1.05 0.15 a b c d e e/2 h plane d e a1 a2 a reference jedec std mo-153, variation ac. 4. inches b n ccc aaa bbb 01 e1 e l l1 e d c a2 a1 dim a min max millimeters min dimensions nom max nom

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