for technical support and more information, see inside back cover or visit www.ti.com/powertrends features description the PT7742 is a 20 amp current booster for the pt7708 housed in the same 27-pin sip package. multiple PT7742 boosters will operate in parallel with one pt7708 product, boosting output current in increments of 20a. combinations of a pt7708 regulator and PT7742 current boosters can supply power for virtually any multiple mega-processor applica- tion. a PT7742 current booster adds a parallel output stage that is driven di- rectly by the regulator. this allows the system to run in perfect synchron- ization to provide a low noise solution. the PT7742 only operates in com- bination with a pt7708 series regulator, and is not a stand-alone product. please refer to the pt7708 data sheet for the performance specifications. the booster uses the same 27-pin case and has the same package options as its companion regulator. PT7742?3.3v 20 amp ?current booster? for pt7708 integrated switching regulator ordering information PT7742 ? ? 20a current boost ? tracks vo of a pt7708 ? high efficiency ? input voltage range: 3.1v to 3.6v ? synchronized with pt7708 ? 27-pin sip package ? connect up to 2 in parallel for 60 amps standard application (for dimensions and pc board layout, see package styles 800 and 810.) pin-out information pin function 1 do not connect 2 do not connect 3 do not connect 4 do not connect 5 do not connect 6 do not connect 7v in 8v in 9v in 10 v in 11 v in 12 do not connect 13 gnd pin function 14 gnd 15 gnd 16 gnd 17 gnd 18 gnd 19 gnd 20 v out 21 v out 22 v out 23 v out 24 v out 25 v out 26 do not connect 27 master sync in c in + c out + load v in vid0 vid1 vid2 vid3 v out gnd gnd stby* l1 1h remote sense ( ) remote sense (+) programming pins c in + l1 1h PT7742 20-25 13-19 27 7-11 vo vin gnd synch in pt7708 4321 26 20-25 12 5 13-19 27 7-11 vo vin gnd sns(+) sns(-) synch out stby vid3 - vid0 c out + pt series suffix (pt1234 x ) case/pin configuration vertical through-hole n horizontal through-hole a horizontal surface mount c external capacitors: the PT7742 requires a minimum ouput capacitance of 330f for proper operation. the PT7742 also requires an input capacitance of 1500f, which must be rated for a minimum of 1.4arms of ripple current. for transient or dynamic load applications additional capacitance may be required. for more information refer to the application note regarding capacitor selection for this product. input filter: an input filter inductor is optional for most applications. the inductor must be sized to handle 20adc with a typical value of 1h. slts085 (revised 6/30/2000)
application notes for technical support and more information, see inside back cover or visit www.ti.com/powertrends pt7708/pt7709, PT7742/pt7743 capacitor recommendations for the pt7708/09 regulators and PT7742/43 current boosters input capacitors the recommended input capacitance is determined by 1.4 ampere minimum ripple current rating and 1500f minimum capacitance. capacitors listed below must be rated for a minimum of 2x the input voltage with +5v operation. ripple current and 100m ? equivalent series resistance (esr) values are the major considerations along with temperature when selecting the proper capacitor. output capacitors the minimum required output capacitance is 330f with a maximum esr less than or equal to 100m ? . failure to observe this requirement may lead to regulator instability or oscillation. electrolytic capacitors have poor ripple per- formance at frequencies greater than 400khz, but excellent low frequency transient response. above the ripple fre- quency ceramic decoupling capacitors are necessary to improve the transient response and reduce any microproces- sor high frequency noise components apparent during higher current excursions. preferred low esr type capaci- tor part numbers are identified in the table 1 below. note: (n/r) is not recommended for this application, due to extremely low equivalent series resistance (esr) table 1 capacitors characteristic data tantalum characteristics tantalum capacitors with a minimum 10v rating are recommended on the output bus, but only the avx tps series, sprague 594/595 series, or kemet t495/t510 series. the avx tps series, sprague series or kemet series capacitors are specified over other types due to their higher surge current, excellent power dissipation and ripple current ratings. as an ex ample, the taj series by avx is not recommended. this series exhibits considerably higher esr, reduced power dissipation and lower ripple current capability. the taj series is a less reliable compared to the tps series when determining power dissipation capability. capacitor table table 1 identifies the characteristics of capacitors from a number of vendors with acceptable esr and ripple current (rms) ratings. the suggested minimum quantities per regu- lator for both the input and output buses are identified. this is not an extensive capacitor list. the table below is a selection guide for input and output capacitors. other capacitor vendors are available with comparable rms ripple current rating and esr (equivalent series resistance at 100khz). these critical parameters are necessary to insure both optimum regulator performance and long capacitor life. r o t i c a p a cr o t i c a p a c r o t i c a p a c r o t i c a p a cr o t i c a p a c / r o d n e v/ r o d n e v / r o d n e v / r o d n e v/ r o d n e v s e i r e ss e i r e s s e i r e s s e i r e ss e i r e s s c i t s i r e t c a r a h c r o t i c a p a cs c i t s i r e t c a r a h c r o t i c a p a c s c i t s i r e t c a r a h c r o t i c a p a c s c i t s i r e t c a r a h c r o t i c a p a cs c i t s i r e t c a r a h c r o t i c a p a cy t i t n a u qy t i t n a u q y t i t n a u q y t i t n a u qy t i t n a u q g n i k r o wg n i k r o w g n i k r o w g n i k r o wg n i k r o w e g a t l o ve g a t l o v e g a t l o v e g a t l o ve g a t l o v ) f ( e u l a v) f ( e u l a v ) f ( e u l a v ) f ( e u l a v) f ( e u l a vt n e l a v i u q e ) r s e (t n e l a v i u q e ) r s e ( t n e l a v i u q e ) r s e ( t n e l a v i u q e ) r s e (t n e l a v i u q e ) r s e ( e c n a t s i s e r s e i r e se c n a t s i s e r s e i r e s e c n a t s i s e r s e i r e s e c n a t s i s e r s e i r e se c n a t s i s e r s e i r e s m u m i x a m c 5 0 1m u m i x a m c 5 0 1 m u m i x a m c 5 0 1 m u m i x a m c 5 0 1m u m i x a m c 5 0 1 e l p p i re l p p i r e l p p i r e l p p i re l p p i r ) s m r i ( t n e r r u c) s m r i ( t n e r r u c ) s m r i ( t n e r r u c ) s m r i ( t n e r r u c) s m r i ( t n e r r u c l a c i s y h pl a c i s y h p l a c i s y h p l a c i s y h pl a c i s y h p ) m m ( e z i s) m m ( e z i s ) m m ( e z i s ) m m ( e z i s) m m ( e z i s t u p n it u p n i t u p n i t u p n it u p n i s u bs u b s u b s u bs u b t u p t u ot u p t u o t u p t u o t u p t u ot u p t u o s u bs u b s u b s u bs u b r e b m u n r o d n e vr e b m u n r o d n e v r e b m u n r o d n e v r e b m u n r o d n e vr e b m u n r o d n e v c i n o s a n a p c f g t m e c a f r u s a f v 6 1 v 5 3 v 0 1 v 6 1 0 0 2 2 0 3 3 0 8 6 0 0 8 1 8 3 0 . 0 ? 5 6 0 . 0 ? ? 0 9 0 . 0 ? 2 3 0 . 0 a m 0 0 0 2 a m 5 0 2 1 a m 5 5 7 a m 0 0 0 2 5 . 6 1 x 8 1 5 . 6 1 x 5 . 2 1 5 . 2 1 x 0 1 5 1 x 8 1 1 1 1 1 1 1 n 2 2 2 c 1 c f v e e q l 1 3 3 v 1 c f v e e 1 8 6 a 1 a f u e e a 2 8 1 c 1 a f u e e d e t i n u n o c - i m e h c s e i r e s v f l v 5 2 v 6 1 v 6 1 0 3 3 0 0 2 2 0 7 4 4 8 0 . 0 ? 8 3 0 . 0 ? 4 8 0 . 0 ? 2 4 0 = 2 / ? a m 5 2 8 a m 0 3 6 1 2 x a m 5 2 8 6 1 x 0 1 0 2 x 6 1 6 1 x 0 1 1 1 1 1 l l 6 1 x 0 1 m 1 3 3 b v 5 2 v x l l l 0 2 x 6 1 m 2 2 2 b v 6 1 v x l l l 6 1 x 0 1 m 1 7 4 b v 6 1 v x l n o c i h c i n s e i r e s l p s e i r e s m p v 0 1 v 0 1 v 5 2 0 8 6 0 0 8 1 0 3 3 0 9 0 . 0 ? 4 4 0 . 0 ? 5 9 0 . 0 ? a m 0 7 7 a m 0 2 4 1 a m 0 5 7 5 1 x 0 1 5 1 x 6 1 5 1 x 0 1 1 1 1 1 6 h h m 1 8 6 a 1 l p u 6 h h m 2 8 1 a 1 l p u 6 h p m 1 3 3 e 1 l p u s s n o c s o v s v 0 1 v 0 1 0 3 3 0 3 3 6 0 0 . 0 = 4 / w 5 2 0 . 0 ? 5 0 0 . 0 = 4 / 0 2 0 . 0 ? a m 0 0 8 9 > a m 0 0 8 9 > 5 . 0 1 x 0 1 6 . 2 1 x 3 . 0 1 4 4 r / n ) e t o n ( m 0 3 3 s s 0 1 g t m e c a v f u s ( m 0 3 3 v s 0 1 x v a m u l a t a n a t s e i r e s - s p t v 0 1 v 0 1 0 3 3 0 3 3 0 2 = 5 / 0 0 1 . 0 ? 0 6 0 . 0 ? a m 0 0 5 3 a m 6 2 8 1 x l 3 . 7 x w 3 . 4 h 1 . 4 5 5 1 1 0 0 1 0 r 0 1 0 m 7 3 3 v s p t 0 6 0 0 r 0 1 0 m 7 3 3 v s p t e u g a r p s m u l a t n a t d 4 9 5 / d 5 9 5 v 0 1 v 0 1 0 3 3 0 8 6 1 1 0 . 0 = 4 / w 5 4 0 . 0 ? 0 9 0 . 0 ? a m 0 0 5 4 > a m 0 6 6 1 > x l 3 . 7 x w 7 . 5 h 0 . 4 5 2 1 1 t 2 r 0 1 0 0 x 7 3 3 d 4 9 5 t n u o m e c a f r u s t 2 r 0 1 0 0 x 7 8 6 d 5 9 5 t e m e k m u l a t n a t 5 9 4 t / 0 1 5 t s e i r e s v 0 1 v 0 1 0 3 3 0 2 2 5 3 0 . 0 ? 0 7 0 . 0 ? 5 3 0 . 0 = 2 / ? a m 0 0 0 2 a m 0 0 0 2 > l 3 . 7 x w 3 . 4 h 0 . 4 x 5 6 1 2 s a 0 1 0 m 7 3 3 x 0 1 5 s a 0 1 0 m 7 2 2 x 5 9 4 t t n u o m e c a f r u s p a c s o p o y n a s b p t v 0 10 2 20 4 0 . 0 ? a m 0 0 0 3x l 2 . 7 x w 3 . 4 h 1 . 3 62 m 0 2 2 b p t 0 1 t n u o m e c a f r u s
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