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wt1117a 1.0a low dropout precision linear regulators general description: applications: weitron hpp://www .weitron.com.tw weitr on 1/11 rev-a 18-oct-06 features: lead( p b ) - f r ee p b * high e?ciency linear regulators * post regulators for switching supplies * microprocessor supply * hard drive controllers * battery chargers * adjustable power supply * adjustable or fixed output * output current of 1.0a * dropout voltage(typical) 1.15v @1.0a * line regulation 0.2% max. * load regulation 0.4% max. * fast transient response * current limit protection * thermal shutdown protection wt1117a of positive adjustable and fixed regulators is designed to provide 1.0a output with low dropout voltage performance. on-chip trimming adjusts the r eference voltage to 1.5%. for usage on working in post regulators or microprocessor power supplies, low voltage operation and fast transient response are required. wt1117a is available in surface-mount sot-223 and to-252 packag es.
wt1117a 2/11 rev-a 18-oct-06 weitron http://www .weitron.com.tw ordering information marking information & pin configurtions ( t o p v iew) t o-25 2 (d p ak) o n fixe d version s pi n 1 = gnd, o n adjustabl e version s pi n 1 = a t a b = v out dj v v/vv v = outpu t v oltag e (5 0 = 5.0 v , 285 = 2.85 v , x = adj ) a = assembl y location y = y ear w w = w eekly v in v out adj / gnd* 1117-vv yaww so t -223 v in v out adj/gnd* 1117-vv package shipping to-252 to-252 to-252 sot-223 sot-223 sot-223 ordering number wt1117an-x wt1117ad-x WT1117AN-15 wt1117ad-15 wt1117an-18 wt1117ad-18 wt1117an-25 wt1117ad-25 wt1117an-285 wt1117ad-285 wt1117an-30 wt1117ad-30 wt1117an-33 wt1117ad-33 wt1117an-50 wt1117ad-50 output voltage adj adj 1.5 1.8 1.8 1.5 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel 2,500 units/tape&reel to-252 sot-223 2.5 2.5 to-252 sot-223 2.85 2.85 to-252 to-252 to-252 sot-223 sot-223 sot-223 3.3 3.3 5.0 5.0 3.0 3.0 yaww
ty p i ca l a p p l i cat i o n weitron http://www .weitron.com.tw wt1117a 3/11 (adjustabl e v ersion) v out gnd v in wt 1 1 17a-3.3 (fixe d v ersion) + + c 10f t ant 1 c2 10f t an t min . v out = 3.3v v > 4.75v in v out adj v in + + c 10f t ant c2 10f t an t min . v out = 3.45v v > 4.75v in wt 1 1 17a-adj r1 133 1.0% r2 232 1.0% 2 3 1 2 3 1 notes: 1 . c 1 need e d i f devi c e i s f a r f r o m f ilt e r capacito r s 2 . c 2 minim u m val u e requir e d f o r stabili t y v v r2 out = x ( 1 + ) + i re f adj x r2 r1 v in v out gnd thermal shutdown bandgap reference output current limit error amplifier + - v in v out adj thermal shutdown bandgap reference output current limit error amplifier + - (adjustabl e v ersion) (fixe d v ersion) block diagram rev-a 18-oct-06
weitron http://www .weitron.com.tw wt1117a 4/11 rev-a 18-oct-06 parameter operatin g junctio n t emperatur e range contro l section powe r t ransistor powe r dissipation inpu t v oltage lea d t emperature(soldering , 10sec) storag e t emperatur e range therma l characteristics so t -223 therma l resistance , junction-to-case d p ak therma l resistance , junction-to-case symbol value internall y limited w t lead v in 7.0 300 -4 0 t o 125 -4 0 t o 150 v c c p d t stg -6 5 t o + 150 15 c t j r jc 6.0 c / w unit
weitron http://www .weitron.com.tw wt1117a 5/11 rev-a 18-oct-06 electrical characteristics typicals and limits appearing in normal type apply for tj 25c parameter symbol min t yp max unit condition referenc e v oltage outpu t v oltage wt 1 1 17a-adj v ref i =10ma , v = 5v 10m a i 1.0a , 2.65 v v 7v ou t in ou t in v = 0 i 1.0a in out v +1.5 v t o 7 v out 1.232 1.225 1.250 1.250 1.268 1.275 v % lin e regulation loa d regulation reg line reg load % % 1.15 2 1.3 7 dropou t v oltage curren t limit minimu m loa d current wt 1 1 17a-adj v d i cl i o min i =1.0a out v - v =1.5v i n out v =5 v , v adj=0v in 1.0 - - - - - - - - - - - - - - - - v a ma ma groun d current i q 7 13 35 0.005 0.003 72 90 adjus t pi n current t em p . co e f ficie n t therma l regulation rippl e rejection (not e 1) i load =10ma , 2.65 v v 7v in v - v =1.5 v , =10ma i n out i load t , a 30m s pulse =25 60 a %/w db wt 1 1 17a-adj i adj t c r a v - v =1.5 v , =1.0a i n out i load % / c 0.04 0.20 0.20 0.40 i =10ma, (1. 5 v + v ) load out v 7v out v v + 1.5v i =10m a t o 1.0a i n out load = v v + 1.5v i =10m a t o 1.0a i n out load = i =10ma , v = +1.5v ou t in v out % all all al l fixed v ersions all all not e 1 120h z inpu t rippl e : ( ) adj c fo r ad j =2 5 f -1.5 +1.5 - 2 + 2 all all all
weitron http://www .weitron.com.tw wt1117a typical performance characteristics 6/11 rev-a 18-oct-06 1.00 0.95 0.90 0.85 0.80 0.75 0 20 0 40 0 60 0 80 0 1000 i (ma) out v t u o p o r d fig.1 dropout voltage vs. output current 0.10 0.08 0.06 0.04 0.02 0.00 -0.02 -0.04 -0.06 -0.08 -0.10 -0.12 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 10 0 1 1 0 12 0 130 t c j ( ) v t u p t u o ) % ( n o i t a i v e d e g a t l o fig.2 reference voltage vs. temperature 70 65 60 55 50 45 40 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 10 0 1 1 0 12 0 130 t emperatur e c ( ) t n e r r u c n i p t s u j d a a ) ( 85 75 65 55 45 35 25 15 10 1 1 0 1 0 1 0 1 0 10 2 3 4 5 6 frequency(hz) ) b d ( n o i t c e j e r e l p p i r fig.3 adjust pin current vs. temperature fig.4 ripple rejection vs. frequency 300 200 100 0 -100 -200 1000 500 0 0 1 2 3 4 5 6 7 8 9 10 t i m s ( ) v ) a m ( p e t s d a o l ) v m ( n o i t a i v e d e g a t l o fig.5 transient response 3.5 3.3 3.1 2.9 2.7 2.5 2.3 2.1 1.9 1.7 1.5 1. 0 1. 5 2. 0 2. 5 3. 0 3. 5 4.0 v - v i n out(v) ) a ( i c s fig.6 short circuit current vs. v in - v out t 0c case = t 25c case = t 125c case = i = 10ma o v 3 3v c c 22 f t antalum c 0 1f out ou t in adj = . = = = . t 25c i 1 0a v v 3 0v v 1 0v p p c 0 1f case out adj = = . ( - ) = . = . - = . i n out ripple
weitron http://www .weitron.com.tw wt1117a 7/11 rev-a 18-oct-06 application information adjustable operation stability considerations v = v x ( ) + i x r2 ou t re f adj r 1 + r2 r1 v = i x esr v ref i adj c adj r1 r2 c 2 c 1 v in v out v in v out adj wt 1 1 17a figure1. resistor divider scheme wt1117a linear regulators provide fixed and adjustable output v oltages at currents up to 1.0a. these regulators are protected against overcurrent conditions and include therma l shutdown protection. the wt1117a's have a composite pnp-npn output transistorand require an output capa citor for stability. a detailed procedure for selecting this capacitor follows. the wt1117a has an output voltage range of 1.25 v to 5.5 v. an external resistor divider sets the output voltage as shown in figure 1. the regulator maintains a fixed 1.25v (ty pical) reference between the output pin and the adjust pin. a resistor divider network r1 and r2 causes a fixed current to flow to ground. this current creates a voltage across r2 that adds to the 1.25v across r1 and sets the overall output voltage. the adjust pin current (typically 35a) also flows through r2 and adds a small error t hat should be taken into account if precise adjustment of v out is necessary. the output voltage is set according to the formula: the term iadj r2 represents the error added by the adjust pin c urrent. r1 is chosen so that the minimum load current is at least 2.0ma r1 and r2 should be the same type e.g. metal film for best tracking over temperature. while not requir ed, a bypass capacitor from the adjust pin to ground will improve ripple rejection and transient response. a 0.1f t antalum capacitor is recommended for first cut design. type and value may be varied to obtainoptimum perfo rmance vs. price. t he output c ompens a tion capaci t or helps t o de t e r mine th r ee main cha r a c t e r istics of a linear r egul a t o r s pe r f o r man c e: sta r t -up del a y ,load t r ansie n t r espons e , and loop stabili t y . t he capaci t or v alue and t ype is based on c ost, a v ailabili t y , si z e and t empe r a tu r e c onst r ain s , a ta n talum or aluminum ele c t r olytic capaci t or is p r e f e r r e d , as a ?lm or c e r amic capaci t or with almost z e r o esr can cause i nstabili t y . an aluminum ele c t r olytic capaci t or is the least expensi v e t yp e . but when the ci r cuit ope r a t es a t l o w t empe r a tu r e s , both the v alue and esr of the capaci t or will v a r y widelt. f or optimum pe r f o r man c e o v er the full ope r a ting t empe r a tu r e r ang e , a ta n talum capaci t or is best, a 22f ta n talum capaci t or will w o r k ?ne in most applic a tion s , but with high cu r r e n t r egul a t ors such as the w t1117a higher capacitan c e v alues will imp r o v e the t r ansie n t r esponse and stabili t y . m ost applic a tions f or the w t1117 a s i n v ol v e la r ge changes in load cu r r e n t, so the output capaci t or must supply insta n taneous load cu r r e n t. t he esr of the output capaci t or causes an immedi a t e d r op in output v oltage g i v en b y : in microprocessor applications an output capacitor network of several tantalum and ceramic capacitors in parallel is commonly used. this reduces overall esr and minimizes the instantaneous output voltage drop under transient load conditions. the output capacitor network should be placed as close to the load as possible for the best results. used with large output capacitance values and theinput voltage is instantaneously shorted to ground, damage can occur. in this case, a diode connected as shown above in figure1.
weitron http://www .weitron.com.tw wt1117a 8/11 rev-a 18-oct-06 (a ) fixe d v ersion (b ) adjustabl e v ersion v in v out c adj wt 1 1 17a-adj a dj v in v out c1 c2 r1 r2 wt 1 1 17a-3.3 gnd v in v out c1 in4002 c2 v in v out in4002 figure2 (a),(b) protection diode scheme for large output capacitors w hen la r ge e x t e r nal capaci t ors a r e used with most linear r egul a t o r , it is wise t o add p r o t e c tion diode s . i f the input v oltage of the r egul a t or is sho r t e d , the output capaci t or will discha r ge i n t o the output of the r egul a t o r . t he discha r ge cu r r e n t depends on the v alue of capaci t o r , output v oltag e , and r a t e a t which v in d r op s . i n the w t1117a linear r egul a t or s , the discha r ge p a th is th r ough a la r ge jun c tion, and p r o t e c tion diodes a r e no r mally not neede d . h o w e v e r , damage can o c cur if the r egul a t or is used with la r ge output capacitan c e v alues and the input v oltage is insta n taneously sho r t ed t o g r oun d . i n this cas e , a diode c onne c t ed as sh o wn ab o v e in f igu r e 2. t he w t1117a a r e th r ee t e r minal r egul a t or s . f or which, they cannot p r o vide true r emo t e load sensin g . l oad r egul a tion is limi t ed b y the r esistan c e of the c ondu c t ors c onne c ting the r egul a t or t o the loa d . f or best r esults the w t 1117a should be c onne c t ed a r e as sh o wn in f igu r e 3. p r otection diodes output v oltage sensing calculating powe r dissipation and heat sink requi r ements wt 1 1 17a-3.3 v in v out r load r c gnd v in conductor parasitic resistance (a ) fixe d v ersion (b ) adjustabl e v ersion wt 1 1 17a-adj a dj v out v in v in r c r load r1 r2 conductor parasitic resistance figure3 (a),(b) conductor parasitic resistance effects are minimized by this gr ounding scheme for fixed and adjustable output regulators t he w t1117a p r ecision linear r egul a t ors include the r mal shu t d o wn and cu r r e n t limit ci r cuit r y t o p r o t e c t the devi c e s . h o w e v e r , high p o w er r egul a t ors no r mally ope r a t e a t high jun c tion t empe r a tu r e s . i t is impo r ta n t t o calcul a t e the p o w er dissip a tion and jun c tion t empe r a tu r es a c cu r a t ely t o be su r e th a t y ou use and adequ a t e he a t sin k . t he case is c onne c t ed t o v out on the w t1117a, and ele c t r ical isol a tion m a y be r equi r ed f or some applic a tion s . t he r mal c ompound should al w a y s be used with high cu r r e n t r egul a t ors like the w t1117a.
weitron http://www .weitron.com.tw wt1117a 9/11 rev-a 18-oct-06 t he the r mal cha r a c t e r istics of an ic depend f our fa c t ors: 1. m aximum ambie n t t empe r a tu r e t a ( c ) 2. p o w er dissip a tion p d ( w a tts) 3. m aximum jun c tion jun c tion t empe r a tu r e t j ( c ) 4. t he r mal r esistan c e jun c tion t o ambie n t r ja (c/ w ) t he r el a tionship of these f our fa c t ors is exp r essed b y equ a tion (1): m aximum ambie n t t empe r a tu r e and p o w er dissip a tion a r e de t e r mined b y the desi g n while the maximum jun c tion t empe r a tu r e and the r mal r esistan c e depend on the manufa c tu r er and the pac k age t yp e . t he maximum p o w er dissip a tion f or a r egul a t or is exp r essed b y equ a tion (2): whe r e: v in(max) is the maximum input v oltag e , v out(min) is the minimum output v oltag e , i out(max) is the maximum output cu r r e n t i q is the maximum quies c e n t cu r r e n t a t i out(max) . a he a t sink e ? e c ti v ely inc r eases the su r fa c e a r ea of the pac k age t o imp r o v e the ? o w of he a t a w a y f r om the ic i n t o the ai r . each m a t e r ial in the he a t ? o w p a th be t w een the ic and the e n vi r onme n t has a the r mal r esistan c e . like se r ies ele c t r ical r esistan c e s , these r esistan c e a r e summed t o de t e r mine r ja the t otal the r mal r esistan c e be t w een the jun c tion and the ai r . t his is exp r essed b y equ a tion (3): w he r e all of the f oll o wing a r e in c/w r jc is the r mal r esistan c e of jun c tion t o cas e , r cs is the r mal r esistan c e of case t o he a t sin k , r sa is the r mal r esistan c e of he a t sink t o ambie n t air t he v alue f or r ja is calcul a t ed using equ a tion (3) and the r esult can be substitu t ed in equ a tion (1) . t he v alue f or r jc is 3.5c/w f or a g i v en pac k age t ype based on an a v e r age die si z e . f or a high cu r r e n t r egul a t or such as the w t1117a the majo r i t y of the he a t is gene r a t ed in the p o w er t r ansis t or se c tion. t j =t a + p d x r ja ........(1) p = { v - v } i + v i d(max ) in(max ) out(min ) out(ma x in(max ) q ) ........(2) r ja =r jc + r cs x r sa ........(3)
weitron http://www .weitron.com.tw wt1117a 10/11 rev-a 18-oct-06 sot-223 package outline dimensions 0 10 ~ unit : mm 3 0 0 0 10 . . 7 0 0 0 15 . . 1 75typ . 0 32 5 0 005 . . 1 6 0 0 05 . . 0.06 0 04 . to-252-3 package outline dimensions 6.5 0 0 10 . 5.3 0 0 10 . 1.4 0 . 0 10 2.3 0 0 10 . 0.5 1 0 005 . 1 2 0 25 . 0 . unit : mm 9.5 0 0 25 . 0.6 0 0 05 . 0.5 1 0 05 . 4.6 0 0 10 . 6 5 0 0 20 . . 3. 5 .15 0 0 5.5 0 . 0 10 2.3 0 0 05 . 2.3 0 0.05 4 6 0 0 10 . . 0.7 3 0 05 . 1 0 0 0 10 . . 0 0 05 .8 0 .
weitron http://www .weitron.com.tw wt1117a 11/11 rev-a 18-oct-06 ordering number wt1117 a - xx x circui t t ype output current = 1.0a package d : to-252 n : sot-223 output voltage - x : adj - 15 : 1.5v - 18 : 1.8v - 25 : 2.5v - 285 : 2.85v - 30 : 3.0v - 33 : 3.3v - 50 : 5.0v

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