1/10 L5973D may 2002 this is preliminary information on a new product now in development or undergoing evaluation. details are subject to change wit hout notice. n 2.5a internal switch n operating input voltage from 4.4v to 36v n 3.3v / ( 2%) reference voltage n output voltage adjustable from 1.235v to 35v n low dropout operation: 100% duty cycle n 250khz internally fixed frequency n voltage feedforward n zero load current operation n internal current limiting n inhibit for zero current consumption n synchronization n protection against feedback disconnection n thermal shutdown applications: n consumer: stb, dvd, tv, vcr,car radio, lcd monitors n networking: xdsl, modems,dc-dc modules n computer: printers, audio/graphic cards, optical storage, hard disk drive n industrial: chargers, car battery dc-dc converters description the L5973D is a step down monolithic power switch- ing regulator with a minimum switch current limit of 2.5a so it is able to deliver more than 2a dc current to the load depending on the application conditions. the output voltage can be set from 1.235v to 35v. the high current level is also achieved thanks to an so8 package with exposed frame, that allows to re- duce the r th(j-amb) down to approximately 40c/w the device uses an internal p-channel d-mos tran- sistor (with a typical rdson of 250m w ) as switching element to minimize the size of the external compo- nents. an internal oscillator fixes the switching frequency at 250khz. having a minimum input voltage of 4.4v only, it is particularly suitable for 5v bus, available in all com- puter related applications. pulse by pulse current limit with the internal frequen- cy modulation offers an effective constant current short circuit protection. hsop8 - exposed pad ordering number: L5973D preliminary data 2.5a switch step down switching regulator test application circuit vin=4.4 to 35v c1 10uf 35v ceramic d1 stps2l25u vcc comp gnd out fb inh sync vref 1 3 7 5 6 4 8 2 r3 4.7k l1 33uh coilcraft r1 5.6k r2 3.3k c3 22nf 3.3v c4 san y o poscap 100uf 10v L5973D vout=3.3v c2 220pf
L5973D 2/10 pin connection pin description thermal data (*) package mounted on board absolute maximum ratings n pin function 1 out regulator output. 2 sync master/slave synchronization. 3 inh a logical signal (active high) disables the device. if inh not used the pin must be grounded. when it is open an internal pull-up disable the device. 4 comp e/a output for frequency compensation. 5 fb feedback input. connecting directly to this pin results in an output voltage of 1.23v. an external resistive divider is required for higher output voltages. 6 vref 3.3v v ref . no cap is requested for stability. 7 gnd ground. 8 vcc unregulated dc input voltage. symbol parameter value unit r th (j-amb) thermal resistance junction to ambient max. 40 (*) c/w symbol parameter value unit v 8 input voltage 40 v v 1 output dc voltage output peak voltage at t = 0.1 m s -1 to 40 -5 to 40 v v i 1 maximum output current int. limit. v 4 , v 5 analog pins 4 v v 3 inh -0.3v to v cc v 2 sync -0.3 to 4 v p tot power dissipation at t amb 60c 2.25 w t j operating junction temperature range -40 to 150 c t stg storage temperature range -55 to 150 c out sync inh comp 1 3 2 4 vcc vref gnd fb 8 7 6 5 d98in955
3/10 L5973D electrical characteristics (t j = 25c, v cc = 12v, unless otherwise specified.) (*) specification referred to tj from 0 to 125c. symbol parameter test condition min. typ. max. unit v cc operating input voltage range v o = 1.235v; i o = 2a * 4.4 36 v v d dropout voltage v cc = 4.4v; i o = 2a * 0.5 1 v i l maximum limiting current v cc = 4.4v to 36v * 2.5 3 3.5 a f s switching frequency * 212 250 280 khz 225 250 275 khz duty cycle 0 100 % dynamic characteristics (see test circuit ). v 5 voltage feedback 4.4v < v cc < 36v, 20ma < i o < 2a 1.220 1.235 1.25 v * 1.198 1.235 1.272 v h efficiency v o = 5v, v cc = 12v 90 % dc characteristics i qop total operating quiescent current *35ma i q quiescent current duty cycle = 0; v fb = 1.5v 2.5 ma i qst-by total stand-by quiescent current v inh > 2.2v * 50 100 m a v cc = 36v; v inh > 2.2v * 80 150 m a inhibit inh threshold voltage device on 0.8 v device off 2.2 v error amplifier v oh high level output voltage vfb = 1v 3.5 v v ol low level output voltage vfb = 1.5v 0.4 v i o source source output current v comp = 1.9v; v fb = 1v 200 300 m a i o sink sink output current v comp = 1.9v; v fb = 1.5v 1 1.5 ma i b source bias current 2.5 4 m a dc open loop gain r l = 50 57 db gm transconductance i comp = -0.1ma to 0.1ma v comp = 1.9v 2.3 ms sync function high input voltage v cc = 4.4v to 36v 2.5 v ref v low input voltage v cc = 4.4v to 36v 0.74 v slave sink current v sync = 0.74v v sync = 2.33v 0.11 0.21 0.25 0.45 ma ma master output amplitude i source = 3ma 2.75 3 v output pulse width no load, v sync = 1.65v 0.20 0.35 m s reference section reference voltage 3.234 3.3 3.366 v i ref = 0 to 5ma v cc = 4.4v to 36v * 3.2 3.3 3.399 v line regulation i ref = 0ma v cc = 4.4v to 36v 510mv load regulation i ref = 0 to 5ma 8 15 mv short circuit current 10 8 30 ma
L5973D 4/10 figure 1. line regulation figure 2. output voltage vs. junction temperature figure 3. quiescent current vs. junction temperature figure 4. shutdown current vs.junction temperature figure 5. switching frequency vs.junction temperature 3.276 3.28 3.284 3.288 3.292 3.296 3.3 3.304 3.308 3.312 010203040 vcc (v) tj = 125c tj = 25c vcc = 12v vo = 3.3v vo (v) t j (c) vcc=12v 1.2 1.21 1.22 1.23 1.24 1.25 -50 0 50 100 150 vo (v) vcc = 12v 1.2 1.4 1.6 1.8 2 -50 050 100 150 tj (c) iq (ma) vcc = 12v dc = 0% 30 40 50 60 70 -50 0 50 100 150 ishd ( m a) vcc = 12v tj (c) 220 230 240 250 260 -50 0 50 100 150 t j ( c ) fsw ( khz ) vcc = 12v vo = 3.3v
5/10 L5973D application circuit in figure 6 is shown the demo board application circuit, where the input supply voltage, vcc, can range from 4.4v to 25v due to the rated voltage of the input capacitor and the output voltage is adjustable from 1.235v to v cc . figure 6. demo board application circuit table 1. component list reference part number description manufacturer c1 10 m f, 25v tokin c2 10tpb100m 100 m f, 10v sanyo, poscap c3 c1206c221j5gac 220pf, 5%, 50v kemet c4 c1206c223k5rac 22nf, 10%, 50v kemet r1 5.6k, 1%, 0.25w neohm r2 3.3k, 1%, 0.25w neohm r3 2.7k, 1%, 0.25w neohm d1 stps2l25u 2a, 25v st l1 do3316p-153 15 m h, 3a coilcraft vinmax=25v c1 10uf 25v tokin d1 stps2l25u vcc comp gnd out fb inh sync vref L5973D 1 3 7 5 6 4 8 2 r3 4.7k l1 15uh coilcraft r1 5.6k r2 3.3k c3 22nf 3.3v c4 san y o poscap 100uf 10v vout=3.3v c2 220pf
L5973D 6/10 figure 7. pcb layout (component side) figure 8. pcb layout (bottom side) figure 9. pcb layout (front side) below some graphs show the tj versus output current in different conditions of the input and output voltage and some efficiency measurements. 42mm 34mm
7/10 L5973D figure 10. junction temperature vs. output current (v cc = 5v) figure 11. junction temperature vs. output current (v cc = 12v) figure 12. efficiency vs. output current (v cc = 5v) figure 13. efficiency vs. output curren (v cc = 12v)t 20 30 40 50 60 70 80 90 100 110 120 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 io(a) tj(c) vin=5v tamb=25c vo=2.5v vo=3.3v vo=1.8v 20 30 40 50 60 70 80 90 100 110 120 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 io (a) tj (c) vin=12v tamb=25c vo=3.3v vo=2.5v vo=5v 60 65 70 75 80 85 90 95 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 io (a) efficiency (%) vcc=5v vo=1.8v vo=2.5v vo=3.3v 60 65 70 75 80 85 90 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2. 4 io (a) efficiency (%) vcc=12v vo=2.5v vo=3.3v vo=5v
L5973D 8/10 application ideas figure 14. positive buck-boost regulator figure 15. buck-boost regulator figure 16. dual output voltage with auxiliary winding vin=5v c1 10uf 10v ceramic d1 stps2l25u vcc comp gnd out fb inh sync vref L5973D 1 3 7 5 6 4 8 2 r3 4.7k l1 15uh r1 5.6k r2 3.3k c3 22nf 3.3v c4 100uf 16v vout=12v/0.6a c2 220pf d2 stps2l25u m1 stn4ne03l vin=5v c1 10uf 10v ceramic d1 stps2l25u vcc comp gnd out fb inh sync vref L5973D 1 3 7 5 6 4 8 2 r3 4.7k l1 15uh r1 5.6k r2 3.3k c4 22nf 3.3v c5 100uf 16v vout=-12v/0.6a c3 220pf c2 10uf 25v ceramic vin=12v c1 10uf 25v ceramic d1 stps25l25u vcc comp gnd out fb inh sync vref L5973D 1 3 7 5 6 4 8 2 r3 4.7k c3 22nf 3.3v vout=3.3v 0.5a c2 220pf vout1=5v 50ma c5 47uf 10v lp=22uh d2 1n4148 c4 100uf 10v n1/n2=2
9/10 L5973D outline and mechanical data dim. mm inch min. typ. max. min. typ. max. a 1.350 1.750 0.531 0.069 0.100 0.250 0.004 0.010 1.100 1.650 0.043 0.065 0.330 0.510 0.013 0.020 0.190 0.250 0.07 0.010 4.800 5.000 0.189 0.197 3.800 4.000 0.150 0.157 1.270 0.05 5.800 6.200 0.228 0.244 0.250 0.500 0.010 0.020 0.400 1.270 0.016 0.05 k 0? (min), 8? (max) ddd 0.100 0.010 (1) dimension d does not include mold flash, protusions or gate burrs shall not exeed 0.15mm (both side). hsop8 7195016 (exposed pad) a1 a2 b c d e e h h l exposed pad: d1 = 3.1mm e1 = 2.41mm
information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the co nsequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specifications mentioned in this publicati on are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectronics prod ucts are not authorized for use as critical components in life support devices or systems without express written approval of stmicroelectro nics. the st logo is a registered trademark of stmicroelectronics a 2002 stmicroelectronics - all rights reserved stmicroelectronics group of companies australia - brazil - canada - china - finland - france - germany - hong kong - india - israel - italy - japan -malaysia - malta - morocco - singapore - spain - sweden - switzerland - united kingdom - united states. http://www.st.com 10/10 L5973D
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