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Datasheet File OCR Text: |
this is information on a product in full production. october 2012 doc id 13103 rev 13 1/35 1 l4995 5v, 500ma low drop voltage regulator datasheet ? production data features operating dc supply voltage range 5.6v to 31v low dropout voltage low quiescent current consumption reset circuit sensing of output voltage down to 1v programmable reset pulse delay with external capacitor programmable watchdog (a) timer with external capacitor thermal shutdown and short circuit protection wide temperature range (t j = -40c to 150c) enable (a) input for enabling/disabling the voltage regulator description l4995 is a family of monolithic integrated 5 v voltage regulators with a low drop voltage at currents of up to 500 ma, available in both 12 and 24 pin packages. the output voltage regulating element consists of a p-channel mos and regulation is performed regardless of input voltage transients of up to 40v. the high precision of the output voltage is obtained using a pre-trimmed reference voltage. the l4995 family is protected against short circuit and overtemperature protection switches off the devices in the case of extremely high power dissipation. the l4995 integrates the watchdog, enable and externally programmable reset circuits. the l4995a features the externally programmable reset and enable. finally the l4995r features the externally programmable reset. the combination of such features makes this device particularly flexible and suitable to supply microprocessor systems in automotive applications. max dc supply voltage v s 40v max output voltage tolerance v 0 +/-2% max dropout voltage v dp 500mv output current i 0 500ma quiescent current i qn 3a (1) 1. typical value with regulator disabled a. watchdog and enable facilities are available according to device summary table. powersso- 12 powersso-24 table 1. device summary package order codes tube tape and reel powersso-12 (exposed pad) l4995j - l4995aj - l4995rj l4995jtr - l4995ajtr - l4995rjtr powersso-24 (exposed pad) l4995k - l4995ak - l4995rk l4995ktr - l4995aktr - l4995rktr p/n watchdog reset enable l4995j - l4995k x x x l4995aj - l4995ak - x x l4995rj - l4995rk - x - www.st.com
contents l4995 2/35 doc id 13103 rev 13 contents 1 block diagrams and pins descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1 absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2 thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.4 electrical characteristics curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.5 test circuit and waveforms plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.5.1 load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.1 voltage regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.2 reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.3 watchdog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4 package and pcb thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.1 powersso-12 thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.2 powersso-24 thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 5 package and packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.1 ecopack ? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.2 powersso-24 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 5.3 powersso-12 packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 5.4 powersso-24 packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 6 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 l4995 list of tables doc id 13103 rev 13 3/35 list of tables table 1. device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 table 2. pins descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 table 3. absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 table 4. thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 table 5. general . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 table 6. reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 table 7. watchdog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 table 8. enable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 table 9. powersso-12 thermal parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 table 10. powersso-24 thermal parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 table 11. powersso-12 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 table 12. powersso-24 mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 table 13. document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 list of figures l4995 4/35 doc id 13103 rev 13 list of figures figure 1. block diagram of l4995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 figure 2. block diagram of l4995a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 figure 3. block diagram of l4995r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 figure 4. pins configurations (l4995) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 figure 5. output voltage vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 6. output voltage vs v s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 7. drop voltage vs output current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 8. current consumption vs output current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 figure 9. current consumption vs input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 figure 10. current limitation vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 figure 11. current limitation vs input voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 12. short circuit current vs input voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 13. output voltage vs enable voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 14. v en_high vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 15. v en_low vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 16. v rhth vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 figure 17. v rlth vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 18. v whth vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 19. v wlth vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 20. i cr and i cwc vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 21. i dr and i cwd vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 22. t wop vs t j . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 figure 23. psrr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 figure 24. load regulation test circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 figure 25. maximum load variation response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 figure 26. l4995 application schematic (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 27. stability region (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 figure 28. behavior of output current versus regulated voltage v o . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 figure 29. reset timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 30. watchdog timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 figure 31. powersso-12 pc board (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 figure 32. rthj-amb vs pcb copper area in open box free air condition . . . . . . . . . . . . . . . . . . . . . . 20 figure 33. powersso-12 thermal impedance junction ambient single pulse . . . . . . . . . . . . . . . . . . . 21 figure 34. thermal fitting model of vreg in powersso-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 figure 35. powersso-24 pc board (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 figure 36. rthj-amb vs pcb copper area in open box free air condition . . . . . . . . . . . . . . . . . . . . . . 23 figure 37. powersso-24 thermal impedance junction ambient single pulse . . . . . . . . . . . . . . . . . . . 24 figure 38. thermal fitting model of v reg in powersso-24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 figure 39. powersso-12 package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 figure 40. powersso-24 package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 figure 41. powersso-12 tube shipment (no suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 figure 42. powersso-12 tape and reel shipment (suffix ?tr?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 figure 43. powerss0-24 tube shipment (no suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 figure 44. powersso-24 tape and reel shipment (suffix ?tr?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 l4995 block diagrams and pins descriptions doc id 13103 rev 13 5/35 1 block diagrams and pins descriptions figure 1. block diagram of l4995 figure 2. block diagram of l4995a 9 r v 9 r 9 v ( q 9 f u : l 5 h v 9 f z 6 3 6 % n 6 c w 6 w i 6 c r 6 2 e s 6 o ) s ) % n ) c w ) o ' . $ z d w f k g r j 9 r o w d j h 5 h i h u h q f h / r z 9 r o w d j h 5 h v h w 6 w d u w x s p 9 b 9 ( " 1 ( . 4 9 r v 9 r 9 v ( q 9 f u 5 h v 6 3 6 % n 6 c r 6 2 e s 6 o ) s ) % n ) o ' . $ 9 r o w d j h 5 h i h u h q f h / r z 9 r o w d j h 5 h v h w 6 w d u w x s p 9 b 9 ' ! 0 ' - 3 block diagrams and pins descriptions l4995 6/35 doc id 13103 rev 13 figure 3. block diagram of l4995r table 2. pins descriptions pin name powersso-12 pin # powersso-24 pin # function e n 1 13, 14, 15 enable input (l4995 and l4996a only, otherwise not connected). if high regulator, watchdog and reset are operating. if low regulator, watchdog and reset are shutdown. connect to vs if not used. nc 2, 4, 8 3, 5, 6, 9, 11 not connected. gnd 3 16, 17, 18 ground reference. -tabtab, 1, 12 substrate of the chip: connect the pins or the tab to gnd. r es 5 19, 20, 21 reset output. it is pulled down when output voltage goes below v o_th or frequency at wi is too low. leave floating if not used. v cr 6 22, 23, 24 reset timing adjust. a capacitor between v cr pin and gnd. sets the reset delay time (trd). leave floating if reset is not used. v cw 72 watchdog timer adjust (l4995 only, otherwise not connected). a capacitor between v cw pin and gnd. sets the time response of the watchdog monitor. 9 r v 9 r 9 v 9 f u 5 h v 6 3 6 % n 6 c r 6 2 e s 6 o ) s ) o ' . $ 9 r o w d j h 5 h i h u h q f h / r z 9 r o w d j h 5 h v h w 6 w d u w x s p 9 b 9 ' ! 0 ' - 3 l4995 block diagrams and pins descriptions doc id 13103 rev 13 7/35 figure 4. pins configurations (l4995) w i 94 watchdog input (l4995 only, otherwise not connected). if the frequency at this input pin is too low, the reset output is activated. v os 10 7 regulator voltage output sensing. v o 11 8 5 voltage regulator output. block to ground with a capacitor >100nf (needed for regulator stability). v s 12 10 supply voltage. block to ground directly at v s pin with a ceramic capacitor (e.g. 200nf). table 2. pins descriptions (continued) pin name powersso-12 pin # powersso-24 pin # function 4 ! " s u b s t r a t e 4 ! " s u b s t r a t e s u b s t r a t e s u b s t r a t e ' ! 0 ' - 3 electrical specifications l4995 8/35 doc id 13103 rev 13 2 electrical specifications 2.1 absolute maximum ratings stressing the device above the rating listed in the ?absolute maximum ratings? table may cause permanent damage to the device. these are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. refer also to the stmicroelectronics sure program and other relevant quality documents. table 3. absolute maximum ratings symbol parameter value unit v vsdc dc supply voltage - 0.3 to 40 v i vsdc input current internally limited v vo (1) 1. using the typical application schematic with cout= 10 f and iout=0 a, when the regulator is switched-on, an overshoot exceeding 6 v could o ccur.this behavior does not impact the reliability of the regulator. dc output voltage - 0.3 to 6 v i vo dc output current internally limited v wi watchdog input voltage -0.3 to v vo + 0.3 v v od r es output voltage -0.3 to v vo + 0.3 v i od r es output current internally limited v cr v cr voltage - 0.3 to v vo + 0.3 v v cw watchdog delay voltage - 0.3 to v vo + 0.3 v v en enable input - 0.3 to v vsdc +0.3 v t j junction temperature - 40 to 150 c v esd esd voltage level (hbm-mil std 883c) 2 kv v esd esd voltage level (cdm aec-q100-011) 750 v l4995 electrical specifications doc id 13103 rev 13 9/35 2.2 thermal data for details, please refer to section 4.1: powersso-12 thermal data and section 4.2: powersso-24 thermal data . mm 2.3 electrical characteristics values specified in this section are for v s = 5.6v to 31v, t j = -40 c to +150 c unless otherwise stated. table 4. thermal data (1) 1. the values quoted are for pcb 77mm x 86mm x 1.6mm, fr4, double layer; copper thickness 0.070mm copper area 3cm2 thermal vias, thermal vias separation 1.2 mm, thermal via diameter 0.3 mm +/- 0.08 mm, cu thickness on vias 0.025 mm. symbol parameter value unit r thj-case thermal resistance junction to case: powersso-12 powersso-24 5 4 k/w k/w r thj-amb thermal resistance junction to ambient: powersso-12 powersso-24 52 38 k/w k/w table 5. general pin symbol parameter test condition min. typ. max. unit v o v o_ref output voltage v s = 5.6 to 31v i o = 0 to 500ma 4.95.005.1 v v o i short short circuit current v s = 13.5v (1) 550 800 1050 ma v o i lim (2) output current limitation v s = 13.5v (1) 600 900 1250 ma v s , v o v line line regulation voltage v s = 5.6 to 31v i o = 0 to 500ma 25 mv v o v load load regulation voltage i o = 0 to 500ma 25 mv v s , v o v dp (3) drop voltage i o = 400ma 270 500 mv v s , v o svr ripple rejection f r = 100 hz (4) 55 db v s , v o i qs current consumption with regulator disabled v s = 13.5v, e n = low 310 a v s , v o i qn_1 current consumption with regulator enabled v s = 13.5v, i o < 1ma, 90 160 a v s , v o i qn_50 current consumption with regulator enabled v s = 13.5v, i o = 50ma, 290 400 a electrical specifications l4995 10/35 doc id 13103 rev 13 v s , v o i qn_150 current consumption with regulator enabled v s = 13.5v, i o = 150ma, 740 1000 a v s , v o i qn_250 current consumption with regulator enabled v s = 13.5v, i o = 250ma, 11.4ma v s , v o i qn_500 current consumption with regulator enabled v s = 13.5v, i o = 500ma, 2.1 2.7 ma t w thermal protection temperature 150 190 c t w_hy thermal protection temperature hysteresis 10 c 1. see figure 28 . 2. measured output current when the output voltage has dropped 100mv from its nominal value obtained at vs=13.5v and i o = 250ma . 3. vs-v o measured when the output voltage has dropped 100mv from its nominal value obtained at vs=13.5v and i o = 250ma . 4. guaranteed by design. table 6. reset pin symbol parameter test condition min. typ. max. unit r es v res_l reset output low voltage r ext = 5k to v o , v o > 1v 0.4 v r es i res_lkg reset output high leakage current v res = 5v 1 a r es r res pull up internal resistance (versus v o ) 10 20 40 k r es v o_th v o out of regulation threshold v s = 5.6 to 31v i o = 1 to 500ma 6% 8% 10% below v o_ref v cr v rlth reset delay circuit low threshold v s = 13.5v 10% 13% 16% v o_ref v cr v rhth reset delay circuit high threshold v s =13.5v 44% 47% 50% v o_ref v cr i cr charge current v s = 13.5v 8 15 30 a v cr i dr discharge current v s = 13.5v 8 15 30 a r es t rr reset reaction time (1) 1. when v o becomes lower than 4v, the reset reaction time decreases down to 2s assuring a faster reset condition in this particular case. v o = v o_ th -100mv 100 250 700 s r es t rd reset delay time v s = 13.5v, c tr = 47nf 12 33 73 ms table 5. general (continued) pin symbol parameter test condition min. typ. max. unit l4995 electrical specifications doc id 13103 rev 13 11/35 table 7. watchdog pin symbol parameter test condition min. typ. max. unit w i vih input high voltage v s = 13.5v 3.5 v w i vil input low voltage v s = 13.5v 1.5 v w i vih input hysteresis v s = 13.5v 500 mv w i i wi pull down current v s = 13.5v v wi = 3.5v 610 a v cw v wlth low threshold v s = 13.5v 10% 13% 16% v o_ref v cw v whth high threshold v s = 13.5v 44% 47% 50% v o_ref v cw i cwc charge current v s = 13.5v, v cw = 0.1v 51020 a v cw i cwd discharge current v s = 13.5v, v cw = 2.5v 1.25 2.5 5 a v cw t wop watchdog period v s = 13.5v, c tw = 47nf 20 40 80 ms r es t wol watchdog output low time v s = 13.5v, c tw = 47nf 4816ms table 8. enable pin symbol parameter test condition min. typ. max. unit e n v en_low e n input low voltage 1 v e n v en_high e n input high voltage 3 v e n v en_hyst e n input hysteresis 830 mv e n i en pull down current v s = 13.5v 10 18 a electrical specifications l4995 12/35 doc id 13103 rev 13 2.4 electrical characteristics curves figure 5. output voltage vs t j figure 6. output voltage vs v s figure 7. drop voltage vs output current figure 8. current consumption vs output current figure 9. current consumption vs input voltage figure 10. current limitation vs t j 4 j ? # 6 o ? r e f 6 6 s 6 ) m ! ' ! 0 ' - 3 6 s 6 6 o ? r e f 6 ) m ! 4 j ? # ' ! 0 ' - 3 ) o m ! 6 d p 6 4 j ? # 4 j ? # ' ! 0 ' - 3 ) o m ! ) q n ? ! 6 s 6 4 j ? # % n ( i g h ' ! 0 ' - 3 6 s 6 ) q n ? ! 4 j ? # % n ( i g h ) o m ! ) o m ! ) o m ! ) o m ! ' ! 0 ' - 3 4 j ? # ) l i m m ! 6 s 6 ' ! 0 ' - 3 l4995 electrical specifications doc id 13103 rev 13 13/35 figure 11. current limitation vs input voltage figure 12. short circuit current vs input voltage e figure 13. output voltage vs enable voltage figure 14. v en_high vs t j figure 15. v en_low vs t j figure 16. v rhth vs t j 6 s 6 ) l i m m ! 4 j ? # 4 j ? # ' ! 0 ' - 3 6 s 6 ) s h o r t m ! 4 j ? # 4 j ? # ' ! 0 ' - 3 6 e n 6 6 o 6 ' ! 0 ' - 3 4 j ? # 6 e n ? h i g h 6 6 s 6 t o 6 ' ! 0 ' - 3 4 j ? # 6 e n ? l o w 6 6 s 6 t o 6 ' ! 0 ' - 3 4 j ? # 6 r h t h 6 o ? r e f 6 s 6 t o 6 ' ! 0 ' - 3 electrical specifications l4995 14/35 doc id 13103 rev 13 figure 17. v rlth vs t j figure 18. v whth vs t j figure 19. v wlth vs t j figure 20. i cr and i cwc vs t j figure 21. i dr and i cwd vs t j figure 22. t wop vs t j 4 j ? # 6 r l t h 6 o ? r e f 6 s 6 t o 6 ' ! 0 ' - 3 4 j ? # 6 w h t h 6 o ? r e f 6 s 6 t o 6 ' ! 0 ' - 3 4 j ? # 6 w l t h 6 o ? r e f 6 s 6 t o 6 ' ! 0 ' - 3 4 j ? # ) c r ) c w c ? ! 6 s 6 t o 6 6 c w 6 ) c r ) c w c ' ! 0 ' - 3 4 j ? # ) d r ) c w d ? ! 6 s 6 t o 6 6 c w 6 ) d r ) c w d ' ! 0 ' - 3 4 j ? # 4 w o p m s 6 s 6 t o 6 # t w n & ' ! 0 ' - 3 l4995 electrical specifications doc id 13103 rev 13 15/35 2.5 test circuit and waveforms plot 2.5.1 load regulation figure 24. load regulation test circuit figure 23. psrr 0 , 0 0 1 0 , 0 0 2 0 , 0 0 3 0 , 0 0 4 0 , 0 0 5 0 , 0 0 6 0 , 0 0 7 0 , 0 0 8 0 , 0 0 0 , 1 0 1 , 0 0 1 0 , 0 0 10 1 0 0 , 0 0 1 0 0 0 , 0 0 1 0 0 00 0 0 , 0 0 c 0 = 4.7 f = 4 . 7 f gapgm s 0007 3 frequency [khz] p s rr [db] ' ! 0 ' - 3 electrical specifications l4995 16/35 doc id 13103 rev 13 figure 25. maximum load variation response 0,00e+00 5,00e-05 1,00e-04 1,50e-04 2,00e-04 2,50e-04 3 ,00e-04 3 ,50e-04 4,00e-04 time [s] v 0 [ 1v / div ] i 0 [ 200ma / div ] gapgms00081 l4995 application information doc id 13103 rev 13 17/35 3 application information figure 26. l4995 application schematic (1) 1. the input capacitor cs > 200nf is necessary for the smoothing of line disturbances. the output capacitor c01 > 100nf is necessary for the stability of the regulation loop. in order to dampen output voltage oscillations during high load current surges, it is recommended an additi onal electrolytic capacitor c02 > 10f to be placed at the output pin. figure 27. stability region (1) 1. the curve which describes the minimum esr is deriv ed from characterization data on the regulator with connected ceramic capacitors which feature low esr va lues (at 100 khz). any capacitor with further lower esr than the given plot value must be evaluated in each and every case. 6 o s 6 o # o w a t c h d o g 6 s 6 i 7 i 6 c w 6 c r # t r # t w 2 e s g n d 6 o l t a g e 2 e f e r e n c e , o w 6 o l t a g e 2 e s e t 3 t a r t u p m 6 ? 6 % n # o 6 o s 6 o # o w a t c h d o g 6 s 6 i 7 i 6 c w 6 c r # t r # t w 2 e s g n d 6 o l t a g e 2 e f e r e n c e , o w 6 o l t a g e 2 e s e t 3 t a r t u p m 6 ? 6 % n # o ' ! 0 ' - 3 0.001 0.01 0.1 1 10 100 0.5 5 101520253035404550 co (uf) esr (ohm) esr min esr max unstable region stability region undefined region application information l4995 18/35 doc id 13103 rev 13 3.1 voltage regulator voltage regulator uses a p-channel transistor as a regulating element. with this structure, very low dropout voltage at current up to 500ma is obtained. the output voltage is regulated up to transient input supply voltage of 40v. no functional interruption due to over-voltage pulses is generated. a short circuit protection to gnd is provided. the voltage regulator is active when e n is high. figure 28. behavior of output current versus regulated voltage v o 3.2 reset the reset circuit supervises the output voltage v o . the v o_th reset threshold is defined with the in-ternal reference voltage and a resistor output divider. if the output voltage becomes lower than v o_th then r es goes low with a reaction time t rr . the reset low signal is guaranteed for an output voltage v o greater than 1v. when the output voltage becomes higher than v o_th then r es goes high with a delay t rd . this delay is obtained by an internal oscillator. the oscillator period is given by: equation 1 t osc = [(v rhth -v rlth ) x c tr ] / i cr + [(v rhth -v rlth ) x c tr ] / i dr where: i cr :is an internally generated charge current i dr :is an internally generated discharge current v rhth , v rlth :are two voltages defined with the output voltage and a resistor output divider c tr :is an external capacitance. t rd is given by: equation 2 t rd = (v rhth x c tr )/i cr + 3 x t osc vo vo_ref iout ishort ilim l4995 application information doc id 13103 rev 13 19/35 reset is active when e n is high. figure 29. reset timing diagram 3.3 watchdog a connected microcontroller is monitored by the watchdog input w i . if pulses are missing, the reset output pin is set to low. the pulse sequence time can be set within a wide range with the external capacitor, c tw . the watchdog circuit discharges the capacitor c tw , with the constant current icwd. if the lower threshold v wlth is reached, a watchdog reset is generated. to prevent this the microcontroller must generate a positive edge during the discharge of the capacitor before the voltage has reached the threshold v wlth . in order to calculate the minimum time t, during which the micro-controller must output the positive edge, the following equation can be used: equation 3 (v whth -v wlth ) x c tw = i cwd x t every w i positive edge switches the current source from discharging to charging. the same happens when the lower threshold is reached. when the voltage reaches the upper threshold, v whth , the current switches from charging to discharging. the result is a saw-tooth voltage at the watchdog timer capacitor c tw . figure 30. watchdog timing diagram trr < trr trd to s c vrhth vrlth re s vcr vo wi vo u t_th trr < trr trd to s c vrhth vrlth re s vcr vo wi vo u t_th gapgm s 00077 : l 9 f z 5 h v 9 z k w k 9 z o w k 7 z r s 7 z r o : l 9 f z 5 h v 9 z k w k 9 z o w k 7 z r s 7 z r o ' ! 0 ' - 3 package and pcb thermal data l4995 20/35 doc id 13103 rev 13 4 package and pcb thermal data 4.1 powersso-12 thermal data figure 31. powersso-12 pc board (1) 1. layout condition of r th and z th measurements (pcb: double layer, thermal vias, fr4 area= 77mm x 86mm,pcb thickness=1.6mm, cu thickness=70 m (front and back side) thermal vias separation 1.2 mm, thermal via diameter 0.3 mm +/- 0.08 mm, cu thickness on vias 0.025 mm, footprint dimension 4.1 mm x 6.5 mm). figure 32. r thj-amb vs pcb copper area in open box free air condition ( " 1 ( $ ' 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 0 2 4 6 8 1 0 r t h j _a _ a m b ( c / w ) p c b c u h ea e a t s i n k a r ea e a ( c m ^ 2 ) gapgm s 000 8 2 l4995 package and pcb thermal data doc id 13103 rev 13 21/35 figure 33. powersso-12 thermal impedance junction ambient single pulse equation 4: pulse calculation formula where = t p /t figure 34. thermal fitting model of vreg in powersso-12 0,1 1 10 100 0,0001 0,001 0,01 0,1 1 10 100 1000 time ( s) zth ( c/ w) footprint 8 cm 2 2 cm 2 z th r th z thtp 1 ? () + ? = ' ! 0 ' - 3 package and pcb thermal data l4995 22/35 doc id 13103 rev 13 table 9. powersso-12 thermal parameter area/island (cm 2 )footprint28 r1 (c/w) 0.45 r2 (c/w) 1.79 r3 (c/w) 7 r4 (c/w) 10 10 9 r5 (c/w) 22 15 10 r6 (c/w) 26 20 15 c1 (w.s/c) 0.001 c2 (w.s/c) 0.0022 c3 (w.s/c) 0.05 c4 (w.s/c) 0.2 0.1 0.1 c5 (w.s/c) 0.27 0.8 1 c6 (w.s/c) 3 6 9 l4995 package and pcb thermal data doc id 13103 rev 13 23/35 4.2 powersso-24 thermal data figure 35. powersso-24 pc board (1) 1. layout condition of r th and z th measurements (pcb: double layer, thermal vias, fr4 area= 77mm x 86mm,pcb thickness=1.6mm, cu thickness=70 m (front and back side) thermal vias separation 1.2 mm, thermal via diameter 0.3 mm +/- 0.08 mm, cu thickness on vias 0.025 mm, footprint dimension 4.1 mm x 6.5 mm). figure 36. r thj-amb vs pcb copper area in open box free air condition gapgcft00418 5 7 + m b d p e ? & |