Text preview for : Micronta Digital Logic Probe 22-303.pdf part of Micronta 22-303 Hand Held Digital Logic Probe from Tandy Corp. circa. 1985, English / French
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LOGICPROBE DIGITAL
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WHATIS A TOGICPROBE?
ThisLogicProbeis on economicql ond useful device for testing logiccircuit. disploys HIGH ond LOW o lt the ond o PULSE with differeni coloredLEDs ond oudible signols vohogetestpointsof o digitolcircuit. lels ol lt you "peekinside" CMOS ond TTL/LS ihe lCs.
YOUR CONNECTING TOGICPROBE
Your Logic Probe hos been designed to operole from 'l ony power supply from 4.7 to 5 volts. During testing, sttoch the longer clip leods of the Logic Probe to the power supply. Connecl the block leod to the negotive (-) ond red leod to the posilive (t) terminol of the pow er suppl y.The short bl ock ground l eqd should be oitoched to o ground neor lhe point to be testedto ensure exoct performonce of the Logic Probe. N oi e: A di ode i s odded on the negoti vepo wer line for prolection from o reversedpolority. Since there is o potenliol difference (opprox. 0.6V) between the input ground wire ond lhe negotive power leod, meosuremenlis defined to be conducled by using inpvt ground terminol. will deviote if the some power supply Thresholds to for Logic Probe ond the systems be fested is used simulloneously. : Never opply voltoge to lhe Logic Probe. over l5V DC
SP EC I F I C AT I ON S
Thresholds TTL/LS Vcc):LO : 0.8Vt0.2V {5V Ht -_ 2.2V+0.2V (VccRonge: CMOS/MOS 4.7V to 15V): LO : 30% Vcc Hl - 7O"/"Ycc Inputlmpedonce : 100kohm Min. Detectoble Pulse Width : 5Ons Mox. InputFrequency : lOMHz Pulse,/Normol : Switch Selectoble (Beep) with Light Disploy ond Sound Power SupplyMox. Stond-by Current: lOmA ot 5V 30mA qt l5V Mox. Operoting Current : 2OmAqt 5V 80mA ot l5V Copyrighl 1985 TondyCorporotion
Couiion
US IN G Y O UR TOGICPROBE
your LogicProbeos described Connect obove. 2. Sei fhe devicetype switch CMOS or TTL/LS to depending upon which"fomily"of logic devices you ore going lo lesf. Sel the mode swilchto eitherNORMALor PULSE. mode, LogicProbe indicote In the PULSE the will the logic levelof ihe pulsetroin.In the NORMALmode, the unitwill indicote DC Logicstoie. the Touch exposed the metoltip of your LogicProbeto the TTL/LS circuitpoint to be tested.lf the LOW (green) LEDlights ond the unil mokes low tone o o sound (beep), it indicotes level lower thon the threshold voltogeof obout0.8 volts.lf the lllGH (red) tED lightsond o high tone sound(beep) it , q of indicotes level obove the threshold obout2.2 volts.lf the circuit to be testedis the CMOS/MOS c ircuit: LOW : 30% Vcc \!cc HIGH -- 7O"/o lf there is no LEDlit ond no sound (beep) emitted, voltoges the level is either betweenthe threshold (yellow)LED the circuitis "open". lf the PULSE or o is blinking, indicotes pulsetroinoi the testing it position.) node. (The mode switch is in PULSE '1. 5. To onolyzefhe duty cycleof o pulsetroin,you con levelof the HIGH (red)LED comporeihe brightness with the LOW (greenfLED. ihonthe LOW LED, lf the HIGH(red)LEDis brighter lf form hoso longerhigh-durotion.theLOW fhe pulse the (green) thonlhe HIGH(red)LED, LEDis brighter of low-durotion the pulseis longer. Coution: Never opply more voltogeto the tip pin of voltoge. lhe LogicProbelhqn the supply
LEDSTATES H IGH TOW P U TS E BEEP
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Logic "0' no pulse octivrl/ Logic "1 " no pulse ochvity Teslpoint on open circuit Out of toleronce signol N ol pow er ed Squore wove pulse oclivrty Logic "0" pulse ocfivity Logi c " l " pul s eoc tr v i t y
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I TH E FIG. IN TE R P R E TIN GtE D SA N D B E E P
TROU BLESHOOTING DIGITAL
l. StqricGote Anolysis commonds s{ Thetruth tobie(o tobuloticn the output must kno*n for o giventype be for o giveninput) of gote. loqictobles shown. ore Themosicommon
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2. DynomicGote Anolysis A gote moy oppeorfunctionol when observed sfoticolly (constont inpulDC level) moyfoil underoctuolcircuil bul (pulsing operofion inputsignol). Figure shows 2 how will chongeo negotive pulseio o positive on inverler pulse. of thisinformotion indicoted your Logic All is by Probe.
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FIG.2 INVERTER OPERATION
HINTSON DIGITAT TROUBLESHOOTING
Once o foultis locotedin the circuit your LogicProbe, by it mustnexl be determined whetherthe foultis in the lC or in someshortexternol the node.For exomple, to if on outputfrom o gote is olwoyslow, eitherfhe gote is bod or the orinfedcircuit trockto the node is shorted to the logiclow. One method distinguishing for beiween ihe iwo is lo free the pin of the lC underlesl ond then usethe LogicProbeto onolyzethe flootingoutpul. Use of o LogicPulser (suchos o MICRONTA Cqi. No. 22-304) con moke trouble-shooting even eosier by ollowingyou to conlrol the signolflowing the circuit.Complete instruciions usingyour Logic on Probewith o LogicPulserore included with the Logic Pulser. inputs lo oll connecl unused l. Wth CMOS devices, "Flooting" moycouse errotic inputs Vccor ground. deviceoperotion. mustbe connecled oll 2. With TTVLS devices, inputs lf to something. on inpulshouldolwoysbe high, conneclit to Vcc. lf on inputshouldolwoysbe low, devices contoin if connect fo ground.lf fhe TTVLS inputs gotes, connect unused oll OR,AND, or NAND to o usedinputon fhe somedevice. froublein digitol problems oftencouse 3 . Powersupply lo Mokesurethe powersupplied eochdevice circuifs. (A for the device. "hot" limits is withinthe specified problem.) groundis onother common woy lo locoteo problemin o 4. Oflen the quickest is lo stortol outputond work bock.lf digilolcircuit first is the circuit drivenby o multivibrotor, checkthe ond of the multivibrotor lhen go to the output outpuf ond work bock.
TECHNICAT TALKABOUT DIGITAT ETECTRONICS
Di g i to lc ir c uif s e non l i n e o rd e v i c e so n d o p e ro te o t or soturolionlevels. As sh o wn in F ig.3, if t h e v o l to g e i s i n c re o s e d n A t hen o ot so me v olue t he s t oteo f C w i l l c h o n g e fro m o l o gi c 0 l o o l ogic 1 . T he oc f u o l v o l to g e o t w h i c h th i s o c c urs is termed the thresholdvoltoge for the fomily. (Typicolly 0 .8 V fo r low ond 2. 2Y fo r h i g h i n th e T T Lfo m i l y o r 3 0 % for low ond 7O"/" for high in the CMOS fomily, where we d e fi ne:
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V1 refers to the volioge ot which C chonges stote from l o g i c 0 t o logic l. ) When testingo gote stoticolly, would be cousedio A go HIGH ( + V ) ond C m o n i to re d(c h o n g e s m L OW fro to H IGH) .W hen t es t in gth e g o te d y n o mi c o l l y A mi g ht , be p u l s edwit h q s quo rew o v e o n d C m o n i to re d .T h e g o te i s b od if no c hong e o c c u rs , ro v i d e dth e o m p l i t ude p o f th e squor ewov e ot A p o s s e s ro u g h th e W L l e vel . th
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TESTING FIG.3 STATIC AND DYNAMIC
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Withino givenfomily, gote is bod if it givesriselo the (See tronsitions occurin the undefined thof region. Fig.4 for CMOS.) exomple, HTLhosthresholds For the of B.5Vond 6.5V,whichcompores fovorobly the to 70%-3O% progromming the CMOSswitch of oosition. Anolysis o wove lroin incorporotes ospects: of two the repetition rote ond lhe durotion(osshownin Fig.5). The rotio of the durotion the repetition to rote is often the % dvtycycle. exomple, the onolysis colled For in of o squorewove,the durotionis holf of the repelition rote ond consequently o 50?/o hos duty cycle. The repetition rote is the someos the frequency the wove of (Low) troin.In qddition, pulseis termedos negotive the if the logiclevelremoins highfor mostof the cycleond pulse low os shownin Fig.5. is (HIGH) Theconverse termed positive pulse shown o os in Fig.6. The(HlGH,LOW)LEDs hoverelotive will intensiiies proportionol lhe duty cycle.For exomple, the duty to if thenthe HIGHLED cycleis l0% ond o negotive exists, will hovethe greotest intensify becouse LOW LED the is on only 10% oI the time. the frequency As becomes lower (below40 Hz)the octuoltronsitions ihe (HIGH, of LOW) LEDs con be resolved the humoneye. by However, durotionof ihe HIGH LEDwith respecl the to the LOW LEDis stillproporlionol the duf cycle. to 12
A positive pulsing wovetroinwithdutycycleobove507o pulsing becomes negolive wovetroinwith o dutycycle o of less thon 50%. Forexomple, posilive o wovetroin with o 75% dulycycleis equivolenl o negotive to wove troin with o dufy cycleof 25"/".
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IN CASE PROBLEMS... OF
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' lf your LogicProbeseems be workingimproperly, lo try thesehints: 1. Moke sureyour LogicProbeis properlyconnected or grounded. 2. l( lhe PULSE blinks LED continuously o logic for .ondition, power supplymoy requireexfro the (Toomuch"noise" comingfrom lhe power fihering. is supply.) you ore 3. Moke surethe problem not in the circuit is testing. exomple, the circuiior deviceis For if "deod", LEDs light. completely no will
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FIG.5. NEGATIVE-GOING PULSE
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SONDE QU'EST-CE QU'UNE LOGIOUE
L a so n de logiquees t u n o u ti l d l a l o i s 6 c o n o rn i q u e et p ra ti q ues er v antd la v e ri fi c a ti o n ' u n c i rc u i t l o g i q u e. d El l e i ndiqueles 6t at s H AU T S e t B AS e t L ' IMP U L S I ON e a ve c des v oy ant sa DEL d e c o u l e u rsd i ffe re n te s t d es si g n a uxs onor esau po i n t d e c o n tro l ed e te n s ro nd {.n E ci rcu i t num er ique. ll e p e rm e td e s o n d e r l e s c rrc rr:s ' ha i n t6 g r6s T L/ LS ( logi q u etra n s i s to r-tra n s i s to r u te T r d e n si t e)et a CM O S ( s e m i -c o n d u c te ud m 6 ta l -o x y de co mp l 6m ent air e) .
BRANCHEMENT LOGIQUE DE LA SONDE
C ette sonde l ogi quea 6t6 conguepour fonct ionneri parti rd' une sourced' al i mentati on 4.7 a 15 volt s. de P endantl a v6ri fi cati on, appl i querl es pi ncesde la sonde l ogi quesur I' al i mentati on. el i erl e condu ct eurnoir i la R (-) et l e conducteurrouge A la bor ne borne negati ve posi ti ve(+ ) de l a sourced' al i mentati on. conduct eur Le noi r court de l a massedoi t 6tre rel i 6 d une m assed proxi mi t6du poi nt d v6ri fi erafi n d' obtenirdes r 6sult at s exacts. R emarque: ne di ode est mont6esur l e cot e ngat if U pour servi rde protecti onc ont r e une d' al i mentati on de i nversi on l a pol ari te.l l exi steune di ff6 r ence de potenti eld' envi ron V entre l e conducteurde m asse 0.6 et d' entr6e l e conducteurn6gati f;l a mesur edoit se Les fai re en uti l i santl a borne de massed' entr 6e. si ni veauxde seui l changeront l a meme alim ent at ion pour l a sonde logiqueet les est uti l i seesi mul tanement systemes v6ri fi er. d N A vertl gsement e j amai ssoumettrel a sonde logiqued a une tensi onsup6ri eure 15 V C C .
FI CH ET E C H N I OU E
Se ui l s TTL / LS ( V c c de 5V ): BAS = 0.8V 10.2V H AU T = 2 .2 V + O .2 V CMO S / M O S( V c c d e 4 .7 V a 1 5 V): B,AS= 300/o Vcc de HAUT = 700/o Vcc de l mp 6 danc ed' ent r de L a rg e urd' im puls ion 6 te c ta b l e d mi n i m ale Fr6 q u enc e ent r 6em a x i ma l e d' Mo d e im puls ions / no rm a l Co u ra ntd' at t ent e a x . d ' a l i me n ta ti o n m Co u ra ntm ax im ald' u ti l i s a ti o n 1 0 0 k i l o h ms 50 ns 1 0 MH z p a r s e l e c teur 1 0 m Ai 5 V 3 0 mA a 1 5V 2 0 mA a 5 V 8 0 mA i 1 5 V
T ous dr or t sr es e rv e s 9 8 5 ,T a n d y C o rp o ra ti o n 1
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EN CAS DE PROBLEMES
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S i l a sonde l ogi quene sembl epas foncti onner normal ement, appl i querl es consei l ssui va nt s: que l a sonde l ogi queest bi en br anch6e ou 1. S ' assurer mi se d l a masse. 2. S i l e voyanta D E L P U LS Ecl i gnotesans ar r t pour peut avoir besoind'un un 6tat l ogi que,I' al i mentati on (brui t trop 6l evepr ovenant fi l tragesuppl 6mentai re de I' al i mentati on). que l e probl emene provi entp as du cir cuit 3. S ' assurer est veri fi e. ar exempl e, l e ci rcui t ou l e d isposit if P si en compl dtement panne,aucun voyantd DEL ne s' al l umera.
F16ouence e d Fig. 5 lmpulsion n6gatlve
Fig. 6 lmpulslon posltive
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UTILISER COMMENT LA SONDE LOGIQUE
1 . Bra nc herla s onde lo g i q u ed e l a fa g o n d e c ri te p r6 c 6dem m ent . a 2 . R6 g lerle s 6lec t eur e ty p e d e d i s p o s i ti f C MOS ou d TTL / LS s uiv antla f a mi l l ed e c i rc u i tsl o g i q u e sa ve ri f er . i 3 . Me tt r ele s 6lec t eur e mo d e a N OR M ALo u PU L SE d l En m ode P ULS E ,la s o n d e l o g i q u ed 6 te c te ra e n i veaulogiquedu t r a i n d ' i m p u l s i o n sEn mo d e . n o rm al.elle indioue ral e n i v e a uC C . m6 e 4. Ap p l iquerI ' ex t 16m i te ta l l i q u e x p o s e ed e l a s o nce l o g i q ues ur le point d u c i rc u i tT T L /L S d v 6 ri fre rSr te vo ya nta DE L LO W ( v e rt)s ' a l l u mee t q u e l a s o n d e i fa i t ent endr eune t on a l i t6g ra v e ,c e l a s i g n i f e q u e l e n i ve aues t plus bas q u e l a te n s i o nd e s e u i l d ' e n v i r on 0 .8 v olt . S i le v oy an ta D E L H IGH (ro u g e )s ' a l i u m eet q u 'u net onalit 6aigu e s e fa i t e n te n d re , e l a i n d i q u e c u n n iv eauau- des s u s u s e u i l d ' e n v i ro n2 .2 v o l ts .S i d l e ci r c uit d v er if iere s t d u ty p e C MOS /M O S ,o n a a l o rs les v aleur ss ui v a n te s : ETAT BAS = 30% Vcc Vcc Elnr HRur = 7oolo Si a u cu n v oy antne s ' a l l u m ee t a u c u n eto n a l i t6n e s e fa i t e n tendr e, ' es tque l e n i v e a us e s i tu e e n tre l e s c te n si o nsde s euil ou qu e l e c i rc u i t e s t o u v e rt.S i l e vo ya n t P ULS E( jaune)d D E L c l i g n o te ,c e l a i n d i q u eun (l tra i n d 'i m puls ions n o e u d d e v 6 ri fi c a ti o n e s 6 l e c t eur au de mo d e es t d la pos it i o nPU L SE ). 5. P our anal yserl e pourcentage uti l i sat ion d' d'un t r ain d' i mpul si ons, peut comparerl e ni veaud'int ensit 6 on l umi neuse voyantrouge d D E L H IGH d celui du du voyant vert i DEL LOW. S i l e voyantrouge d D E L H IGH est pl u s br illantque l e voyanta D E L LOW , I' i mpul si on un e dur 6e olus a longue a I'etathaut. Si le voyant vert A DEL LOW est pl us bri l l antque l e voyantrouge d D E L HI G H, I' i mpul si on une pl us l onguedur6e A l '6t atbas. a A V E R TIS S E ME N T: e j amai sappti quer t a point ede N a touche de l a sonde l ogi queune tensi onsu p6r ieur e a cel l e de l a sourced' al i mentati on.
ETAT U tr J U EL SO N H IGH LOW P U LS E
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DES PANNES RECHERCHE NUMERIQUES DES CIRCUITS
1. Analyse de porle statlque On d oit c onnait r ela ta b l e d e v 6 ri t6(u n i a b l e a ud es 6 ta t sde s or t ieen f o n c ti o nd ' u n e e n trd ed o n n e e ) p o u r un t y pe par t t c u l i e r e P o rte . d s L e s t ablesde logr q u el e s p l u s c o u ra n te s o n t: 2. Analyse dynamlque de porte L' anal yse stati quepeut l ai ssercroi re qu' une por t e foncti onne(ni veaud' entree C constant)bien qu'en C (si r6al i t6l e ci rcui t soi t d6tectueux gnald'ent r 6epulse) . La fi gure 2 i l l ustrecommentun i nverseur r ansf or m e t une i mpul si onn6gati ve une i mpul si onposit ive. en Tous sont donnespar l a so nde logique. ces rensei gnements
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Un e fo is que la s onde l o g i q u ea re p d r6u n e a n o ma l i e s d a n s l e c ir c uit ,on doit p a r l a s u i te d 6 te rm i n e r i I'a n o m alie e t r ouv eda n s l e c i rc u i t i n t6 g reo u d a n s un s s ex co u rt-c ir c uit t 6r ieu ra u n o e u d .P a r e x e mp l e , i l a sortie d'une porte est toujours d I'etatbas, alors soit q u e l a por t e es t d6f ectu e u s es o i t q u e l e c i rc u i t i mp ri me , j u sq u 'aunoeud es t en c o u rt-c i rc u i t I' e ta tl o g i q u ebas d l la Po u r d 6t er m iner pa n n e ,o n p e u t d 6 b ra n c h e r a b ro ch edu Cl A v er if ie re t u ti l i s e re n s u i l el a s o n d e l o g i q u epour analy s e rl a s o rti ed 6 b ra n c h 6 e . (c r L 'u sa ge un g6n6r at e u d ' i mp u l s i o n so g i q u e s o mmel e l d' Mi cro n t a22- 304)peut v o u s p e rm e ttre e d e te rm i n er d de e n co replusf ac ilem enlte s tro u b l e s n v o u s p e rme ttant e co n trolerle pas s age s i g n a ld a n s l e c i rc u i t.U n mo de du d 'e mo loiddt ail16 t f ou rn i a v e c l e o e n d ra te u r es logiques . d 'i mp uls ions 1. A vec l es di sposi ti fs C MOS ,raccordert out es les a entr6esinutilis6es Vcc ou d la masse.Les entrdes a peuvententrai ner non connect6es un foncti onnement1169ul i er di sposi ti f. i du 2. P our l es di sposi ti fs TTL/LS ,toutes l es ent r 6es doi vent6tre raccord6es. i une entr6edoit t oujour s S 6tre A l ' 6tathaut, l a raccorder V cc. S i u ne ent r 6e a doit toujours Ctrea I'etatbas, la raccorderd la masse. i l e di sposi ti f S TTLILS conti entdes por t es OU , E T ou N ON -E T,raccordertoutes l e s sor t ies i nuti l i s6es une entr6een servi cesur l e m 6m e d di soosi ti.f 3. D es probl emes al i mentati on d' sont souventA I' ori gi ne pannesdans l es ci rcui tsnum 6r iques. de que I' al i mentati on chaqued isposit if S ' assurer de se si tue dans l es l i mi tesrecommand6es e m asse (un sous tensi onconsti tueaussiun probl dm ecour ant ) . 4. P our l ocal i ser rapi dement probl emedans un un ci rcui t num6ri que, peut commencerA la sor t ieet on remontervers I' entrde. i l e ci rcui t est att aquepar S un mul ti vi brateur, fi erd' abordl a sortiede ce veri derni er,pui s passerd l a sorti edu ci rcuit et r em ont er vers I'entree.
SUR TECHNIOUES LES RENSEIGNEMENTS
n s L e s ci rc uit snum 6r iqu e s o n t d e s d i s p o s i ti fs o n qui d l i n 6 a i res f onc t ion n e n t d e s n i v e a u xd e s a tu ra tion C o mm e I ' indiquela f ig u re 3 , s i l a te n s i o na u g m e n teen A, l '6 ta tde C pas s ede l ' 6 ta tl o g i q u e0 d l ' e ta tl o g i q u et t L a te ns ionr eellede ce c h a n g e me n d ' e ta tc o n s ti tu el a te n si o nde s euil de la fa m i l l e(e n g 6 n 6 ra l0 .8 V p o u r l '6 ta tb as et 2. 2V pou r l ' 6 ta th a u t d a n s l a fa mi l l eT TL. pour l'6tat haut dans la pour I'etat bas et 700/c et 300/o fa mi l l eCM O S ) qui s e d 6 fi n i ta i n s i :
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d la Vr re p r 6s ent e t ens i o nd e p a s s a g e e C d e I' e ta t .l l o g i q ue0 d I ' et atlogi q u e . s Po u r la v er if ic at ion ta ti q u ed ' u n e o o rte ,o n fe ra i t p a sse rA d I ' et athaut 1 + y ; e t o n te ra i t p a s s e rC d e I ' etat d b a s a l ' 6t athaut .P ou r u n e v 6 ri fi c a ti o n y n a mi q u ed' une p o rte ,on peut s oum e ttre a d e s i m p u l s i o n s a rr6 e set A c s C. d 6 cl e nc her La por te e s t d 6 fe c tu e u s e ' i l n e s e p ro d u it auc un c hang e m e n s i I' a mp l i tu d e e l ' o n d e d t ca rr6 een A pas s epa r l a te n s i o nd e d 6 c l e n c h e me nt VTL .
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