MCl~19 2-OF-8 KEYPAD-TO-BINARY ENCODER The MC14419 is designed for phone dialer system applications, but finds many applications as a keypad-to-binary encoder. The device contains a 2-of-8 to binary encoder, a strobe generator, and an illegal state detector. The encoder has four row inputs and four column inputs, and is designed to accept inputs from 16 keyswitches arranged in a 4x 4 matrix. For an output on the four data lines, one and only one row along with one and only one column input line must be activated. All other combinations are suppressed by the illegal state detector to eliminate false data output. The strobe generator produces a strobe pulse when any of the 10 keys corresponding output to numerals O through can be used to eliminate erroneous 9 are depressed. The strobe data entry due to contact bounce. For a strobe output to occur, the key row and column input lines must remain stable for 80 clock pulses after activation. When the *,,}tt contact bounce has settled and 80 clock pulses have occurred, the outt’ put will be a single strobe pulse equal in width to that of the clock low.#}’ $! .<~>,,,, \,..? state. The strobe generator will output one and only one pulse eq,ch j,< time a numerical key is depressed. After the pulse has occurred,,$x+se and bounce due to contact break will not cause another stro@#iQQ15&. 5 ms a~t~~th,$last With a 16 kHz input clock frequency, the pulse occurs .++\,%, ‘./\\. bounce. )~~<.?, !F,::’k:+> ‘!%. ‘i\}. >f,i$ . Suppressed Output for Illegal Input Codes ,>.> ““ L SUFFIX P SUFFIX CERAMIC PACKAGE PLASTIC PACKAGE CASE 620 CASE W ORDERING INFORMATION MC14XXX — suffix Denotes L = Ceramic L P = Plastic n PIN ASSIGNMENT 1 RI v~~ 16 2 R2 Clock 15 3 4 5 6 7 8 R3 ST R4 D4 13 cl D3 12 C2 02 11 C3 D1 10 Vss C4 9 14 This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; howver, it is advised that normal precautions b taken to avoid application of anv voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it IS recommended constrained to Vout) < VDD. MOTOROLA — INC , lW that the Vin range and VSS Vout < (Vin be or DS9892 MAXIMUM RATINGS (Voltages referenced to VSS, Pin 8.) Rating DC Supply Symbol Voltage Input Voltage, I All Inputs Operating Drain per Pin Temperature Storage Temperature V in ELECTRICAL Range t 05 to Vss -0.5 Voltage Operating Range “l” <0.8 Vdc) Drive Current (VOH = 2.5 Vdc) Source (VOL = 0.4 Vdc) Sink Input -40 to +85 ‘c Tstg -65 to +1 50 ‘c .<<c&fb.’~” .:&iri”k~r$W Max Vdc Min Max Min Typ Max VDD — 3.0 6.0 3,0 5.0 5.0 – 0.01 — 0 6.0,9 ,. Fqg o,@#’t. ‘ ~‘i,.::~.i. “ — 5.0 4,99 — 4.99 VNL 5.0 1.5 – 1,5 VNH 5.0 1.4 — 1.5 IOH 5.0 -0.23 – -0.20 !OL 5.0 0.23 — 5.0 — IIH Leakage Current 25°C +*.*- ..!. ‘,’~t- $;>.\ ,$s: 4,95 ,, !*.,,,, .,.!.. ::,./:.’.*,:,. 2.25 1,4 ?. 2 ,J~R ‘*_ 1,5 5.0 ,$.y,;f~f’’’”~’‘ ,8.” <\, t\. ,}: o ,2g:’:*, “i?~~$8 . — “~t\: >,,,,, . — – _ — 10 Unit 6.0 Vdc 0.05 Vdc – Vdc – Vdc — Vdc -0,16 — mAdc 0.16 – mAdc — — pAdc 215 pAdc ,$> ~.~:!. . ..*. (Vin = VDD) Pullup Resistor Source Current (Row TA Symbol Level Noise Immunity (AVout mAdc \,,*,. .,. Vout “O” Level Voltage Output I 10 40°c VDD Output I CHARACTERISTICS Characteristic Supply V dc VDD I Range Vdc +6.0 to -0.5 I DC Current Unit Value VDD and Column IIL 5,0 Cin — 265 250 330 125 5.0 – – Inputs) (Vin = VSS) Input Capacitance (Vin = VSS) Standby Supply (fclock IDDS Current = 16 kHz, No Keys SupPlV Current Function as a of Clock FrequencV* (No Keys Depressed) ●The formula 3.0 given is for the typical Rise and Fall Times, Propagation DelaV Time, Data Output ,>’’?4.. )+~. J’” .$,)),*X<;+’ ~. 6.* t~,,’ ‘~ * lDDs .,> ‘“ ~g~: .( ,~, ,,. .<:,.~+,:: i \;\&.*?.*,~~ *,/,), ?,$,. *’ ,>, characteri3X~:s~@rilV. ,h.#.\. ~ ~i<. Character~@&$~*’: Output ., Q,f t~~$$#4 Q@$&r~Qolumn 1) Input to ( Figure 1%$. ~~~~’ ,??.> \.. 3.0 — 1.0 3.0 — 6,0 15 — 5.0 15 — 30 60 – 20 60 — 120 IDDS = 0.09 pA/kHz SVmbol (Figure pF ,:k) 5.0 Depressed) Standby — ,,t., ‘r,tf tpLH, pAdc ~Adc + 3.0 PA VDD Min Tvp Max Unit 5.0 — 300 — ns 5.0 — 1000 — ns 3.0 to 6.0 4.0 16 80 kHz tpHL Clock Pulse Freque~&~;@#R& .q~) “.*>.L ,....“~,!e, , ,,,,, $,>,1 ~~ \y,,..~ .),“~~ $. PR F FIGURE 2 – TYPICAL PRF Clock Frequencv kH Z STROBE PULSE DELAY TIMES tST * Strobe Pulse DelaV Time ms ~ *tST= MOTOROLA @ (l/p Semiconductor RF) ● 80, with PRF in kHz, tST in m$ Products Inc. FIGURE 3 –STROBE I nf Row Key 1 ● * R4 R3 R2R1 1110 2 1110 3 1110 A 1110 4 1101 5 1101 6 1101 B 1101 7 1o11 8 1o11 9 1 c 1o11 GENERATOR TIMING DIAGRAM ‘o n n o n ~ 011 ‘1 0...1 1I111O 1110 1010 1101 0000 1 1 011 1111 011 0111 A o 0 0000 nbinations 0 16 ‘7 GAS E 6%-05 (PLASTIC) ,0 8,-1 –+Fk L q —A UNE 1. LEADS WITHIN O.13mm (0.005) RADIUS OF TRUE POSITION AT SEATING PLANE AT MAXIMUM MATERIAL CONDITION. 2. PACKAGE INOEX: NOTCH IN LEAD NDTCH IN CERAMIC OR INK OOT. 3. DIM “VTO CENTER OF LEADS WHEN FDRMED PARALLEL. 4. OIM “A’’AND ‘,B”DO NOT INCLUDE GLASS RUN-OUT, 5. DIM “F” MAY NARROW TO 0.76 mm (0.030) WHERE THE LEAD ENTERS THE CERAMIC BOOY. MOTOROLA @ 1 LEAOSWITHIN013 mm(0.005)RADIUSOFTRUE POSITIONAT SEATINGPL4NE AT MAXIMUM MATERIALCONOITION 2. DIMENSION ~ TO CENTEROF LEADSWHEN FORMEDPARALLEL, 3. ;;~~~SION “B’ DOESNOTINCLUOEMOLD _. 4, ‘~ OIMENSION IS FORFULL LEADS.,,HALF LEADSARE OPTIONALAT LEAOPOSITIONS1,8, 9,AN016. 5. ROUNDEOCORNERSOPTIONAL, Semiconductor Producb Inc. ,,* FIGURE 4- TYPICAL KEYPAD INTERFACE -- APPLICATION Motorola reserves the right to make changes without further notice to any products herein to improve reliability, function or design. Motorola does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. Motorola and@, are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Employment Opportunity/ Affirmative Action Employer. m MOTOROLA Semiconductor Products Inc. 3501 ED BLUESTEIN BLVD., AUSTIN, TEXAS 78721 ● A SUBSIDIARY OF MOTOROLA INC.