Download: Order this document SEMICONDUCTOR TECHNICAL DATA by AN1235/D INTRODUCTION (NCI) was created to provided an organization to produce

Order this document SEMICONDUCTOR TECHNICAL DATA by AN1235/D Prepared by: Onis Cogburn INTRODUCTION (NCI) was created to provided an organization to produce captions and promote the service. In 1980 the closed cap- Designed primarily for the hearing impaired, closed cap- tioning for the hearing impaired officially made its debut as a tioning is applicable to many other applications. While the nationwide service. hearing impaired may benefit the most from the closed cap- Although it was hoped public pressure would drive the de- tion service, viewers without hearing problems can also velopment o...
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Order this document SEMICONDUCTOR TECHNICAL DATA by AN1235/D

Prepared by: Onis Cogburn INTRODUCTION (NCI) was created to provided an organization to produce captions and promote the service. In 1980 the closed cap- Designed primarily for the hearing impaired, closed cap- tioning for the hearing impaired officially made its debut as a tioning is applicable to many other applications. While the nationwide service. hearing impaired may benefit the most from the closed cap- Although it was hoped public pressure would drive the de- tion service, viewers without hearing problems can also velopment of the technology, the service languished until benefit. The ability to read and hear the program or movie Congress, after many hearings and the assurance that cost dialog will help both the young and the illiterate learn to read. would be small, passed the Television Decoder Circuitry Act Just being able to have the service available in noisy sur- of 1990. This legislation requires all TVs sold after July of roundings such as sporting events is attractive. The service 1993 that have screens larger than 13 inches have circuitry is also expected to provide dual language capability in the for decoding line 21 closed captioning. near future. This feature can increase the literacy of the indi- EEG Enterprises, a long time pioneer in the closed caption vidual by providing a method for studying a foreign language. industry, partnered with Motorola to produce the MC144143 Being able to read in one language and hear the equivalent Closed Caption Decoder IC. The device provides an eco- in a second language is an attractive method for learning a nomical solution for decoding and displaying closed caption- second language. ing on TV. The MC144143 may be designed into existing circuitry to produce TVs and VCRs capable of decoding and HISTORY displaying closed caption data or it may be used to build a stand alone decoder for TVs presently in use. The present closed captioning technology has its begin- nings in 1971. The National Bureau of Standards was study- ing the possibility of encoding real time clock information on HOW CLOSED CAPTIONING WORKS line 1 of the vertical blanking interval (VBI). Engineers at the American Broadcasting Company recognized the technology Line 21 of field 1 of the NTSC VBI contains the closed cap- as a way of transmitting closed captioning. ABC captioned tion information. The structure of the line 21 is shown in Fig- an episode of “The Mod Squad” and showed it to a group of ure 1. The information contained in line 21 contains not only hearing impaired people near the end of 1971. The reaction raw data but also timing information. A “color burst” is pres- of the test audience was so enthusiastic the NAB (National ent on the “back porch” of the horizontal sync pulse and Association of Broadcasters) began studying ways of estab- seven cycles of the 503.5 kHz “run–in clock” burst is trans- lishing a national closed captioning system. The Health mitted following the color burst information. Immediately fol- Education and Welfare department provided funding for the lowing the run–in clock is a 4.15 µs interval for stabilizing of development of encoders for the broadcast industry and low the data collection clock and locking and with the run–in cost decoders for use by viewers while PBS provided the ini- clock burst. Following this “timing” interval is a start bit fol- tial expertise for the design of this equipment. lowed by 16 bits of digital information transmitted as two In 1976 the Federal Communications Commission (FCC) 8–bit words formatted per the USA Standard Code of In- set aside line 21, field 1 of the VBI specifically for closed cap- formation Interchange (USASCII;x3.4–1967) with odd parity. tioning. ABC, NBC, and PBS agreed to participate in the The clock rate of 503.5 kHz is 32 times the horizontal sweep closed captioning service. The National Captioning Institute frequency. 10.50 ± 0.5 µs 4.15 ± 0.1 µs 33.764 µs 12.910 µs 0.12 µsPPµb1 b3 b5 b7 b1 b3 b5 b710.076 s b2 b4 b6 AR b2 b4 b6

A R

I I 2.0 µsTTYY12345678910 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 CHARACTER 1 CHARACTER 2 Figure 1. NTSC Line 21 Timing M OMoTtoOroRla,O InLc.A 1994 8/94 AN1235, 100 IRE (REFERENCE WHITE) CELL WIDTH = 1.324 µs

COLOR BURST

0 IRE (BLANKING LEVEL) CHAR LUM = 42.370 µs –40 IRE BOX = 45.018 µs 13.5 µs 35.73 µs CENTER OF ACTIVE VIDEO Figure 2. Character Box Timing The data format chosen for the closed caption system is a (video mux) is sufficient to decode the line 21 information and modified ASCII table. The normal 7–bit ASCII table defines integrate the information into the TV display. The MC144143 two types of characters, non–printing control characters decodes the line 21 information and from this information de- used for command execution and printable text characters. termines what text will be displayed and where on the screen The non–printing control codes have been expanded to in- it will be displayed. The output of the decoder chip is a lumi- clude additional commands necessary for the smooth opera- nance (or RGB) video signal representing only that part of tion of the system. The asterisk, back slash, up carat, the display where the text is to be displayed. The “BOX” sig- underline, apostrophe, brackets, and tilde were replaced with accented foreign characters to facilitate the display of non– nal is a control signal which tells the analog switch when text English languages. In addition, 15 additional characters were is to be displayed. defined by special character commands. Refer to the The video signal is routed to both the MC144143 and one MC144143 data sheet for a description of these characters input of the analog switch. Unless text information is present and the control codes used for positioning, text manipulation, (indicated by the BOX output), the video signal will be and processor instructions. passed through the analog switch unaffected. When the BOX signal indicates the presence of text information, the THE MC144143 analog switch (video mux) selects the “LUM” signal (lumines- The heart of the Closed Caption Decoder discussed here cence or brightness), from the MC144143 and passes this is the MC144143. This device contains all of the circuitry signal to the output. This switching always occurs within the necessary for detecting line 21, slicing and decoding the digi- line. Normal video is presented at the output of the analog tal data from line 21, and organizing the data into a format switch before any text appears on a line and after the text presentable for NTSC TV display. It contains a character ends on that line. This is to ensure that sync and color burst ROM containing all of the modified ASCII characters defined information are unaffected by the decoding and display pro- by the FCC specification for closed captioning. The display is cess. a character ROM based type with the ability to place text A typical application circuit is shown in Figure 4. The val- anywhere on the TV screen as defined by the line 21 control ues shown on the schematic are the recommended values codes. for most applications. (For specific implementations and for The MC144143 is a line–21 closed–caption decoder in- loop filter calculations, refer to the MC144143 data sheet.) tended for use in television receivers or set–top decoders The video buffer may be of any design capable of driving a conforming to the NTSC standard. The capability for proces- sing and displaying all of the latest standard line–21 closed– 470 ohm load with voltage gain of one. The video line driver caption format transmissions is included. The device design depends on the particular application (output imped- requires a closed–caption encoded composite video signal, ance, output voltage, etc.) for its design and may or may not a horizontal sync signal, and an external keyer to produce include DC restoration as one of its features. The analog captioned video. RGB outputs are provided, along with a switch may be as simple as a pair of DMOS transistors or a luminance and a box signal, allowing simple interface to both complete analog switch such as the MC74HC4053. color and black–and–white TV receivers. Display storage is accomplished with an on–chip RAM. A modified ASCII character set, which includes several non– SECTION 1 English characters, is decoded by an on–chip ROM. An on– The simplified decoder operation is shown in Figure 3. The screen character appears as a white or colored dot matrix on MC144143 decoder circuitry along with an analog switch a black background. AN1235 MOTOROLA CHAR 1 CHAR 2 CHAR 3 CHAR 32, MC144143

BOX

IN LUM Y1 E

VIDEO MUX

Y2 VIDEO IN VIDEO OUT

Figure 3. Simplified Decoder VDD

C1 * C2R 0.1 µFd * 470 560 pFd 47 k 10 k MC144143 0.1 µFd 2.7 k

DECODE

ON/OFF 1.0 µFd VIDEO BUFFER

HSYNC

VIDEO IN5kY1 VIDEO VIDEO OUT E SWITCH VIDEO LINE

DRIVER

Y2 * Decouple VDD to VSS with 0.1 µFd low ESR caps between pins 14, 15 and 9, 10 keeping leads as short as possible.

Figure 4. Typical Application Circuit MOTOROLA AN1235

10 k 10 k 10 k, Captions (video–related information) can be up to four MC144143, MC555, MC74HC4053, and the MC14576 with rows appearing anywhere on the screen and can be dis- their associated circuitry. The decoder section accepts a played in two modes: roll–up or pop–on. With roll–up cap- composite NTSC signal input, decodes the line 21 informa- tions, the row scrolls up and new information appears at the tion, mixes the normal composite video with the displayable bottom row each time a carriage return is received. Pop–on closed caption text and buffers the output for monitor input or captions work with two memories. One memory is displayed RF modulator input. The second section contains the while the other is used to accumulate new data. A special MC1374 RF Modulator IC and its associated circuitry. command causes the information to be exchanged in the two The MC144143 decoder circuit is the same as shown in memories, thus causing the entire caption to appear at once. the MC144143 data sheet. Of particular importance is the When text (non–video related information) is displayed, network tied to pin 13 and that associated with pin 11. The the rows contain a maximum of 32 characters over a black input circuitry of pin 11 of the MC144143 is a low pass filter box which overwrites the screen. Eight rows of characters for minimizing noise to the input clamp circuit and the net- are displayed in the text mode. work connected to pin 13 is the PLL loop filter network. Nei- An on–chip processor controls the manipulation of data for ther of these circuits should be modified without a good storage and display. Also controlled are the loading, addres- understanding of clamp circuits and PLL operation (see loop sing, and clearing of the display RAM. The processor trans- filter calculation section of the MC144143 data sheet). fers the data received to the RAM during scan lines 21 The bandwidth of line 21 is limited to approximately through 42. The operation of the display RAM, character 600 kHz. The 470 ohm resistor and the 560 pF capacitor ROM, and output logic circuits are controlled during scan connected to pin 11 of the MC144143 form a 600 kHz low lines 43 through 237. Several functions of the MC144143 are pass filter. For most applications this is adequate. Some controlled via a port which may be configured to be serial or measure of improvement in noise immunity can be achieved parallel. by usingaπtype LC filter adjusted for 470 ohms impedance, Characters are displayed as white or colored, dot–matrix but the cost of the components usually does not justify the characters on a black background. The characters are de- improvement in performance. The input of the MC144143 is scribed by a 6–by–9 dot pattern within a character cell which itself enough noise resistant for most applications. is 8 dots wide by 13 dots high. This provides a one–dot bor- The network connected to pin 13 of the MC144143 deter- der of black around each character and provision for one row mines how the VCO within the decoder IC will respond to the for underline, offset by a row of black, between the character video input signal. The VCO in the decoder IC must be able and the bottom edge of the cell. Character luminance has to handle a wide range of signal conditions. At one extreme normally been set at 90 IRE units and the surrounding black is the weak or “snowy” picture. The decoder must be able to box at 10 IRE units. decode line 21 down to a condition where the picture borders The Character ROM contains a dot–matrix pattern of on the unwatchable. In addition the text must be presented each character. Each dot from the character ROM repre- with a minimum of “jitter”. At the other extreme is the neces- sents a single picture element or ‘pixel’ and each picture ‘dot’ sity of decoding “bad” tapes; those from poor recordings or is made up of a square of four pixels. Pixels 1 and 2 are gen- from rental stores where the tape has been stretched from erated during field one and pixels 3 and 4 during field two. repeated playing. Alternate rows and columns are read out of each field to pro- When presented with a weak signal, the VCO within the duce an interleaved and rounded character. A display row PLL circuitry of the MC144143 will be continually bombarded contains a maximum of 32 characters plus a leading and with noise which will tend to cause the VCO to bounce trailing blank box, each a character cell in width, making the around. This is corrected by reducing the value of the resis- overall width of a display row 34x8= 272 dots. Successive tance in the loop filter while increasing the capacitance in se- display rows are butted together, so that the total display is ries with this resistance. This must be adjusted along a 195 dots high. precise curve dictated by a set of complex equations (see The black box (34 character cells wide by 195 dots high) loop filter calculation section of the MC144143 data sheet). results in a box size of 45.018 µs in width by 195 TV scan Although these values can be arrived at empirically, it is time lines in height. A scan line is two adjacent picture lines. The consuming and requires sophisticated testing equipment. first line is generated during field one and the second line is Acceptable values for reasonable jitter with weak signals are generated during field two. When centered in the video dis- 3.3K ohms to 4.7K ohms for R24 with a value for C5 of about play, this box starts 13.5 µs after the leading edge of H in 0.1 µF. The usual value for C6 is 3300 pF. scan line 43 and extends to scan line 237. This places the The disadvantage of using the lower resistance values display approximately within the safe title area for NTSC re- (R24 = 3.3K ohms) is stability problems encountered when ceivers. Character width is 42.37 µs and is approximately using a VCR to display old or poorly recorded tapes. This dif- centered on the screen, resulting in a leading and trailing ficulty is traceable to the design of the VCR recording mech- 1.32 µs black border. anism. To record and playback video information, the VCR For additional information on line 21 programming, loop fil- must be able to record one field as a single continuous track. ter calculations, EMI (electromagnetic interference) suppres- This is done by spinning the record/playback head and wrap- sions, and other MC144143 features, see the MC144143 ping the tape around the head mechanism so that the head is data sheet. in contact with the tape for about 180 degrees of rotation. The information is then recorded as a diagonal strip of in- THE SET TOP CONVERTER OPERATION formation on the tape. Two or more heads are mounted to the rotating mechanism and the signal switched between the The closed caption set top decoder (Figure 6) is composed heads so that one records/plays back the even fields and the of two sections. The decoder section, composed of the other the odd fields. Head switching occurs normally in the AN1235 MOTOROLA, last few lines of a field; usually 5 to 10 lines before the end of whose function was discussed previously. As pointed out in the field but may occur on some recordings during the VBI the discussion of the MC144143, a more sophisticated filter (vertical blanking interval). such as an LC filter could be used but probably wouldn’t im- Herein lies the problem. As the tape is repeatedly played prove performance enough to offset the added cost. the tape will stretch. This is aggravated during the head The MC74HC4053 is four single pole double throw analog switch line where the stretching causes the line containing switches. The speed of this device is adequate for pixel by the head switch “transient” to be longer. Additionally, poor pixel switching of NTSC generated video. Although only one equipment or misadjustment can cause excessive head of the four switches is needed and the required operation switch “transients”. Errors due to tape stretching and head could be obtained from discrete DMOS FETs, it is still prob- switch “transients” of more than 15 µs can be observed in the ably the cheapest. The “BOX” output of the MC144143 is normally 64 µs line length. used to control the switch and determines whether the de- The error introduced by the head switch is referred to as a coded closed caption text or normal video appears at the out- “transient” because it occurs only once per field; at the point put of the ’4053. This switching is done intraline so that of head switching. The VCO sees this transient as a jerk normal video sync and color burst information are not inter- which causes the frequency to jump. The length of time nec- rupted by the decoder. Normal video is always present at the essary to return to its correct frequency is determined by the beginning of every line and at the end of every line. Closed values chosen for the loop filter. For low values of R (3.3K or caption text is present only within the line and only during the less), the VCO in the MC144143 may not be able to return to lines chosen during the encoding. The position of the text is its correct operating frequency before line 21 is encountered. always predetermined at the time of encoding of the video If its frequency is not correct, it will not decode the line 21 signal. data. Values for R of 6.8K to 8.2K or higher with values of C5 U3, the MC14576C, is a dual video amplifier. The on–chip less than 0.082 µF will ensure that nearly all tapes will be de- gain–selling resistors set the noninverting gain of the coded, however, excessive jitter may result when very weak MC14576C to 6 db. The (A) section is used as a buffer/video and/or noisy signals are decoded. clamp. The (B) section is a line driver output for monitor con- Pin 8 of the MC144143 performs a unique function. The nection. The extra circuitry connected to the (A) section is frequency control for the decoder IC is a VCO in a PLL type necessary because of the nature of the video signal. The of circuit. The reference frequency for the PLL operation is composite video signal is a non–symmetrical voltage. The derived from the sync stripped from the composite video by positive peaks of the waveform do not equal the negative the sync detector circuits within the MC144143. As long as peaks. While this is necessary to convey the video informa- composite video is provided, the VCO will be locked to the tion, it does pose a problem that must be addressed. The dc horizontal sync signal. level of the video waveform is continually changing. If some During normal operation, a video signal will not always be method is not used (i.e., a dc restoration circuit for example), available. When changing TV channels or when the VCR is the intensity of the closed caption text will vary line by line not on, no video will appear at the input of the decoder. In and be determined by the background brightness. Q1 and these cases, the VCO would drift due to lack of reference associated circuitry reduce this condition to an acceptable input. The designers of the chip realized this and added an minimum. additional input for a second reference frequency; this is Input video from J1 is passed to pin 3 of U3A by the video pin 8. switch U4. C3 will charge through R3 causing the voltage on Pin 8 does not function the same as the reference signal pin 2 of U3A to rise. Since this pin is the inverting input of the derived from the video signal. Its purpose is only to keep the op amp, the output voltage, pin 1, will fall. When this voltage VCO within a range that will allow the PLL circuitry to “pull– drops to approximately 0.7 V, Q1 is turned on clamping the in” and lock to the horizontal sync of the composite video sig- output of U3A and preventing the voltage from dropping any nal. Normally this signal is derived from the sweep circuits of lower. The video input at pin 3 of U3A will result in an output the TV receiver. In the set top closed caption decoder circuit where clamping occurs at the negative sync tips. This main- we use a 555 timer circuit to generate a 15 kHz signal which tains the dc value essentially constant, varying only minimal- functions as a frequency control when a video signal is ab- ly during the VBI. sent. The question invariably arises, “Why not use the output of THE RF MODULATOR the VCR or the video signal itself as an input for this pin?” The answer lies with the previous discussion of the VCR op- If viewing on a standard TV is to be expected, a RF modu- eration and the effects of the head switch. The video signal lator must be incorporated into the circuitry. This device ac- can be decoded and the sync stripped off and used as an in- cepts the output of the decoder plus audio obtained from a put to pin 8 but the circuitry would be at least as complicated separate source (such as the audio output of a VCR) and as the 555 circuitry and with VCR operation, the head switch produces a TV signal (usually on channel 3 or 4). The PC results in an excessive amount of jitter as the VCO is jerked board layout provides a space which may be allocated for RF around during the switch. modulator circuitry. The RF modulator chosen may be a gen- Q2 is a simple video buffer and 600 kHz filter for the video eral purpose stand alone type, a PCB mountable module, or input to the MC144143. An integrated circuit current buffer an IC such as the MC1374. An optional audio amplifier could be used; however, none can approach the cost of a (shown in Figure 5) may be incorporated where the standard simple emitter circuit using the venerable 2N3904 (or equiva- VCR audio output is insufficient to drive the audio input of the lent). The filter itself is the two components R18 and C10 RF modulator chosen. MOTOROLA AN1235, + 5V12.2 k R103 C102 0.1 µFd 2 27 k R101 C103 AUDIO OUT120.047 µFd C101 AUDIO IN21210 µFd 2N3904 220 R104 15 k R102 820 R105 C104 47 µFd

Figure 5. Optional Audio Amplifier AN1235 MOTOROLA

, The MC1374 and associated circuitry can form the RF this EMI. This is sufficient for the PC board layout shown at modulator for the decoder. Video information from the decod- the end of this document, but if a double sided or single sided er and audio from the VCR modulate the carrier generated PC board design without ground plane is contemplated, it is by the MC1374 to produce a TV signal receivable on channel recommended the EMI information in the MC144143 data 3 or 4 by a NTSC television receiver. For a complete descrip- sheet be referred to prior to design. tion of the MC1374 operation, please refer to the data sheet for the MC1374 and/or the AN829 application note. REFERENCES POWER SUPPLY 1. “Closed Caption Decoder”, Motorola Data Sheet MC144143/D. Power for the set–top–decoder is obtained from any con- venient AC source whose RMS value is between 10 Vac and 2. “Color TV Modulator with Sound”, Motorola Data Sheet 20 Vac. The AC is rectified by diode D4 and filtered by the MC1374/D. electrolytic capacitor C24. An inexpensive MC7805 voltage 3. “Triple 2–Channel Analog Multiplexer/Demultiplexer”, regulator is used to obtain the necessary5Vsupply voltage. Motorola Data Sheet MC74HC4053/D. Additional filtering is provided by the electrolytic capacitor 4. “Dual Video Amp for5VOperation – “C” Version”, C23. Motorola Data Sheet MC14576C/D. In cases where weak channel reception of channel 10 is expected. EMI may occur due to the digital nature of the 5. “Timing Circuit,” Motorola Data Sheet MC1455D/D. MC144143. A ferrite bead (RFB) has been placed in series 6. “Fixed–Voltage, 3–Terminal Regulator for Positive Polar- with the VDD pins along with a 0.1 µFd capacitor to suppress ity Power Supplies”, Motorola Data Sheet MC7805/D. MOTOROLA AN1235,

Figure 6. Set Top Decoder Schematic AN1235 MOTOROLA

U5 D4 MC7805 VI VO +V 1N4001 C24 GND C23 R3 R4 47 µF C14 C15100 µF2k1k–V 15 V 0.1 µF 0.1 µF 15 V 1/4 W 1/4 W D1 D2 1N4001 1N4001 R10 R11 C161µ10 k 47 k Q1 R7 0.1 FL1 1/4 W 1/4 W 2N3904R8 R9 10 k 10 k 10 k RFB C17 C201/4 W 1/4 W 1/4 W D3 U4 R1 0.1 µF 1N4001 0.1 µF3 k DECODE 2 U1 MC74HC4053 15 V ON/OFF 18 MC144143 1 R13 12 14 1/4W385kX0 X +17 2 13 1 X1 R2 U3A 16 3 15 1.5k2_Y1/4W415 4 R12 2 Y0 MC14576C/A 14 5 10 k C214R24 Y1 Z C3 13 6 1/4 W 0.1 µF 4.7 k 12754.7 µF 1/4 W Z0118315 V Z1 10 9 C5 C6 C7 C22 R5 6 165k0.1 µF INH V3300 pF 0.1 µF 0.1 µF 11

A

10 7 C21BG980.1 µF C1CG25 µF R15 C19 R18 C1015 V 4.7 k 0.1 µF 470 560 pF 1/4 W 1/4 W R21 J1 C81kC18 M1 Q2 C9µ840.1 µF2N3904 0.1 F RF MOD 10 µFPRC4 V J3 15 V R19 U2 100 µF CC MC1455 5 15 V GND1.8 k + R14 R16 R17 1/4W3Q27VIDEO 75 4.7 k 470 TR76_U3B 1/4 W 1/4 W 1/4 W DIS GND CASE R23 R205575 AUDIOTHR CV 3.3 k MC14576C/B 1/4 W 1/4WGC12 R6 1 0.1 µF J4 1.8 k J2 1/4 W C11 0.01 µF C13 0.047 µF R22 10 k, COMPONENT SIDE SILKSCREEN 4.50 MOTOROLA AN1235 6.00, COMPONENT SIDE SOLDERMASK 4.50 AN1235 MOTOROLA 6.00, TOP, SIGNAL 1, LAYER 1 4.50 MOTOROLA AN1235 6.00, BOTTOM, SIGNAL 2, LAYER 2 4.50 AN1235 MOTOROLA 6.00, SOLDER SIDE SOLDERMASK 4.50 MOTOROLA AN1235 6.00,

DRILLMASTER AN1235 MOTOROLA

6.00 5.000 3.300 3.100 4.50 3.50 DRILL MAP

HOLE

FIGURE SIZE QTY 36.0–P 184 40.0–P 8 156.0–P 1 230.0–P 5 136.0–N 4 .200 0 4.600 4.800,

TV SET TOP CLOSED–CAPTION DECODER PARTS LIST

Item Quantity Reference Part11R19 1.8k25J1, J2, J3, J4, + V31C1 25 µF 4 13 C2, C5, C7, C9, C14, C15, C16, 0.1 µF C17, C18, C19, C20, C21, C2251C3 4.7 µF62C4, C23 100 µF71C6 3300 pF81C8 10 µF91C10 560 pF 10 1 C11 0.01 µF 11 1 C12 0.1 µF 12 1 C13 0.047 µF 13 1 C24 47 µF 14 3 D1, D3, D4 1N4001 15 1 D2 1N4001 16 1 Decode On/Off (SPST Switch) 17 1 L1 RFB (Ferrite Bead) 18 1 M1 RF Mod 19 2 Q1, Q2 2N3904 20 1 R13k21 1 R2 1.5 k 22 1 R32k23 2 R4, R211k24 2 R5, R135k25 1 R6 1.8 k 26 6 R7, R8, R9, R10, R12, R22 10 k 27 1 R11 47 k 28 2 R14, R23 75 29 3 R15, R16, R24 4.7 k 30 2 R17, R18 470 31 1 R20 3.3 k 32 1 U1 MC144143 33 1 U2 MC1455 34 1 U3A MC14576B/A 35 1 U3B MC14576B/B 36 1 U4 MC74HC4053 37 1 U5 MC7805 Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters can and do vary in different applications. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola and are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer.

MOTOROLA AN1235

, Literature Distribution Centers: USA: Motorola Literature Distribution; P.O. Box 20912; Phoenix, Arizona 85036. EUROPE: Motorola Ltd.; European Literature Centre; 88 Tanners Drive, Blakelands, Milton Keynes, MK14 5BP, England. JAPAN: Nippon Motorola Ltd.; 4-32-1, Nishi-Gotanda, Shinagawa-ku, Tokyo 141, Japan. ASIA PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Center, No. 2 Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong.

AN1235 ◊ CODELINE TO BE PLACED HERE MOTAONR12O35L/AD

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