M494

M494 STMICROELECTRONICS | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 22

Technical content

SINGLE-CHIP VOLTAGE TUNING SYSTEM WITH

4 ANALOG CONTROLS AND µP INTERFACE

(Plastic Package) ORDER CODE : M494B1 .NON-VOLATILE MEMORY FOR 20 PRO- GRAM WORDS (17 BIT x 20) - TUNING VOLTAGE 12 BITS - BAND 2 BITS - MULTI STANDARD 2 BITS - PROGRAM SKIP BIT 1 BIT - 10,000 MODIFY CYCLES PER WORD - MIN. 10 YEARS DATA RETENTION .13 BIT VOLTAGE SYNTHESIZER (BRM + PWM) .NV MEMORY FOR 4 ANALOG CONTROLS (6 BIT x 4) .4 BAND SWITCH OUTPUTS (VHF I & III, UHF, CATV) .5 x 7 KEYBOARD .2 AUDIO VISUAL OUTPUTS (VCR & PC) .2 CODED MULTI STANDARD OUTPUTS (e.g. PAL, SECAM, NTSC etc.) .DIRECT 1 1/2 DIGIT 7 SEGMENT COMMON ANODE LED DISPLAY DRIVING .PCM REMOTE CONTROL RECEIVER (M708 transmitter) .5-BIT DATA INPUT + CONTROL LINE FOR P INTERFACE .LINEAR AFC DEFEAT OUTPUT .FLYBACK/SYNC. COINCIDENCE INPUT FOR SEMI-AUTOMATIC SEARCH .STANDBY OUTPUT .OPTION SELECT : 16 OR 20 PROGRAMS .POWER UP MODE .PROGRAM SKIP DEFEAT .AV OPTIONS .1 * OR DECADE MODE OPTION IN 20 PRO- GRAM OPTION .TEMPORARY ANALOG UP/DOWN INDICA- TOR ON LED DISPLAY .BAND SKIP OPTION .455 TO 510kHz CHEAP CERAMIC RESONATOR .VDD =5 V ± 5%. VPP = 25V± 1V

DESCRIPTION

The M494 is a monolithic LSI integrated circuit fabricated in SGS-THOMSON’s EPM2 process; an N-channel, Planox, double poly MOS process ca- pable of including a floating gate NV memory cell (EEPROM). The i.c. has been designed as a complete digital TV tuning system based on the voltage synthesis principle and as a replacement for all the conven- tional potentiometers and band switches particu- larly in low cost TV sets. It also provides some functions normally only associated with higher cost sets. NV memory is integrated on the chip together with all the necessarycontrol circuitry to providethe program memory. Separate NV memory is also integrated to provide the memory for four analog controls. A seven segment LED display can be directly driven by the chip to display the program selected, and the direction of movement of the analog controls. Provision is made for a remote control receiver both on and off chip, the latter is interfaced via a data input and single control line. (This enables control by a microprocessor). A local keyboard can be used with the device in a variety of configurations. An option select pin provides for different program number options, power up op- tions and skip associated functions. This device is another significant step towards the complete inte- gration of TV control circuitry. The device is packaged in a 40 pin DIL plastic package.

g f e d c b a AV0 AV1 MEMORY TIMING V PP VSS V DD UHF CATV VHF 1 VHF 3 OSC. OUT OSC. IN TUNING CONTRAST MS 0 MS 1 BRIGHTNESS TEST 1 DATA HANDSHAKE STANDBY AFC DEFEAT FB/SYNC COINCIDENCE REMOTE CONTROL VOLUME SATURATION 494-01.EPS PIN CONNECTIONS ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VDD Supply Voltage – 0.3 to 7 V VPP Memory Supply Voltage – 0.3 to 26 V VI Input Voltage – 0.3 to 15 V VO(off) Off State Input Voltage 15 V IOL Output Low Current LED Driver Outputs : pin a-g pin h + i All other Outputs mA mA mA t PD Max. Delay between Memory Timing & Memory Supply Pulses 5 µs Ptot Total Package Power Dissipation 1 W Tstg Storage Temperature – 25 to + 125 °C Top Operating Temperature 0 to + 70 °C C os Capacitance on Option Select Pin 100 pF R os Resistance on Option Select Pin 1 k Ω C dk Capacitance on data outputs & keyboard inputs when lines are connected by a keyboard switch closure 150 pF R k Series Resistance of Single Keyboard Switch 10 k Ω C rts Capacitance on Data Handshake Pin 50 pF Stresses above those under ”Absolute Maximum Ratings” may causes permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 494-01.TBL M494

STATIC ELECTRICAL CHARACTERISTICS (Tamb =0t o7 0°C, VDD = 5V unless otherwise specified) Pins Symbol Parameter Test Conditions Min. Typ. Max. Unit Memory Supply I PP Memory Supply Current VPP = 25V Write Peak Write Average Erase Peak Erase Average Read Peak Read Average 2.5 mA mA mA mA mA mA R Pull Down 25 k Ω Memory Timing V OL VDD = 4.75V, IOL = 2.5mA 8 V IO(off) Leakage V DD = 4.75V, VO = 26V 100 µA Tuning V OL VDD = 4.75V, IOL = 5mA 1 V VDD IDD Supply Current V DD = 5.25V 100 mA RC V I pk to pk 0.5 13.2 V FB/sync. Coin. Input VIL 0.8 V VIH 2.0 V IIL VDD = 5.25V, VIL = 0.8V – 0.4 mA R Pull up 30 k Ω Vol. Brigh. Sat. Contr. DACs VOL VDD = 4.75V, IOL = 4mA 1 V IO(off) VDD = 5.25V, VO = 13.2V 50 µA h+i V IL 1.5 V VIH 3.5 V IIL VDD = 5.25V, VIL = 1.5V – 50 µA R Pull up 200 k Ω VOH VDD = 4.75V, IOL = 30mA 1.5 V D0, D1 D2, D3 V IL 1.5 V VIH 3.5 V IIL VDD = 5.25V, VIL = 1.5V – 0.4 mA VOL VDD = 4.75V, IOL = 1mA 0.4 V IO(off) VO(off)= 5.5V 25 µA R Pull up 30 K Ω MS0, MS1 AFC def. AV0, AV1 VOL VDD = 4.75V, IOL = 1mA 0.4 V IO(off) VDD = 5.25V, VO 13.2V 50 µA Option Select V IL 1.5 V VIH 3.5 V IIL VDD = 5.25V, VIL = 1.5V – 0.4 mA R Pull up 30 k Ω Standby V OL VDD = 4.75V, IOL = 100µA 0.4 V IO VDD = 4.75V, VO = 0.7V 1.6 mA a, b, c, d, e, f, g V IL 1.5 V VIH 3.5 V IIL VDD = 5.25V, VIL = 1.5V – 50 µA R Pull up 200 k Ω VOL VDD = 4.75V, IOL = 15mA 1.5 V Display Drive V OL VDD = 4.75V, IOL = 5mA 0.4 V IO(off) VDD = 5.25V, VO = 13.2V 50 µA UHF, III, I, CATV V OL VDD = 4.75V, IOL = 1mA 3 V VOH VDD = 4.75V, IOH = – 150µA 2.4 V VIL 1.5 V VIH 3.5 V IO(off) VDD = 5.25V, VO = 13.2V 50 µA Data Handshake VOL VDD = 4.75V, IOL = 1mA 3 V VOH VDD = 4.75V, IOH = 150µA 2.4 V VIL 1.5 V VIH 3.5 V IIL VDD = 5.25V, VIL = 1.5V – 0.4 mA R Pull up 30 k Ω IO(off) VDD = 5.25V, VO = 13.2V 50 µA 494-02.TBL M494

τ 1 =R C τ 2 =R i.C 1.5V 494-04.EPS Figure 3 FUNCTIONAL DESCRIPTION (continued) Several tests are performed on the signal : a) Measurement of the pulse distance T (time base synchronization). b) Check of the bit positions relative to the time base windows. c) Check of the parity bit. d) Check of the absence of pulses between parity and stop pulses. e) Check of the noise level. The receiver checks the noise level for a time T after each pulse detected. If all these tests are successful the received word is stored and decoded. If not it is rejected. The transmission is terminated on reception of the end of transmission (EOT) code or if the internal timer measures a transmission interruption of more than 550ms. For more detail concerning the operation of the RC receiver refer to SGS-THOMSON Tech- nical Note No. 155 pp11-12. The RC receiver and the local keyboard have the same command source priority i.e. a local com- mand is not accepted until a previously accepted RC command has been completely executed and the EOT code transmitted. Similarly if a local com- mand is under execution then an RC command will not be accepted. The RC truth table and com- mands are shown on the next page. Analog Control Outputs Four analog control outputs are implemented to provide for Volume, Brightness, Saturation and Contrast from four 6 bit D/A’s. These D/A’s use the Pulse Width Modulation technique to synthesize a pulse train of constant frequency but variable pulse width (PWM). Each output delivers a 7.8kHz square wave whose duty cycle is variable in 63 steps. External RC filtering and level shifting is required to realise a static DC voltage from the pulse train. If the analog outputs are continuously varied by command from the keyboard or data command sources the outputs will change approx. every 112ms (fck = 500kHz) or approx. every 102ms if the command is issued from the RC command source. One analog control is specifi- cally designed asa volume controlas mute circuitry is built in. On start up reset the analog control outputs except volume are enabled after a period of approx. 1.1 seconds. In the Standby and Off states all the analog control outputs are pulled to logic LO. The normalise command reads the contents of each analog memory sequentially to its corre- sponding counter and D/A output. Tuning Output The tuning voltage is generated from a 13 bit counter.The programmemory stores the 12 MSB’s of the tuning word. The range of the AFC circuitry is at least 3 bits so the LSB of the tuning counter does not affect the resolution of tuning. The contents of the counter are converted using a PWM and a Bit Rate Multiplier (BRM) technique. 13 bits gives 8192 steps which yields a resolution of approximately 3.9mV with a max. tuning voltage of 32V. This corresponds to a resolution of about 75kHz in the UHF band. The 5 MSB’s of the tuning word are converted using PWM and the remaining 8 bits using BRM. Thus as the tuning word in- creases fromall zeroes the numberof pulsesin one period increases to 256 with all the pulses being the same length (t o =2 µs). For values larger then

256 PWM conversion takes place where the num-

ber of pulses in one period stays constant at 256 but the width changes. When the pulse width reaches 15to two successive pulses ”link” together and the number of pulses decreases (see Figure 4). The pulse train is fed to an external low pass filter to realise a DC voltage. The temperature depend- ence of this system is predominantly the switching times of the output pulses and as there are only a maximum of 256 pulsesin one period the tempera- ture stability is very good. In Standbyand Off states the tuningoutput is pulled to logic LO. 256 No OF PULSES TUNING VOLTAGE1V 31V 494-05.EPS Figure 4 M494

FUNCTIONAL DESCRIPTION (continued) Table 1 :Remote Control Commands (address 10, code = 1010) Command Number Function Code

16 Programs 20 Programs C1 C2 C3 C4 C5 C6

Mute (toggle) Program 1 Program 2 Program 3 Program 4 EOT Standby Mute (toggle) Program 1 Program 2 Program 3 Program 4 Contrast up Contrast down Program 5 Program 6 Program 7 Program 8 Contrast up Contrast down Program 5 Program 6 Program 7 Program 8 Memory Seq. up Memory Seq. down Program 9 Program 10 Program 11 Program 12 Memory Seq. up Memory Seq. down Program 9 Program 0 – 10 (decade) + 10 (decade) Normalise On/stby (tog.) Program 13 Program 14 Program 15 Program 16 Normalise On/stby (tog.) NOP NOP NOP Volume up Volume down Brightness up Brightness down Saturation up Saturation down Volume up Volume down Brightness up Brightness down Saturation up Saturation down The above table showns the difference between the 16 and 20 program options with respect to the remote control commands. Commands 16, 17, 18 &21 change function between the two options. Commands 22, 23 & 24 should not be used in the 20 program option, as they have no function. NOP = No operation Program Memory NV memory (EEPROM) is integrated on the chip to provide storage for up to 20 stations. Each memory location is 17 bits in lengthproviding 12 bits for tuning voltage, 2 bits for band, 2 bits for two coded multi-standard outputs and 1 bit pro- gram skip flag. Individual program words canbe read on command from the keyboard, remote or data command sources but can only be written on command from the keyboard. There are two methods for storing a program (writ- ing the memory) : pre and post tuning selection of the programnumber. See Commands, section 7. Reading each memory location in sequence (up or down) can also be achieved from all the command sources. All memory timing functions are provided on chip and only one external transistor is required to switch the external memory supply (25V). There are essentiallytwo operationscarried out on the memory : Write/Modify and Read. The Write/Modify cycle consists of 3 steps : a) All ”1s” are written to the bits of the addressed word. b) All bits of the word are erased. c) The new contents are written. Using this method allthe bitsof the addressedword are aged the same. For more detail concerningthe write, erase and read current waveforms at the Memory Supply pin see M491 datasheet. Memory For Analog Controls The memory for the analog controls is electrically identical to the main programmemory but is organ- ised as four 6-bit words located in two sequentially addressed words at the memory. Each word cor- responds to the Volume, Brightness, Saturation and Contrast outputs. At power on reset and nor- malise command each memory word is read out to its corresponding counter and D/A in sequence. M494

FUNCTIONAL DESCRIPTION (continued) Display The M494 is capable of directly driving a 1 digit common anode LED display at the max. sink cur- rent of 15mA per segment. The h+i pin is capable of sinking a max. currentof 30mAso that these two segments can be driven from the same pin and be the same brightness as the other segments. On instruction from the internal command decoder the displayshows programme number, direction of analog controlmovement, decade changeor Mem- ory Addressing function active. Analog controls in this context are defined as Tuning, Volume, Con- trast, Saturation & Brightness. The formats of the display for analog control direction, decadechange and Memory Addressing are shown below respec- tively : For the analog controls the above condition is displayed with an ”overrun” time of 300ms. i.e. the display will show the ”arrows” for a period of 300ms after the release of any analog control up or down key. The Memory Addressing function display flashesat 5Hzafter the Memory Addressing function is commanded and continues to flash until a programme is selected or any other command is given. In 1 * the g segment only flashes at 5Hz and continues to flash until a programme number is selected or any other command is given. If in Memory Addressing and 1 * is pressed then the display above is shown with segments g & d only flashing at 5Hz until a programme number is se- lected or any other commands is given. When Store or Set Skip Flag commands areexecuted the whole display is flashed at 5Hz for 1 second. Keyboard It is possible to implement a keyboard with a max. size of 35 keys as a 5 x 7 array. Fig. 8 shows the arrangement of the key matrix. Each key connects a row (a-g) with a column (D0-D4) with a max. resistance of 10kΩ . De-bounce logic is integrated on the chip that only allows acceptance of a com- mand if the key is closed for longer than 40ms except for the On/Standby and On/Off commands where the relevant keys must beclosed for approxi- mately 100ms. This is equivalent to 2 received RC commands). UP DOWN MEMORY ADDRESSING |* I* AND MEM. ADDR. 494-08.EPS For the main keyboard matrix (a-g x D0-D4), if the logic detects two keys closed simultaneously the display is blanked to indicate this condition to the user and no command is executed. When the logic detects only one key pressed the display will re-il- luminate and the command be executed. This avoids confusionasto which command should be executed and provides feed back to the user. For the Option select line all options/commands can be active simultaneously. 1 * mode or decade mode can be selected on the option select line by the presence of a diode or not respectively. These two modes are only active for the 20 program option and are described below : In 1 * mode the display will toggle in & out of the condition shown in the Display Section. Access to programs in the first decade is made by simply pressing any 0-9 program key and access to pro- grams in the second decade, whatever the current program is made by pressing 1 * followed by any 0-9 program key. In decade mode on pressing either±10 (decade) keys the display will light or extinguish the half digit respectively and simultaneously effect the tuning information.e.g. if the deviceis in program 3 press- ing + 10 (decade) key will give program 13 and then pressing - 10 (decade) key will give program 3. Pressing - 10 (decade) again will have no effect. The 20 program option select acts like an enable for the 1 * or decade modes. i.e. the 1 * or decade modes are only selectable in the 20 program op- tion. In 16 program option the function of the 1* key, program key 0, -10 (decade) & + 10 (decade) are changed to no function, programme 10, 11 & 12 respectively. i.e. The difference between fig. 7 & 8 for those keys that change function. If the 1 * key is pressed followed by brightness up for example the device will increase the brightness only and reset the 1 * commandi.e. the last command from any command source will al- ways be executed if it is a single keystroke command and the 1 * command will be reset by it.It is possibleto press the 1 * key on the keyboard and then a program 0-9 command from RC or Data command sources or vice versa. Thus there are 2 methods of selecting a program from the keyboard for the 16 program option : direct access (only up to 12 programs) or Memory sequence up/down. And there are 3 methods of selecting a program from the keyboard for the 20 program option : 1 * mode, decade mode and Memory sequence up/down. M494

FUNCTIONAL DESCRIPTION (continued) M494 NORMALIZE CONTRAST UP STORE PROGRAM ON/STANDBY (TOGGLE) CONTRAST DOWN STORE ANALOG VALUES VOLUME UP BRIGHTNESS UP TUNE UP VOLUME DOWN BRIGHTNESS DOWN TUNE DOWN SET SKIP FLAG ON/OFF (TOGGLE) BAND SEQUENCE SATURATION UP MEMORY SEQUENCE UP MS SEQUENCE MUTE (TOGGLE) SATURATION DOWN MEMORY SEQUENCE DOWN MEMORY ADDRESSING P/U* OFF 16* AV1* a b c d e f OPTION SELECT g AV2 P/U STANDBY SKIP OFF h+i * = DEFAULT P/U = POWER UP 494-09.EPS Figure 7 :Keyboard 16 Programs M494

FUNCTIONAL DESCRIPTION (continued) M494 NORMALIZE CONTRAST UP STORE PROGRAM ON/STANDBY (TOGGLE) CONTRAST DOWN STORE ANALOG VALUES VOLUME UP BRIGHTNESS UP TUNE UP VOLUME DOWN BRIGHTNESS DOWN TUNE DOWN SET SKIP FLAG ON/OFF (TOGGLE) BAND SEQUENCE SATURATION UP MEMORY SEQUENCE UP MS SEQUENCE MUTE (TOGGLE) SATURATION DOWN MEMORY SEQUENCE DOWN MEMORY ADDRESS ING P/U* OFF AV1* a b c d e f OPTION SELECT g AV2 P/U STANDBY SKIP OFF h+i -10 DECADE +10 DECADE DECADE* MODE 1*MODE * = DEFAULT P/U = POWER UP 494-10.EPS Figure 8: Keyboard 20 Programs M494

FUNCTIONAL DESCRIPTION (continued) Data Input Shown below are the codes for the commands : see Table 2. The Data input will accept signals whose timing is defined in Figure 6 and electrical characteristics defined in the table of static electrical charac- teristics. The EOT code must be transmitted after each command after a min. period of 112ms. Band Outputs Four band outputs are provided for selection of the signal band : VHF I & III, UHF and CATV. Band skip logic is implemented so that by tieing the relevant pin to V SS a band can be skipped in regions of no transmission in that band. The bands can be se- lected only in a rolling sequence by the band se- quence keyboard command. The sequence is as follows : VHF III, UHF , VHF I, CATV. Multi Standard Outputs Two coded multi standard outputs (or general pur- pose TV system flags) are provided so that the TV set can be designed for use in areas of more than one transmission standard. This function requires an externaldecoder to realise 4 different standards e.g. PAL 1, PAL 2, NTSC, SECAM etc. The multi standard sequence command available from the keyboard gives a simple binary count at the two outputs : 00, 01, 10, 11, 00 etc. In Standby and Off states the multistandard outputs are pulled to logic LO. Table 2 :Data Commands Command Number Function Code

16 Programs 20 Programs D0 D1 D2 D3 D4

– 10 (decade) + 10 (decade) Program 13 Program 14 Program 15 Program 16 Normalise Volume up NOP NOP NOP Normalise Volume up Volume down Contrast up Contrast down Brightness up Brightness down Saturation up Volume down Contrast up Contrast down Brightness up Brightness down Saturation up Saturation down Memory Seq. up. Memory Seq. down On/standby (toggle) Standby Mute (toggle) Saturation down Memory Seq. up. Memory Seq. down On/standby (toggle) Standby Mute (toggle) NO TRANSMISSION (pulled up) 1 1 1 1 The above table shown the difference between the 16 and 20 program options with respect to the Data input commands. Commands 10, 11, 12 & 13 change function between the two options. Commands 14, 15 & 16 should not be used in the 20 program option, as they have no function. NOP = No operation. M494

FUNCTIONAL DESCRIPTION (continued) Skip Function Program skip is implemented in the M494 by a single memory bit associated with each program word. The bit acts as a flag to the device to indicate that the program word should be skipped and the next program word read from the memory in as- cending or descending order if the skip flag is set. Programs are skipped only when accessed using the memory sequenceup/down commands. Direct access to a program from the keyboard, RC or data command sources will always override the skip commanded from RC then prog. 7 will be tuned even if there is nc prog. stored in that memory location. In order to program the skip bit and to defeat its function when required two commands are avail- able : set skip flag and skip defeat. The skip defeat switch is designed to be activated by a facia panel on the TV set under which are infrequently used controls. On the set skip flag command the M494 stores the current contents of the tuning, band and MS count- ers and sets the skip bit. After the set skip flag operation the contents of the tuning, band and MS counters will not change and the device continues to output these values. The operation is transpar- ent to the user in terms of function but is indicated on the display by the program number flashing at 5Hz for 1 second. In order to reset the skip bit for any program word the desired program should be selected with skip defeated. A station should then be tuned, if required, and then the store command issued. The store command automatically resets the skip flag. The skip defeat command enables the reading and writing (plus resetting of skip flag) of memorywords whose skip flag is set. If skip is defeated the device will only access the number of programs selected by the option select i.e. If 16 programs only are selected then skip defeat will NOT enable access to all 20 programs. Reset There are two conditions under which the M494 is reset : power on and start up (On command). Power on reset is triggered whenever V DD falls below about 3V. The duration of this reset is 110ms after VDD has been restored. Power On Reset (Powered down to Off or Standby states) After the reset period of 110ms : a) The program counter is set to program1. b) The outputs are disabled as defined in the Off and Standby states. See Standby & Off definitions. c) The option selection, keyboard, momentary on switch and, when in standby,thedisplay, RC and data inputs become active. For the ”activity level” of the keyboard in Off and standby states. See Standby & Off definitions. d) An internal register is set to indicate that the device has powered up from the powered down state. Start Up Reset (Standby or Off states to On state) A start up reset is instigated by the reception of the commands given in the definition of terms or the Standby section. The following then occurs : a) The internal register indicating that the device has powered up from the powered down state is read : I) If the register is set than the memory word addressed by the program counter is loaded into the tuning counter and then the analog values are read rom the memory. II) If the register is reset then the previously selected tuning and analog values are left unchanged. b) The AFC is defeated and the volume muted for a period of approx 1.7 seconds or 0.6 seconds longer than the other analog outputs. c) The tuning and analogue outputs, except volume, are enabledafter approx. 1.1 seconds. d) The volume output is enabled after 1.7 seconds e) The standby output is pulled up internally to logic HI f) The internal register is reset. If the device has either of the power up options (power up in Off or standby states) selected then it will performa power up reset but all the outputsand commandsources will remain disabled, then onthe On command, a start up reset will be performed. If the device is required to power up in the On state using the momentary mechanical switch con- nected to the h+i pin then it will perform an ordinary power on reset followed immediately by a start up reset. The outputs and command sources will be enabled after the periods defined above. M494

FUNCTIONAL DESCRIPTION (continued) Manual Tuning Manual tuning commands tune up or down, are available from keyboard only and are provided to allow both manual station search and tuning adjustments. If a continuous tuning up or down command is made from the keyboard the speed of movement of the tuning counter is as shown in fig. 10 for the UHF and CATV bands. Time t o is the start time for the key being pressed. When the FB/sync. coincidenceinput is a logic HI the tuning speed is reduced to 16 steps/sec. If, at time t o the FB/sync. coincidence input is at logic LO than the tuning.sweep speed jumps immediately to 512 steps/sec. For VHF III & I all these levels are shifted up by a factor of 2 & 4 respectively giving slowest speeds of 8 steps/sec. and 16 steps/sec. and highest speeds of 1024 steps/sec and 2048 steps/sec. If the continuity of command is broken by releasing the keyboard for example then the tuning speed returns to its slowest speed when the FB/sync. coincidenceinput is at logic HI. If the upper orlower limit of a band is reachedduring manualtuning then tuning will continue in the same direction from the opposite limit after a 480ms delay to allow for the discharge of the external network. The tuning counter is 13 bits in length giving a range of 8192 steps. The UHF band has a band- width of approx. 400MHz. Thus in the UHF band the slowest speed of 4 steps/sec. gives a tuning speed of about 200kHz/sec. The fastest speed of 512 step/sec. corresponds to a total band sweep time of 16 seconds. Program Memory Sequence A continuousup/down program memory command from keyboard produces a program change every 500ms. From remote control and data command sources a continuous program memory sequence command produces a program change approx. every 500ms or every 5 received commands. A memory sequence up or down command issued from any source will bringthe device out of standby to the program selected before standby was com- manded. The memory sequence up or down will not then commence until the command is stopped and reissued from any source (until an EOT has been received or internally generated). 512 FB/SYNC. COINCIDENCE FB/SYNC. COINCIDENCE FB/SYNC. COINCIDENCE Time (sec) t 0 123 TUNING SWEEP SPEED (STEP/SEC) 494-12.EPS Figure 10 :Tuning Sweep Speed (UHF & CATV BANDS) M494

FUNCTIONAL DESCRIPTION (continued) Mute The sound mute function is available as a toggle command from all command sources. There are other commands and functions during which the sound is muted : - FB/sync. coincidence - If there is no FB/sync. coincidence under any conditions the sound is muted. - Startup reset- the sound is muted for approx.1.7 seconds. - Program change - the sound is muted for 0.6 seconds on any program change ; direct, 1 * + 0-9 program (only after the second keystroke), ±10 (decade) & Memory sequenceup/down con- tinuous or single keystrokes. - Standby & Off states - the sound is muted. - Band sequence - same as program change. The sound is demuted under the following condi- tions : - When the mute command is received from any source. - When the device is commanded On from standby of Off, i.e. if the device was muted when the standby command was issued then when On is commanded it will always start up with the sound demuted after the reset and settling period of approx. 17 seconds. - Volume up - if volume up is commanded whilst the sound is muted then the volume will increase from zero. - Volume down - if volume down is commanded whilst the sound is muted then there is no effect. - Any program change - the sound is NOT de- muted. Momentary On Switch Provision is made for a momentary switch con- nected between the h+i pin and ground to forcethe M494 to make Power on and Start up resets auto- matically so that the device attains the On state immediately. The condition of the h+i pin is latched after the reset period of 110ms. Therefore the period of switch contact closure should be a min. of 120ms. Figures. 11 & 12 respectively show in flow diagram form the two methods for storing a station : pretun- ing program selection and post tuning program selection. Figures. 13, 14 & 15 show the select programme subroutine for Figures. 11 & 12 for either 16 program option or 20 program option with 1*o r±10 (decade modes). M494

Programs 1-12 KB, D,RC (16 opt.) Reads the contents of the memory location : 2MSB’s to the MS counter, next 2 MSB’s to the band counter next 12 MSB’s to the tuning counter and D/A and LSB to skip flag register. Initiates an on command only after standby. Programs 0-9 KB, D, RC (20 opt.) Reads the contents of the memory location : 2MSB’s to the MS counter, next 2 MSB’s to the band counter next 12 MSB’s to the tuning counter and D/A and LSB to skip flag register. Initiates an on command only after stndby. Programs 13-16 D, RC (16 opt.) Reads the contents of the memory location : 2 MSB’s to the MS counter, next 2 MSB’s to the band counter next 12 MSB’s to the tuning counter and D/A and LSB to skip flag register. Initiates a on command only after standby. – 10 (decade) KB, D, RC (20 opt.) Sustracts 10 from the current program (if possible). Initiates an on command only after standby. + 10 (decade) KB, D, RC, (20 opt.) Adds 10 to thecurrent program (if possible). Initiates an on command only after standby. 1* KB, D, RC (20 opt.) Commands the M494 to wait for a 0-9 program command or to reset on any other command. Display shows half digit and g segment flashing at 5Hz. Initiates an on command only after standby. Vol. up/down Bri. up/down Sat. up/down Con. up/down KB, D, RC Increments up or down the relevant analog control counter every keystrobe or continuously every 112ms from KB and every 102ms from the RC and data inputs. The display shows an up/down arrow for 300ms min. Tune up/down KB Increments up or down the tuning counter. The speed or increment/decrement is defined by Figure 10. The display shows an up/down arrow for 300ms min. Mem. up/down KB, D, RC The program number (memory location) is incremented/decremented. Mute (toggle) KB, D, RC Volume Mute. See mute section. Standby D, RC Commands the standby state. On/standby (toggle) KB, D, RC Commands the standby state from the on state and the on state from the standby state. ON/OFF KB Commands the on state when in the off state and commands the off state when in the on state. See standby section. Store Program KB The currently addressed memory location is written from the tuning, band and MS counters and the skip flag is reset. See fig. 11. Execution of this command is indicated by the display flashing at 5Hz for 1 second. Store analog Controls KB The analog control memories are written in sequence from the analog control counters. Execution of this command is indicated by the display flashing at 5Hz for 1 second. Band Sequence KB Command the next band in the sequence as defined in bands outputs section. One step for each key strobe. MS Sequence KB Increments the MS counter by binary one. One step for each key strobe. Normalise Analog KB, D, RC Reads the analog memories in sequence to their corresponding D/A’s. The analog control outputs are disabled during the read sequence. Memory Addressing KB Strobes the program selected immediately after the memory addressing command (post tuning program selection). See Figure 12. Set Skip Flag KB Sets the skip flag on the currently selected program. Execution of this command is indicated by the display flashing at 5Hz for 1 second. Skip Defeat OS Defeats the function of the skip bit to allow reading and writing of the currently selected program. KB = Keyboard; D = Data; RC = Remove Control; OS = Option Select. Figures 11 & 12 respectively show in flow diagram from the two methods for storing a station : pretun- ing program selection and post tuning program selection. Figures 13, 14 & 15 show the select program subroutine for Figures 11 & 12 for either 16 pro- gram option or 20 program option with 1* or± 10 (decade modes). M494

COMMANDS (continued) SET SKIP FLAG & STORE SELECT PROGRAM TUNE UP/DOWN STORE BEGIN END END SET SKIP FLAG AT CURRENT PROGRAMME ? CONTINUE ? Yes No No Yes No Yes SELECTED PROGRAMME NO. FLASHES AT 5Hz FOR 1 SECOND STATION TUNED ? 494-19.EPS Figure 11 :Normal Methods for Storing a Station (preselection of program number) M494

R18 5.6kΩ 10µF VOL R20 5.6kΩ 10µF R24 5.6kΩ C9 10µF C10 10µF R17 22k Ω R19 22k Ω R22 5.6kΩ R21 22k Ω R23 22k Ω SAT LUM CON R25 8.2kΩ R26 8.2kΩ R27 8.2kΩ R28 8.2kΩ R29 10kΩ R30 10kΩ BC177 BC177 R31 10kΩ R32 10kΩ BC177 BC177 VHF I VHF III CATV UHF R35 680Ω DL4DL3DL2DL1 R33 R34 R10 1.5kΩ +12V +5V 391920 6.8kΩ 4.7kΩ 22µF BC297 82kΩ 5.6k Ω BF259 357 680Ω 1kΩ BC177 Relay +5/12V TAA550 C2 100nF R13 33kΩ R14 33kΩ 150nF R15 56k Ω R16 82kΩ 100nF 100nF R12 3.3k Ω R11 3.9kΩ BSX93 High Voltage R39 2.2kΩ 4.7nF Tuning Voltage 16Store Prog 15Store Analog 14Tune Up 13Tune Down 11Band Seq 10Prg Up 9Prg Down abcdefghi 25 40 26 12 32 36 37 R36 5.6kΩ AFC DEF OUT FB Sync +5V AV0 AV1 C12 100nF Osc C11 100nF 29 30 2 x 5.6kΩ R38R37 MS1MS0 M494 b ce fh i a d TDA8160 +5V M708 500kHz 1.6kΩ 2 x 5.6kΩ R1 (kΩ )= VH (V) - 33V 11mA R2 = R1/4 494-24.EPS TYPICAL APPLICATION M494

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics.  1995 SGS-THOMSON Microelectronics - All Rights Reserved Purchase of I 2C Components of SGS-THOMSON Microelectronics, conveys a license under the Philips I2C Patent. Rights to use these components in a I2C system, is granted provided that the system conforms to the I2C Standard Specifications as defined by Philips. SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. PM-DIP40.EPS PACKAGE MECHANICAL DATA

40 PINS - PLASTIC PACKAGE

Dimensions Millimeters Inches a1 0.63 0.025 b 0.45 0.018 b1 0.23 0.31 0.009 0.012 b2 1.27 0.050 D 52.58 2.070 E 15.2 16.68 0.598 0.657 e 2.54 0.100 e3 48.26 1.900 F 14.1 0.555 i 4.445 0.175 L 3.3 0.130 M494