UN13750 Programmable Encoder/Decoder Single chip contains both - PDF document

UN13750 Programmable Encoder/Decoder Single chip contains both Encoder and Decoder. Schmitt Trigger input provides excellent noise immunity. 3V to 11 V operation. Applications. alarm control system, security system On chip oscillator uses non-critical RC components. cordless telephone, remote control. Cross interference of recetver is virtually eliminated Interfaces with RF, ultrasonic, or infrared modulators I by circuitry which requires 4 valid words to be received, and demodulators each within 64ms of the other. General Description T h e U M 3 7 5 0 E n c o d e r / D e c o d e r is a CMOS/LSI digital comparison on the next word. If all 12 bits are received code Transmitter-Receiver system. Working in the trans- correctly, a “valid” signal is generated. This signal clears a mit (encoder) mode, the UM3750 will sequentially encode 64ms counter and triggers a 3-stage counter. The 3-stage counter counts the “valid” pluses and when 4 pulses have and transmit 12 bits of input. Each of the 12 bits may been detected, the TX/RX output pin goes low. After the be 1 or 0 to allow 4096 different codes. TX/RX output pin goes low, the next “valid” must be received within 128ms, giving a one valid in 6 requirement In the receive (decoder) mode, the incoming signal is to keep the TX/RX output pin. compared to the local code In a sequential manner Once an error IS detected the system will reset and beain its Pin Configurations “cc TX/RX OUTPUT “cc TX/RX OUTPUT RECEIVER INPUT RECEIVER INPUT MODE SELECT MODE SELECT “SS “ s s R.C. INPUT R.C INPUT A12 A l l A12 A l l A10 A10 NC 2 - 3

urn3750 Block Diagram R.C.INPUT - - - - - - - RID WD CPCLK 64ms/128ms TIM0 I I TIMER L i 7 ERROR STATE VLD COMPARATOR CONTROLLER I CLR VALID 4 INIT MXCLKR COUNTER MXD T/R OUT A l - A l 2 Block Diagram Description CLR: Clear signal of Comparator CLK of Comparator CPCLK ERROR: Error signal from Comparator WXCLKR: CLK of Multiplexer when in Receiver mode : TIMER time-out signal (64ms or 128ms) TIMO WXCLKT CLK of Multiplexer when in Transmitter mode T/R OUT: Transmit/Receiver output pin Output data of Multiplexer (one of Al, A2 .... MXD: INIT: Reset signal of Valid 4 Counter A12) W D : Word detected signal RID Sampled data by Sampling CKT Transmitter output TXO: “Valid” signal. It is used to trigger Valid 4 VLD. PXO: Receiver output Counter and reset 64ms/128ms Timer 2 - 4

UM3750 Absolute Maximum Ratings* *Comments -0 3v to 11v P o w e r S u p p l y V o l t a g e Stresses above those ilsted Iunder “Absolute Maximum Ratings” may cause permanent damage to the dewce. O p e r a t i n g T e m p e r a t u r e - 2 0 Deg to 70 D e g C These are stress ratings only. Functional operation of Storage Temperature (Tstg) --55 Deg to 150 Deg C this device at these or any other conditions above those indtcated in the operational sections of this specification Applied Voltage on any Pin IS not implled and exposure to absolute maximuln rating vss PO.3 < v,, < v,, +o 3 c o n d i t i o n s f o r e x t e n d e d pertods may affect device rell- ability. D.C. Electrical Characteristics (T, = 25°C. vDD = 9V ilnless otherwise specified) Input Level Input Resistor _ _ 2 0 0 K 1.2M R to Vcc kl5% exclusive _ F _ Oscillator Frequency 100 K H z of external components Pin Designation Pin No. Designation Description A l - A l 2 l - 1 2 These data select lines are used to set the addresses of the encoder/decoder pair They have on-chip pull-up resistors. R.C. INPUT 1 3 R . C . i n p u t pin for sinqle pin oscillator. A reslstor IS h o o k e d f r o m this pin to Vcc a n d a capacttor f r o m this pin t o G N D The frequency = 2lRC. The ground pin of the UM3750. 1 4 Vss M O D E S E L E C T This pin changes the IC f r o m R e c e i v e m o d e TO T r a n s m i t m o d e , B y 1 5 g r o u n d i n g this pin the IC IS put Into the Receive mode. By connecting to VC- the IC IS put into the Transmit m o d e The receiver input receives the digital PCM waveform from the detect 1 6 R E C E I V E R CIrClllt. INPUT In the transmit mode, this output pin produces the PCM waveform for 17 TXIRX transmlttlnq. In the receive mode, this output pin provides the come O U T P U T partson result and detects low If comparison is ok. The positive power supply pin of the UM3750. 1 8 V c c 2 - 5

t E z F B _____ tiz = =-~ -_ _ _- UM3750 Connection Diagram for Transmitter/Receiver Output Waveform (based on 100 KHz) Typical 2 - 6

Decoder Flowchart Stand by Mode Reset Count Y es No N o + Data In? N O Count - Count +1 is R eset 64m s, 64ms Timer 128ms, Timer Overflow Yes ? _!:_I- No Activates the TX//RX O u t p u t Yes V N o TX,‘RX Output Ordering Information I Part No. Package 1 2 - 7

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