UN13750
Programmable
Encoder/Decoder
Single chip contains both Encoder and Decoder.
3V to 11 V operation.
On chip oscillator uses non-critical RC components.
Cross interference of
recetver
is virtually eliminated
by circuitry which requires 4 valid words to be received,
each within 64ms of the other.
General Description
The UM3750 Encoder/Decoder is a CMOS/LSI digital
code Transmitter-Receiver system. Working in the transmit (encoder) mode, the
UM3750 will sequentially encode
and transmit 12 bits of input. Each of the 12 bits may
be 1 or 0 to allow 4096 different codes.
In the receive (decoder) mode, the incoming signal is
compared to the local code
an error IS detected the system
In
a sequential manner
will
reset and beain its
Once
Pin Configurations
“cc
TX/RX OUTPUT
RECEIVER INPUT
MODE SELECT
“ss
R.C INPUT
A12
All
A10
Schmitt Trigger input provides excellent noise immunity.
Applications. alarm control system, security system
cordless telephone, remote control.
Interfaces with RF, ultrasonic, or infrared modulators
and demodulators
comparison on the next word.
correctly, a “valid” signal is generated. This signal
64ms counter and triggers a
If all 12 bits are
3-stage
counter. The
received
clears a
3-stage
counter counts the “valid” pluses and when 4 pulses have
been detected, the TX/RX output pin goes low. After the
TX/RX output pin goes low, the next “valid” must be
received within
128ms,
giving a one valid in 6 requirement
to keep the TX/RX output pin.
“cc
TX/RX OUTPUT
RECEIVER INPUT
MODE SELECT
“SS
R.C.
INPUT
A12
All
A10
NC
I
2-3
Block
urn3750
Diagram
R.C.INPUT - - - - - -
CPCLK
COMPARATOR
I
RID
I
L
MXCLKR
MXD
-
ERROR
CLR
WD
7
STATE
CONTROLLER
TIM0
i
VLD
INIT
64ms/128ms
TIMER
I
VALID 4
COUNTER
Al-Al2
Block
Diagram Description
CPCLK
WXCLKR: CLK of Multiplexer when in Receiver mode
WXCLKT
MXD:
RID
VLD.
CLK of Comparator
CLK of Multiplexer when in Transmitter mode
Output data of Multiplexer (one of Al, A2
A12)
Sampled data by Sampling CKT
“Valid” signal. It is used to trigger Valid 4
Counter and
reset 64ms/128ms
Timer
....
2-4
CLR:
ERROR:
TIMO :
T/R OUT:
INIT:
WD:
TXO:
PXO:
Clear signal of Comparator
Error signal from Comparator
TIMER time-out signal
Transmit/Receiver output pin
Reset signal of Valid 4 Counter
Word detected signal
Transmitter output
Receiver output
T/R
OUT
(64ms or 128ms)
UM3750
Absolute Maximum Ratings*
Power Supply Voltage
Operating Temperature -20 Deg to 70 Deg C
Storage Temperature
Applied Voltage on any Pin
(Tstg)
vss
PO.3
D.C. Electrical Characteristics
Input Level
Input Resistor
to Vcc
Oscillator
Frequency
-0
3v to 11v
--55 Deg to 150 Deg C
<
_
F
(T,
v,, < v,,
=
25°C. vDD
+o 3
=
200K
_
9V ilnless
*Comments
Stresses above those
Ratings” may cause permanent damage to the
These are stress ratings only.
this device at these or any other conditions above those
indtcated
in the operational sections of this
IS
not
implled
conditions for extended
ability.
otherwise specified)
_
100
and exposure to absolute
1.2M
_
ilsted
Iunder “Absolute Maximum
Functional operation of
pertods
R
KHz
maximuln
may affect device
kl5%
of external
components
dewce.
specification
rating
rell-
exclusive
Pin Designation
Pin No.
l-12
13
14
15
16
17
18
Designation
Al - Al2
R.C. INPUT
Vss
MODE SELECT
RECEIVER
INPUT
TXIRX
OUTPUT
Vcc
Description
These data select
pair
They have
R.C. input
pin
to
Vcc
2lRC.
The ground
This pin changes
grounding
to
VC-
the IC IS
The receiver input receives the digital PCM waveform
CIrClllt.
In the
transmit
transmlttlnq.
partson
result and detects low If comparison is ok.
The
positive
lines
are used to set the addresses of the encoder/decoder
on-chip
pull-up resistors.
pin
for
sinqle pin
and a
capacttor
pin
of the UM3750.
the IC from Receive mode TO Transmit mode, By
this
pin
the
put into the Transmit
mode,
In the receive mode,
power supply
oscillator. A
from
IC IS put Into the Receive mode. By connecting
this
output
pin
pin
of the UM3750.
reslstor IS
this pin
to GND
mode
produces the PCM waveform for
this
output
hooked from
pin
provides the
2-5
The frequency =
from
this
the detect
come
Bt
E
z
F
_____
tiz = =-~
-_
_
_-
Connection Diagram for Transmitter/Receiver
Output Waveform (based on 100 KHz)
UM3750
Typical
2-6
Decoder Flowchart
Stand by Mode
Reset Count
Yes
No
+
No
Data
In?
Ordering Information
Count - Count +1
R
eset 64m s,
128ms,
Timer
Activates the
TX//RX
Output
TX,‘RX
Output
I
_!:_I-
No
No
Part No. Package
NO
is
64ms Timer
Overflow
?
1
Yes
Yes
V
2-7
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