SC2268 Datasheet, PDF (3/6 Pages) Silan Microelectronics Joint-stock – REMOTE CONTROL ENCODER

Silan
Semiconductors
FUNCTIONAL DESCRIPTION
1. KEY INPUT
Up to eight keys can be directly connected to pins I1 ~
I8. Please refer to the diagram right.
Furthermore, SC2268 has a buit-in pull-low resistor of
about 60K ~ 110KΩ which reduces the need for
external components.
SC2268
Vcc
1 I1
2 I2
3 I3
4 I4 _SC2268
5 I5
6 I6
7 I7
8 I8
2. OSCILLATOR
An oscillation circuit can be constructed using the
CMOS inverter and Built-in Feedback resistor, 455kHz
crystal and two 220pf capacitors. The carrier frequency
is 38kHz.
Unless any of the 8 keys (I1~I8) is being operated,
the oscillation is automatically stopped. Thus, power
consumption is considerably reduced.
SC2268
OSCI
15
OSCO
14
220pf
455kHz
220pf
3. TRANMISSION WAVEFORM
When any of the 8 keys (I1 ~ I8) is set to “High”, the TxOUT outputs one start word followed by 2 identical
data words and a space. The code will be continuously outputted until the key is released. If for any
reason, the key was released during the code transmission process, the code that is being transmitted
during the key release action will still be completely outputted. Please refer to the following diagram.
I1 ~ I8
Tx OUT
Start
Word
Data
Word
Data
Word
Space
Start
Word
Data
Word
Data
Word
Space
20ms
80ms
1 Frame = 80ms
*OSC = 455kHz
Start
Word
Data
Word
Data
Word
Space
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
Rev: 1.0 2000.12.31
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