SAA3008P 데이터 시트보기 (PDF) - Philips Electronics
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SAA3008P Datasheet PDF : 17 Pages
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Philips Semiconductors
Infrared remote control transmitter
(RECS 80 low voltage)
Preliminary specification
SAA3008
Table 3 Pulse timing
PARAMETER
Modulation period
Modulation LOW time
Modulation HIGH time
Modulation pulse width
Basic unit of pulse spacing
Word length for subsystem
addresses
0 to 7
8 to 20
Pulse separation for
logic 0
logic 1
reference time
toggle bit
Start pattern
SYMBOL
tM
tML
tMH
tPW
to
DURATION
12tosc
8tosc
4tosc
5tM +tMH
1152tosc
DURATION at fOSC = 455 kHz;
tOSC = 2.2 µs
26.4 µs
17.6 µs
8.8 µs
140.8 µs
2.53 ms
tW
55296tosc
121.44 ms
tW
59904tosc
132.56 ms
tb
2to
tb
3to
tb
3to
tb
2to
3to
tb
2 × 1.5to
5.06 ms
7.59 ms
7.59 ms
5.06 ms
7.59 ms
2 × 3.79 ms
OPERATION
Keyboard
In the standby mode all drivers DRV0N-DRV6N are ON
but are non-conducting due to their open drain
configuration. When a key is pressed, a completed drain
connection pulls down one or more of the sense lines to
ground. Referring to Fig.5, the power-up sequence for the
IC commences as a key is pressed. The oscillator
becomes active and then, following the debounce time
(tDB), the output drivers become active successively.
Within the first scan cycle the transmission mode,
subsystem address and the selected command code are
sensed and loaded into an internal data latch. In a multiple
keystroke sequence (Fig.6) the command code is always
altered according to the sensed key.
Multiple keystroke protection
The keyboard is protected against multiple keystrokes.
If more than one key is pressed the circuit will not generate
a new REMO sequence (Fig.6).
In a multiple keystroke sequence the scan repetition rate
is increased to detect the release of the key as soon as
possible.
There are two restrictions caused by the special structure
of the keyboard matrix:
• The keys switching directly to ground (codes 7, 15, 23,
31, 39, 47, 55, 63) are not completely covered by
multiple keystroke protection. If one sense input is
switched to ground, other keys on that sense line are
ignored.
• The sense lines SEN5N and SEN6N are not protected
against multiple keystrokes on the same driver line
because this has been used to define codes 56 to 63.
Output sequence
The output operation starts when the code of the selected
key has been loaded into the internal command register.
A burst of pulses, including the latched address and
command codes, is generated at the output REMO for as
long as the key is pressed. The format of the output pulse
train is as shown in Figs 3 and 4. The operation is
terminated by releasing the key, or by pressing more than
one key at the same time. Once a sequence has been
started, the transmitted words will always be completed
after the key has been released.
The toggle bit T0 is incremented if the key is released for
a minimum time tREL (Fig.5). In a multiple keystroke
sequence the toggle bit remains unchanged.
December 1988
9
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