SCC68681 Ver la hoja de datos (PDF) - Philips Electronics
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SCC68681 Datasheet PDF : 29 Pages
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Philips Semiconductors
Dual asynchronous receiver/transmitter (DUART)
Product data
SCC68681
SYMBOL
X1/CLK
PIN
PLCC44 DIP40
36
32
X2
RxDA
RxDB
TxDA
37
33
35
31
11
10
33
30
TxDB
13
11
OP0
OP1
OP2
OP3
OP4
OP5
OP6
OP7
IP0
IP1
IP2
32
29
14
12
31
28
15
13
30
27
16
14
29
26
17
15
8
7
5
4
40
36
IP3
IP4
IP5
VCC
GND
NC
3
2
43
39
42
38
44
40
22
20
1, 12,
–
23, 34
TYPE
NAME AND FUNCTION
I Crystal 1: Crystal connection or an external clock input. A crystal of a clock the appropriate
frequency (nominally 3.6864 MHz) must be supplied at all times. For crystal connections see
Figure 8, Clock Timing.
I Crystal 2: Crystal connection. See Figure 8. If a crystal is not used it is best to keep this pin not
connected. It must not be grounded.
I Channel A Receiver Serial Data Input: The least significant bit is received first. ‘Mark’ is HIGH,
‘space’ is LOW.
I Channel B Receiver Serial Data Input: The least significant bit is received first. ‘Mark’ is HIGH,
‘space’ is LOW.
O Channel A Transmitter Serial Data Output: The least significant bit is transmitted first. This
output is held in the ‘mark’ condition when the transmitter is disabled, idle or when operating in
local loopback mode. ‘Mark’ is HIGH, ‘space’ is LOW.
O Channel B Transmitter Serial Data Output: The least significant bit is transmitted first. This
output is held in the ‘mark’ condition when the transmitter is disabled, idle, or when operating in
local loopback mode. ‘Mark’ is HIGH, ‘space’ is LOW.
O Output 0: General purpose output or Channel A request to send (RTSAN, active-LOW). Can be
deactivated automatically on receive or transmit.
O Output 1: General purpose output or Channel B request to send (RTSBN, active-LOW). Can be
deactivated automatically on receive or transmit.
O Output 2: General purpose output, or Channel A transmitter 1× or 16× clock output, or Channel A
receiver 1× clock output.
O Output 3: General purpose output or open-drain, active-LOW counter/timer interrupt output or
Channel B transmitter 1× clock output, or Channel B receiver 1× clock output.
O Output 4: General purpose output or Channel A open-drain, active-LOW, RxRDYA/FFULLA
interrupt output.
O Output 5: General purpose output or Channel B open-drain, active-LOW, RxRDYB/FFULLB
interrupt output.
O Output 6: General purpose output or Channel A open-drain, active-LOW, TxRDYA interrupt
output.
O Output 7: General purpose output, or Channel B open-drain, active-LOW, TxRDYB interrupt
output.
I Input 0: General purpose input or Channel A clear to send active-LOW input (CTSAN). Pin has
an internal VCC pull-up device supplying 1 to 4 µA of current.
I Input 1: General purpose input or Channel B clear to send active-LOW input (CTSBN). Pin has
an internal VCC pull-up device supplying 1 to 4 µA of current.
I Input 2: General purpose input, or Channel B receiver external clock input (RxCB), or
counter/timer external clock input. When the external clock is used by the receiver, the received
data is sampled on the rising edge of the clock. Pin has an internal VCC pull-up device supplying
1 to 4 µA of current.
I Input 3: General purpose input or Channel A transmitter external clock input (TxCA). When the
external clock is used by the transmitter, the transmitted data is clocked on the falling edge of the
clock. Pin has an internal VCC pull-up device supplying 1 to 4 µA of current.
I Input 4: General purpose input or Channel A receiver external clock input (RxCA). When the
external clock is used by the receiver, the received data is sampled on the rising edge of the
clock. Pin has an internal VCC pull-up device supplying 1 to 4 µA of current.
I Input 5: General purpose input or Channel B transmitter external clock input (TxCB). When the
external clock is used by the transmitter, the transmitted data is clocked on the falling edge of the
clock. Pin has an internal VCC pull-up device supplying 1 to 4 µA of current.
I Power Supply: +5 V supply input.
I Ground.
– Not connected.
2004 Apr 06
4
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