scn2681t NXP Semiconductors, scn2681t Datasheet - Page 10

• Manufacturer Part Number: scn2681t
• Description: Dual Asynchronous Receiver/transmitter Duart
• Manufacturer: NXP Semiconductors

1. Minimum frequencies are not tested but are guaranteed by design.
Philips Semiconductors
NOTE:
2004 Mar 22
X1/CLK
When using an external clock it is preferred to drive X2 and leave X1 open.
X2 is the input to the internal driver, while X1 is the output.
R1 is only required if U1 will not drive to X2 high level.
Previous specifications indicated X2 should be grounded and X1
should be driven. This is still acceptable. It is electrically easier to drive
the amplifier input than to overdrive its output.
CTCLK
Dual asynchronous receiver/transmitter (DUART)
RxC
t
f
t
f
t
f
t
f
t
t
TxC
SYMBOL
SYMBOL
CLK
CLK
CTC
CTC
RX
RX
TX
TX
TXD
TCS
SYMBOL
SYMBOL
t
t
t
t
CLK
CTC
Rx
Tx
(1X OUTPUT)
TxD output delay from TxC external clock input on IP pin
Output delay from TxC LOW at OP pin to TxD data output
(INPUT)
X1/CLK HIGH or LOW time
X1/CLK frequency
CTCLK (IP2) HIGH or LOW time
CTCLK (IP2) frequency
RxC HIGH or LOW time
RxC frequency (16X)
TxC HIGH or LOW time
TxC frequency (16X)
TxC
TxC
TxD
t
t
t
t
CLK
CTC
Rx
Tx
(1X)
(1X)
1
1
1
1
1
PARAMETER
PARAMETER
EXTERNAL SOURCE
PARAMETER
PARAMETER
t
TXD
DRIVING FROM
Figure 7. Clock Timing
(1 OR 16 CLOCKS)
Figure 8. Transmit
1 BIT TIME
U1
OPEN
1K
10
t
TCS
+5V
R1
X2
X1
CRYSTAL SERIES RESISTANCE3 SHOULD BE LESS THAN 180
C2
C1
Min
110
90
55
55
R1: 100K - 1Meg (See design note)
C1 = C2: 0-5pF + (STRAY < 5pF)
2
0
0
0
0
0
3.6864MHz
R2 = 50k to 150k
LIMITS
3.6864
Typ
Min
–
–
–
–
–
–
–
–
–
X1
X2
–
0
SD00103
LIMITS
R2
SCN2681
74LS04
SCN2681T
Max
Max
300
100
–
4
–
8
–
8
1
–
4
1
1K
+5V
TO THE REST
OF THE DUART
CIRCUITS
Product data
CLOCK
TO OTHER
CHIPS
UNIT
UNIT
UNIT
UNIT
SD00091
MHz
MHz
MHz
MHz
MHz
MHz
ns
ns
ns
ns
ns
ns