scc68681 NXP Semiconductors, scc68681 Datasheet - Page 24

• Manufacturer Part Number: scc68681
• Description: Dual Asynchronous Receiver/transmitter
• Manufacturer: NXP Semiconductors

Philips Semiconductors
2004 Apr 06
NOTES:
1. INTRN or OP3 – OP7 when used as interrupt outputs.
2. The test for open drain outputs is intended to guarantee switching of the output transistor. Measurement of this response is referenced from the mid point of the switching signal, V
Dual asynchronous receiver/transmitter (DUART)
a point 0.5 volts above V
pronounced and can greatly affect the resultant measurement.
NOTE:
C1 AND C2 SHOULD BE BASED ON MANUFACTURER’S SPECIFICATION. PARASITIC CAPACITANCE SHOULD BE
INCLUDED WITH C1 AND C2. R1 IS ONLY REQUIRED IF U1 WILL NOT DRIVE TO X1 INPUT LEVELS
X1/CLK
CTCLK
RxC
TxC
C1 = C2 = 24 pF FOR C
OL
. This point represents noise margin that assures true switching has occurred. Beyond this level, the effects of external circuitry and test environment are
FREQUENCY:
LOAD CAPACITANCE (C
TYPE OF OPERATION:
t
t
L
CLK
CTC
t
t
Rx
Tx
= 20 pF
3.6864 MHz
INTERRUPT
(READ OR
OUTPUT
WRITE)
L
TYPICAL CRYSTAL SPECIFICATION
):
CSN
X1
X2
Figure 9. Interrupt timing
Figure 8. Clock timing
1
t
t
CLK
CTC
t
t
Rx
Tx
SCC68681
2 – 4 MHz
12 – 32 pF
PARALLEL RESONANT, FUNDAMENTAL MODE
24
4 pF
3 pF
50 TO
150 k
V
t
M
IR
V
OL
RESISTOR REQUIRED
WHEN U1 IS A TTL DEVICE
V
+0.5V
OL
TO INTERNAL CLOCK DRIVERS
U1
+5 V
R1
1 k
NC
SCC68681
SD00725
X1
X2
Product data
SD00116
M
, to