Philips Semiconductors
Product specification
Enhanced octal universal asynchronous
receiver/transmitter (Octal UART)
SCC2698B
t
CLK
+5V
t
CTC
t
Rx
Tx
t
R1
1K
X1/CLK
CTCLK
RxC
X1
X2
U1
TxC
RESISTOR REQUIRED
WHEN U1 IS A TTL DEVICE
t
CLK
t
CTC
NC
t
Rx
t
Tx
SCC2698B
C1 = C2 = 24pF FOR C = 20PF
L
X1
X2
3pF
50 TO
150 KΩ
TO INTERNAL CLOCK DRIVERS
3.6864MHz
4pF
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
TYPICAL CRYSTAL SPECIFICATION
FREQUENCY:
LOAD CAPACITANCE (C ):
2 – 4MHZ
12 – 32pF
L
TYPE OF OPERATION:
PARALLEL RESONANT, FUNDAMENTAL MODE
SD00137
Figure 9. Clock Timing
1 BIT TIME
(1 OR 16 CLOCKS)
TxC
(INPUT)
t
TXD
TxD
t
TCS
TxC
(1X OUTPUT)
SD00146
Figure 10. Transmit Timing
23
2000 Jan 31
NXP [ NXP ]
