Philips SCC2691 Product Data Sheet page 16

Philips Semiconductors
Universal asynchronous receiver/transmitter (UART)
RDN
t
PS
MPI
WRN
MPO
WRN
INTERRUPT
OUTPUT
RDN
INTERRUPT
OUTPUT
NOTES:
1. INTRN or MPO 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 midpoint of the switching signal,
V , to a point 0.5V above V . This point represents noise margin that assures true switching has occurred. Beyond this level, the effects of external circuitry and test environment
M OL
are pronounced and can greatly affect the resultant measurement.
t
CLK
t
CTC
t
Rx
t
Tx
X1/CLK
C/T CLK
RxC
TxC
DRIVING
FROM EXTERNAL
SOURCE
CLK 5V
470
N/C
2006 Aug 04
t
PH
Figure 5. I/O Timing
1
1
Figure 6. Interrupt Timing
t
CLK
t
CTC
t
Rx
t
Tx
X1
X2
Figure 7. Clock Timing
t
PD
V
M
t
IR
V
OL
t
IR
V +0.5V
OL
Y1 = 3.6864MHz, C
C1 = C2 = 24pF
C1
C2
TYPICAL CRYSTAL SPECIFICATION
FREQUENCY. . . . . . . . . . . . . . 2–4MHz
LOAD CAPACITANCE (C ). . . 20 or 32pF (typical)
L
TYPE OF OPERATION . . . . . .PARALLEL RESONANT, FUND. MODE
16
Product data sheet
SCC2691
SD00125
+0.5V
V
OL
V
OL
SD00126
= 20pF
L
X1/CLK
Y1 SCC2691
50k
to
150k
X2
SD00127