Philips Semiconductors Product data sheet
SC28C94Quad universal asynchronous receiver/transmitter (QUART)
2006 Aug 09
31
C1 and C2 should be chosen according to the
crystal manufacturer’s specification.
C1 and C2 values will include any parasitic
capacitance of the wiring.
X1/CLK
CTCLK
RxC
TxC
t
CLK
t
CTC
t
Rx
t
Tx
t
CLK
t
CTC
t
Rx
t
Tx
+5V
1K required for
TTL gate.
X1
X2
C1 = C2 = 24pF FOR C
L
= 20PF
X1
X2
3.6864MHz
3pF
4pF
50 KOHMs
TO
150 KOHMs
26C94
NOTES:
C1 and C2 should be based on manufacturer’s specification.
X1 and X2 parasitic capacitance IS 1-2pF AND 3-5pF, respectively.
GAIN: at 4MHz 8 to 14db; at 8MHz 2 to 6db
PHASE: at 4MHz 272° to 276°; at 8MHz 272° to 276°
TYPICAL CRYSTAL SPECIFICATION
FREQUENCY: 2 – 4MHZ
LOAD CAPACITANCE (C
L
): 12 – 32pF
TYPE OF OPERATION: PARALLEL RESONANT, FUNDAMENTAL MODE
NC
C1
C2
MUX
To
remainder
of circuit
÷ 2
38.4kHz CLOCK
BRG
TO I/O CHANGE-OF-STATE DETECTORS
22
STANDARD
BAUD
RATES
SD00172
POWER DOWN
Figure 13. Clock Timing
TxC
(INPUT)
TxD
TxC
(1X OUTPUT)
1 BIT TIME
(1 OR 16 CLOCKS
t
TCS
t
TXD
SD00173
Figure 14. Transmit Clock Timing
