Philips Semiconductors

Product data

SCC68681

Dual asynchronous receiver/transmitter (DUART)

2004 Apr 06

24

X1/CLK

CTCLK

RxC

TxC

+5 V

R1

1 k

Ω

X1

X2

X1

X2

3.6864 MHz

3 pF

4 pF

50 TO

150 k

Ω

TO INTERNAL CLOCK DRIVERS

SCC68681

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:

2 – 4 MHz

12 – 32 pF

TYPE OF OPERATION:

PARALLEL RESONANT, FUNDAMENTAL MODE

NC

SD00725

RESISTOR REQUIRED

WHEN U1 IS A TTL DEVICE

U1

Figure 8. Clock timing

NOTES:

1. INTRN or OP3 – OP7 when used as interrupt outputs.

pronounced and can greatly affect the resultant measurement.

VM

VOL

CSN

(READ OR

WRITE)

OUTPUT

tIR

SD00116

Figure 9. Interrupt timing