Philips Semiconductors

Product specification

SC28L91

3.3V–5.0V Universal Asynchronous

Receiver/Transmitter (UART)

2000 Sep 22

36

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 midpoint of the switching

test environment are pronounced and can greatly affect the resultant measurement.

VM

VOL +0.5V

VOL

WRN

OUTPUT

tIR

VM

VOL +0.5V

VOL

RDN

OUTPUT

tIR

SD00136

Figure 10. Interrupt Timing (80xxx mode)

C1 = C2

tCLK

tCTC

tRx

tTx

X1/CLK

CTCLK

RxC

TxC

tCLK

tCTC

tRx

tTx

470

Ω

X1

X2*

CLK

*NOTE: X2 MUST BE LEFT OPEN.

X2

3.6864MHz

X1

C1

C2

SC28L91

NOTE:

RESISTOR REQUIRED

FOR TTL INPUT.

TO UART

CIRCUIT

50k

Ω

to

100k

Ω

3pF

3pF

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 and X1 X2 pins.

Gain at 3.6864MHz: 9 to 13 dB

2pF

4pF

Package capacitance approximately 4pF.

SD00704

PARASITIC CAPACITANCE

PARASITIC CAPACITANCE

Figure 11. Clock Timing