ST16C650A(2005) View Datasheet(PDF) - Exar Corporation

Part Name

Description

Manufacturer

ST16C650A
(Rev.:2005)

2.90V TO 5.5V UART WITH 32-BYTE FIFO

Exar Corporation 

xr

REV. 5.0.1

ST16C650A

2.90V TO 5.5V UART WITH 32-BYTE FIFO

2.6 Interrupt

The output function of interrupt, INT, output changes according to the operating bus type and various factors.

Table 3 summarizes its behavior in Intel and PC mode of operation. Multiple interrupts can be wire-OR’ed. This

is accomplished by setting MCR bit-5 to a logic 1 and connecting a 1KΩ to 10KΩ resistor between this pin and

ground to provide an acceptable logic 0 level.

TABLE 3: INTERRUPT OUTPUT (INT AND IRQA) FUNCTIONS

SEL INPUT

S3 INPUT

MCR BIT-5

(INT TYPE

SELECT)

MCR BIT-3

(IRQN

ENABLE)

INTERRUPT OUTPUT (INT OR IRQA)

Intel Bus Mode

1

don’t care

0

don’t care INT is logic 0 for inactive interrupt.

INT is logic 1 for active interrupt (active high)

1

don’t care

1

don’t care INT is three-state for inactive interrupt

INT is logic 1 for active interrupt (open source). Requires a 1K-

10KΩ resistor to GND.

PC Mode

0

0

don’t care don’t care IRQA is three-state. Either IRQB or IRQC is used, see Table 1.

0

1

don’t care

0

IRQA is three-state.

0

1

0

1

IRQA is logic 0 for inactive interrupt.

IRQA is logic 1 for active interrupt (active high).

0

1

1

1

IRQA is three-state for no interrupt.

IRQA is logic 1 for active interrupt (active high, open source).

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