XR16L651 Datasheet, PDF (12/56 Pages) Exar Corporation – 2.25V TO 5.5V UART WITH 32-BYTE FIFO

XR16L651
2.25V TO 5.5V UART WITH 32-BYTE FIFO
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REV. 1.3.0
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, Motorola 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, INT# AND IRQA) FUNCTIONS
IM# INPUT
(INTEL/
MOTOROLA)
PCMODE#
INPUT
S3 INPUT
MCR BIT-5
(INT TYPE
SELECT)
MCR BIT-3
(IRQN
ENABLE)
INTERRUPT OUTPUT (INT, INT# OR IRQA)
Intel Bus Mode
0
1
don’t care
0
don’t care INT is logic 0 for inactive interrupt.
INT is logic 1 for active interrupt (active high)
0
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.
Motorola Bus Mode
1
1
don’t care
0
don’t care INT# is three-state for inactive interrupt.
INT# is logic 0 for active interrupt (active low, open
drain). Requires a 1K-10KΩ resistor to VCC.
1
1
don’t care
1
don’t care INT# is three-state.
PC Mode
0
0
0
don’t care don’t care IRQA is three-state. Either IRQB or IRQC is used,
see Table 1.
0
0
1
don’t care
0
IRQA is three-state.
0
0
1
0
1
IRQA is logic 0 for inactive interrupt.
IRQA is logic 1 for active interrupt (active high).
0
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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