PCI950

IRQSER DESERIALIZER

SCPS015A – JULY 1997 – REVISED JANUARY 1998

2

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

I/O

FUNCTION

NAME

NO.

I/O

TYPE

FUNCTION

ACTIVE

25

O

Device active. When the PCI950 is busy, this output is low and when the PCI950 is idle, this output is

high.

CLKRUN

34

I/O

PCI clock run. CLKRUN is used by the central resource to request permission to stop the PCI clock or

to slow the PCI clock rate. When the PCI950 is busy and CLKRUN is sampled high, then CLKRUN is

driven low for two clock cycles. If CLKRUN is not used, it can be tied low. See Note 1.

DRIVEMODE

13

I

Drive mode. When this input is high and the PCI950 samples a low on the IRQSER line during the sample

phase of the IRQ data frame, then the PCI950 drives the IRQSER line high during the recovery phase.

When this input is low and the PCI950 samples a low level on the IRQSER line during the sample phase

of the IRQ data frame, then the PCI950 three-states the IRQSER line during the recovery phase.

GND

5, 14, 27,

30, 40

—

Device ground terminals

INTA, INTB,

INTC, INTD

15, 16,

17, 18

O

PCI-style interrupts. These are four parallel PCI-style Interrupts, INTA–INTD. The PCI950 provides the

PCI interrupts in an open-drain environment, which requires the system vendor to implement a pullup

resistor on each implemented interrupt.

IRQ0, IRQ1,

IRQ3–15

23, 22,

38,12, 9,

4, 3, 44,

2, 1, 48,

47, 42,

41, 37

O

ISA-style interrupts. These are 15 parallel ISA interrupts, IRQ0, 1, 3–15. The PCI950 provides the ISA

interrupts in an open-drain environment, which requires the system vendor to implement a pullup resistor

on each implemented interrupt.

IRQ2/SMI

21

O

System management interrupt. The PCI950 provides the SMI interrupt in an open-drain environment,

which requires the system vendor to implement a pullup resistor on each implemented interrupt.

IRQSER

24

I/O

Serial interrupt stream from PC Card controller. This input is connected to the IRQSER output from the

TI PC Card controller.

NC

7, 8, 10,

11, 19,

26, 31,

43, 45

—

No connection

PCLK

28

I

PCI-bus clock. The PCI-bus clock operates at frequencies ranging from 0–33 MHz.

POLLMODE

32

I

Poll mode. Selects between quiet mode and continuous mode. When this input is low, the PCI950 is in

quiet mode. When this input is high, the PCI950 is in continuous mode. The POLLMODE signal is

sampled during the rising edge of a start frame. After reset, the PCI950 generates the first cycle, and

the stop-frame width in this cycle is set based on the POLLMODE input level. Any change in POLLMODE

input causes the PCI950 to generate a start pulse.

RSTIN

36

I

Device reset. When RSTIN is asserted low, the internal counters are reset and all output buffers are put

in a high-impedance state (three stated). After RSTIN is deasserted, the PCI950 defaults to continuous

mode.

SHUTD

35

I

Shutdown. When SHUTD input is low, the internal clock is stopped and the outputs are placed in a

high-impedance state (three stated). When SHUTD input is high, the device is in normal operation.

During continuous mode of operation, the recommended use of SHUTD is to first assert STOP input,

check that ACTIVE is high, and then assert SHUTD to stop the clock. During quiet mode of operation,

the SHUTD input can be asserted after ACTIVE is sampled high.

STOP

29

I

Stop continuous mode. The default number of idle clocks between stop and start frame in continuous

mode is one. But the STOP pin can be used to insert more than one idle state. If the PCI950 is in

continuous mode and if during an IRQSER cycle the STOP input is driven low, then after completion of

the IRQSER cycle any number of idle states can be inserted. The next start frame is initiated by PCI950

when STOP is driven high. If STOP is not to be used, then it must be tied high. See Note 1.

VCC

6, 20, 33,

39, 46

—

Device 5-V power-supply terminals

NOTE 1: Unused active-low inputs must be pulled up to VCC using a 43 kW resistor, and unused active-high inputs must be pulled down to GND

using a 43 k

W resistor.