TABLE 2. Pin Descriptions

Pin Name

Description

No.

Pins

I/O

VCC

3

N/A

Power

GND

3

N/A

Ground

TMS

B

1

I

BACKPLANE TEST MODE SELECT: Controls sequencing through the TAP Controller of the

’STA111. Also controls sequencing of the TAPs which are on the local scan chains. This input

has a 25K

Ω pull-up resistor and no ESD clamp diode (ESD is controlled with an alternate

method). When the device is power-off (V

load to ground (Note 4). When V

to be a capacitive load with the pull-up to ground.

TDI

B

1

I

BACKPLANE TEST DATA INPUT: All backplane scan data is supplied to the ’STA111 through

this input pin. This input has a 25K

Ω pull-up resistor and no ESD clamp diode (ESD is

controlled with an alternate method). When the device is power-off (V

appears to be a capacitive load to ground (Note 4). When V

to V

TDO

B

1

O

BACKPLANE TEST DATA OUTPUT: This output drives test data from the ’STA111 and the

local TAPs, back toward the scan master controller. This output has 24mA of drive current.

When the device is power-off (V

load (Note 4).

TCK

B

1

I

TEST CLOCK INPUT FROM THE BACKPLANE: This is the master clock signal that controls

all scan operations of the ’STA111 and of the local scan ports. This input has no pull-up

resistor and no ESD clamp diode (ESD is controlled with an alternate method). When the

device is power-off (V

4). When V

load to ground.

TRST

B

1

I

TEST RESET: An asynchronous reset signal (active low) which initializes the ’STA111 logic.

This input has a 25K

Ω pull-up resistor and no ESD clamp diode (ESD is controlled with an

alternate method). When the device is power-off (V

capacitive load to ground (Note 4). When V

input appears to be a capacitive load with the pull-up to ground.

TRIST

B

1

O

BACKPLANE TRI-STATE NOTIFICATION OUTPUT: This signal is high when the backplane

scan port is TRI-STATEd. This pin is used for backplane physical layer changes (i.e.; TTL to

LVDS). This output has 12mA of drive current.

A

B

1

I

BACKPLANE PASS-THROUGH INPUT: A general purpose input which is driven to the Y

a single selected LSP. (Not available when multiple LSPs are selected). This input has an

internal pull-up resistor.

Y

B

1

O

BACKPLANE PASS-THROUGH OUTPUT: A general purpose output which is driven from the

A

has 24mA of drive current.

S

(0-6)

7

I

SLOT IDENTIFICATION: The configuration of these pins is used to identify (assign a unique

address to) each ’STA111 on the system backplane (Note 1).

OE

1

I

OUTPUT ENABLE for the Local Scan Ports, active low. When high, this active-low control

signal TRI-STATEs all local scan ports on the ’STA111, to enable an alternate resource to

access one or more of the three local scan chains.

TDO

(0-2)

3

O

TEST DATA OUTPUTS: Individual output for each of the local scan ports (Note 2). These

outputs have 24mA of drive current.

TDI

(0-2)

3

I

TEST DATA INPUTS: Individual scan data input for each of the local scan ports (Note 2).

TMS

(0-2)

3

O

TEST MODE SELECT OUTPUTS: Individual output for each of the local scan ports. TMS

n

does not provide a pull-up resistor (which is assumed to be present on a connected TMS

input, per the IEEE 1149.1 requirement) (Note 2). These outputs have 24mA of drive current.

TCK

(0-2)

3

O

LOCAL TEST CLOCK OUTPUTS: Individual output for each of the local scan ports. These

are buffered versions of TCK

B (Note 2). These outputs have 24mA of drive current.

www.national.com

4