SCANSTA111 datasheet(4/31 Pages) NSC

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TABLE 2. Pin Descriptions

Pin Name

Description

No.

Pins

I/O

VCC

N/A

Power

GND

N/A

Ground

TMS

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

DD floating), this input appears to be a capacitive

load to ground (Note 1). When V

DD = 0V (i.e.; not floating but tied to VSS) this input appears

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

TDI

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

DD floating), this input

appears to be a capacitive load to ground (Note 1). When V

DD = 0V (i.e.; not floating but tied

to V

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

TDO

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

DD = 0V or floating), this output appears to be a capacitive

load (Note 1).

TCK

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

DD floating), this input appears to be a capacitive load to ground (Note

1). When V

DD = 0V (i.e.; not floating but tied to VSS) this input appears to be a capacitive

load to ground.

TRST

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

DD floating), this input appears to be a

capacitive load to ground (Note 1). When V

DD = 0V (i.e.; not floating but tied to VSS) this

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

TRIST

(B,0-2)

TRI-STATE NOTIFICATION OUTPUT: This signal is asserted high when the associated TDO

is TRI-STATEd. Associated means TRIST

B is for TDOB, TRIST1 is for TDO1, etc. This output

has 12mA of drive current.

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

n of

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

internal pull-up resistor.

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

n of a single selected LSP. (Not available when multiple LSPs are selected). This output

has 24mA of drive current.

(0-6)

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

address to) each ’STA111 on the system backplane .

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)

TEST DATA OUTPUTS: Individual output for each of the local scan ports . These outputs

have 24mA of drive current.

TDI

(0-2)

TEST DATA INPUTS: Individual scan data input for each of the local scan ports .

TMS

(0-2)

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

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

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

TCK

(0-2)

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

are buffered versions of TCK

B . These outputs have 24mA of drive current.

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