Texas Instruments 5962-9172601M3A Datasheet

SN54BCT8244A, SN74BCT8244A

SCAN TEST DEVICES

WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

Members of the Texas Instruments

SCOPE

Octal Test-Integrated Circuits

Functionally Equivalent to ’F244 and

 Family of Testability Products

’BCT244 in the Normal-Function Mode

Compatible With the IEEE Standard

1149.1-1990 (JTAG) Test Access Port and Boundary-Scan Architecture

Test Operation Synchronous to Test Access Port (TAP)

Implement Optional Test Reset Signal by Recognizing a Double-High-Level Voltage (10 V) on TMS Pin

SCOPE

 Instruction Set

– IEEE Standard 1149.1-1990 Required

Instructions, Optional INTEST, CLAMP

and HIGHZ – Parallel-Signature Analysis at Inputs – Pseudo-Random Pattern Generation

From Outputs – Sample Inputs/Toggle Outputs

Package Options Include Plastic Small-Outline (DW) Packages, Ceramic Chip Carriers (FK), and Standard Plastic and Ceramic 300-mil DIPs (JT, NT)

description

The ’BCT8244A scan test devices with octal buffers are members of the Texas Instruments SCOPE testability integrated-circuit family . This family of devices supports IEEE Standard 1 149.1-1990 boundary scan to facilitate testing of complex circuit-board assemblies. Scan access to the test circuitry is accomplished via the 4-wire test access port (TAP) interface.

SN54BCT8244A . . . JT PACKAGE

SN74BCT8244A ... DW OR NT PACKAGE

SN54BCT8244A . . . FK PACKAGE

1A2 1A1

2OE

1OE

1Y1 1Y2

NC – No internal connection

(TOP VIEW)

24 23 22 21 20 19 18 17 16 15 14 13

2Y1

2OE 1A1 1A2 1A3 1A4 2A1 V

2A2 2A3 2A4 TDI TCK

2A2

2Y2

2A3

25 24 23 22 21 20 19

2Y3

2A4 TDI TCK NC TMS TDO 2Y4

1OE

1Y1

1Y2

1Y3

1Y4

GND

2Y1

2Y2

2Y3

2Y4

TDO

TMS

(TOP VIEW)

1A3

1A4

2A1NCV

3212827

426

5 6 7 8 9 10 11

12 13

14 15 16 17

1Y3

1Y4

GND

In the normal mode, these devices are functionally equivalent to the ’F244 and ’BCT244 octal buffers. The test circuitry can be activated by the TAP to take snapshot samples of the data appearing at the device terminals or to perform a self test on the boundary-test cells. Activating the TAP in normal mode does not affect the functional operation of the SCOPE octal buffers.

In the test mode, the normal operation of the SCOPE octal buffers is inhibited and the test circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry can perform boundary-scan test operations, as described in IEEE Standard 1149.1-1990.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

SCOPE is a trademark of Texas Instruments Incorporated.

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

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On products compliant to MIL-PRF-38535, all parameters are tested unless otherwise noted. On all other products, production processing does not necessarily include testing of all parameters.

SN54BCT8244A, SN74BCT8244A SCAN TEST DEVICES WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

description (continued)

Four dedicated test terminals control the operation of the test circuitry: test data input (TDI), test data output (TDO), test mode select (TMS), and test clock (TCK). Additionally, the test circuitry performs other testing functions such as parallel-signature analysis (PSA) on data inputs and pseudo-random pattern generation (PRPG) from data outputs. All testing and scan operations are synchronized to the TAP interface.

The SN54BCT8244A is characterized for operation over the full military temperature range of –55°C to 125°C. The SN74BCT8244A is characterized for operation from 0°C to 70°C.

FUNCTION TABLE

(normal mode, each buffer)

INPUTS

OE A

H X Z

L LL L H H

OUTPUT

logic symbol

†

This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.

Pin numbers shown are for the DW, JT, and NT packages.

†

SCAN

TDI

TMS

TCK

1OE

2OE

1A1 1Y1

1A2

1A3 1Y3

1A4 1Y4

2A1 2Y1

2A2

2A3 2Y3

2A4

TDI TMS

TCK-IN

TCK-OUT

EN1 EN2

’BCT8244A

TDO

2 3

1Y2

4 5 7 8

2Y2

2Y4

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functional block diagram

1OE

1A1

2OE

2A1

Boundary-Scan Register

One of Four Channels

SN54BCT8244A, SN74BCT8244A

SCAN TEST DEVICES

WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

1Y1

2Y1

TDI

TMS

TCK

Pin numbers shown are for the DW, JT, and NT packages.

TAP

Controller

One of Four Channels

Bypass Register

Boundary-Control

Instruction Register

TDO

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SN54BCT8244A, SN74BCT8244A SCAN TEST DEVICES WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

Terminal Functions

TERMINAL NAME DESCRIPTION

1A1–1A4, 2A1–2A4

GND Ground

1OE, 2OE

TCK

TDI

TDO

TMS

1Y1–1Y4, 2Y1–2Y4 Normal-function data outputs. See function table for normal-mode logic.

Normal-function data inputs. See function table for normal-mode logic. Internal pullups force these inputs high if left unconnected.

Normal-function output-enable inputs. See function table for normal-mode logic. Internal pullups force these inputs high if left unconnected.

Test clock. One of four terminals required by IEEE Standard 1149.1-1990. Test operations of the device are synchronous to TCK. Data is captured on the rising edge of TCK and outputs change on the falling edge of TCK. An internal pullup forces TCK to a high level if left unconnected.

T est data input. One of four terminals required by IEEE Standard 1 149.1-1990. TDI is the serial input for shifting data through the instruction register or selected data register. An internal pullup forces TDI to a high level if left unconnected.

Test data output. One of four terminals required by IEEE Standard 1149.1-1990. TDO is the serial output for shifting data through the instruction register or selected data register. An internal pullup forces TDO to a high level when it is not active and is not driven from an external source.

T est mode select. One of four terminals required by IEEE Standard 1149.1-1990. TMS directs the device through its TAP controller states. An internal pullup forces TMS to a high level if left unconnected. TMS also provides the optional test reset signal of IEEE Standard 1149.1-1990. This is implemented by recognizing a third logic level, double high (V

), at TMS.

IHH

Supply voltage

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SN54BCT8244A, SN74BCT8244A

SCAN TEST DEVICES

WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

test architecture

Serial-test information is conveyed by means of a 4-wire test bus, or TAP, that conforms to IEEE Standard 1 149.1-1990. Test instructions, test data, and test control signals all are passed along this serial-test bus. The TAP controller monitors two signals from the test bus, TCK and TMS. The TAP controller extracts the synchronization (TCK) and state control (TMS) signals from the test bus and generates the appropriate on-chip control signals for the test structures in the device. Figure 1 shows the TAP-controller state diagram.

The T AP controller is fully synchronous to the TCK signal. Input data is captured on the rising edge of TCK, and output data changes on the falling edge of TCK. This scheme ensures that data to be captured is valid for fully one-half of the TCK cycle.

The functional block diagram shows the IEEE Standard 1149.1-1990 4-wire test bus and boundary-scan architecture and the relationship among the test bus, the T AP controller, and the test registers. As shown, the device contains an 8-bit instruction register and three test-data registers: an 18-bit boundary-scan register, a 2-bit boundary-control register, and a 1-bit bypass register.

Test-Logic-Reset

TMS = H

TMS = L

Run-Test/Idle Select-DR-Scan

TMS = L

Capture-DR

TMS = L

Shift-DR

TMS = L

TMS = H

Exit1-DR

TMS = L

Pause-DR

TMS = L

TMS = H

Exit2-DR

TMS = H

TMS = HTMS = H

TMS = H TMS = H

TMS = L

Select-IR-Scan

TMS = H

TMS = L

Capture-IR

TMS = L

Shift-IR

TMS = L

TMS = H

Exit1-IR

TMS = L

Pause-IR

TMS = L

TMS = H

Exit2-IR

TMS = H

Update-DR

TMS = LTMS = H

Figure 1. TAP-Controller State Diagram

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Update-IR

TMS = LTMS = H

SN54BCT8244A, SN74BCT8244A SCAN TEST DEVICES WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

state diagram description

The T AP controller is a synchronous finite state machine that provides test control signals throughout the device. The state diagram shown in Figure 1 is in accordance with IEEE Standard 1149.1-1990. The TAP controller proceeds through its states based on the level of TMS at the rising edge of TCK.

As shown, the T AP controller consists of 16 states. There are six stable states (indicated by a looping arrow in the state diagram) and ten unstable states. A stable state is a state the T AP controller can retain for consecutive TCK cycles. Any state that does not meet this criterion is an unstable state.

There are two main paths through the state diagram: one to access and control the selected data register and one to access and control the instruction register. Only one register can be accessed at a time.

Test-Logic-Reset

The device powers up in the T est-Logic-Reset state. In the stable Test-Logic-Reset state, the test logic is reset and is disabled so that the normal logic function of the device is performed. The instruction register is reset to an opcode that selects the optional IDCODE instruction, if supported, or the BYP ASS instruction. Certain data registers also can be reset to their power-up values.

The state machine is constructed such that the T AP controller returns to the Test-Logic-Reset state in no more than five TCK cycles if TMS is left high. The TMS pin has an internal pullup resistor that forces it high if left unconnected or if a board defect causes it to be open circuited.

For the ’BCT8244A, the instruction register is reset to the binary value 11111111, which selects the BYPASS instruction. The boundary-control register is reset to the binary value 10, which selects the PSA test operation.

Run-T est/Idle

The T AP controller must pass through the Run-T est/Idle state (from T est-Logic-Reset) before executing any test operations. The Run-Test/Idle state also can be entered following data-register or instruction-register scans. Run-Test/Idle is a stable state in which the test logic may be actively running a test or may be idle.

The test operations selected by the boundary-control register are performed while the T AP controller is in the Run-Test/Idle state.

Select-DR-Scan, Select-lR-Scan

No specific function is performed in the Select-DR-Scan and Select-lR-Scan states, and the T AP controller exits either of these states on the next TCK cycle. These states allow the selection of either data-register scan or instruction-register scan.

Capture-DR

When a data-register scan is selected, the TAP controller must pass through the Capture-DR state. In the Capture-DR state, the selected data register may capture a data value as specified by the current instruction. Such capture operations occur on the rising edge of TCK, upon which the TAP controller exits the Capture-DR state.

Shift-DR

Upon entry to the Shift-DR state, the data register is placed in the scan path between TDI and TDO and, on the first falling edge of TCK, TDO goes from the high-impedance state to an active state. TDO enables to the logic level present in the least-significant bit of the selected data register.

While in the stable Shift-DR state, data is serially shifted through the selected data register on each TCK cycle. The first shift occurs on the first rising edge of TCK after entry to the Shift-DR state (i.e., no shifting occurs during the TCK cycle in which the T AP controller changes from Capture-DR to Shift-DR or from Exit2-DR to Shift-DR). The last shift occurs on the rising edge of TCK, upon which the TAP controller exits the Shift-DR state.

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

SN54BCT8244A, SN74BCT8244A

SCAN TEST DEVICES

WITH OCTAL BUFFERS

SCBS042E – FEBRUARY 1990 – REVISED JULY 1996

Exit1-DR, Exit2-DR

The Exit1-DR and Exit2-DR states are temporary states that end a data-register scan. It is possible to return to the Shift-DR state from either Exit1-DR or Exit2-DR without recapturing the data register.

On the first falling edge of TCK after entry to Exit1-DR, TDO goes from the active state to the high-impedance state.

Pause-DR

No specific function is performed in the stable Pause-DR state, in which the TAP controller can remain indefinitely. The Pause-DR state suspends and resumes data-register scan operations without loss of data.

Update-DR

If the current instruction calls for the selected data register to be updated with current data, then such update occurs on the falling edge of TCK, following entry to the Update-DR state.

Capture-IR

When an instruction-register scan is selected, the TAP controller must pass through the Capture-IR state. In the Capture-IR state, the instruction register captures its current status value. This capture operation occurs on the rising edge of TCK, upon which the TAP controller exits the Capture-IR state.

For the ’BCT8244A, the status value loaded in the Capture-IR state is the fixed binary value 10000001.

Shift-IR

Upon entry to the Shift-IR state, the instruction register is placed in the scan path between TDI and TDO and, on the first falling edge of TCK, TDO goes from the high-impedance state to an active state. TDO enables to the logic level present in the least-significant bit of the instruction register.

While in the stable Shift-IR state, instruction data is serially shifted through the instruction register on each TCK cycle. The first shift occurs on the first rising edge of TCK after entry to the Shift-IR state (i.e., no shifting occurs during the TCK cycle in which the TAP controller changes from Capture-IR to Shift-IR or from Exit2-IR to Shift-IR). The last shift occurs on the rising edge of TCK, upon which the T AP controller exits the Shift-IR state.

Exit1-IR, Exit2-IR

The Exit1-IR and Exit2-IR states are temporary states that end an instruction-register scan. It is possible to return to the Shift-IR state from either Exit1-IR or Exit2-IR without recapturing the instruction register.

On the first falling edge of TCK after entry to Exit1-IR, TDO goes from the active state to the high-impedance state.

Pause-IR

No specific function is performed in the stable Pause-IR state, in which the TAP controller can remain indefinitely. The Pause-IR state suspends and resumes instruction-register scan operations without loss of data.

Update-IR

The current instruction is updated and takes effect on the falling edge of TCK, following entry to the Update-IR state.

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