SN54ABTH18646A_14

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描述:SCAN TEST DEVICES WITH 18-BIT TRANSCEIVERS AND REGISTERS

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SCAN TEST DEVICES WITH 18-BIT TRANSCEIVERS AND REGISTERS

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SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
Members of the Texas Instruments  
One Boundary-Scan Cell Per I/O  
SCOPE Family of Testability Products  
Architecture Improves Scan Efficiency  
Members of the Texas Instruments  
Widebus Family  
SCOPE Instruction Set  
– IEEE Standard 1149.1-1990 Required  
Instructions and Optional CLAMP and  
HIGHZ  
– Parallel-Signature Analysis at Inputs  
– Pseudo-Random Pattern Generation  
From Outputs  
– Sample Inputs/Toggle Outputs  
– Binary Count From Outputs  
– Device Identification  
Compatible With the IEEE Standard  
1149.1-1990 (JTAG) Test Access Port and  
Boundary-Scan Architecture  
Include D-Type Flip-Flops and Control  
Circuitry to Provide Multiplexed  
Transmission of Stored and Real-Time Data  
Bus Hold on Data Inputs Eliminates the  
Need for External Pullup Resistors  
– Even-Parity Opcodes  
B-Port Outputs of ’ABTH182646A Devices  
Have Equivalent 25-Series Resistors, So  
No External Resistors Are Required  
Packaged in 64-Pin Plastic Thin Quad Flat  
(PM) Packages Using 0.5-mm  
Center-to-Center Spacings and 68-Pin  
Ceramic Quad Flat (HV) Packages Using  
25-mil Center-to-Center Spacings  
State-of-the-Art EPIC-ΙΙB BiCMOS Design  
SN54ABTH18646A, SN54ABTH182646A . . . HV PACKAGE  
(TOP VIEW)  
9
8
7
6
5
4
3
2
1 68 67 66 65 64 63 62 61  
1A3  
1A4  
1A5  
GND  
1A6  
1A7  
1A8  
1A9  
NC  
1B4  
1B5  
1B6  
GND  
1B7  
1B8  
1B9  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
60  
59  
58  
57  
56  
55  
54  
53  
52  
51  
50  
49  
48  
47  
46  
45  
44  
V
CC  
NC  
V
2B1  
2B2  
2B3  
2B4  
GND  
2B5  
2B6  
2B7  
CC  
2A1  
2A2  
2A3  
GND  
2A4  
2A5  
2A6  
27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43  
NC – No internal connection  
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, Widebus, and EPIC-ΙΙB are trademarks of Texas Instruments Incorporated.  
Copyright 1996, Texas Instruments Incorporated  
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.  
UNLESS OTHERWISE NOTED this document contains PRODUCTION  
DATA information 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.  
1
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
SN74ABTH18646A, SN74ABTH182646A . . . PM PACKAGE  
(TOP VIEW)  
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49  
1A3  
1A4  
1A5  
GND  
1A6  
1A7  
1A8  
1A9  
1B4  
1B5  
1B6  
GND  
1B7  
1B8  
1B9  
1
48  
47  
46  
45  
44  
43  
42  
41  
40  
39  
38  
37  
36  
35  
34  
33  
2
3
4
5
6
7
8
V
CC  
9
V
2B1  
2B2  
2B3  
2B4  
GND  
2B5  
2B6  
2B7  
CC  
10  
11  
12  
13  
14  
15  
16  
2A1  
2A2  
2A3  
GND  
2A4  
2A5  
2A6  
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32  
description  
The ’ABTH18646A and ’ABTH182646A scan test devices with 18-bit bus transceivers and registers are  
members of the Texas InstrumentsSCOPE testability integrated-circuit family. This family of devices supports  
IEEE Standard 1149.1-1990 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.  
In the normal mode, these devices are 18-bit bus transceivers and registers that allow for multiplexed  
transmission of data directly from the input bus or from the internal registers. They can be used either as two  
9-bit transceivers or one 18-bit transceiver. The test circuitry can be activated by the TAP to take snapshot  
samples of the data appearing at the device pins or to perform a self test on the boundary-test cells. Activating  
the TAP in the normal mode does not affect the functional operation of the SCOPE bus transceivers and  
registers.  
Transceiver function is controlled by output-enable (OE) and direction (DIR) inputs. When OE is low, the  
transceiver is active and operates in the A-to-B direction when DIR is high or in the B-to-A direction when DIR  
is low. When OE is high, both the A and B outputs are in the high-impedance state, effectively isolating both  
buses.  
Data flow is controlled by clock (CLKAB and CLKBA) and select (SAB and SBA) inputs. Data on the A bus is  
clocked into the associated registers on the low-to-high transition of CLKAB. When SAB is low, real-time A data  
is selected for presentation to the B bus (transparent mode). When SAB is high, stored A data is selected for  
presentation to the B bus (registered mode). The function of the CLKBA and SBA inputs mirrors that of CLKAB  
andSAB, respectively. Figure1showsthefourfundamentalbus-managementfunctionsthatareperformedwith  
the ’ABTH18646A and ’ABTH182646A.  
2
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
description (continued)  
In the test mode, the normal operation of the SCOPE bus transceivers and registers is inhibited, and the test  
circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry  
performs boundary-scan test operations according to the protocol described in IEEE Standard 1149.1-1990.  
Four dedicated test pins observe and 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.  
Improved scan efficiency is accomplished through the adoption of a one boundary-scan cell (BSC) per I/O pin  
architecture. This architecture is implemented in such a way as to capture the most pertinent test data. A  
PSA/COUNTinstruction also is included to ease the testing of memories and other circuits where a binary count  
addressing scheme is useful.  
Active bus-hold circuitry holds unused or floating data inputs at a valid logic level.  
The B-port outputs of ’ABTH182646A, which are designed to source or sink up to 12 mA, include 25-series  
resistors to reduce overshoot and undershoot.  
The SN54ABTH18646A and SN54ABTH182646A are characterized for operation over the full military  
temperature range of –55°C to 125°C. The SN74ABTH18646A and SN74ABTH182646A are characterized for  
operation from –40°C to 85°C.  
FUNCTION TABLE  
(normal mode, each 9-bit section)  
INPUTS  
DATA I/O  
OPERATION OR FUNCTION  
OE  
X
X
H
H
L
DIR  
X
CLKAB  
CLKBA  
SAB  
X
SBA  
X
A1 – A9  
Input  
B1 – B9  
X
Unspecified  
Input  
Store A, B unspecified  
Store B, A unspecified  
Store A and B data  
X
X
X
X
Unspecified  
X
X
X
Input  
Input  
X
L
L
X
X
X
X
X
X
Input disabled  
Output  
Input disabled  
Input  
Isolation, hold storage  
Real-time B data to A bus  
Stored B data to A bus  
Real-time A data to B bus  
Stored A data to B bus  
L
X
X
X
X
X
L
L
L
X
H
Output  
Input disabled  
Output  
L
H
H
L
X
Input  
L
H
X
Input disabled  
Output  
The data-output functions can be enabled or disabled by various signals at OE and DIR. Data-input functions are always enabled; i.e., data at  
the bus pins is stored on every low-to-high transition of the clock inputs.  
3
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
DIR CLKAB CLKBA SAB  
SBA  
L
DIR  
H
CLKAB CLKBA SAB  
SBA  
X
OE  
L
OE  
L
L
X
X
X
X
X
L
REAL-TIME TRANSFER  
BUS B TO BUS A  
REAL-TIME TRANSFER  
BUS A TO BUS B  
DIR CLKAB CLKBA SAB  
SBA  
X
DIR  
CLKAB CLKBA SAB  
SBA  
OE  
X
OE  
X
X
X
X
X
X
X
X
L
L
L
X
X
X
X
X
H
H
X
X
X
H
H
X
STORAGE FROM  
A, B, OR A AND B  
TRANSFER STORED DATA  
TO A AND/OR B  
Figure 1. Bus-Management Functions  
4
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
functional block diagram  
V
CC  
62  
Boundary-Scan Register  
1OE  
53  
55  
54  
59  
60  
1DIR  
1CLKBA  
1SBA  
1CLKAB  
1SAB  
C1  
1D  
63  
51  
1A1  
1B1  
C1  
1D  
One of Nine Channels  
V
CC  
21  
2OE  
30  
27  
28  
2DIR  
2CLKBA  
2SBA  
23  
22  
2CLKAB  
2SAB  
C1  
1D  
10  
40  
2A1  
2B1  
C1  
1D  
One of Nine Channels  
Bypass Register  
Boundary-Control  
Register  
Identification  
Register  
V
58  
CC  
TDO  
Instruction  
Register  
24  
TDI  
V
CC  
56  
TMS  
TCK  
TAP  
Controller  
26  
Pin numbers shown are for the PM package.  
5
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
Terminal Functions  
TERMINAL NAME  
DESCRIPTION  
1A1–1A9,  
2A1–2A9  
Normal-function A-bus I/O ports. See function table for normal-mode logic.  
1B1–1B9,  
2B1–2B9  
Normal-function B-bus I/O ports. See function table for normal-mode logic.  
Normal-function clock inputs. See function table for normal-mode logic.  
1CLKAB, 1CLKBA,  
2CLKAB, 2CLKBA  
1DIR, 2DIR  
GND  
Normal-function direction controls. See function table for normal-mode logic.  
Ground  
Normal-functionoutput enables. See function table for normal-mode logic. An internal pullup at each terminal forces the  
terminal to a high level if left unconnected.  
1OE, 2OE  
1SAB, 1SBA,  
2SAB, 2SBA  
Normal-function select controls. See function table for normal-mode logic.  
Testclock. OneoffourterminalsrequiredbyIEEEStandard1149.1-1990.Testoperationsofthedevicearesynchronous  
to TCK. Data is captured on the rising edge of TCK and outputs change on the falling edge of TCK.  
TCK  
TDI  
Test data input. One of four terminals required by IEEE Standard 1149.1-1990. 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.  
TDO  
TMS  
Test 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.  
V
CC  
Supply voltage  
6
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – 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  
1149.1-1990. All test instructions, test data, and test control signals are passed along this serial-test bus. The  
TAP controller monitors two signals from the test bus, TCK and TMS. The function of the TAP controller is to  
extract the synchronization (TCK) and state control (TMS) signals from the test bus and generate the  
appropriate on-chip control signals for the test structures in the device. Figure 2 shows the TAP-controller state  
diagram.  
The TAP 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 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 TAP controller, and the test registers. As shown, the  
device contains an 8-bit instruction register and four test-data registers: a 52-bit boundary-scan register, a 3-bit  
boundary-control register, a 1-bit bypass register, and a 32-bit device-identification register.  
Test-Logic-Reset  
TMS = H  
TMS = L  
TMS = H  
TMS = H  
TMS = H  
Run-Test/Idle  
Select-DR-Scan  
TMS = L  
Select-IR-Scan  
TMS = L  
TMS = L  
TMS = H  
TMS = H  
Capture-DR  
TMS = L  
Capture-IR  
TMS = L  
Shift-DR  
Shift-IR  
TMS = L  
TMS = L  
TMS = H  
TMS = H  
TMS = H  
Exit1-IR  
TMS = H  
Exit1-DR  
TMS = L  
TMS = L  
Pause-DR  
TMS = H  
Pause-IR  
TMS = H  
Exit2-IR  
TMS = L  
TMS = L  
TMS = L  
TMS = L  
Exit2-DR  
TMS = H  
TMS = H  
Update-DR  
Update-IR  
TMS = H  
TMS = L  
TMS = H  
TMS = L  
Figure 2. TAP-Controller State Diagram  
7
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
state diagram description  
TheTAPcontrollerisasynchronousfinitestatemachinethatprovidestestcontrolsignalsthroughoutthedevice.  
The state diagram shown in Figure 2 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 TAP 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 TAP 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 Test-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 BYPASS instruction. Certain data  
registers also can be reset to their power-up values.  
The state machine is constructed such that the TAP 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 ’ABTH18646A and ’ABTH182646A, the instruction register is reset to the binary value 10000001, which  
selects the IDCODE instruction. Bits 51–48 in the boundary-scan register are reset to logic 0, ensuring that  
these cells, which control A-port and B-port outputs, are set to benign values (i.e., if test mode were invoked,  
the outputs would be at high-impedance state). Reset values of other bits in the boundary-scan register should  
be considered indeterminate. The boundary-control register is reset to the binary value 010, which selects the  
PSA test operation.  
Run-Test/Idle  
The TAP controller must pass through the Run-Test/Idle state (from Test-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 provided as a stable state in which the test logic can be actively running a test or can be idle.  
The test operations selected by the boundary-control register are performed while the TAP 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 TAP 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 can 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.  
8
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
Shift-DR (continued)  
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 TAP 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.  
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 can suspend and resume 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, 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 ’ABTH18646A and  
’ABTH182646A, 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 TAP 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 can suspend and resume 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.  
9
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
register overview  
With the exception of the bypass and device-identification registers, any test register can be thought of as a  
serial-shift register with a shadow latch on each bit. The bypass and device-identification registers differ in that  
they contain only a shift register. During the appropriate capture state (Capture-IR for instruction register,  
Capture-DR for data registers), the shift register can be parallel loaded from a source specified by the current  
instruction. During the appropriate shift state (Shift-IR or Shift-DR), the contents of the shift register are shifted  
out from TDO while new contents are shifted in at TDI. During the appropriate update state (Update-IR or  
Update-DR), the shadow latches are updated from the shift register.  
instruction register description  
The instruction register (IR) is eight bits long and tells the device what instruction is to be executed. Information  
contained in the instruction includes the mode of operation (either normal mode, in which the device performs  
itsnormallogicfunction, ortestmode, inwhichthenormallogicfunctionisinhibitedoraltered), thetestoperation  
to be performed, which of the four data registers is to be selected for inclusion in the scan path during  
data-register scans, and the source of data to be captured into the selected data register during Capture-DR.  
Table 3 lists the instructions supported by the ’ABTH18646A and ’ABTH182646A. The even-parity feature  
specified for SCOPE devices is supported in this device. Bit 7 of the instruction opcode is the parity bit. Any  
instructions that are defined for SCOPE devices but are not supported by this device default to BYPASS.  
During Capture-IR, the IR captures the binary value 10000001. As an instruction is shifted in, this value is shifted  
out via TDO and can be inspected as verification that the IR is in the scan path. During Update-IR, the value  
that has been shifted into the IR is loaded into shadow latches. At this time, the current instruction is updated  
and any specified mode change takes effect. At power up or in the Test-Logic-Reset state, the IR is reset to the  
binary value 10000001, which selects the IDCODE instruction. The IR order of scan is shown in Figure 3.  
Bit 7  
Parity  
(MSB)  
Bit 0  
(LSB)  
TDI  
TDO  
Bit 6  
Bit 5  
Bit 4  
Bit 3  
Bit 2  
Bit 1  
Figure 3. Instruction Register Order of Scan  
10  
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data register description  
boundary-scan register  
The boundary-scan register (BSR) is 52 bits long. It contains one boundary-scan cell (BSC) for each  
normal-function input pin, one BSC for each normal-function I/O pin (one single cell for both input data and  
output data), and one BSC for each of the internally decoded output-enable signals (1OEA, 2OEA, 1OEB,  
2OEB). The BSR is used 1) to store test data that is to be applied externally to the device output pins, and/or  
2)tocapturedatathatappearsinternallyattheoutputsofthenormalon-chiplogicand/orexternallyatthedevice  
input pins.  
The source of data to be captured into the BSR during Capture-DR is determined by the current instruction. The  
contents of the BSR can change during Run-Test/Idle as determined by the current instruction. At power up or  
in Test-Logic-Reset, BSCs 51–48 are reset to logic 0, ensuring that these cells, which control A-port and B-port  
outputs, are set to benign values (i.e., if test mode were invoked, the outputs would be at high-impedance state).  
Reset values of other BSCs should be considered indeterminate.  
When external data is to be captured, the BSCs for signals 1OEA, 2OEA, 1OEB, and 2OEB capture logic values  
determined by the following positive-logic equations: 1OEA = 1OE 1DIR, 2OEA = 2OE 2DIR,  
1OEB = 1OE DIR, and 2OEB = 2OE DIR. When data is to be applied externally, these BSCs control the  
drive state (active or high impedance) of their respective outputs.  
The BSR order of scan is from TDI through bits 51–0 to TDO. Table 1 shows the BSR bits and their associated  
device pin signals.  
Table 1. Boundary-Scan Register Configuration  
BSR BIT  
NUMBER  
DEVICE  
SIGNAL  
BSR BIT  
NUMBER  
DEVICE  
SIGNAL  
BSR BIT  
NUMBER  
DEVICE  
SIGNAL  
51  
50  
49  
48  
47  
46  
45  
44  
43  
42  
41  
40  
39  
38  
37  
36  
2OEB  
1OEB  
2OEA  
1OEA  
2DIR  
35  
34  
33  
32  
31  
30  
29  
28  
27  
26  
25  
24  
23  
22  
21  
20  
19  
18  
2A9-I/O  
2A8-I/O  
2A7-I/O  
2A6-I/O  
2A5-I/O  
2A4-I/O  
2A3-I/O  
2A2-I/O  
2A1-I/O  
1A9-I/O  
1A8-I/O  
1A7-I/O  
1A6-I/O  
1A5-I/O  
1A4-I/O  
1A3-I/O  
1A2-I/O  
1A1-I/O  
17  
16  
15  
14  
13  
12  
11  
10  
9
2B9-I/O  
2B8-I/O  
2B7-I/O  
2B6-I/O  
2B5-I/O  
2B4-I/O  
2B3-I/O  
2B2-I/O  
2B1-I/O  
1B9-I/O  
1B8-I/O  
1B7-I/O  
1B6-I/O  
1B5-I/O  
1B4-I/O  
1B3-I/O  
1B2-I/O  
1B1-I/O  
1DIR  
2OE  
1OE  
2CLKAB  
1CLKAB  
2CLKBA  
1CLKBA  
2SAB  
8
7
6
5
1SAB  
4
2SBA  
3
1SBA  
2
1
0
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boundary-control register  
The boundary-control register (BCR) is three bits long. The BCR is used in the context of the boundary-run test  
(RUNT) instruction to implement additional test operations not included in the basic SCOPE instruction set.  
Such operations include PRPG, PSA, and binary count up (COUNT). Table 4 shows the test operations that  
are decoded by the BCR.  
During Capture-DR, the contents of the BCR are not changed. At power up or in Test-Logic-Reset, the BCR is  
reset to the binary value 010, which selects the PSA test operation. The BCR order of scan is shown in  
Figure 4.  
Bit 2  
(MSB)  
Bit 0  
(LSB)  
TDI  
TDO  
Bit 1  
Figure 4. Boundary-Control Register Order of Scan  
bypass register  
The bypass register is a 1-bit scan path that can be selected to shorten the length of the system scan path,  
reducing the number of bits per test pattern that must be applied to complete a test operation. During  
Capture-DR, the bypass register captures a logic 0. The bypass register order of scan is shown in  
Figure 5.  
TDI  
TDO  
Bit 0  
Figure 5. Bypass Register Order of Scan  
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device-identification register  
The device-identification register (IDR) is 32 bits long. It can be selected and read to identify the manufacturer,  
part number, and version of this device.  
For the ’ABTH18646A , the binary value 00000000000000101001000000101111 (0002902F, hex) is captured  
(during Capture-DR state) in the IDR to identify this device as Texas Instruments SN54/74ABTH18646A.  
For the ’ABTH182646A , the binary value 00000000000000101101000000101111 (0002D02F, hex) is captured  
(during Capture-DR state) in the IDR to identify this device as Texas Instruments SN54/74ABTH182646A.  
The IDR order of scan is from TDI through bits 31–0 to TDO. Table 2 shows the IDR bits and their significance.  
Table 2. Device-Identification Register Configuration  
IDR BIT  
NUMBER  
IDENTIFICATION  
SIGNIFICANCE  
IDR BIT  
NUMBER  
IDENTIFICATION  
SIGNIFICANCE  
IDR BIT  
NUMBER  
IDENTIFICATION  
SIGNIFICANCE  
31  
30  
29  
28  
VERSION3  
VERSION2  
VERSION1  
VERSION0  
27  
26  
25  
24  
23  
22  
21  
20  
19  
18  
17  
16  
15  
14  
13  
12  
PARTNUMBER15  
PARTNUMBER14  
PARTNUMBER13  
PARTNUMBER12  
PARTNUMBER11  
PARTNUMBER10  
PARTNUMBER09  
PARTNUMBER08  
PARTNUMBER07  
PARTNUMBER06  
PARTNUMBER05  
PARTNUMBER04  
PARTNUMBER03  
PARTNUMBER02  
PARTNUMBER01  
PARTNUMBER00  
11  
10  
9
MANUFACTURER10  
MANUFACTURER09  
MANUFACTURER08  
MANUFACTURER07  
MANUFACTURER06  
MANUFACTURER05  
MANUFACTURER04  
MANUFACTURER03  
MANUFACTURER02  
MANUFACTURER01  
MANUFACTURER00  
8
7
6
5
4
3
2
1
LOGIC1  
0
Note that for TI products, bits 11–0 of the device-identification register always contain the binary value 000000101111  
(02F, hex).  
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instruction-register opcode description  
The instruction-register opcodes are shown in Table 3. The following descriptions detail the operation of each  
instruction.  
Table 3. Instruction-Register Opcodes  
BINARY CODE  
BIT 7 BIT 0  
MSB LSB  
SELECTED DATA  
REGISTER  
SCOPE OPCODE  
DESCRIPTION  
MODE  
00000000  
10000001  
10000010  
00000011  
10000100  
00000101  
00000110  
10000111  
10001000  
00001001  
00001010  
10001011  
00001100  
10001101  
10001110  
00001111  
All others  
EXTEST  
IDCODE  
Boundary scan  
Identification read  
Boundary scan  
Device identification  
Boundary scan  
Bypass  
Test  
Normal  
Normal  
Normal  
Normal  
Normal  
Modified test  
Test  
SAMPLE/PRELOAD  
Sample boundary  
BYPASS  
BYPASS  
BYPASS  
HIGHZ  
Bypass scan  
Bypass scan  
Bypass  
Bypass scan  
Bypass  
Control boundary to high impedance  
Control boundary to 1/0  
Bypass scan  
Bypass  
CLAMP  
Bypass  
BYPASS  
Bypass  
Normal  
Test  
RUNT  
Boundary-run test  
Bypass  
READBN  
READBT  
CELLTST  
TOPHIP  
SCANCN  
SCANCT  
BYPASS  
Boundary read  
Boundary scan  
Boundary scan  
Boundary scan  
Bypass  
Normal  
Test  
Boundary read  
Boundary self test  
Boundary toggle outputs  
Boundary-control register scan  
Boundary-control register scan  
Bypass scan  
Normal  
Test  
Boundary control  
Boundary control  
Bypass  
Normal  
Test  
Normal  
Bit 7 is used to maintain even parity in the 8-bit instruction.  
The BYPASS instruction is executed in lieu of a SCOPE instruction that is not supported in the ’ABTH18646A or ’ABTH182646A.  
boundary scan  
This instruction conforms to the IEEE Standard 1149.1-1990 EXTEST instruction. The BSR is selected in the  
scan path. Data appearing at the device input and I/O pins is captured in the associated BSCs. Data that has  
been scanned into the I/O BSCs for pins in the output mode is applied to the device I/O pins. Data present at  
the device pins is passed through the BSCs to the normal on-chip logic. For I/O pins, the operation of a pin as  
input or output is determined by the contents of the output-enable BSCs (bits 51–48 of the BSR). When a given  
output enable is active (logic 1), the associated I/O pins operate in the output mode. Otherwise, the I/O pins  
operate in the input mode. The device operates in the test mode.  
identification read  
This instruction conforms to the IEEE Standard 1149.1-1990 IDCODE instruction. The IDR is selected in the  
scan path. The device operates in the normal mode.  
sample boundary  
This instruction conforms to the IEEE Standard 1149.1-1990 SAMPLE/PRELOAD instruction. The BSR is  
selected in the scan path. Data appearing at the device input pins and I/O pins in the input mode is captured  
in the associated BSCs, while data appearing at the outputs of the normal on-chip logic is captured in the BSCs  
associated with I/O pins in the output mode. The device operates in the normal mode.  
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bypass scan  
This instruction conforms to the IEEE Standard 1149.1-1990 BYPASS instruction. The bypass register is  
selected in the scan path. A logic 0 value is captured in the bypass register during Capture-DR. The device  
operates in the normal mode.  
control boundary to high impedance  
This instruction conforms to the IEEE Standard 1149.1a-1993 HIGHZ instruction. The bypass register is  
selected in the scan path. A logic 0 value is captured in the bypass register during Capture-DR. The device  
operates in a modified test mode in which all device I/O pins are placed in the high-impedance state, the device  
input pins remain operational, and the normal on-chip logic function is performed.  
control boundary to 1/0  
This instruction conforms to the IEEE Standard 1149.1a-1993 CLAMP instruction. The bypass register is  
selected in the scan path. A logic 0 value is captured in the bypass register during Capture-DR. Data in the I/O  
BSCs for pins in the output mode is applied to the device I/O pins. The device operates in the test mode.  
boundary-run test  
The bypass register is selected in the scan path. A logic 0 value is captured in the bypass register during  
Capture-DR. The device operates in the test mode. The test operation specified in the BCR is executed during  
Run-Test/Idle. The five test operations decoded by the BCR are: sample inputs/toggle outputs (TOPSIP),  
PRPG, PSA, simultaneous PSA and PRPG (PSA/PRPG), and simultaneous PSA and binary count up  
(PSA/COUNT).  
boundary read  
The BSR is selected in the scan path. The value in the BSR remains unchanged during Capture-DR. This  
instruction is useful for inspecting data after a PSA operation.  
boundary self test  
The BSR is selected in the scan path. All BSCs capture the inverse of their current values during Capture-DR.  
In this way, the contents of the shadow latches can be read out to verify the integrity of both shift-register and  
shadow-latch elements of the BSR. The device operates in the normal mode.  
boundary toggle outputs  
The bypass register is selected in the scan path. A logic 0 value is captured in the bypass register during  
Capture-DR. Data in the shift-register elements of the selected output-mode BSCs is toggled on each rising  
edge of TCK in Run-Test/Idle, updated in the shadow latches, and applied to the associated device I/O pins on  
each falling edge of TCK in Run-Test/Idle. Data in the input-mode BSCs remains constant. Data appearing at  
the device input or I/O pins is not captured in the input-mode BSCs. The device operates in the test mode.  
boundary-control-register scan  
The BCR is selected in the scan path. The value in the BCR remains unchanged during Capture-DR. This  
operation must be performed before a boundary-run test operation to specify which test operation is to be  
executed.  
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boundary-control register opcode description  
TheBCRopcodesaredecodedfromBCRbits20asshowninTable4. Theselectedtestoperationisperformed  
while the RUNT instruction is executed in the Run-Test/Idle state. The following descriptions detail the operation  
of each BCR instruction and illustrate the associated PSA and PRPG algorithms.  
Table 4. Boundary-Control Register Opcodes  
BINARY CODE  
BIT 2 BIT 0  
MSB LSB  
DESCRIPTION  
X00  
X01  
X10  
011  
111  
Sample inputs/toggle outputs (TOPSIP)  
Pseudo-random pattern generation/36-bit mode (PRPG)  
Parallel-signature analysis/36-bit mode (PSA)  
Simultaneous PSA and PRPG/18-bit mode (PSA/PRPG)  
Simultaneous PSA and binary count up/18-bit mode (PSA/COUNT)  
While the control input BSCs (bits 51–36) are not included in the toggle, PSA, PRPG, or COUNT algorithms,  
theoutput-enableBSCs(bits51–48oftheBSR)controlthedrivestate(activeorhighimpedance)oftheselected  
device output pins. These BCR instructions are valid only when both bytes of the device are operating in one  
direction of data flow (that is, 1OEA 1OEB and 2OEA 2OEB) and in the same direction of data flow (that is,  
1OEA = 2OEA and 1OEB = 2OEB). Otherwise, the bypass instruction is operated.  
sample inputs/toggle outputs (TOPSIP)  
Data appearing at the selected device input-mode I/O pins is captured in the shift-register elements of the  
associated BSCs on each rising edge of TCK. Data in the shift-register elements of the selected output-mode  
BSCs is toggled on each rising edge of TCK, updated in the shadow latches, and applied to the associated  
device I/O pins on each falling edge of TCK.  
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pseudo-random pattern generation (PRPG)  
A pseudo-random pattern is generated in the shift-register elements of the selected BSCs on each rising edge  
of TCK, updated in the shadow latches, and applied to the associated device output-mode I/O pins on each  
falling edge of TCK. Figures 6 and 7 illustrate the 36-bit linear-feedback shift-register algorithms through which  
the patterns are generated. An initial seed value should be scanned into the BSR before performing this  
operation. A seed value of all zeroes does not produce additional patterns.  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
=
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
Figure 6. 36-Bit PRPG Configuration (1OEA = 2OEA = 0, 1OEB = 2OEB = 1)  
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pseudo-random pattern generation (PRPG) (continued)  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
=
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
Figure 7. 36-Bit PRPG Configuration (1OEA = 2OEA = 1, 1OEB = 2OEB = 0)  
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parallel-signature analysis (PSA)  
Data appearing at the selected device input-mode I/O pins is compressed into a 36-bit parallel signature in the  
shift-register elements of the selected BSCs on each rising edge of TCK. Data in the shadow latches of the  
selected output-mode BSCs remains constant and is applied to the associated device I/O pins. Figures 8 and 9  
illustrate the 36-bit linear-feedback shift-register algorithms through which the signature is generated. An initial  
seed value should be scanned into the BSR before performing this operation.  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
=
=
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
Figure 8. 36-Bit PSA Configuration (1OEA = 2OEA = 0, 1OEB = 2OEB = 1)  
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parallel-signature analysis (PSA) (continued)  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
=
=
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
Figure 9. 36-Bit PSA Configuration (1OEA = 2OEA = 1, 1OEB = 2OEB = 0)  
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simultaneous PSA and PRPG (PSA/PRPG)  
Data appearing at the selected device input-mode I/O pins is compressed into an 18-bit parallel signature in  
the shift-register elements of the selected input-mode BSCs on each rising edge of TCK. At the same time, an  
18-bit pseudo-random pattern is generated in the shift-register elements of the selected output-mode BSCs on  
each rising edge of TCK, updated in the shadow latches, and applied to the associated device I/O pins on each  
falling edge of TCK. Figures 10 and 11 illustrate the 18-bit linear-feedback shift-register algorithms through  
which the signature and patterns are generated. An initial seed value should be scanned into the BSR before  
performing this operation. A seed value of all zeroes does not produce additional patterns.  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
=
=
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
Figure 10. 18-Bit PSA/PRPG Configuration (1OEA = 2OEA = 0, 1OEB = 2OEB = 1)  
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simultaneous PSA and PRPG (PSA/PRPG) (continued)  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
=
=
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
Figure 11. 18-Bit PSA/PRPG Configuration (1OEA = 2OEA = 1, 1OEB = 2OEB = 0)  
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simultaneous PSA and binary count up (PSA/COUNT)  
Data appearing at the selected device input-mode I/O pins is compressed into an 18-bit parallel signature in  
the shift-register elements of the selected input-mode BSCs on each rising edge of TCK. At the same time, an  
18-bit binary count-up pattern is generated in the shift-register elements of the selected output-mode BSCs on  
each rising edge of TCK, updated in the shadow latches, and applied to the associated device I/O pins on each  
falling edge of TCK. Figures 12 and 13 illustrate the 18-bit linear-feedback shift-register algorithms through  
which the signature is generated. An initial seed value should be scanned into the BSR before performing this  
operation.  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
MSB  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
LSB  
=
=
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
Figure 12. 18-Bit PSA/COUNT Configuration (1OEA = 2OEA = 0, 1OEB = 2OEB = 1)  
23  
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simultaneous PSA and binary count up (PSA/COUNT) (continued)  
2B9-I/O 2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O  
1B9-I/O 1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O  
MSB  
2A9-I/O 2A8-I/O 2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O  
LSB  
=
=
1A9-I/O 1A8-I/O 1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O  
Figure 13. 18-Bit PSA/COUNT Configuration (1OEA = 2OEA = 1, 1OEB = 2OEB = 0)  
24  
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timing description  
All test operations of the ’ABTH18646A and ’ABTH182646A are synchronous to TCK. Data on the TDI, TMS,  
andnormal-functioninputsiscapturedontherisingedgeofTCK. DataappearsontheTDOandnormal-function  
output pins on the falling edge of TCK. The TAP controller is advanced through its states (as shown in Figure 2)  
by changing the value of TMS on the falling edge of TCK and then applying a rising edge to TCK.  
A simple timing example is shown in Figure 14. In this example, the TAP controller begins in the  
Test-Logic-Reset state and is advanced through its states, as necessary, to perform one instruction-register  
scan and one data-register scan. While in the Shift-IR and Shift-DR states, TDI is used to input serial data, and  
TDO is used to output serial data. The TAP controller is then returned to the Test-Logic-Reset state. Table 5  
details the operation of the test circuitry during each TCK cycle.  
Table 5. Explanation of Timing Example  
TCK  
CYCLE(S)  
TAP STATE  
AFTER TCK  
DESCRIPTION  
TMS is changed to a logic 0 value on the falling edge of TCK to begin advancing the TAP controller toward  
the desired state.  
1
Test-Logic-Reset  
2
3
4
Run-Test/Idle  
Select-DR-Scan  
Select-IR-Scan  
The IR captures the 8-bit binary value 10000001 on the rising edge of TCK as the TAP controller exits the  
Capture-IR state.  
5
6
Capture-IR  
Shift-IR  
TDO becomes active and TDI is made valid on the falling edge of TCK. The first bit is shifted into the TAP  
on the rising edge of TCK as the TAP controller advances to the next state.  
One bit is shifted into the IR on each TCK rising edge. With TDI held at a logic 1 value, the 8-bit binary value  
11111111 is seriallyscannedintotheIR.Atthesametime,the8-bitbinaryvalue10000001isseriallyscanned  
out of the IR via TDO. In TCK cycle 13, TMS is changed to a logic 1 value to end the IR scan on the next  
TCK cycle. The last bit of the instruction is shifted as the TAP controller advances from Shift-IR to Exit1-IR.  
7–13  
Shift-IR  
14  
15  
16  
Exit1-IR  
Update-IR  
TDO becomes inactive (goes to the high-impedance state) on the falling edge of TCK.  
The IR is updated with the new instruction (BYPASS) on the falling edge of TCK.  
Select-DR-Scan  
The bypass register captures a logic 0 value on the rising edge of TCK as the TAP controller exits the  
Capture-DR state.  
17  
18  
Capture-DR  
Shift-DR  
TDO becomes active and TDI is made valid on the falling edge of TCK. The first bit is shifted into the TAP  
on the rising edge of TCK as the TAP controller advances to the next state.  
19–20  
21  
Shift-DR  
Exit1-DR  
The binary value 101 is shifted in via TDI, while the binary value 010 is shifted out via TDO.  
TDO becomes inactive (goes to the high-impedance state) on the falling edge of TCK.  
In general, the selected data register is updated with the new data on the falling edge of TCK.  
22  
Update-DR  
23  
Select-DR-Scan  
Select-IR-Scan  
Test-Logic-Reset  
24  
25  
Test operation completed  
25  
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timing description (continued)  
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25  
TCK  
TMS  
TDI  
TDO  
TAP  
Controller  
State  
3-State (TDO) or Don’t Care (TDI)  
Figure 14. Timing Example  
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)  
Supply voltage range, V  
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 7 V  
CC  
Input voltage range, V : except I/O ports (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 7 V  
I
I/O ports (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to 5.5 V  
Voltage range applied to any output in the high state or power-off state, V  
. . . . . . . . . . . . . . –0.5 V to 5.5 V  
O
Current into any output in the low state, I : SN54ABTH18646A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 mA  
O
SN54ABTH182646A (A port or TDO) . . . . . . . . . . . . . . . . 96 mA  
SN54ABTH182646A (B port) . . . . . . . . . . . . . . . . . . . . . . . 30 mA  
SN74ABTH18646A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 mA  
SN74ABTH182646A (A port or TDO) . . . . . . . . . . . . . . . 128 mA  
SN74ABTH182646A (B port) . . . . . . . . . . . . . . . . . . . . . . . 30 mA  
Input clamp current, I (V < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –18 mA  
IK  
OK  
I
Output clamp current, I  
(V < 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –50 mA  
O
Maximum package power dissipation at T = 55°C (in still air) (see Note 2): PM package . . . . . . . . . . . 1 W  
Storage temperature range, T  
A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C  
stg  
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and  
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not  
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.  
NOTES: 1. The input and output negative-voltage ratings may be exceeded if the input and output clamp-current ratings are observed.  
2. The maximum package power dissipation is calculated using a junction temperature of 150°C and a board trace length of 75 mils.  
Formoreinformation, refertothePackageThermalConsiderationsapplicationnoteintheABTAdvancedBiCMOSTechnologyData  
Book, literature number SCBD002.  
26  
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recommended operating conditions  
SN54ABTH18646A SN74ABTH18646A  
UNIT  
MIN  
4.5  
2
MAX  
MIN  
4.5  
2
MAX  
V
V
V
V
Supply voltage  
5.5  
5.5  
V
V
CC  
IH  
High-level input voltage  
Low-level input voltage  
Input voltage  
0.8  
0.8  
V
IL  
0
V
0
V
CC  
V
I
CC  
I
I
High-level output current  
Low-level output current  
Input transition rise or fall rate  
Operating free-air temperature  
–24  
48  
–32  
mA  
mA  
ns/V  
°C  
OH  
64  
OL  
t/v  
10  
10  
T
–55  
125  
–40  
85  
A
electrical characteristics over recommended operating free-air temperature range (unless  
otherwise noted)  
SN54ABTH18646A  
PARAMETER  
TEST CONDITIONS  
T
A
= 25°C  
T
A
= –55°C to 125°C  
UNIT  
V
TYP  
MIN  
MAX  
MIN  
MAX  
V
V
V
V
CC  
V
CC  
V
CC  
V
CC  
V
CC  
= 4.5 V,  
= 4.5 V,  
= 5 V,  
I = –18 mA  
–1.2  
–1.2  
IK  
I
I
I
I
I
= –3 mA  
= –3 mA  
= –24 mA  
= 48 mA  
2.5  
3
2.5  
3
OH  
OH  
OH  
OL  
V
OH  
OL  
= 4.5 V,  
= 4.5 V,  
2
2
0.55  
0.55  
V
CLK, DIR, S, TCK  
V
= 0 to 5.5 V,  
V = V  
or GND  
or GND  
±1  
±1  
CC  
I
CC  
V
CC  
= 0 to 5.5 V,  
I
I
µA  
A or B ports  
V
CC  
V
CC  
V
CC  
= 5.5 V,  
= 5.5 V,  
= 5.5 V,  
V = V  
I
V = V  
I
V = GND  
I
V = 0.8 V  
I
±20  
10  
±20  
10  
CC  
CC  
I
I
OE, TDI, TMS  
OE, TDI, TMS  
µA  
µA  
IH  
–40  
75  
–150  
500  
–500  
10  
–40  
–150  
IL  
220  
I
A or B ports  
V
CC  
= 4.5 V  
µA  
I(hold)  
V = 2 V  
I
–75  
–180  
TDO  
TDO  
V
V
= 5.5 V,  
= 5.5 V,  
V
V
= 2.7 V, OE = 2 V  
= 0.5 V, OE = 2 V  
10  
µA  
µA  
I
I
CC  
CC  
CC  
O
O
OZH  
–10  
–10  
OZL  
V
V
= 0 to 2.1 V,  
= 2.7 V or 0.5 V,  
I
I
±50  
±50  
µA  
µA  
TDO  
TDO  
OZPU  
OE = 0.8 V  
O
V
V
= 2.1 V to 0,  
= 2.7 V or 0.5 V,  
CC  
O
OZPD  
OE = 0.8 V  
I
I
I
V
V
V
= 0,  
V or V 4.5 V  
±100  
50  
µA  
µA  
off  
CC  
CC  
CC  
I
O
Outputs high  
= 5.5 V,  
= 5.5 V,  
V
= 5.5 V  
50  
–200  
3.9  
24  
CEX  
O
O
§
V
= 2.5 V  
–50  
–110  
1.7  
20  
–200  
3.9  
24  
–50  
mA  
O
Outputs high  
Outputs low  
V
I
= 5.5 V,  
= 0,  
CC  
O
I
A or B ports  
mA  
CC  
V = V  
I
or GND  
CC  
= 5.5 V, One input at 3.4 V,  
Outputs disabled  
1
3
3
V
CC  
Other inputs at V  
1.5  
1.5  
mA  
I  
CC  
or GND  
CC  
V = 2.5 V or 0.5 V  
C
C
C
Control inputs  
A or B ports  
TDO  
5
10  
8
pF  
pF  
pF  
i
I
V
= 2.5 V or 0.5 V  
= 2.5 V or 0.5 V  
io  
o
O
O
V
§
All typical values are at V  
= 5 V.  
CC  
includes the off-state output leakage current.  
The parameter I  
I(hold)  
Not more than one output should be tested at a time, and the duration of the test should not exceed one second.  
This is the increase in supply current for each input that is at the specified TTL voltage level rather than V  
or GND.  
CC  
27  
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electrical characteristics over recommended operating free-air temperature range (unless  
otherwise noted)  
SN74ABTH18646A  
PARAMETER  
TEST CONDITIONS  
T
A
= 25°C  
T
A
= –40°C to 85°C  
UNIT  
TYP  
MIN  
MAX  
MIN  
MAX  
V
V
V
V
V
= 4.5 V,  
= 4.5 V,  
= 5 V,  
I = –18 mA  
–1.2  
–1.2  
V
IK  
CC  
CC  
CC  
I
I
I
I
I
I
I
= –3 mA  
= –3 mA  
= –24 mA  
= –32 mA  
= 48 mA  
= 64 mA  
2.5  
3
2.5  
3
OH  
OH  
OH  
OH  
OL  
OL  
V
OH  
2
V
CC  
= 4.5 V  
2
2
0.55  
0.55  
0.55  
0.55  
V
OL  
V
= 4.5 V  
V
CC  
CC  
CLK, DIR, S, TCK  
V
= 0 to 5.5 V,  
V = V  
or GND  
or GND  
±1  
±1  
I
CC  
V
CC  
= 0 to 5.5 V,  
I
I
µA  
A or B ports  
V
CC  
V
CC  
V
CC  
= 5.5 V,  
= 5.5 V,  
= 5.5 V,  
V = V  
I
±20  
10  
±20  
10  
CC  
CC  
I
I
OE, TDI, TMS  
OE, TDI, TMS  
V = V  
I
µA  
µA  
IH  
V = GND  
I
–40  
75  
–150  
500  
–40  
75  
–150  
500  
IL  
V = 0.8 V  
I
220  
A or B ports  
V
CC  
= 4.5 V  
µA  
I
I(hold)  
V = 2 V  
I
–75  
–180 –500  
–75  
–500  
V
V
= 2.1 V to 5.5 V,  
= 2.7 V, OE = 2 V  
CC  
O
TDO  
TDO  
TDO  
TDO  
10  
10  
–10  
±50  
±50  
µA  
µA  
µA  
µA  
I
I
I
I
OZH  
V
V
= 2.1 V to 5.5 V,  
= 0.5 V, OE = 2 V  
CC  
O
–10  
±50  
±50  
OZL  
V
V
= 0 to 2.1 V,  
= 2.7 V or 0.5 V, OE = 0.8 V  
CC  
O
OZPU  
OZPD  
V
V
= 2.1 V to 0,  
= 2.7 V or 0.5 V,  
CC  
O
OE = 0.8 V  
I
I
I
V
V
V
= 0,  
V or V 4.5 V  
±100  
50  
±100  
50  
µA  
µA  
off  
CC  
CC  
CC  
I
O
Outputs high  
= 5.5 V,  
= 5.5 V,  
V
= 5.5 V  
CEX  
O
O
§
V
= 2.5 V  
–50  
–110 –200  
–50  
–200  
2.2  
24  
mA  
O
Outputs high  
Outputs low  
1.7  
20  
1
2.2  
24  
2
V
I
= 5.5 V,  
= 0,  
CC  
O
I
A or B ports  
mA  
CC  
V = V  
or GND  
I
CC  
Outputs disabled  
2
V
= 5.5 V, One input at 3.4 V,  
CC  
Other inputs at V  
1.5  
1.5  
mA  
I  
CC  
or GND  
CC  
V = 2.5 V or 0.5 V  
C
C
C
Control inputs  
A or B ports  
TDO  
5
10  
8
pF  
pF  
pF  
i
I
V
= 2.5 V or 0.5 V  
= 2.5 V or 0.5 V  
io  
o
O
O
V
§
All typical values are at V  
= 5 V.  
CC  
The parameter I  
includes the off-state output leakage current.  
I(hold)  
Not more than one output should be tested at a time, and the duration of the test should not exceed one second.  
This is the increase in supply current for each input that is at the specified TTL voltage level rather than V or GND.  
CC  
28  
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SCBS166D – AUGUST 1993 – REVISED JULY 1996  
timing requirements over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (normal mode) (see Figure 15)  
SN54ABTH18646A SN74ABTH18646A  
UNIT  
MIN  
MAX  
MIN  
MAX  
f
t
t
t
Clock frequency  
Pulse duration  
Setup time  
CLKAB or CLKBA  
0
100  
0
100  
MHz  
ns  
clock  
CLKAB or CLKBA high or low  
A before CLKABor B before CLKBA↑  
A after CLKABor B after CLKBA↑  
3
3
w
3
3
ns  
su  
h
Hold time  
0.9  
0.5  
ns  
timing requirements over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (test mode) (see Figure 15)  
SN54ABTH18646A SN74ABTH18646A  
UNIT  
MIN  
MAX  
MIN  
MAX  
f
t
Clock frequency  
Pulse duration  
TCK  
0
50  
0
50  
MHz  
ns  
clock  
TCK high or low  
8
8
w
A, B, CLK, DIR, OE, or S before TCK↑  
TDI before TCK↑  
6
6
t
Setup time  
Hold time  
4.5  
3
4.5  
3
ns  
ns  
su  
h
TMS before TCK↑  
A, B, CLK, DIR, OE, or S after TCK↑  
TDI after TCK↑  
1.5  
1
1.5  
1
t
TMS after TCK↑  
1.5  
50*  
1*  
1.5  
50  
1
t
t
Delay time  
Rise time  
Power up to TCK↑  
ns  
d
V
CC  
power up  
µs  
r
*On products compliant to MIL-PRF-38535, this parameter is not production tested.  
29  
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SCBS166D – AUGUST 1993 – REVISED JULY 1996  
switching characteristics over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (normal mode) (see Figure 15)  
SN54ABTH18646A  
FROM  
(INPUT)  
TO  
(OUTPUT)  
V
T
= 5 V,  
= 25°C  
V
= 4.5 V to 5.5 V,  
CC  
A
CC  
T = –55°C to 125°C  
A
PARAMETER  
UNIT  
MIN  
100  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
TYP  
150  
3.1  
3.3  
3.6  
3.8  
3.8  
3.9  
3.9  
4
MAX  
MIN  
100  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
MAX  
f
t
t
t
t
t
t
t
t
t
t
t
t
t
t
CLKAB or CLKBA  
A or B  
MHz  
ns  
max  
PLH  
PHL  
PLH  
PHL  
PLH  
PHL  
PZH  
PZL  
PZH  
PZL  
PHZ  
PLZ  
PHZ  
PLZ  
4.7  
5.0  
5.6  
5.8  
6.0  
6.5  
6.3  
6.5  
6.7  
6.9  
8.8  
6.9  
9
5.2  
6
B or A  
B or A  
B or A  
B or A  
B or A  
B or A  
B or A  
6.8  
7
CLKAB or CLKBA  
SAB or SBA  
DIR  
ns  
ns  
ns  
ns  
ns  
ns  
7.8  
8.2  
7.5  
7.8  
7.6  
7.7  
10.3  
9.1  
10.2  
9.4  
4.2  
4.3  
5.9  
4.7  
6
OE  
DIR  
2
2
2
2
OE  
2
4.8  
7.1  
2
switching characteristics over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (normal mode) (see Figure 15)  
SN74ABTH18646A  
FROM  
(INPUT)  
TO  
(OUTPUT)  
V
T
= 5 V,  
= 25°C  
V
= 4.5 V to 5.5 V,  
CC  
A
CC  
T = –40°C to 85°C  
A
PARAMETER  
UNIT  
MIN  
100  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
TYP  
150  
3.1  
3.3  
3.6  
3.8  
3.8  
3.9  
3.9  
4
MAX  
MIN  
100  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
MAX  
f
t
t
t
t
t
t
t
t
t
t
t
t
t
t
CLKAB or CLKBA  
A or B  
MHz  
ns  
max  
PLH  
PHL  
PLH  
PHL  
PLH  
PHL  
PZH  
PZL  
PZH  
PZL  
PHZ  
PLZ  
PHZ  
PLZ  
4.7  
5.0  
5.6  
5.8  
6.0  
6.5  
6.3  
6.5  
6.7  
6.9  
8.8  
6.9  
9
5
5.4  
5.9  
6.1  
6.6  
6.8  
7
B or A  
B or A  
B or A  
B or A  
B or A  
B or A  
B or A  
CLKAB or CLKBA  
SAB or SBA  
DIR  
ns  
ns  
ns  
ns  
ns  
ns  
7.2  
7.4  
7.6  
10  
4.2  
4.3  
5.9  
4.7  
6
OE  
DIR  
2
2
8.1  
9.7  
7.6  
2
2
OE  
2
4.8  
7.1  
2
30  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
switching characteristics over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (test mode) (see Figure 15)  
SN54ABTH18646A  
FROM  
(INPUT)  
TO  
(OUTPUT)  
V
T
= 5 V,  
= 25°C  
V
= 4.5 V to 5.5 V,  
CC  
A
CC  
T = –40°C to 85°C  
A
PARAMETER  
UNIT  
MIN  
50  
2.5  
2.5  
2
TYP  
90  
MAX  
MIN  
50  
2.5  
2.5  
2
MAX  
f
TCK  
MHz  
ns  
max  
t
6.1  
6.5  
3.6  
3.7  
7.1  
7.2  
3.7  
3.9  
8.5  
7.2  
5.1  
4
11  
10.8  
5.1  
13.1  
12.6  
5.8  
7
PLH  
PHL  
PLH  
PHL  
PZH  
PZL  
PZH  
PZL  
PHZ  
PLZ  
PHZ  
PLZ  
TCK↓  
A or B  
TDO  
t
t
t
t
t
t
t
t
t
t
t
TCK↓  
TCK↓  
TCK↓  
TCK↓  
TCK↓  
ns  
ns  
ns  
ns  
ns  
2
5.1  
2
4
11.5  
11.8  
5.7  
4
13.9  
14.2  
6.6  
6.9  
18  
A or B  
TDO  
4
4
2
2
2
6.2  
2
4
14.2  
13.3  
6.8  
4
A or B  
TDO  
3
3
17.5  
7.4  
6.4  
3
3
2.5  
5.5  
2.5  
switching characteristics over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (test mode) (see Figure 15)  
SN74ABTH18646A  
FROM  
(INPUT)  
TO  
(OUTPUT)  
V
T
= 5 V,  
= 25°C  
V
= 4.5 V to 5.5 V,  
CC  
A
CC  
T = –40°C to 85°C  
A
PARAMETER  
UNIT  
MIN  
50  
2.5  
2.5  
2
TYP  
90  
MAX  
MIN  
50  
2.5  
2.5  
2
MAX  
f
TCK  
MHz  
ns  
max  
t
6.1  
6.5  
3.6  
3.7  
7.1  
7.2  
3.7  
3.9  
8.5  
7.2  
5.1  
4
11  
10.8  
5.1  
13.1  
12.4  
5.6  
5.6  
13.4  
13.6  
6.6  
6.9  
15  
PLH  
PHL  
PLH  
PHL  
PZH  
PZL  
PZH  
PZL  
PHZ  
PLZ  
PHZ  
PLZ  
TCK↓  
A or B  
TDO  
t
t
t
t
t
t
t
t
t
t
t
TCK↓  
TCK↓  
TCK↓  
TCK↓  
TCK↓  
ns  
ns  
ns  
ns  
ns  
2
5.1  
2
4
11.5  
11.8  
5.7  
4
A or B  
TDO  
4
4
2
2
2
6.2  
2
4
13  
4
A or B  
TDO  
3
13.3  
6.8  
3
15  
3
3
7.2  
6.3  
2.5  
5.5  
2.5  
31  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
recommended operating conditions  
SN54ABTH182646A SN74ABTH182646A  
UNIT  
MIN  
4.5  
2
MAX  
MIN  
4.5  
2
MAX  
V
CC  
V
IH  
V
IL  
V
I
Supply voltage  
5.5  
5.5  
V
V
V
V
High-level input voltage  
Low-level input voltage  
Input voltage  
0.8  
0.8  
0
V
CC  
0
V
CC  
A port, TDO  
B port  
–24  
–12  
48  
–32  
–12  
64  
I
High-level output current  
Low-level output current  
mA  
mA  
OH  
OL  
A port, TDO  
B port  
I
12  
12  
t/v  
Input transition rise or fall rate  
Operating free-air temperature  
10  
10  
ns/V  
T
A
–55  
125  
–40  
85  
°C  
PRODUCT PREVIEW information concerns products in the formative or  
design phase of development. Characteristic data and other  
specifications are design goals. Texas Instruments reserves the right to  
change or discontinue these products without notice.  
32  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
electrical characteristics over recommended operating free-air temperature range (unless  
otherwise noted)  
T
= 25°C  
SN54ABTH182646A SN74ABTH182646A  
A
PARAMETER  
TEST CONDITIONS  
UNIT  
MIN TYP  
MAX  
MIN  
MAX  
MIN  
MAX  
V
V
V
V
= 4.5 V, I = 18 mA  
–1.2  
–1.2  
–1.2  
V
IK  
CC  
CC  
CC  
I
= 4.5 V,  
= 5 V,  
I
I
I
I
I
I
I
I
I
I
I
I
= –3 mA  
= –3 mA  
= –24 mA  
= –32 mA  
= –1 mA  
= –1 mA  
= –3 mA  
= –12 mA  
= 48 mA  
= 64 mA  
= 8 mA  
2.5  
3
2.5  
3
2.5  
3
OH  
OH  
OH  
OH  
OH  
OH  
OH  
OH  
OL  
OL  
OL  
OL  
A port, TDO  
2
2
V
CC  
= 4.5 V  
2*  
2
3.35  
3.85  
3.1  
V
OH  
V
V
V
= 4.5 V,  
= 5 V,  
3.35  
3.85  
3.1  
2.6*  
3.3  
3.8  
3
CC  
CC  
B port  
V
V
= 4.5 V  
= 4.5 V  
= 4.5 V  
CC  
2.6  
0.55  
0.55*  
0.8  
0.55  
0.8  
A port, TDO  
B port  
CC  
0.55  
0.65  
0.8  
V
OL  
V
V
V
CC  
= 12 mA  
0.8*  
CLK, DIR, S,  
TCK  
= 0 to 5.5 V,  
or GND  
CC  
±1  
±20  
10  
±1  
±20  
10  
±1  
±20  
10  
V = V  
I
CC  
I
I
µA  
V
= 5.5 V,  
or GND  
CC  
CC  
V = V  
A or B ports  
I
OE, TDI,  
TMS  
I
I
V
= 5.5 V, V = V  
µA  
µA  
IH  
CC  
CC  
I
CC  
OE, TDI,  
TMS  
V
= 5.5 V, V = GND  
–40  
–150  
500  
–40  
–150  
–40  
–150  
IL  
I
V = 0.8 V  
75  
220  
75  
500  
I
I
A or B ports  
V
CC  
= 4.5 V  
= 5.5 V,  
µA  
I(hold)  
V = 2 V  
I
–75  
–180 –500  
–75  
–500  
V
V
CC  
O
TDO  
TDO  
TDO  
TDO  
10  
10  
10  
–10  
±50  
±50  
µA  
µA  
µA  
µA  
I
I
I
I
OZH  
= 2.7 V,  
OE = 2 V  
V
V
= 5.5 V,  
CC  
O
–10  
±50  
±50  
–10  
OZL  
= 0.5 V,  
OE = 2 V  
V
V
= 0 to 2.1 V,  
= 2.7 V or 0.5 V, OE = 0.8 V  
CC  
O
OZPU  
OZPD  
V
V
= 2.1 V to 0,  
= 2.7 V or 0.5 V, OE = 0.8 V  
CC  
O
I
I
V
V
V
V
= 0,  
V or V 4.5 V  
±100  
50  
±100  
50  
µA  
µA  
off  
CC  
CC  
CC  
CC  
I
O
Outputs high  
A port, TDO  
B port  
= 5.5 V,  
= 5.5 V,  
= 5.5 V,  
V
O
V
O
V
O
= 5.5 V  
50  
–200  
–100  
2.2  
CEX  
= 2.5 V  
= 2.5 V  
–50  
–25  
–110 –200  
–55 –100  
–50  
–25  
–50  
–25  
–200  
–100  
2.2  
§
I
O
mA  
mA  
mA  
Outputs high  
Outputs low  
1.7  
23  
2.2  
27  
V
= 5.5 V,  
= 0,  
CC  
27  
27  
I
O
I
A or B ports  
CC  
V = V  
or  
I
CC  
Outputs  
disabled  
1
2
2
2
GND  
V
= 5.5 V, One input at 3.4 V,  
CC  
Other inputs at V  
1.5  
1.5  
1.5  
I  
CC  
or GND  
CC  
* On products compliant to MIL-PRF-38535, this parameter does not apply.  
§
All typical values are at V  
= 5 V.  
CC  
includes the off-state output leakage current.  
The parameter I  
I(hold)  
Not more than one output should be tested at a time, and the duration of the test should not exceed one second.  
This is the increase in supply current for each input that is at the specified TTL voltage level rather than V or GND.  
CC  
PRODUCT PREVIEW information concerns products in the formative or  
design phase of development. Characteristic data and other  
specifications are design goals. Texas Instruments reserves the right to  
change or discontinue these products without notice.  
33  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
electrical characteristics over recommended operating free-air temperature range (unless  
otherwise noted) (continued)  
T
= 25°C  
SN54ABTH182646A SN74ABTH182646A  
MIN MAX MIN MAX  
A
PARAMETER  
TEST CONDITIONS  
V = 2.5 V or 0.5 V  
UNIT  
MIN TYP  
MAX  
C
C
C
Control inputs  
A or B ports  
TDO  
5
pF  
pF  
pF  
i
I
V
= 2.5 V or 0.5 V  
= 2.5 V or 0.5 V  
10  
8
io  
o
O
O
V
All typical values are at V  
= 5 V.  
CC  
timing requirements over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (normal mode) (see Figure 15)12  
SN54ABTH182646A SN74ABTH182646A  
UNIT  
MIN  
MAX  
MIN  
MAX  
f
t
t
t
Clock frequency  
Pulse duration  
Setup time  
CLKAB or CLKBA  
0
100  
0
100  
MHz  
ns  
clock  
CLKAB or CLKBA high or low  
A before CLKABor B before CLKBA↑  
A after CLKABor B after CLKBA↑  
3
3
w
3
3
ns  
su  
h
Hold time  
0.5  
0.5  
ns  
timing requirements over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (test mode) (see Figure 15)  
SN54ABTH182646A SN74ABTH182646A  
UNIT  
MIN  
MAX  
MIN  
MAX  
f
t
Clock frequency  
Pulse duration  
TCK  
0
50  
0
50  
MHz  
ns  
clock  
TCK high or low  
8
8
w
A, B, CLK, DIR, OE, or S before TCK↑  
TDI before TCK↑  
6
6
t
Setup time  
Hold time  
4.5  
3
4.5  
3
ns  
ns  
su  
h
TMS before TCK↑  
A, B, CLK, DIR, OE, or S after TCK↑  
TDI after TCK↑  
1.5  
1
1.5  
1
t
TMS after TCK↑  
1.5  
50  
1
1.5  
50  
1
t
t
Delay time  
Rise time  
Power up to TCK↑  
ns  
d
V
CC  
power up  
µs  
r
PRODUCT PREVIEW information concerns products in the formative or  
design phase of development. Characteristic data and other  
specifications are design goals. Texas Instruments reserves the right to  
change or discontinue these products without notice.  
34  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
switching characteristics over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (normal mode) (see Figure 15)12  
V
T
= 5 V,  
= 25°C  
CC  
A
SN54ABTH182646A SN74ABTH182646A  
FROM  
(INPUT)  
TO  
(OUTPUT)  
PARAMETER  
UNIT  
MIN  
TYP  
MAX  
MIN  
MAX  
MIN  
MAX  
CLKAB or  
CLKBA  
f
100  
150  
100  
100  
MHz  
ns  
max  
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
3.5  
4.1  
3.1  
3.3  
4.3  
4.9  
3.6  
3.8  
4.4  
4.8  
3.8  
3.9  
3.9  
4
5.1  
5.8  
4.7  
5
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
5.8  
6.4  
5.2  
5.6  
7
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
1.5  
2
5.3  
6.1  
5
PLH  
PHL  
PLH  
PHL  
PLH  
PHL  
PLH  
PHL  
PLH  
PHL  
PLH  
PHL  
PZH  
PZL  
PZH  
PZL  
PHZ  
PLZ  
PHZ  
PLZ  
A
B
B
A
ns  
ns  
ns  
ns  
ns  
ns  
ns  
ns  
ns  
5.4  
6.5  
7.4  
5.9  
6.1  
7.2  
7.8  
6.6  
6.8  
7
6.2  
7
CLKAB  
CLKBA  
SAB  
SBA  
DIR  
B
8.1  
6.2  
6.5  
7.6  
8.3  
6.8  
7.2  
7.5  
7.7  
8.1  
8.4  
10.3  
8.7  
10.5  
8.7  
5.2  
5.5  
6.9  
7.4  
5.6  
6
A
B
A
6.3  
6.5  
6.7  
6.9  
8.8  
6.9  
9
B or A  
B or A  
B or A  
B or A  
7.2  
7.4  
7.6  
10  
4.2  
4.3  
5.9  
4.7  
6
OE  
DIR  
2
2
2
8.1  
9.7  
7.6  
2
2
2
OE  
2
4.8  
7.1  
2
2
switching characteristics over recommended ranges of supply voltage and operating free-air  
temperature (unless otherwise noted) (test mode) (see Figure 15)  
V
T
= 5 V,  
= 25°C  
CC  
A
SN54ABTH182646A SN74ABTH182646A  
FROM  
(INPUT)  
TO  
(OUTPUT)  
PARAMETER  
UNIT  
MIN  
50  
2.5  
2.5  
2
TYP  
90  
MAX  
MIN  
50  
2.5  
2.5  
2
MAX  
MIN  
50  
2.5  
2.5  
2
MAX  
f
t
t
t
t
t
t
t
t
t
t
t
t
TCK  
MHz  
ns  
max  
PLH  
PHL  
PLH  
PHL  
PZH  
PZL  
PZH  
PZL  
PHZ  
PLZ  
PHZ  
PLZ  
6.1  
6.5  
3.6  
3.7  
7.1  
7.2  
3.7  
3.9  
8.5  
7.2  
5.1  
4
11  
10.8  
5.1  
14.5  
14  
7
13.1  
12.4  
5.6  
5.6  
13.4  
13.6  
6.6  
6.9  
15  
TCK↓  
A or B  
TDO  
TCK↓  
TCK↓  
TCK↓  
TCK↓  
TCK↓  
ns  
ns  
ns  
ns  
ns  
2
5.1  
2
7
2
4
11.5  
11.8  
5.7  
4
14.5  
15  
7.5  
8
4
A or B  
TDO  
4
4
4
2
2
2
2
6.2  
2
2
4
13  
4
18  
17.5  
8
4
A or B  
TDO  
3
13.3  
6.8  
3
3
15  
3
3
3
7.2  
6.3  
2.5  
5.5  
2.5  
8
2.5  
PRODUCT PREVIEW information concerns products in the formative or  
design phase of development. Characteristic data and other  
specifications are design goals. Texas Instruments reserves the right to  
change or discontinue these products without notice.  
35  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
SN54ABTH18646A, SN54ABTH182646A, SN74ABTH18646A, SN74ABTH182646A  
SCAN TEST DEVICES WITH  
18-BIT TRANSCEIVERS AND REGISTERS  
SCBS166D – AUGUST 1993 – REVISED JULY 1996  
PARAMETER MEASUREMENT INFORMATION  
7 V  
S1  
500 Ω  
Open  
GND  
From Output  
Under Test  
TEST  
S1  
t
t
/t  
Open  
7 V  
PLH PHL  
/t  
C
= 50 pF  
L
t
500 Ω  
PLZ PZL  
/t  
(see Note A)  
Open  
PHZ PZH  
LOAD CIRCUIT  
3 V  
0 V  
1.5 V  
Timing Input  
Data Input  
t
w
t
t
h
su  
3 V  
0 V  
3 V  
0 V  
Input  
1.5 V  
1.5 V  
1.5 V  
1.5 V  
VOLTAGE WAVEFORMS  
PULSE DURATION  
VOLTAGE WAVEFORMS  
SETUP AND HOLD TIMES  
3 V  
0 V  
3 V  
0 V  
Output  
Control  
1.5 V  
Input  
1.5 V  
1.5 V  
1.5 V  
t
PZL  
t
t
t
PHL  
PLH  
PHL  
t
PLZ  
Output  
Waveform 1  
S1 at 7 V  
V
V
3.5 V  
OH  
1.5 V  
1.5 V  
1.5 V  
1.5 V  
Output  
V
V
+ 0.3 V  
– 0.3 V  
OL  
V
OL  
OL  
(see Note B)  
t
PHZ  
t
PLH  
t
PZH  
Output  
Waveform 2  
S1 at Open  
(see Note B)  
V
OH  
V
V
OH  
OH  
1.5 V  
1.5 V  
Output  
0 V  
OL  
VOLTAGE WAVEFORMS  
PROPAGATION DELAY TIMES  
INVERTING AND NONINVERTING OUTPUTS  
VOLTAGE WAVEFORMS  
ENABLE AND DISABLE TIMES  
LOW- AND HIGH-LEVEL ENABLING  
NOTES: A.  
C includes probe and jig capacitance.  
L
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.  
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.  
C. All input pulses are supplied by generators having the following characteristics: PRR 10 MHz, Z = 50 , t 2.5 ns, t 2.5 ns.  
O
r
f
D. The outputs are measured one at a time with one transition per measurement.  
Figure 15. Load Circuit and Voltage Waveforms  
36  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
IMPORTANT NOTICE  
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue  
any product or service without notice, and advise customers to obtain the latest version of relevant information  
to verify, before placing orders, that information being relied on is current and complete. All products are sold  
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those  
pertaining to warranty, patent infringement, and limitation of liability.  
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in  
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent  
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily  
performed, except those mandated by government requirements.  
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF  
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL  
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR  
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER  
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO  
BE FULLY AT THE CUSTOMER’S RISK.  
In order to minimize risks associated with the customer’s applications, adequate design and operating  
safeguards must be provided by the customer to minimize inherent or procedural hazards.  
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent  
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other  
intellectual property right of TI covering or relating to any combination, machine, or process in which such  
semiconductor products or services might be or are used. TI’s publication of information regarding any third  
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.  
Copyright 1998, Texas Instruments Incorporated  

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