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參數(shù)資料
| 型號(hào)： | SN74ABT8240 |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | Scan Test Devices With Octal Buffers(掃描測(cè)試裝置(帶八緩沖器)) |
| 中文描述： | 掃描測(cè)試設(shè)備與八路緩沖器（掃描測(cè)試裝置（帶八緩沖器）） |
| 文件頁數(shù)： | 7/19頁 |
| 文件大?。?/td> | 391K |
| 代理商： | SN74ABT8240 |
SN54ABT8240, SN74ABT8240
SCAN TEST DEVICES WITH OCTAL BUFFERS
SCBS484 – JULY 1994
3–7
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
register overview
With the exception of the bypass register, any test register can be thought of as a serial-shift register with a
shadow latch on each bit. The bypass register differs in that it contains 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 specifies what instruction is to be executed. Information
contained in the instruction includes the mode of operation (either normal mode, in which the device performs
its normal logic function, or test mode, in which the normal logic function is inhibited or altered), the test operation
to be performed, which of the three 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
′
ABT8240. 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 11111111, which selects the BYPASS instruction. The IR order of scan is illustrated in Figure 2.
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
TDO
TDI
Bit 7
Parity
(MSB)
Bit 0
(LSB)
Figure 2. Instruction Register Order of Scan
data register description
boundary-scan register
The boundary-scan register (BSR) is 18 bits long. It contains one boundary-scan cell (BSC) for each
normal-function input pin, and one BSC for each normal-function output pin. The BSR is used 1) to store test
data that is to be applied internally to the inputs of the normal on-chip logic and/or externally to the device output
pins, and/or 2) to capture data that appears internally at the outputs of the normal on-chip logic and/or externally
at the device 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, the value of each BSC is reset to logic 0 except for BSCs 17–16 which are reset to
logic 1.
The BSR order of scan is from TDI through bits 17–0 to TDO. Table 1 shows the BSR bits and their associated
device pin signals.
P
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| SN74ABT8245DW | 功能描述:特定功能邏輯 Scan Test Device RoHS:否 制造商:Texas Instruments 產(chǎn)品: 系列:SN74ABTH18502A 工作電源電壓:5 V 封裝 / 箱體:LQFP-64 封裝:Tube |
| SN74ABT8245DWE4 | 功能描述:特定功能邏輯 Scan Test Device w/Octal Bus Trnscvr RoHS:否 制造商:Texas Instruments 產(chǎn)品: 系列:SN74ABTH18502A 工作電源電壓:5 V 封裝 / 箱體:LQFP-64 封裝:Tube |
| SN74ABT8245DWG4 | 功能描述:特定功能邏輯 Scan Test Devices RoHS:否 制造商:Texas Instruments 產(chǎn)品: 系列:SN74ABTH18502A 工作電源電壓:5 V 封裝 / 箱體:LQFP-64 封裝:Tube |
| SN74ABT8245DWR | 功能描述:特定功能邏輯 Scan Test Device RoHS:否 制造商:Texas Instruments 產(chǎn)品: 系列:SN74ABTH18502A 工作電源電壓:5 V 封裝 / 箱體:LQFP-64 封裝:Tube |
| SN74ABT8245DWRE4 | 功能描述:特定功能邏輯 Scan Test Device w/Octal Bus Trnscvr RoHS:否 制造商:Texas Instruments 產(chǎn)品: 系列:SN74ABTH18502A 工作電源電壓:5 V 封裝 / 箱體:LQFP-64 封裝:Tube |
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