tmp19a44fda TOSHIBA Semiconductor CORPORATION, tmp19a44fda Datasheet - Page 576

• Manufacturer Part Number: tmp19a44fda
• Description: 32bit Tx System Risc
• Manufacturer: TOSHIBA Semiconductor CORPORATION

JTAG Interface
substrate
Input from
Input to
substrate
23.3.2
JTDI
The instruction code is shifted from the least significant bit to the instruction register.
The bypass register has a one-bit width. If the TAP controller is in the Shift-DR state (bypass state), data
at the TDI pin is shifted into the bypass register, and the output from the bypass register is shifted out to
the TDO output pin.
Simply put, the bypass register is a circuit for bypassing the devices in a serial boundary scan chain
connected to the substrates that are not required for a test to be conducted. Fig. 23-5 shows the logical
position of the bypass register in a boundary scan chain.
If the bypass register is used, the speed of access to boundary scan registers in an active IC in a data
path used for substrate level testing can be increased.
Fig. 23-4 Direction of a Shift of the Instruction Code to the Instruction Register
TDI
JTDO
Bypass Register
IC package
Substrate
JTDO
JTDI
Most significant
Fig. 23-5 Function of the Bypass Register
JTDO
JTDI
TMP19A44(rev1.3) 23-4
JTDO
JTDI
JTDI
JTDO
Least significant
Pad cell of boundary scan register
Bypass register
TMP19A44
TDO
2010-04-01