MT54V1MH18E Micron Semiconductor Products, Inc., MT54V1MH18E Datasheet - Page 17

• Manufacturer Part Number: MT54V1MH18E
• Description: 18Mb QDR SRAM, 2.5V Vdd, Hstl, 4-Word Burst,
• Manufacturer: Micron Semiconductor Products, Inc.

IEEE 1149.1 Serial Boundary Scan
(JTAG)
access port (TAP). This port operates in accordance
with IEEE Standard 1149.1-1990 but does not have the
set of functions required for full 1149.1 compliance.
These functions from the IEEE specification are
excluded because their inclusion places an added
delay in the critical speed path of the SRAM. Note that
the TAP controller functions in a manner that does not
conflict with the operation of other devices using
1149.1 fully-compliant TAPs. The TAP operates using
JEDEC-standard 2.5V I/O logic levels.
register, boundary scan register, bypass register, and
ID register.
Disabling the JTAG Feature
JTAG feature. To disable the TAP controller, TCK must
be tied LOW (V
TDI and TMS are internally pulled up and may be
unconnected. Alternately, they may be connected to
V
unconnected. Upon power-up, the device will come up
in a reset state which will not interfere with the opera-
tion of the device.
Test Access Port (TAP)
Test Clock (TCK)
All inputs are captured on the rising edge of TCK. All
outputs are driven from the falling edge of TCK.
18Mb: 2.5V V
MT54V1MH18E_16_F.fm – Rev. F, Pub. 3/03
DD
The SRAM incorporates a serial boundary scan test
The SRAM contains a TAP controller, instruction
It is possible to operate the SRAM without using the
The test clock is used only with the TAP controller.
through a pull-up resistor. TDO should be left
DD
, HSTL, QDRb4 SRAM
SS
) to prevent clocking of the device.
17
NOTE:
Test MODE SELECT (TMS)
controller and is sampled on the rising edge of TCK. It
is allowable to leave this ball unconnected if the TAP is
not used. The ball is pulled up internally, resulting in a
logic HIGH level.
Test Data-In (TDI)
into the registers and can be connected to the input of
any of the registers. The register between TDI and TDO
is chosen by the instruction that is loaded into the TAP
instruction register. For information on loading the
instruction register, see Figure 7. TDI is pulled up
internally and can be unconnected if the TAP is
unused in an application. TDI is connected to the most
significant bit (MSB) of any register, as illustrated in
Figure 8.
Test Data-Out (TDO)
out from the registers. The output is active depending
upon the current state of the TAP state machine, as
1
0
The 0/1 next to each state represents the value
of TMS at the rising edge of TCK.
The TMS input is used to give commands to the TAP
The TDI ball is used to serially input information
The TDO output ball is used to serially clock data-
TEST-LOGIC
RUN-TEST/
2.5V V
Micron Technology, Inc., reserves the right to change products or specifications without notice.
RESET
IDLE
0
TAP Controller State Diagram
1
DD
1 MEG x 18, 512K x 36
, HSTL, QDRb4 SRAM
1
0
Figure 7:
CAPTURE-DR
UPDATE-DR
PAUSE-DR
DR-SCAN
SHIFT-DR
EXIT1-DR
EXIT2-DR
1
SELECT
0
0
1
0
1
1
0
1
1
0
0
©2003 Micron Technology, Inc.
1
0
CAPTURE-IR
UPDATE-IR
PAUSE-IR
1
IR-SCAN
SHIFT-IR
EXIT1-IR
EXIT2-IR
SELECT
0
0
1
0
1
1
0
1
1
0
0