IS61VPS25636A Datasheet, PDF (19/32 Pages) Integrated Silicon Solution, Inc – 256K x 36, 512K x 18 9 Mb SYNCHRONOUS PIPELINED, SINGLE CYCLE DESELECT STATIC RAM

IS61VPS25636A, IS61LPS25636A,IS61VPS51218A,IS61LPS51218A
ISSI ^®
IEEE 1149.1 SERIAL BOUNDARY SCAN (JTAG)
The IS61LPS/VPSxxxxxx products have a serial boundary
scan Test Access Port (TAP) in the PBGA package only.
(The TQFP package not available.) This port operates in
accordance with IEEE Standard 1149.1-1900, but does not
include all functions required for full 1149.1 compliance.
These functions from the IEEE specification are excluded
because they place added delay in the critical speed path
of the SRAM. The TAP controller operates in a manner that
does not conflict with the performance of other devices
using 1149.1 fully compliant TAPs. The TAP operates using
JEDEC standard 2.5V I/O logic levels.
DISABLING THE JTAG FEATURE
The SRAM can operate without using the JTAG feature. To
disable the TAP controller, TCK must be tied LOW (Vss) to
prevent clocking of the device. TDI and TMS are internally
pulled up and may be disconnected. They may alternately
be connected to VDD through a pull-up resistor. TDO should
be left disconnected. On power-up, the device will start in a
reset state which will not interfere with the device operation.
TEST ACCESS PORT (TAP) - TEST CLOCK
The test clock is only used with the TAP controller. All
inputs are captured on the rising edge of TCK and outputs
are driven from the falling edge of TCK.
TEST MODE SELECT (TMS)
The TMS input is used to send commands to the TAP
controller and is sampled on the rising edge of TCK. This
pin may be left disconnected if the TAP is not used. The
pin is internally pulled up, resulting in a logic HIGH level.
TEST DATA-IN (TDI)
The TDI pin is used to serially input information to the
registers and can be connected to the input of any
register. The register between TDI and TDO is chosen by
the instruction loaded into the TAP instruction register.
For information on instruction register loading, see the
TAP Controller State Diagram. TDI is internally pulled up
and can be disconnected if the TAP is unused in an
application. TDI is connected to the Most Significant Bit
(MSB) on any register.
TAP CONTROLLER BLOCK DIAGRAM
0
Bypass Register
210
Instruction Register
TDI
Selection Circuitry
. . . 31 30 29
210
Identification Register
x.....210
Boundary Scan Register*
Selection Circuitry TDO
TCK _{TAP CONTROLLER}
TMS
Integrated Silicon Solution, Inc. — 1-800-379-4774
19
Rev. A
04/29/05