CY7C1470V25-167AXCT Cypress Semiconductor Corp, CY7C1470V25-167AXCT Datasheet - Page 13

• Manufacturer Part Number: CY7C1470V25-167AXCT
• Description: IC SRAM 72MBIT 167MHZ 100LQFP
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY7C1470V25-167AXCT

• Format - Memory: RAM
• Memory Type: SRAM - Synchronous
• Memory Size: 72M (2M x 36)
• Speed: 167MHz
• Interface: Parallel
• Voltage - Supply: 2.375 V ~ 2.625 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 100-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Instruction Register
Three-bit instructions can be serially loaded into the instruction
register. This register is loaded when it is placed between the TDI
and TDO balls as shown in the
Upon power-up, the instruction register is loaded with the
IDCODE instruction. It is also loaded with the IDCODE
instruction if the controller is placed in a reset state as described
in the previous section.
When the TAP controller is in the Capture-IR state, the two least
significant bits are loaded with a binary “01” pattern to allow for
fault isolation of the board-level serial test data path.
Bypass Register
To save time when serially shifting data through registers, it is
sometimes advantageous to skip certain chips. The bypass
register is a single-bit register that can be placed between the
TDI and TDO balls. This allows data to be shifted through the
SRAM with minimal delay. The bypass register is set LOW (V
when the BYPASS instruction is executed.
Boundary Scan Register
The boundary scan register is connected to all the input and
bidirectional balls on the SRAM.
The boundary scan register is loaded with the contents of the
RAM I/O ring when the TAP controller is in the Capture-DR state
and is then placed between the TDI and TDO balls when the
controller is moved to the Shift-DR state. The EXTEST,
SAMPLE/PRELOAD and SAMPLE Z instructions can be used to
capture the contents of the I/O ring.
The Boundary Scan Order tables show the order in which the bits
are connected. Each bit corresponds to one of the bumps on the
SRAM package. The MSB of the register is connected to TDI and
the LSB is connected to TDO.
Identification (ID) Register
The ID register is loaded with a vendor-specific, 32-bit code
during the Capture-DR state when the IDCODE command is
loaded in the instruction register. The IDCODE is hardwired into
the SRAM and can be shifted out when the TAP controller is in
the Shift-DR state. The ID register has a vendor code and other
information described in the Identification Register Definitions
table.
TAP Instruction Set
Overview
Eight different instructions are possible with the three-bit
instruction register. All combinations are listed in the Instruction
Codes table. Three of these instructions are listed as
RESERVED and should not be used. The other five instructions
are described in detail below.
The TAP controller used in this SRAM is not fully compliant to the
1149.1 convention because some of the mandatory 1149.1
instructions are not fully implemented.
The TAP controller cannot be used to load address data or
control signals into the SRAM and cannot preload the I/O buffers.
The SRAM does not implement the 1149.1 commands EXTEST
or INTEST or the PRELOAD portion of SAMPLE/PRELOAD;
rather, it performs a capture of the I/O ring when these
instructions are executed.
Document Number: 38-05290 Rev. *L
TAP Controller Block
Diagram.
SS
)
Instructions are loaded into the TAP controller during the Shift-IR
state when the instruction register is placed between TDI and
TDO. During this state, instructions are shifted through the
instruction register through the TDI and TDO balls. To execute
the instruction once it is shifted in, the TAP controller needs to be
moved into the Update-IR state.
EXTEST
EXTEST is a mandatory 1149.1 instruction which is to be
executed whenever the instruction register is loaded with all 0s.
EXTEST is not implemented in this SRAM TAP controller, and
therefore this device is not compliant to 1149.1. The TAP
controller does recognize an all-0 instruction.
When an EXTEST instruction is loaded into the instruction
register, the SRAM responds as if a SAMPLE/PRELOAD
instruction has been loaded. There is one difference between the
two instructions. Unlike the SAMPLE/PRELOAD instruction,
EXTEST places the SRAM outputs in a high Z state.
IDCODE
The IDCODE instruction causes a vendor-specific, 32-bit code
to be loaded into the instruction register. It also places the
instruction register between the TDI and TDO balls and allows
the IDCODE to be shifted out of the device when the TAP
controller enters the Shift-DR state.
The IDCODE instruction is loaded into the instruction register
upon power-up or whenever the TAP controller is given a test
logic reset state.
SAMPLE Z
The SAMPLE Z instruction causes the boundary scan register to
be connected between the TDI and TDO balls when the TAP
controller is in a Shift-DR state. It also places all SRAM outputs
into a high Z state.
SAMPLE/PRELOAD
SAMPLE/PRELOAD is a 1149.1 mandatory instruction. The
PRELOAD portion of this instruction is not implemented, so the
device TAP controller is not fully 1149.1 compliant.
When the SAMPLE/PRELOAD instruction is loaded into the
instruction register and the TAP controller is in the Capture-DR
state, a snapshot of data on the inputs and bidirectional balls is
captured in the boundary scan register.
The user must be aware that the TAP controller clock can only
operate at a frequency up to 20 MHz, while the SRAM clock
operates more than an order of magnitude faster. Because there
is a large difference in the clock frequencies, it is possible that
during the Capture-DR state, an input or output will undergo a
transition. The TAP may then try to capture a signal while in
transition (metastable state). This will not harm the device, but
there is no guarantee as to the value that will be captured.
Repeatable results may not be possible.
To guarantee that the boundary scan register will capture the
correct value of a signal, the SRAM signal must be stabilized
long enough to meet the TAP controller’s capture set-up plus
hold time (t
The SRAM clock input might not be captured correctly if there is
no way in a design to stop (or slow) the clock during a
SAMPLE/PRELOAD instruction. If this is an issue, it is still
CS
plus t
CH
).
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