CY7C1474BV25-167BGI Cypress Semiconductor Corp, CY7C1474BV25-167BGI Datasheet - Page 13

• Manufacturer Part Number: CY7C1474BV25-167BGI
• Description: IC SRAM 72MBIT 167MHZ 209FBGA
• Manufacturer: Cypress Semiconductor Corp

Specifications of CY7C1474BV25-167BGI

• Format - Memory: RAM
• Memory Type: SRAM - Synchronous
• Memory Size: 72M (1M x 72)
• Speed: 167MHz
• Interface: Parallel
• Voltage - Supply: 2.375 V ~ 2.625 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 209-FBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-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
on page
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 enable 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 shifts the data through the SRAM with
minimal delay. The bypass register is set LOW (V
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 IO 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 IO ring.
The
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
page
TAP Instruction Set
Overview
Eight different instructions are possible with the three-bit
instruction register. All combinations are listed in
Codes” on page
RESERVED and must not be used. The other five instructions
are described in this section in detail.
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 IO 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 IO ring when these instruc-
tions are executed.
Document #: 001-15032 Rev. *D
Boundary Scan Order tables on page 17
16.
12. During power up, the instruction register is loaded
17. Three of these instructions are listed as
“Identification Register Definitions” on
“TAP Controller Block Diagram”
show the order in
“Identification
SS
) when the
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 after it is shifted in, the TAP controller must be
moved into the Update-IR state.
EXTEST
EXTEST is a mandatory 1149.1 instruction which is 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 loads a vendor-specific, 32-bit code into
the instruction register. It also places the instruction register
between the TDI and TDO balls and shifts the IDCODE out of the
device when the TAP controller enters the Shift-DR state.
The IDCODE instruction is loaded into the instruction register
during power up or whenever the TAP controller is in a test logic
reset state.
SAMPLE Z
The SAMPLE Z instruction connects the boundary scan register
between the TDI and TDO pins 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 may undergo a
transition. The TAP may then try to capture a signal while in
transition (metastable state). This does not harm the device, but
there is no guarantee as to the value that is captured.
Repeatable results may not be possible.
To guarantee that the boundary scan register captures the
correct value of a signal, the SRAM signal must be stabilized
long enough to meet the TAP controller’s capture setup 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
CY7C1472BV25, CY7C1474BV25
plus t
CH
).
CY7C1470BV25
Page 13 of 29
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