Cypress CY7C1460AV25, CY7C1464AV25, CY7C1462AV25 manual Bypass Register, TAP Instruction Set

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CY7C1460AV25

CY7C1462AV25

CY7C1464AV25

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 (VSS) 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 length of the Boundary Scan Register for the SRAM in different packages is listed in the Scan Register Sizes table.

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 instruc- tions are described in detail below.

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.

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 pins when the TAP controller is in a Shift-DR state. The SAMPLE Z command puts the output bus into a High-Z state until the next command is given during the “Update IR” state.

SAMPLE/PRELOAD

SAMPLE/PRELOAD is a 1149.1-mandatory instruction. When the SAMPLE/PRELOAD instructions are loaded into the instruction register and the TAP controller is in the Capture-DR state, a snapshot of data on the inputs and output pins 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 times (tCS and tCH). 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 possible to capture all other signals and simply ignore the value of the CK and CK# captured in the boundary scan register.

Once the data is captured, it is possible to shift out the data by putting the TAP into the Shift-DR state. This places the boundary scan register between the TDI and TDO pins.

PRELOAD allows an initial data pattern to be placed at the latched parallel outputs of the boundary scan register cells prior to the selection of another boundary scan test operation.

The shifting of data for the SAMPLE and PRELOAD phases can occur concurrently when required—that is, while data captured is shifted out, the preloaded data can be shifted in.

BYPASS

When the BYPASS instruction is loaded in the instruction register and the TAP is placed in a Shift-DR state, the bypass register is placed between the TDI and TDO pins. The advantage of the BYPASS instruction is that it shortens the boundary scan path when multiple devices are connected together on a board.

EXTEST

The EXTEST instruction enables the preloaded data to be driven out through the system output pins. This instruction also selects the boundary scan register to be connected for serial access between the TDI and TDO in the shift-DR controller state.

EXTEST Output Bus Tri-State

IEEE Standard 1149.1 mandates that the TAP controller be able to put the output bus into a tri-state mode.

The boundary scan register has a special bit located at bit #89 (for 165-FBGA package) or bit #138 (for 209 FBGA package).

Document #: 38-05354 Rev. *D

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Contents Cypress Semiconductor Corporation FeaturesLogic Block Diagram-CY7C1460AV25 1M x Functional Description250 MHz 200 MHz 167 MHz Unit Logic Block Diagram-CY7C1462AV25 2M xLogic Block Diagram-CY7C1464AV25 512K x Selection Guide2M × Pin Configurations Pin Tqfp PinoutCY7C1462AV25 2M × ADV/LD Pin DefinitionsPin Name Type Pin Description Byte Write Select Inputs, active LOW. Qualified withClock input to the Jtag circuitry Power supply inputs to the core of the devicePower supply for the I/O circuitry Type Pin DescriptionBurst Write Accesses Single Read AccessesBurst Read Accesses Single Write AccessesZZ Mode Electrical Characteristics Interleaved Burst Address Table Mode = Floating or VDDLinear Burst Address Table Mode = GND Function CY7C1464AV25 Partial Write Cycle Description1, 2, 3Function CY7C1460AV25 BW d BW c BW b BW a Function CY7C1462AV25Performing a TAP Reset TAP Controller Block Diagram TAP Controller State DiagramDisabling the Jtag Feature Test Access Port TAPTAP Instruction Set Bypass RegisterSet-up Times TAP TimingParameter Description Min Max Unit Clock Output TimesIdentification Register Definitions TAP DC Electrical Characteristics And Operating Conditions5V TAP AC Test Conditions 8V TAP AC Test ConditionsInstruction Code Description Scan Register SizesIdentification Codes Register Name Bit SizeBit# Ball ID Ball Fbga Boundary Scan Order12CY7C1460AV25 1M x 36, CY7C1462AV25 2M x Bit# Ball ID CY7C1464AV25 512K x Bit# Ball ID Ball Fbga Boundary Scan Order 12Ambient Range Electrical Characteristics Over the Operating Range14Maximum Ratings Operating RangeAC Test Loads and Waveforms Capacitance16Thermal Resistance 250 200 167 Parameter Description Unit Min Max Switching Characteristics Over the Operating Range 21NOP, Stall and Deselect Cycles23, 24 Switching WaveformsRead/Write/Timing23, 24 DON’T Care ZZ Mode Timing27Ordering Information 250 Pin Tqfp 14 x 20 x 1.4 mm Package DiagramsBall Fbga 15 x 17 x 1.4 mm Ball Fbga 14 x 22 x 1.76 mm RXU ECN No Issue Date Orig. Description of ChangeDocument History SYT

CY7C1462AV25, CY7C1460AV25, CY7C1464AV25 specifications

The Cypress CY7C1464AV25, CY7C1460AV25, and CY7C1462AV25 are a family of high-performance synchronous SRAM devices that have been designed for applications requiring fast memory access and low latency. These memory chips are particularly appealing for systems in telecommunications, networking, and embedded applications due to their versatility and robust performance specifications.

One of the standout features of the CY7C1464AV25 series is their large capacities. The CY7C1464AV25 offers a capacity of 4 Megabits (512 K x 8), making it well-suited for applications that demand ample memory while maintaining high-speed operations. In contrast, the CY7C1460AV25 and CY7C1462AV25 provide slightly smaller capacities of 1 Megabit (128 K x 8) and 2 Megabits (256 K x 8) respectively, catering to varying system memory requirements.

All three devices utilize Cypress's advanced synchronous SRAM technology. This enables the chips to support burst read and write modes, allowing for rapid data transfer rates. The CY7C1464AV25 delivers a data access time of as low as 5.5 ns, making it highly efficient for data-intensive applications. Additionally, the standard operating voltage of 2.5V aids in reducing power consumption and improving overall system energy efficiency.

The chips are also characterized by a simple interface and compatibility with common bus protocols, which facilitates easy integration into existing systems. They feature a dual-port architecture, allowing multiple data transfers to occur simultaneously, significantly improving throughput.

With a commercial temperature range, all three devices offer reliability and are suited for a wide range of operating environments. The package options include a compact 44-pin TSOP, allowing for space-saving designs in modern electronics.

In summary, the Cypress CY7C1464AV25, CY7C1460AV25, and CY7C1462AV25 provide a powerful blend of capacity, speed, and efficiency, making them ideal choices for demanding applications in various sectors. Their advanced technologies and versatility make them excellent candidates for enhancing system performance while maintaining low power consumption and ensuring reliable operation in various conditions.
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