Cypress CY7C1992BV18, CY7C1393BV18, CY7C1394BV18, CY7C1392BV18 manual Functional Overview

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CY7C1392BV18, CY7C1992BV18 CY7C1393BV18, CY7C1394BV18

Functional Overview

The CY7C1392BV18, CY7C1992BV18, CY7C1393BV18, and CY7C1394BV18 are synchronous pipelined Burst SRAMs equipped with a DDR-II Separate IO interface.

Accesses are initiated on the rising edge of the positive input clock (K). All synchronous input timing is referenced from the rising edge of the input clocks (K and K) and all output timing is referenced to the rising edge of the output clocks (C/C, or K/K when in single clock mode).

All synchronous data inputs (D[x:0]) pass through input registers controlled by the rising edge of the input clocks (K and K). All synchronous data outputs (Q[x:0]) pass through output registers controlled by the rising edge of the output clocks (C/C, or K/K when in single-clock mode).

All synchronous control (R/W, LD, BWS[0:X]) inputs pass through input registers controlled by the rising edge of the input clock (K).

CY7C1393BV18 is described in the following sections. The same basic descriptions apply to CY7C1392BV18, CY7C1992BV18, and CY7C1394BV18.

Read Operations

The CY7C1393BV18 is organized internally as two arrays of 512K x 18. Accesses are completed in a burst of two sequential 18-bit data words. Read operations are initiated by asserting R/W HIGH and LD LOW at the rising edge of the positive input clock (K). The address presented to address inputs is stored in the read address register. Following the next K clock rise the corresponding lowest order 18-bit word of data is driven onto the Q[17:0] using C as the output timing reference. On the subse- quent rising edge of C, the next 18-bit data word is driven onto the Q[17:0]. The requested data is valid 0.45 ns from the rising edge of the output clock (C or C, or K and K when in single clock mode, for 200 MHz and 250 MHz device). Read accesses can be initiated on every rising edge of the positive input clock (K). This pipelines the data flow such that data is transferred out of the device on every rising edge of the output clocks, C/C (or K/K when in single clock mode).

The CY7C1393BV18 first completes the pending read transac- tions, when read access is deselected. Synchronous internal circuitry automatically tri-states the output following the next rising edge of the positive output clock (C).

Write Operations

Write operations are initiated by asserting R/W LOW and LD LOW at the rising edge of the positive input clock (K). The address presented to address inputs is stored in the write address register. On the following K clock rise the data presented to D[17:0] is latched and stored into the 18-bit write data register, provided BWS[1:0] are both asserted active. On the subsequent rising edge of the negative input clock (K) the information presented to D[17:0] is also stored into the write data register, provided BWS[1:0] are both asserted active. The 36 bits of data are then written into the memory array at the specified location. Write accesses can be initiated on every rising edge of the positive input clock (K). This pipelines the data flow such that 18 bits of data can be transferred into the device on every rising edge of the input clocks (K and K).

When Write access is deselected, the device ignores all inputs after the pending write operations are completed.

Byte Write Operations

Byte write operations are supported by the CY7C1393BV18. A write operation is initiated as described in the Write Operations section. The bytes that are written are determined by BWS0 and BWS1, which are sampled with each set of 18-bit data words. Asserting the appropriate Byte Write Select input during the data portion of a write latches the data being presented and writes it into the device. Deasserting the Byte Write Select input during the data portion of a write enables the data stored in the device for that byte to remain unaltered. This feature can be used to simplify read/modify/write operations to a byte write operation.

Single Clock Mode

The CY7C1393BV18 can be used with a single clock that controls both the input and output registers. In this mode the device recognizes only a single pair of input clocks (K and K) that control both the input and output registers. This operation is identical to the operation if the device had zero skew between the K/K and C/C clocks. All timing parameters remain the same in this mode. To use this mode of operation, tie C and C HIGH at power on. This function is a strap option and not alterable during device operation.

DDR Operation

The CY7C1393BV18 enables high-performance operation through high clock frequencies (achieved through pipelining) and double data rate mode of operation.

If a read occurs after a write cycle, address and data for the write are stored in registers. The write information must be stored because the SRAM cannot perform the last word write to the array without conflicting with the read. The data stays in this register until the next write cycle occurs. On the first write cycle after the read(s), the stored data from the earlier write is written into the SRAM array. This is called a posted write.

Depth Expansion

Depth expansion requires replicating the LD control signal for each bank. All other control signals can be common between banks as appropriate.

Programmable Impedance

An external resistor, RQ, must be connected between the ZQ pin on the SRAM and VSS to enable the SRAM to adjust its output driver impedance. The value of RQ must be 5x the value of the intended line impedance driven by the SRAM. The allowable range of RQ to guarantee impedance matching with a tolerance of ±15% is between 175Ω and 350Ω, with VDDQ = 1.5V. The output impedance is adjusted every 1024 cycles at power up to account for drifts in supply voltage and temperature.

Echo Clocks

Echo clocks are provided on the DDR-II to simplify data capture on high-speed systems. Two echo clocks are generated by the DDR-II. CQ is referenced with respect to C and CQ is referenced with respect to C. These are free-running clocks and are synchronized to the output clock of the DDR-II. In the single clock mode, CQ is generated with respect to K and CQ is generated with respect to K. The timing for the echo clocks is shown in Switching Characteristics on page 23.

Document #: 38-05623 Rev. *D

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Contents Features ConfigurationsFunctional Description Selection GuideDoff Logic Block Diagram CY7C1392BV18CLK Logic Block Diagram CY7C1393BV18 Logic Block Diagram CY7C1394BV18512K Array Gen Read Data Reg ControlPin Configuration Ball Fbga 13 x 15 x 1.4 mm PinoutCY7C1392BV18 2M x CY7C1992BV18 2M x CY7C1393BV18 1M x CY7C1394BV18 512K xSynchronous Read/Write Input. When Pin DefinitionsPin Name Pin Description Power Supply Inputs to the Core of the Device Power Supply Inputs for the Outputs of the DeviceIs Referenced with Respect to TDO for JtagFunctional Overview Application Example Shows four DDR-II SIO used in an applicationTruth Table Write Cycle DescriptionsOperation CommentsWrite cycle description table for CY7C1992BV18 follows Write cycle description table for CY7C1394BV18 followsDevice Into the device. D359 remains unalteredIeee 1149.1 Serial Boundary Scan Jtag Idcode TAP Controller State Diagram State diagram for the TAP controller followsTAP Controller Block Diagram TAP Electrical CharacteristicsTAP AC Switching Characteristics TAP Timing and Test ConditionsIdentification Register Definitions Scan Register SizesInstruction Codes Register Name Bit SizeBoundary Scan Order Bit # Bump IDDLL Constraints Power Up Sequence in DDR-II SramPower Up Sequence Maximum Ratings Electrical CharacteristicsDC Electrical Characteristics Input LOW Voltage Vref Document # 38-05623 Rev. *D AC Electrical CharacteristicsInput High Voltage Vref + Capacitance Thermal ResistanceParameter Description Test Conditions Max Unit Parameter Description Test Conditions Fbga UnitSwitching Characteristics Parameter Min MaxHigh LOWParameter Min Max Output Times DLL TimingSwitching Waveforms BurstOrdering Information 250 167 Package Diagram Ball Fbga 13 x 15 x 1.4 mmNXR Document HistorySYT Sales, Solutions, and Legal Information Worldwide Sales and Design Support Products PSoC SolutionsVKN/PYRS USB
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