Linear Burst Address Table Mode = GND | Cypress CY7C1486V25 guide

CY7C1480V25

CY7C1482V25

CY7C1486V25

DQs are automatically tri-stated whenever a write cycle is detected, regardless of the state of OE.

Single Write Accesses Initiated by ADSC

ADSC Write accesses are initiated when the following condi- tions are satisfied: (1) ADSC is asserted LOW, (2) ADSP is deasserted HIGH, (3) CE1, CE2, CE3 are all asserted active, and (4) the appropriate combination of the write inputs (GW, BWE, and BWX) are asserted active to conduct a write to the desired byte(s). ADSC-triggered write accesses need a single clock cycle to complete. The address presented to A is loaded into the address register and the address advancement logic while being delivered to the memory array. The ADV input is ignored during this cycle. If a global write is conducted, the data presented to the DQs is written into the corresponding address location in the memory core. If a byte write is conducted, only the selected bytes are written. Bytes not selected during a byte write operation remain unaltered. A synchronous self-timed write mechanism has been provided to simplify the write operations.

Because CY7C1480V25/CY7C1482V25/CY7C1486V25 is a common IO device, the Output Enable (OE) must be deasserted HIGH before presenting data to the DQs inputs. Doing so tri-states the output drivers. As a safety precaution, DQs are automatically tri-stated whenever a write cycle is detected, regardless of the state of OE.

Burst Sequences

The CY7C1480V25/CY7C1482V25/CY7C1486V25 provides a two-bit wraparound counter, fed by A1: A0, that implements either an interleaved or linear burst sequence. The interleaved burst sequence is designed specifically to support Intel Pentium applications. The linear burst sequence is designed to support processors that follow a linear burst sequence. The burst sequence is user selectable through the MODE input.

Asserting ADV LOW at clock rise automatically increments the burst counter to the next address in the burst sequence. Both Read and Write burst operations are supported.

Sleep Mode

The ZZ input pin is an asynchronous input. Asserting ZZ places the SRAM in a power conservation “sleep” mode. Two clock cycles are required to enter into or exit from this “sleep” mode. While in this mode, data integrity is guaranteed. Accesses pending when entering the “sleep” mode are not considered valid nor is the completion of the operation guaranteed. The device must be deselected prior to entering the “sleep” mode. CE1, CE2, CE3, ADSP, and ADSC must remain inactive for the duration of tZZREC after the ZZ input returns LOW.

Interleaved Burst Address Table (MODE = Floating or VDD)

First	Second	Third	Fourth
Address	Address	Address	Address
A1: A0	A1: A0	A1: A0	A1: A0
00	01	10	11
01	00	11	10
10	11	00	01
11	10	01	00