Linear Burst Address Table Mode = GND | Cypress CY7C1339G manual

CY7C1339G

signal. Consecutive single Read cycles are supported. Once the SRAM is deselected at clock rise by the chip select and either ADSP or ADSC signals, its output will tri-state immedi- ately.

Single Write Accesses Initiated by ADSP

This access is initiated when both of the following conditions are satisfied at clock rise: (1) ADSP is asserted LOW, and

(2)CE1, CE2, CE3 are all asserted active. The address presented to A is loaded into the address register and the address advancement logic while being delivered to the

memory array. The Write signals (GW, BWE, and BW[A:D]) and ADV inputs are ignored during this first cycle.

ADSP-triggered Write accesses require two clock cycles to complete. If GW is asserted LOW on the second clock rise, the data presented to the DQs inputs is written into the corre- sponding address location in the memory array. If GW is HIGH, then the Write operation is controlled by BWE and BW[A:D] signals. The CY7C1339G provides Byte Write capability that is described in the Write Cycle Descriptions table. Asserting the Byte Write Enable input (BWE) with the selected Byte Write (BW[A:D]) input, will selectively write to only the desired bytes. Bytes not selected during a Byte Write operation will remain unaltered. A synchronous self-timed Write mechanism has been provided to simplify the Write operations.

Because the CY7C1339G is a common I/O device, the Output Enable (OE) must be deserted HIGH before presenting data to the DQs inputs. Doing so will tri-state the output drivers. As a safety precaution, 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 deserted HIGH, (3) CE1, CE2, CE3 are all asserted active, and

(4) the appropriate combination of the Write inputs (GW, BWE, and BW[A:D]) are asserted active to conduct a Write to the desired byte(s). ADSC-triggered Write accesses require 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 will remain unaltered. A synchronous self-timed Write mechanism has been provided to simplify the Write operations.

Because the CY7C1339G is a common I/O device, the Output Enable (OE) must be deserted HIGH before presenting data

to the DQs inputs. Doing so will tri-state 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 CY7C1339G 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 specif- ically 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 will automatically increment 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