CY7C1338B
Document #: 38-05143 Rev. **
Page 5 of 18
data lines are three-stated once a write cycle is detected, re-
gardless of the state of OE.
Single Write Accesses Initiated by ADSC
This write access is initiated when the following conditions are
satisfied at clock rise: (1) CE1, CE2, and CE3 are all asserted
active, (2) ADSC is asserted LOW, (3) ADSP is deasserted
HIGH, and (4) the write input signals (GW, BWE, and BW[3:0])
indicate a write access. ADSC is ignored if ADSP is active LOW.
The addresses presented are loaded into the address register
and the burst counter/control logic and delivered to the RAM
core. The information presented to DQ[31:0] will be written into
the specified address location. Byte writes are allowed. During
byte writes, BW0 controls DQ[7:0], BW1 controls DQ[15:8], BW2
controls DQ[23:16], and BWS3 controls DQ[31:24]. All I/Os are
three-stated when a write is detected, even a byte write. Since
this is a common I/O device, the asynchronous OE input signal
must be deasserted and the I/Os must be three-stated prior to
the presentation of data to DQ[31:0]. As a safety precaution, the
data lines are three-stated once a write cycle is detected, re-
gardless of the state of OE.
Burst Sequences
The CY7C1338B provides an on-chip 2-bit wraparound burst
counter inside the SRAM. The burst counter is fed by A[1:0],
and can follow either a linear or interleaved burst order. The
burst order is determined by the state of the MODE input. A
LOW on MODE will select a linear burst sequence. A HIGH on
MODE will select an interleaved burst order. Leaving MODE
unconnected will cause the device to default to an interleaved
burst sequence.
Sleep Mode
The ZZ input pin is an asynchronous input. Asserting ZZ HIGH
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. Ac-
cesses pending when entering the “sleep” mode are not con-
sidered valid nor is the completion of the operation guaran-
teed. 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. Leaving ZZ unconnected defaults the device into an ac-
tive state.
Table 1. Counter Implementation for the Intel
Pentium®/80486 Processor’s Sequence
First
Address
Second
Address
Third
Address
Fourth
Address
AX + 1, Ax
AX + 1, Ax
AX + 1, Ax
AX + 1, Ax
00
01
10
11
01
00
11
10
10
11
00
01
11
10
01
00
Table 2. Counter Implementation for a Linear Sequence
First
Address
Second
Address
Third
Address
Fourth
Address
AX + 1, Ax
AX + 1, Ax
AX + 1, Ax
AX + 1, Ax
00
01
10
11
01
10
11
00
10
11
00
01
11
00
01
10
ZZ Mode Electrical Characteristics
Parameter
Description
Test Conditions
Min.
Max.
Unit
ICCZZ
Snooze mode
standby current
ZZ > VDD − 0.2V
10
mA
tZZS
Device operation to
ZZ
ZZ > VDD − 0.2V
2tCYC
ns
tZZREC
ZZ recovery time
ZZ < 0.2V
2tCYC
ns
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