CY7C1370DV25
CY7C1372DV25
Document #: 38-05558 Rev. *D Page 8 of 27
signals. The CY7C1370DV25/CY7C1372DV25 provides byte
write capability that is described in the Write Cycle Description
table. Asserting the Write Enable input (WE) with the selected
Byte Write Select (BW) 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.
Byte write capability has been included in order to greatly
simplify Read/Modify/Write sequences, which can be reduced
to simple byte write operations.
Because the CY7C1370DV25 and CY7C1372DV25 are
common I/O devices, data should not be driven into the device
while the outputs are active. The Output Enable (OE) can be
deasserted HIGH before presenting data to the DQ and DQP
(DQa,b,c,d/DQPa,b,c,d for CY7C1370DV25 and DQa,b/DQPa,b
for CY7C1372DV25) inputs. Doing so will three-state the
output drivers. As a safety precaution, DQ and DQP
(DQa,b,c,d/DQPa,b,c,d for CY7C1370DV25 and DQa,b/DQPa,b
for CY7C1372DV25) are automatically three-stated during the
data portion of a write cycle, regardless of the state of OE.
Burst Write Accesses
The CY7C1370DV25/CY7C1372DV25 has an on-chip burst
counter that allows the user the ability to supply a single
address and conduct up to four WRITE operations without
reasserting the address inputs. ADV/LD must be driven LOW
in order to load the initial address, as described in the Single
Write Access section above. When ADV/LD is driven HIGH on
the subsequent clock rise, the chip enables (CE1, CE2, and
CE3) and WE inputs are ignored and the burst counter is incre-
mented. The correct BW (BWa,b,c,d for CY7C1370DV25 and
BWa,b for CY7C1372DV25) inputs must be driven in each
cycle of the burst write in order to write the correct bytes of
data.
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, and CE3, must remain inactive
for the duration of tZZREC after the ZZ input returns LOW.
First
Address Second
Address Third
Address Fourth
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
Linear Burst Address Table (MODE = GND)First
Address Second
Address Third
Address Fourth
Address
A1,A0 A1,A0 A1,A0 A1,A0
00 01 10 11
01 10 11 00
10 11 00 01
11 00 01 10
ZZ Mode Electrical CharacteristicsParameter Description Test Conditions Min. Max. Unit
IDDZZ Sleep mode standby current ZZ > VDD − 0.2V 80 mA
tZZS Device operation to ZZ ZZ > VDD − 0.2V 2tCYC ns
tZZREC ZZ recovery time ZZ < 0.2V 2tCYC ns
tZZI ZZ active to sleep current This parameter is sampled 2tCYC ns
tRZZI ZZ Inactive to exit sleep current This parameter is sampled 0 ns
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