Cypress Perform CY7C1370D - Manual (Page 8)

CY7C1370D
CY7C1372D
Document #: 38-05555 Rev. *F Page 8 of 28
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 CY7C1370D and CY7C1372D 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
(DQ
a,b,c,d
/DQP
a,b,c,d
for CY7C1370D and DQ
a,b
/DQP
a,b
for
CY7C1372D) inputs. Doing so will tri-state the output drivers.
As a safety precaution, DQ
and DQP (DQ
a,b,c,d
/DQP
a,b,c,d
for
CY7C1370D and DQ
a,b
/DQP
a,b
for CY7C1372D) are
automatically tri-stated during the data portion of a write cycle,
regardless of the state of OE.
Burst Write Accesses
The CY7C1370D/CY7C1372D 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 subse-
quent clock rise, the chip enables (CE
1
, CE
2
, and CE
3
) and
WE inputs are ignored and the burst counter is incremented.
The correct BW (BW
a,b,c,d
for CY7C1370D and BW
a,b
for
CY7C1372D) 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. CE
1
, CE
2
, and CE
3
, must remain inactive
for the duration of t
ZZREC
after the ZZ input returns LOW.
Interleaved Burst Address Table
(MODE = Floating or V
DD
)
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 Characteristics
Parameter Description Test Conditions Min. Max. Unit
I
DDZZ
Sleep mode standby current ZZ
> V
DD
− 0.2V
80 mA
t
ZZS
Device operation to ZZ ZZ
> V
DD
− 0.2V
2t
CYC
ns
t
ZZREC
ZZ recovery time ZZ
< 0.2V
2t
CYC
ns
t
ZZI
ZZ active to sleep current This parameter is sampled 2t
CYC
ns
t
RZZI
ZZ Inactive to exit sleep current This parameter is sampled 0 ns
[+] Feedback