CY7C1441AV33
CY7C1443AV33
CY7C1447AV33
Document #: 38-05357 Rev. *F
Page 9 of 31
Functional Overview
All synchronous inputs pass through input registers controlled
by the rising edge of the clock. Maximum access delay from
the clock rise (tCDV) is 6.5 ns (133-MHz device).
The
CY7C1441AV33/CY7C1443AV33/CY7C1447AV33
supports secondary cache in systems utilizing either a linear
or interleaved burst sequence. The interleaved burst order
supports Pentium and i486™ processors. The linear burst
sequence is suited for processors that utilize a linear burst
sequence. The burst order is user-selectable, and is deter-
mined by sampling the MODE input. Accesses can be initiated
with either the Processor Address Strobe (ADSP) or the
Controller Address Strobe (ADSC). Address advancement
through the burst sequence is controlled by the ADV input. A
two-bit on-chip wraparound burst counter captures the first
address in a burst sequence and automatically increments the
address for the rest of the burst access.
Byte write operations are qualified with the Byte Write Enable
(BWE) and Byte Write Select (BWx) inputs. A Global Write
Enable (GW) overrides all byte write inputs and writes data to
all four bytes. All writes are simplified with on-chip
synchronous self-timed write circuitry.
Three synchronous Chip Selects (CE1, CE2, CE3) and an
asynchronous Output Enable (OE) provide for easy bank
selection and output tri-state control. ADSP is ignored if CE1
is HIGH.
Single Read Accesses
A single read access is initiated when the following conditions
are satisfied at clock rise: (1) CE1, CE2, and CE3 are all
asserted active, and (2) ADSP or ADSC is asserted LOW (if
the access is initiated by ADSC, the write inputs must be
deasserted during this first cycle). The address presented to
the address inputs is latched into the address register and the
burst counter/control logic and presented to the memory core.
If the OE input is asserted LOW, the requested data will be
available at the data outputs a maximum to tCDV after clock
rise. ADSP is ignored if CE1 is HIGH.
Single Write Accesses Initiated by ADSP
This access is initiated when the following conditions are
satisfied at clock rise: (1) CE1, CE2, CE3 are all asserted
active, and (2) ADSP is asserted LOW. The addresses
presented are loaded into the address register and the burst
inputs (GW, BWE, and BWX)are ignored during this first clock
cycle. If the write inputs are asserted active (see Write Cycle
Descriptions table for appropriate states that indicate a write)
on the next clock rise, the appropriate data will be latched and
written into the device. Byte writes are allowed. All I/Os are
tri-stated during 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 tri-stated prior to the presentation of data
to DQs. As a safety precaution, the data lines are tri-stated
once a write cycle is detected, regardless 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 BWX)
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
memory core. The information presented to DQS will be written
into the specified address location. Byte writes are allowed. All
I/Os are tri-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 tri-stated prior
to the presentation of data to DQs. As a safety precaution, the
data lines are tri-stated once a write cycle is detected,
regardless of the state of OE.
Burst Sequences
The
CY7C1441AV33/CY7C1443AV33/CY7C1447AV33
provides an on-chip two-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 a interleaved burst
sequence.
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
Address
A1: A0
Second
Address
A1: A0
Third
Address
A1: A0
Fourth
Address
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
A1: A0
Second
Address
A1: A0
Third
Address
A1: A0
Fourth
Address
A1: A0
00
01
10
11
01
10
11
00
10
11
00
01
11
00
01
10
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