PRELIMINARY
CY7C1345G
Document #: 38-05517 Rev. *A
Page 4 of 17
Functional Overview
All synchronous inputs pass through input registers controlled
by the rising edge of the clock. Maximum access delay from
the clock rise (tC0) is 6.5 ns (133-MHz device).
The CY7C1345G 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 determined 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 (BW[A:D]) 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 CE
1
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) CE
1, 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. During byte
writes, BWA controls DQA and BWB controls DQB, BWC
controls DQC, and BWD controls DQD.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.
ADSP
Input-
Synchronous
Address Strobe from Processor, sampled on the rising edge of CLK, active LOW. When
asserted LOW, addresses presented to the device are captured in the address registers. A[1:0] are
also loaded into the burst counter. When ADSP and ADSC are both asserted, only ADSP is recog-
nized. ASDP is ignored when CE
1 is deasserted HIGH
ADSC
Input-
Synchronous
Address Strobe from Controller, sampled on the rising edge of CLK, active LOW. When
asserted LOW, addresses presented to the device are captured in the address registers. A[1:0] are
also loaded into the burst counter. When ADSP and ADSC are both asserted, only ADSP is recog-
nized.
ZZ
Input-
Asynchronous
ZZ “sleep” Input, active HIGH. When asserted HIGH places the device in a non-time-critical “sleep”
condition with data integrity preserved. For normal operation, this pin has to be LOW or left floating.
ZZ pin has an internal pull-down.
DQs
DQPA,
DQPB
DQPC,
DQPD
I/O-
Synchronous
Bidirectional Data I/O lines. As inputs, they feed into an on-chip data register that is triggered by
the rising edge of CLK. As outputs, they deliver the data contained in the memory location specified
by the addresses presented during the previous clock rise of the read cycle. The direction of the
pins is controlled by OE. When OE is asserted LOW, the pins behave as outputs. When HIGH, DQs
and DQP[A:D] are placed in a tri-state condition.
VDD
Power Supply Power supply inputs to the core of the device.
VSS
Ground
Ground for the core of the device.
VDDQ
I/O Power
Supply
Power supply for the I/O circuitry.
VSSQ
I/O Ground
Ground for the I/O circuitry.
MODE
Input-
Static
Selects Burst Order. When tied to GND selects linear burst sequence. When tied to VDD or left
floating selects interleaved burst sequence. This is a strap pin and should remain static during device
operation. Mode Pin has an internal pull-up.
NC
No Connects. Not Internally connected to the die.
Pin Definitions (continued)
Name
I/O
Description
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