CY7C1218F
Document #: 38-05422 Rev. **
Page 4 of 16
Functional Overview
All synchronous inputs pass through input registers controlled
by the rising edge of the clock. All data outputs pass through
output registers controlled by the rising edge of the clock.
The CY7C1218F 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 three-state control. ADSP is ignored if
CE1 is HIGH.
Single Read Accesses
This access is initiated when the following conditions are
satisfied at clock rise: (1) ADSP or ADSC is asserted LOW,
(2) CE1, CE2, CE3 are all asserted active, and (3) the Write
signals (GW, BWE) are all deasserted HIGH. ADSP is ignored
if CE1 is HIGH. The address presented to the address inputs
(A) is stored into the address advancement logic and the
address register while being presented to the memory array.
The corresponding data is allowed to propagate to the input of
the output registers. At the rising edge of the next clock the
data is allowed to propagate through the output register and
onto the data bus within tCO if OE is active LOW. The only
exception occurs when the SRAM is emerging from a
deselected state to a selected state, its outputs are always
three-stated during the first cycle of the access. After the first
cycle of the access, the outputs are controlled by the OE
signal. Consecutive single Read cycles are supported. Once
the SRAM is deselected at clock rise by the chip select and
either ADSP or ADSC signals, its output will three-state
immediately.
Single Write Accesses Initiated by ADSP
This access is initiated when both of the following conditions
are satisfied at clock rise: (1) ADSP is asserted LOW, and
(2) CE1, CE2, CE3 are all asserted active. The address
presented to A is loaded into the address register and the
address advancement logic while being delivered to the
memory array. The Write signals (GW, BWE, and BW[A:D]) and
ADV inputs are ignored during this first cycle.
ADSP-triggered Write accesses require two clock cycles to
complete. If GW is asserted LOW on the second clock rise, the
data presented to the DQ inputs is written into the corre-
sponding address location in the memory array. If GW is HIGH,
then the Write operation is controlled by BWE and BW[A:D]
signals. The CY7C1218F provides Byte Write capability that is
described in the Write Cycle Descriptions table. Asserting the
Byte Write Enable input (BWE) with the selected Byte Write
(BW[A:D]) 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.
Because the CY7C1218F is a common I/O device, the Output
Enable (OE) must be deasserted HIGH before presenting data
to the DQ inputs. Doing so will three-state the output drivers.
As a safety precaution, DQ are automatically three-stated
whenever a Write cycle is detected, regardless of the state of
OE.
VDD
15,41,65,
91
Power Supply Power supply inputs to the core of the device.
VSS
17,40,67,
90
Ground
Ground for the core of the device.
VDDQ
4,11,20,
27,54,61,
70,77
I/O Power
Supply
Power supply for the I/O circuitry.
VSSQ
5,10,21,
26,55,60,
71,76
I/O Ground
Ground for the I/O circuitry.
MODE
31
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
14,16,38,
39,42,43,
49,50,66
No Connects. Not internally connected to the die
Pin Definitions (continued)
Name
TQFP
I/O
Description
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
