CY7C1480V33
CY7C1482V33
CY7C1486V33
Document #: 38-05283 Rev. *G
Page 8 of 31
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.
Maximum access delay from the clock rise (tCO) is 3.0 ns
(250-MHz device).
The CY7C1480V33/CY7C1482V33/CY7C1486V33 supports
secondary cache in systems utilizing either a linear or inter-
leaved 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 (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
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 3.0 ns (250-MHz device) 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 tri-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 tri-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 BWX) 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 DQs 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 BWX
signals.
The CY7C1480V33/CY7C1482V33/CY7C1486V33 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 (BWX) input, will selec-
tively 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 CY7C1480V33/CY7C1482V33/CY7C1486V33 is a
common I/O device, the Output Enable (OE) must be
deasserted HIGH before presenting data to the DQs inputs.
Doing so will tri-state the output drivers. As a safety
precaution, DQs are automatically tri-stated whenever a Write
cycle is detected, regardless of the state of OE.
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.
TDO
JTAG Serial
Output
Synchronous
Serial data-out to the JTAG circuit. Delivers data on the negative edge of TCK. If the
JTAG feature is not being utilized, this pin should be disconnected. This pin is not
available on TQFP packages.
TDI
JTAG Serial
Input
Synchronous
Serial data-In to the JTAG circuit. Sampled on the rising edge of TCK. If the JTAG
feature is not being utilized, this pin can be disconnected or connected to VDD. This pin
is not available on TQFP packages.
TMS
JTAG Serial
Input
Synchronous
Serial data-In to the JTAG circuit. Sampled on the rising edge of TCK. If the JTAG
feature is not being utilized, this pin can be disconnected or connected to VDD. This pin
is not available on TQFP packages.
TCK
JTAG Clock
Clock input to the JTAG circuitry. If the JTAG feature is not being utilized, this pin
must be connected to VSS. This pin is not available on TQFP packages.
NC
-
No Connects. Not internally connected to the die. 144M,288M, 576M and 1G are
address expansion pins and are not internally connected to the die.
Pin Definitions (continued)
Pin Name
I/O
Description
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