CY7C1306BV25
CY7C1303BV25
Document #: 38-05627 Rev. *A
Page 6 of 19
operation is identical to the operation if the device had zero
skew between the K/K and C/C clocks. All timing parameters
remain the same in this mode. To use this mode of operation,
the user must tie C and C HIGH at power-up.This function is
a strap option and not alterable during device operation.
Concurrent Transactions
The Read and Write ports on the CY7C1303BV25 operate
completely independently of one another. Since each port
latches the address inputs on different clock edges, the user
can Read or Write to any location, regardless of the trans-
action on the other port. Also, reads and writes can be started
in the same clock cycle. If the ports access the same location
at the same time, the SRAM will deliver the most recent infor-
mation associated with the specified address location. This
includes forwarding data from a Write cycle that was initiated
on the previous K clock rise.
Depth Expansion
The CY7C1303BV25 has a Port Select input for each port.
This allows for easy depth expansion. Both Port Selects are
sampled on the rising edge of the Positive Input Clock only (K).
Each port select input can deselect the specified port.
Deselecting a port will not affect the other port. All pending
transactions (Read and Write) will be completed prior to the
device being deselected.
Programmable Impedance
An external resistor, RQ, must be connected between the ZQ
pin on the SRAM and V
SS
to allow the SRAM to adjust its
output driver impedance. The value of RQ must be 5X the
value of the intended line impedance driven by the SRAM, The
allowable range of RQ to guarantee impedance matching with
a tolerance of ±15% is between 175
Ω
and 350
Ω
,
with
V
DDQ
=1.5V. The output impedance is adjusted every 1024
cycles to account for drifts in supply voltage and temperature.
Application Example
[1]
Truth Table
[2, 3, 4, 5, 6, 7]
Operation
K
RPS
WPS
DQ
DQ
Write Cycle:
Load address on the rising edge of K clock; input write
data on K and K rising edges.
L-H
X
L
D(A+0) at
K(t)
↑
D(A+1) at
K(t)
↑
Read Cycle:
Load address on the rising edge of K clock; wait one
cycle; read data on 2 consecutive C and C rising edges.
L-H
L
X
Q(A+0) at
C(t+1)
↑
Q(A+1) at
C(t+1)
↑
NOP: No Operation
L-H
H
H
D = X
Q = High-Z
D = X
Q = High-Z
Standby: Clock Stopped
Stopped
X
X
Previous
State
Previous
State
Notes:
1. The above application shows 4 QDR-I being used.
2. X = Don't Care, H = Logic HIGH, L = Logic LOW,
↑
represents rising edge.
3. Device will power-up deselected and the outputs in a three-state condition.
4. “A” represents address location latched by the devices when transaction was initiated. A+0, A+1 represent the addresses sequence in the burst.
5. “t” represents the cycle at which a Read/Write operation is started. t+1 is the first clock cycle succeeding the “t” clock cycle.
6. Data inputs are registered at K and K rising edges. Data outputs are delivered on C and C rising edges, except when in single clock mode.
7. It is recommended that K = K and C = C when clock is stopped. This is not essential, but permits most rapid restart by overcoming transmission line charging
symmetrically.
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