Cypress CY7C1161V18, CY7C1165V18, CY7C1176V18, CY7C1163V18 User Manual

CY7C1161V18, CY7C1176V18 CY7C1163V18, CY7C1165V18
18-Mbit QDR™-II+ SRAM 4-Word Burst
Architecture (2.5 Cycle Read Latency)

Features

Note
1. The QDR consortium specification for V
DDQ
is 1.5V + 0.1V . The Cyp ress QDR devices exceed th e QDR consorti um specifi catio n and ar e capab le of support ing V
DDQ
= 1.4V to V
DD
.

Functional Description

Separate independent read and write data portsSupports concurrent transactions
300 MHz to 400 MHz clock for high bandwidth
4-word burst to reduce address bus frequency
Double Data Rate (DDR) interfaces on both read and write ports
(data transferred at 800 MHz) at 400 MHz
Read latency of 2.5 clock cycles
Two input clocks (K and K) for precise DDR timingSRAM uses rising edges only
Echo clocks (CQ and CQ) simplify data capture in high speed
systems
Single multiplexed address input bus latches address inputs
for both read and write ports
Separate port selects for depth expansion
Data valid pin (QVLD) to indicate valid data on the output
Synchronous internally self-timed writes
Available in x8, x9, x18, and x36 configurations
Full data coherency providing most current data
Core V
Available in 165-ball FBGA package (13 x 15 x 1.4 mm)
Offered in both Pb-free and non Pb-free packages
Variable drive HSTL output buffers
JTAG 1149.1 compatible test access port
Delay Lock Loop (DLL) for accurate data placement
= 1.8V ± 0.1V; IO V
DD
= 1.4V to V
DDQ
DD
[1]
The CY7C1161V18, CY7C1176V18, CY7C1163V18, and CY7C1165V18 are 1.8V Synchronous Pipelined SRAMs equipped with QDR™-II+ architecture. QDR-II+ architecture consists of two separate ports to access the memory array. The read port has dedicated data outputs to support read operations and the write port has dedicated data inputs to support write operations. QDR-II+ architecture has separate data inputs and data outputs to completely eliminate the need to turn around the data bus that is required with common IO devices. Each port can be accessed through a common address bus. Addresses for read and write addresses are latched onto alternate rising edges of the input (K) clock. Accesses to the QDR-II+ read and write ports are completely independent of one another. In order to maximize data throughput, both read and write ports are equipped with Double Data Rate (DDR) interfaces. Each address location is associated with four 8-bit words (CY7C1161V18), 9-bit words (CY7C1176V18), 18-bit words (CY7C1163V18), or 36-bit words (CY7C1165V18) that burst sequentially into or out of the device. Because data can be trans­ferred into and out of the device on every rising edge of both input clocks K and K
, memory bandwidth is maximized while simpli-
fying system design by eliminating bus turnarounds. Depth expansion is accomplished with port selects for each port.
Port selects allow each port to operate independently. All synchronous inputs pass through input registers controlled by
the K or K registers controlled by the or K or K
input clocks. All data outputs pass through output
input clocks. Writes are
conducted with on-chip synchronous self-timed write circuitry.

Configurations

With cycle read latency of 2.5 cycles: CY7C1161V18 – 2M x 8
CY7C1176V18 – 2M x 9 CY7C1163V18 – 1M x 18 CY7C1165V18 – 512K x 36

Selection Guide

Description 400 MHz 375 MHz 333 MHz 300 MHz Unit
Maximum Operating Frequency 400 375 333 300 MHz Maximum Operating Current 1080 1020 920 850 mA
Cypress Semiconductor Corporation 198 Champion Court San Jose, CA 95134-1709 408-943-2600 Document Number: 001-06582 Rev. *D Revised March 06, 2008
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Logic Block Diagram (CY7C1161V18)

512K x 8 Array
CLK
A
(18:0)
Gen.
K
K
Control
Logic
Address Register
D
[7:0]
Read Add. Decode
Read Data Reg.
RPS
WPS
Q
[7:0]
Control
Logic
Address Register
Reg.
Reg.
Reg.
16
19
8
32
8
NWS
[1:0]
V
REF
Write Add. Decode
Write
Reg
16
A
(18:0)
19
512K x 8 Array
512K x 8 Array
512K x 8 Array
Write
Reg
Write
Reg
Write
Reg
8
CQ
CQ
DOFF
QVLD
512K x 9 Array
CLK
A
(18:0)
Gen.
K
K
Control
Logic
Address Register
D
[8:0]
Read Add. Decode
Read Data Reg.
RPS
WPS
Q
[8:0]
Control
Logic
Address Register
Reg.
Reg.
Reg.
18
19
9
36
9
BWS
[0]
V
REF
Write Add. Decode
Write
Reg
18
A
(18:0)
19
512K x 9 Array
512K x 9 Array
512K x 9 Array
Write
Reg
Write
Reg
Write
Reg
9
CQ
CQ
DOFF
QVLD

Logic Block Diagram (CY7C1176V18)

Document Number: 001-06582 Rev. *D Page 2 of 29
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Logic Block Diagram (CY7C1163V18)

256K x 18 Array
CLK
A
(17:0)
Gen.
K
K
Control
Logic
Address
Register
D
[17:0]
Read Add. Decode
Read Data Reg.
RPS
WPS
Q
[17:0]
Control
Logic
Address
Register
Reg.
Reg.
Reg.
36
18
18
72
18
BWS
[1:0]
V
REF
Write Add. Decode
Write
Reg
36
A
(17:0)
18
256K x 18 Array
256K x 18 Array
256K x 18 Array
Write
Reg
Write
Reg
Write
Reg
18
CQ
CQ
DOFF
QVLD
128K x 36 Array
CLK
A
(16:0)
Gen.
K
K
Control
Logic
Address Register
D
[35:0]
Read Add. Decode
Read Data Reg.
RPS
WPS
Q
[35:0]
Control
Logic
Address Register
Reg.
Reg.
Reg.
72
17
36
144
36
BWS
[3:0]
V
REF
Write Add. Decode
Write
Reg
72
A
(16:0)
17
128K x 36 Array
128K x 36 Array
128K x 36 Array
Write
Reg
Write
Reg
Write
Reg
36
CQ
CQ
DOFF
QVLD

Logic Block Diagram (CY7C1165V18)

Document Number: 001-06582 Rev. *D Page 3 of 29
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Pin Configurations

CY7C1161V18 (2M x 8)
165-Ball FBGA (13 x 15 x 1.4 mm) Pinout
23
4
5
6
7
1
A B
C D
E F G H
J K L M N P
R
A
CQ NC
NC NC
NC
DOFF
NC
NC/72M A
NWS
1
K
WPS
NC/144M
NC NC
NC
NC
NC
TDO
NC
NC
D5
NC
NC
NC
TCK
NC
NC
A NC/288M K NWS
0
V
SS
ANCA
NC V
SS
V
SS
V
SS
V
SS
V
DD
A
V
SS
V
SS
V
SS
V
DD
Q4 NC
V
DDQ
NC NC
NC NC Q7
A
V
DDQ
V
SS
V
DDQ
V
DD
V
DD
Q5 V
DDQ
V
DD
V
DDQ
V
DD
V
DDQ
V
DD
V
SS
V
DD
V
DDQ
V
DDQ
V
SS
V
SS
V
SS
V
SS
A
ANC
V
SS
A
A
A
D4 V
SS
NC V
SS
NC
NC
V
REF
V
SS
V
DD
V
SS
V
SS
A
V
SS
QVLD
NC
Q6
NC
D7
D6
V
DD
A
8
91011
NC
ANC/36M
RPS
CQ
A NC NC Q3
V
SS
NC NC D3 NC
V
SS
NC
Q2
NC
NC
NC
V
REF
NC
NC
V
DDQ
NC
V
DDQ
NC NC
V
DDQ
V
DDQ
V
DDQ
D1V
DDQ
NC
Q1
NC
V
DDQ
V
DDQ
NC
V
SS
NC D0 NC
TDITMS
V
SS
A
NC
A
NC
D2
NC
ZQ
NC
Q0
NC
NC
NC
NC
A
NC/144M
CY7C1176V18 (2M x 9)
23
4
5
6
7
1 A B C
D E F
G H
J K L M N P
R
A
CQ NC NC NC
NC
DOFF
NC
NC/72M A NC K
WPS NC/144M
NC NC
NC
NC
NC
TDO
NC
NC
D6
NC
NC
NC
TCK
NC
NC
A NC/288M K BWS
0
V
SS
ANCA
NC V
SS
V
SS
V
SS
V
SS
V
DD
A
V
SS
V
SS
V
SS
V
DD
Q5 NC
V
DDQ
NC NC
NC NC Q8
A
V
DDQ
V
SS
V
DDQ
V
DD
V
DD
Q6 V
DDQ
V
DD
V
DDQ
V
DD
V
DDQ
V
DD
V
SS
V
DD
V
DDQ
V
DDQ
V
SS
V
SS
V
SS
V
SS
A
ANC
V
SS
A
A
A
D5 V
SS
NC V
SS
NC
NC
V
REF
V
SS
V
DD
V
SS
V
SS
A
V
SS
QVLD
NC
Q7
NC
D8
D7
V
DD
A
8
91011
Q0
ANC/36MRPS
CQ
A
NC
NC Q4
V
SS
NC NC D4 NC
V
SS
NC
Q3
NC
NC
NC
V
REF
NC
NC
V
DDQ
NC
V
DDQ
NC NC
V
DDQ
V
DDQ
V
DDQ
D2V
DDQ
NC
Q2
NC
V
DDQ
V
DDQ
NC
V
SS
NC D1 NC
TDITMS
V
SS
A
NC
A
NC
D3
NC
ZQ
NC
Q1
NC
NC
D0
NC
A
NC
NC
Document Number: 001-06582 Rev. *D Page 4 of 29
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Pin Configurations (continued)
CY7C1163V18 (1M x 18)
165-Ball FBGA (13 x 15 x 1.4 mm) Pinout
23
4
567
1 A B C D E F G H
J K L M N P
R
A
CQ NC NC NC
NC
DOFF
NC
NC/144M NC/36M BWS
1
KWPS NC/288M
Q9 D9
NC
NC
NC
TDO
NC
NC
D13
NC
NC
NC
TCK
NC
D10
A NC K BWS
0
V
SS
ANCA
Q10 V
SS
V
SS
V
SS
V
SS
V
DD
A
V
SS
V
SS
V
SS
V
DD
Q11 D12
V
DDQ
D14 Q14
D16 Q16 Q17
A
V
DDQ
V
SS
V
DDQ
V
DD
V
DD
Q13 V
DDQ
V
DD
V
DDQ
V
DD
V
DDQ
V
DD
V
SS
V
DD
V
DDQ
V
DDQ
V
SS
V
SS
V
SS
V
SS
A
A
V
SS
A
A
A
D11 V
SS
NC V
SS
Q12
NC
V
REF
V
SS
V
DD
V
SS
V
SS
A
V
SS
QVLD
NC
Q15
NC
D17
D15
V
DD
A
8
91011
Q0
ANC/72MRPS
CQ
A NC NC Q8
V
SS
NC Q7 D8 NC
V
SS
NC
Q6
D5
NC
NC
V
REF
NC
Q3
V
DDQ
NC
V
DDQ
NC Q5
V
DDQ
V
DDQ
V
DDQ
D4V
DDQ
NC
Q4
NC
V
DDQ
V
DDQ
NC
V
SS
NC D2 NC
TDITMS
V
SS
A
NC
A
D7
D6
NC
ZQ
D3
Q2
D1
Q1
D0
NC
A
NC
CY7C1165V18 (512K x 36)
23
456
7
1 A B C D E F G H
J K L M N P
R
A
CQ Q27 D27 D28
D34
DOFF
Q33
NC/288M NC/72M
BWS
2
KWPS BWS
1
Q18
D18
Q30
D31
D33
TDO
Q28
D29
D22
D32
Q34
Q31
TCK
D35
D19
A
BWS
3
K
BWS
0
V
SS
ANCA
Q19 V
SS
V
SS
V
SS
V
SS
V
DD
A
V
SS
V
SS
V
SS
V
DD
Q20 D21
V
DDQ
D23 Q23
D25 Q25 Q26
A
V
DDQ
V
SS
V
DDQ
V
DD
V
DD
Q22 V
DDQ
V
DD
V
DDQ
V
DD
V
DDQ
V
DD
V
SS
V
DD
V
DDQ
V
DDQ
V
SS
V
SS
V
SS
V
SS
A
A
NC
V
SS
A
A
A
D20 V
SS
Q29 V
SS
Q21
D30
V
REF
V
SS
V
DD
V
SS
V
SS
A
V
SS
QVLD
Q32
Q24
Q35
D26
D24
V
DD
A
891011
Q0
NC/36M
NC/144M
RPS
CQ
A D17
Q17
Q8
V
SS
D16 Q7 D8 Q16
V
SS
D15
Q6
D5
D9
Q14
V
REF
Q11
Q3
V
DDQ
Q15
V
DDQ
D14 Q5
V
DDQ
V
DDQ
V
DDQ
D4V
DDQ
D12
Q4
Q12
V
DDQ
V
DDQ
D11
V
SS
D10 D2 Q10
TDITMS
V
SS
A
Q9
A
D7
D6
D13
ZQ
D3
Q2
D1
Q1
D0
Q13
A
Document Number: 001-06582 Rev. *D Page 5 of 29
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Pin Definitions

Pin Name IO Pin Description
D
[x:0]
Input-
Synchronous
WPS Input-
Synchronous
, BWS1,
, Input-
1
Synchronous
Input-
Synchronous
3
NWS0, NWS
BWS
0
BWS2, BWS
A Input-
Synchronous
Data Input Signals. Sampled on the rising edge of K and K clocks during valid write operations. CY7C1 161V18−D CY7C1 176V18−D CY7C1 163V18−D CY7C1 165V18−D
[7:0] [8:0] [17:0] [35:0]
Write Port Select Active LOW . Sampled on the rising edge of the K clock. When asserted active, a write operation is initiated. Deasserting deselects the write port. Deselecting the write port causes D
to be ignored.
[x:0]
Nibble Write Select 0, 1 Active LOW (CY7C1161V18 Only). Sampled on the rising edge of the K and K controls D All the nibble write selects are sampled on the same edge as the data. Deselecting a nibble write
clocks during Write operations. Used to select the nibble that is written into the device. NWS0
and NWS1 controls D
[3:0]
[7:4]
.
select causes the corresponding nibble of data to be ignored and not written into the device. Byte Write Select 0, 1, 2, and 3 Active LOW. Sampled on the rising edge of the K and K clocks
during write operations. Used to select the byte that is written into the device during the current portion of the write operation. Bytes not written remain unaltered. CY7C1 176V18 BWS CY7C1 163V18 BWS0 controls D CY7C1 165V18 BWS0 controls D controls D All the Byte Write Selects are sampled on the same edge as the data. Deselecting a Byte Write Select
[35:27].
controls D
0
[8:0].
and BWS1 controls D
[8:0]
, BWS1 controls D
[8:0]
causes the corresponding byte of data to be ignored and not written into the device. Address Inputs. Sampled on the rising edge of the K clock during active read and write operations.
These address inputs are multiplexed for both read and write operations. Internally, the device is organized as 2M x 8 (4 arrays each of 512K x 8) for CY7C1161V18, 2M x 9 (4 arrays each of 512K x 9) for CY7C1176V18, 1M x 18 (4 arrays each of 256K x 18) for CY7C1163V18, and 512K x 36 (4 arrays each of 128K x 36) for CY7C1165V18. Therefore, only 19 address inputs are needed to access the entire memory array of CY7C1161V18 and CY7C1 176V18, 18 address inputs for CY7C1 163V18, and 17 address inputs for CY7C1165V18. These inputs are ignored when the appropriate port is deselected.
[17:9]..
, BWS2 controls D
[17:9]
[26:18],
and BWS3
Q
[x:0]
RPS Input-
Outputs-
Synchronous
Synchronous
Data Output Signals. These pins drive out the requested data during a read operation. Valid data is driven out on the rising edge of both the K and K in single clock mode. When the read port is deselected, Q CY7C1 161V18 Q CY7C1 176V18 Q CY7C1 163V18 Q CY7C1 165V18 Q
[7:0] [8:0] [17:0] [35:0]
. .
. .
clocks during read operations or K and K when
are automatically tri-stated.
[x:0]
Read Port Select Active LOW . Sampled on the rising edge of positive input clock (K). When active, a read operation is initiated. Deasserting causes the read port to be deselected. When deselected, the pending access is enabled to complete and the output drivers are automatically tri-stated following the next rising edge of the K clock. Each read access consists of a burst of four sequential transfers.
QVLD Valid Output
Valid Output Indicator. Indicates valid output data. QVLD is edge-aligned with CQ and CQ.
Indicator
K Input-
Clock
K
Input­Clock
Positive Input Clock Input. Rising edge of K is used to capture synchronous inputs to the device and to drive out data through Q edge of K.
when in single clock mode. All accesses are initiated on the rising
[x:0]
Negative Input Clock Input. K is used to capture synchronous inputs presented to the device and to drive out data through Q
when in single clock mode.
[x:0]
CQ Echo Clock Synchronous Echo Clock Outputs. This is a free running clock and is synchronized to the input
clock (K) of the QDR-II+. The timings for the echo clocks are shown in “Switching Characteristics” on page 23.
Document Number: 001-06582 Rev. *D Page 6 of 29
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Pin Definitions (continued)
Pin Name IO Pin Description
CQ
ZQ Input Output Impedance Matching Input. Used to tune the device outputs to the system data bus
DOFF
TDO Output TDO for JTAG. TCK Input TCK Pin for JTAG. TDI Input TDI Pin for JTAG. TMS Input TMS Pin for JTAG. NC N/A Not Connected to the Die. Can be tied to any voltage level. NC/36M N/A Not Connected to the Die. Can be tied to any voltage level. NC/72M N/A Not Connected to the Die. Can be tied to any voltage level.
NC/144M N/A Not Connected to the Die. Can be tied to any voltage level.
Echo Clock Synchronous Echo Clock Outputs. This is a free running clock and is synchronized to the input
clock (K on page 23.
impedance. CQ, CQ connected between ZQ and ground. Alternatively, this pin is connected directly to V enables the minimum impedance mode. This pin cannot be connected directly to GND or left uncon­nected.
Input DLL Turn Off Active LOW. Connecting this pin to ground turns off the DLL inside the device. The
timings in the DLL turned-off operation are different from those listed in this data sheet. For normal operation, this pin is connected to a pull up through a 10 KΩ or less pull up resistor. The device behaves in QDR-I mode when the DLL is turned off. In this mode, the device operates at a frequency of up to 167 MHz with QDR-I timing.
) of the QDR-II+. The timings for the echo clocks are shown in “Switching Characteristics”
and Q
output impedance are set to 0.2 x RQ, where RQ is a resistor
[x:0]
DDQ
, which
NC/288M N/A Not Connected to the Die. Can be tied to any voltage level.
V
V V V
REF
DD SS DDQ
Input-
Reference
Power Supply Power Supply Inputs to the Core of the Device.
Ground Ground for the Device.
Power Supply Power Supply Inputs for the Outputs of the Device.
Reference Volt age Input. Static input used to set the reference level for HSTL inputs, outputs, and AC measurement points.
Document Number: 001-06582 Rev. *D Page 7 of 29
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Functional Overview

The CY7C1161V18, CY7C1176V18, CY7C1163V18, and CY7C1165V18 are synchronous pipelined burst SRAMs equipped with both a read port and a write port. The read port is dedicated to read operations and the write port is dedicated to write operations. Data flows into the SRAM through the write port and out through the read port. These devices multiplex the address inputs in order to minimize the number of address pins required. By having separate read and write ports, the QDR-II+ completely eliminates the need to “turn-around” the data bus. It avoids any possible data contention, thereby , simplify ing system design. Each access consists of four 8-bit data transfers in the case of CY7C1161V18, four 9-bit data transfers in the case of CY7C1176V18, four 18-bit data transfers in the case of CY7C1163V18, and four 36-bit data transfers in the case of CY7C1165V18 in two clock cycles.
Accesses for both ports are initiated on the positive input clock (K). All synchronous input and output timings are referenced to the rising edge of the Input clocks (K/K
All synchronous data inputs (D controlled by the input clocks (K and K outputs (Q rising edge of the Input clocks (K and K
) pass through output registers controlled by the
[x:0]
[x:0]
All synchronous control (RPS, WPS, BWS through input registers controlled by the rising edge of the input clocks (K and K).
CY7C1163V18 is described in the following sections. The same basic descriptions apply to CY7C1161V18, CY7C1176V18, and CY7C1165V18.

Read Operations

The CY7C1163V18 is organized internally as four arrays of 256K x 18. Accesses are completed in a burst of four sequential 18-bit data words. Read operations are initiated by asserting RPS active at the rising edge of the positive input clock (K). The address presented to address inputs are stored in the Read address register. Following the next two K clock rises, the corre­sponding lowest order 18-bit word of data is driven onto the
using K as the output timing reference. On the subse-
Q
[17:0]
quent rising edge of K, the next 18-bit data word is driven onto the Q have been driven out onto Q
0.45 ns from the rising edge of the Input clock K or K maintain the internal logic, each read access must be allowed to complete. Each read access consists of four 18-bit data words and takes two clock cycles to complete. Therefore, read accesses to the device cannot be initiated on two consecutive K clock rises. The internal logic of the device ignores the second read request. Read accesses can be initiated on every other K clock rise. Doing so pipelines the data flow such that data is transferred out of the device on every rising edge of the input clocks K and K
When the read port is deselected, the CY7C1163V18 first completes the pending read transactions. Synchronous internal circuitry automatically tri-states the outputs following the next rising edge of the negative input clock (K seamless transition between devices without the insertion of wait states in a depth expanded memory.
. This process continues until all four 18-bit data words
[17:0]
[17:0]
.
).
) pass through input registers
). All synchronous data
) also.
) inputs pass
[x:0]
. The requested data is valid
. In order to
). This allows for a

Write Operations

Write operations are initiated by asserting WPS active at the rising edge of the positive input clock (K). On the following K clock rise, the data presented to D the lower 18-bit write data register, provided BWS asserted active. On the subsequent rising edge of the negative input clock (K), the information presented to D into the write data register, provided BWS active. This process continues for one more cycle until four 18-bit
is latched and stored into
[17:0]
[1:0]
[1:0]
is also stored
[17:0]
are both asserted
are both
words (a total of 72 bits) of data are stored in the SRAM. The 72 bits of data are then written into the memory array at the specified location. Therefore, write accesses to the device cannot be initiated on two consecutive K clock rises. The inte rnal logic of the device ignores the second write request. Write accesses are initiated on every other rising edge of the positive input clock (K). Doing so pipelines the data flow such that 18 bits of data can be transferred into the device on every rising edge of the input clocks (K and K
).
When deselected, the write port ignores all inputs after the pending write operations are completed.

Byte Write Operations

Byte write operations are supported by the CY7C1163V18. A write operation is initiated as described in the Write Operations section above. The bytes that are written are determined by BWS
and BWS1, which are sampled with each set of 18-bit data
0
words. Asserting the appropriate byte write select input during the data portion of a write enables the data being presented to be latched and written into the device. Deasserting the byte write select input during the data portion of a write allows the data stored in the device for that byte to remain unaltered. This feature is used to simplify read, modify, and write operations to a byte write operation.

Concurrent Transactions

The read and write ports on the CY7C1163V18 operate completely independent of one another. Because each port latches the address inputs on different clock edges, the user can read or write to any location, regardless of the transaction on the other port. If the ports access the same location when a read follows a write in successive clock cycles, the SRAM delivers the most recent information associated with the specified address location. This includes forwarding data from a write cycle initiated on the previous K clock rise.
Read accesses and write access are scheduled such that one transaction is initiated on any clock cycle. If both ports are selected on the same K clock rise, the arbitration depends on the previous state of the SRAM. If both ports are deselected, the read port takes priority . If a read is initiated on the previous cycle, the write port assumes priority (because read operations cannot be initiated on consecutive cycles). If a write was initiated on the previous cycle, the read port assumes priority (because write operations cannot be initiated on consecutive cycles). Therefore, asserting both port selects active from a deselected state results in alternating read or write operations initiated, with the first access being a read.
Document Number: 001-06582 Rev. *D Page 8 of 29
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CY7C1161V18, CY7C1176V18 CY7C1163V18, CY7C1165V18

Depth Expansion

The CY7C1163V18 has a port select input for each port. This enables easy depth expansion. Both port selects are only sampled on the rising edge of the positive input clock (K). Each port select input can deselect the specified port. Deselecting a port does not affect the other port. All pending transactions (read and write) are completed before the device is deselected.

Programmable Impedance

An external resistor, RQ, must be connected between the ZQ pin on the SRAM and V 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 175Ω and 350Ω output impedance is adjusted every 1024 cycles upon power up to account for drifts in supply voltage and temperature.
to enable the SRAM to adjust its output
SS
, with V
=1.5V. The
DDQ

Echo Clocks

Echo clocks are provided on the QDR-II+ to simplify data capture on high speed systems. Two echo clocks are generated by the QDR-II+. CQ is referenced with respect to K and CQ is refer­enced with respect to K synchronized to the input clock of the QDR-II+. The timings for the echo clocks are shown in the AC timing table.
. These are free running clocks and are

Valid Data Indicator (QVLD)

QVLD is provided on the QDR-II+ to simplify data capture on high speed systems. The QVLD is generated by the QDR-II+ device along with data output. This signal is also edge-aligned with the echo clock and follows the timing of any data pin. This signal is asserted half a cycle before valid data arrives.
DLL
These chips utilize a Delay Lock Loop (DLL) that is designed to function between 120 MHz and the specified maximum clock frequency. The DLL may be disabled by applying ground to the DOFF
pin. When the DLL is turned off, the device behaves in QDR-I mode (with 1.0 cycle latency and a longer access time). For more information, refer to the application note, “DLL Consid-
erations in QDRII/DDRII/QDRII+/DDRII+.” The DLL can also be
reset by slowing or stopping the input clocks K and K minimum of 30 ns. However, it is not necessary for the DLL to be reset in order to lock to the desired frequency. During power up when the DOFF of stable clock.
is tied HIGH, the DLL is locked after 2048 cycles
for a
Document Number: 001-06582 Rev. *D Page 9 of 29
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