CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
72-Mbit QDR®II+ SRAM 2-Word Burst
Architecture (2.0 Cycle Read Latency) with ODT
Features
Configurations
■
Separate independent read and write data ports
❐ Supports concurrent transactions
With Read Cycle Latency of 2.0 cycles:
■
333 MHz clock for high bandwidth
CY7C2555KV18 – 8M x 9
■
2-word burst for reducing address bus frequency
CY7C2542KV18 – 4M x 18
■
Double Data Rate (DDR) interfaces on both read and write
ports (data transferred at 666 MHz) at 333 MHz
CY7C2544KV18 – 2M x 36
■
Available in 2.0 clock cycle latency
■
Two input clocks (K and K) for precise DDR timing
❐ SRAM uses rising edges only
■
Echo clocks (CQ and CQ) simplify data capture in high-speed
systems
■
Data valid pin (QVLD) to indicate valid data on the output
■
On-Die Termination (ODT) feature
❐ Supported for D[x:0], BWS[x:0], and K/K inputs
■
Single multiplexed address input bus latches address inputs
for both read and write ports
■
Separate port selects for depth expansion
■
Synchronous internally self-timed writes
■
QDR®II+ operates with 2.0 cycle read latency when DOFF is
asserted HIGH
CY7C2540KV18 – 8M x 8
■
Operates similar to QDR I device with 1 cycle read latency when
DOFF is asserted LOW
■
Available in x8, x9, x18, and x36 configurations
■
Full data coherency, providing most current data
■
Functional Description
The CY7C2540KV18, CY7C2555KV18, CY7C2542KV18, and
CY7C2544KV18 are 1.8V Synchronous Pipelined SRAMs,
equipped with QDR®-II+ architecture. Similar to QDR II architecture, QDR II+ architecture consists of two separate ports: the
read port and the write port 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 exists with common IO devices. Access to each
port is through a common address bus. Addresses for read and
write addresses are latched on alternate rising edges of the input
(K) clock. Accesses to the QDR II+ read and write ports are
completely independent of one another. To maximize data
throughput, both read and write ports are equipped with DDR
interfaces. Each address location is associated with two 8-bit
words (CY7C2540KV18), 9-bit words (CY7C2555KV18), 18-bit
words (CY7C2542KV18), or 36-bit words (CY7C2544KV18) 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
simplifying system design by eliminating bus “turn-arounds”.
These devices have an On-Die Termination feature supported
for D[x:0], BWS[x:0], and K/K inputs, which helps eliminate
external termination resistors, reduce cost, reduce board area,
and simplify board routing.
Core VDD = 1.8V± 0.1V; IO VDDQ = 1.4V to VDD [1]
❐ Supports both 1.5V and 1.8V IO supply
■
HSTL inputs and variable drive HSTL output buffers
■
Available in 165-Ball FBGA package (13 x 15 x 1.4 mm)
■
Offered in both Pb-free and non Pb-free packages
■
JTAG 1149.1 compatible test access port
■
Phase Locked Loop (PLL) for accurate data placement
Depth expansion is accomplished with port selects, which
enables each port to operate independently.
All synchronous inputs pass through input registers controlled by
the K or K input clocks. All data outputs pass through output
registers controlled by the K or K input clocks. Writes are
conducted with on-chip synchronous self-timed write circuitry.
Selection Guide
Description
Maximum Operating Frequency
Maximum Operating Current
x8
x9
x18
x36
333 MHz
333
790
790
810
990
300 MHz
300
730
730
750
910
250 MHz
250
640
640
650
790
200 MHz
200
540
540
550
660
Unit
MHz
mA
Note
1. The Cypress QDR II+ devices surpass the QDR consortium specification and can support VDDQ = 1.4V to VDD.
Cypress Semiconductor Corporation
Document #: 001-15885 Rev. *F
•
198 Champion Court
•
San Jose, CA 95134-1709
•
408-943-2600
Revised September 23, 2009
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Logic Block Diagram (CY7C2540KV18)
K
CLK
Gen.
DOFF
22
Address
Register
Read Add. Decode
K
Write
Reg
4M x 8 Array
Address
Register
Write
Reg
4M x 8 Array
A(21:0)
22
8
Write Add. Decode
D[7:0]
A(21:0)
RPS
Control
Logic
Read Data Reg.
CQ
16
VREF
WPS
NWS[1:0]
8
Control
Logic
8
Reg.
Reg. 8
Reg.
8
CQ
8
Q[7:0]
QVLD
Logic Block Diagram (CY7C2555KV18)
K
CLK
Gen.
DOFF
22
Address
Register
Read Add. Decode
K
Write
Reg
4M x 9 Array
Address
Register
Write
Reg
4M x 9 Array
A(21:0)
22
9
Write Add. Decode
D[8:0]
A(21:0)
RPS
Control
Logic
Read Data Reg.
CQ
18
VREF
WPS
BWS[0]
9
Control
Logic
9
Reg.
Reg. 9
Reg.
9
CQ
9
Q[8:0]
QVLD
Document #: 001-15885 Rev. *F
Page 2 of 26
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CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Logic Block Diagram (CY7C2542KV18)
K
CLK
Gen.
DOFF
21
Address
Register
Read Add. Decode
K
Write
Reg
2M x 18 Array
Address
Register
Write
Reg
2M x 18 Array
A(20:0)
21
18
Write Add. Decode
D[17:0]
A(20:0)
RPS
Control
Logic
Read Data Reg.
CQ
36
VREF
WPS
BWS[1:0]
18
Control
Logic
18
Reg.
Reg. 18
Reg.
18
CQ
18
Q[17:0]
QVLD
Logic Block Diagram (CY7C2544KV18)
K
CLK
Gen.
DOFF
20
Address
Register
Read Add. Decode
K
Write
Reg
1M x 36 Array
Address
Register
Write
Reg
1M x 36 Array
A(19:0)
20
36
Write Add. Decode
D[35:0]
A(19:0)
RPS
Control
Logic
Read Data Reg.
CQ
72
VREF
WPS
BWS[3:0]
36
Control
Logic
36
Reg.
Reg. 36
Reg.
36
CQ
36
Q[35:0]
QVLD
Document #: 001-15885 Rev. *F
Page 3 of 26
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CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Pin Configuration
The pin configuration for CY7C2540KV18, CY7C2555KV18, CY7C2542KV18, and CY7C2544KV18 follow. [2]
165-Ball FBGA (13 x 15 x 1.4 mm) Pinout
CY7C2540KV18 (8M x 8)
1
2
3
4
5
6
7
8
9
10
11
A
CQ
A
A
WPS
NWS1
K
NC/144M
RPS
A
A
CQ
B
NC
NC
NC
A
NC/288M
K
NWS0
A
NC
NC
Q3
C
NC
NC
NC
VSS
A
A
A
VSS
NC
NC
D3
D
NC
D4
NC
VSS
VSS
VSS
VSS
VSS
NC
NC
NC
E
NC
NC
Q4
VDDQ
VSS
VSS
VSS
VDDQ
NC
D2
Q2
F
NC
NC
NC
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
NC
G
NC
D5
Q5
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
NC
H
DOFF
VREF
VDDQ
VDDQ
VDD
VSS
VDD
VDDQ
VDDQ
VREF
ZQ
J
NC
NC
NC
VDDQ
VDD
VSS
VDD
VDDQ
NC
Q1
D1
K
NC
NC
NC
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
NC
L
NC
Q6
D6
VDDQ
VSS
VSS
VSS
VDDQ
NC
NC
Q0
M
NC
NC
NC
VSS
VSS
VSS
VSS
VSS
NC
NC
D0
N
NC
D7
NC
VSS
A
A
A
VSS
NC
NC
NC
P
NC
NC
Q7
A
A
QVLD
A
A
NC
NC
NC
R
TDO
TCK
A
A
A
ODT
A
A
A
TMS
TDI
CY7C2555KV18 (8M x 9)
1
2
3
4
5
6
7
8
9
10
11
A
CQ
A
A
WPS
NC
K
NC/144M
RPS
A
A
CQ
B
NC
NC
NC
A
NC/288M
K
BWS0
A
NC
NC
Q4
C
NC
NC
NC
VSS
A
A
A
VSS
NC
NC
D4
D
NC
D5
NC
VSS
VSS
VSS
VSS
VSS
NC
NC
NC
E
NC
NC
Q5
VDDQ
VSS
VSS
VSS
VDDQ
NC
D3
Q3
F
NC
NC
NC
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
NC
G
NC
D6
Q6
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
NC
H
DOFF
VREF
VDDQ
VDDQ
VDD
VSS
VDD
VDDQ
VDDQ
VREF
ZQ
J
NC
NC
NC
VDDQ
VDD
VSS
VDD
VDDQ
NC
Q2
D2
K
NC
NC
NC
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
NC
L
NC
Q7
D7
VDDQ
VSS
VSS
VSS
VDDQ
NC
NC
Q1
M
NC
NC
NC
VSS
VSS
VSS
VSS
VSS
NC
NC
D1
N
NC
D8
NC
VSS
A
A
A
VSS
NC
NC
NC
P
NC
NC
Q8
A
A
QVLD
A
A
NC
D0
Q0
R
TDO
TCK
A
A
A
ODT
A
A
A
TMS
TDI
Note
2. NC/144M and NC/288M are not connected to the die and can be tied to any voltage level.
Document #: 001-15885 Rev. *F
Page 4 of 26
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CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Pin Configuration
(continued)
The pin configuration for CY7C2540KV18, CY7C2555KV18, CY7C2542KV18, and CY7C2544KV18 follow. [2]
165-Ball FBGA (13 x 15 x 1.4 mm) Pinout
CY7C2542KV18 (4M x 18)
1
2
3
4
5
6
7
8
9
10
11
A
CQ
NC/144M
A
WPS
BWS1
K
NC/288M
RPS
A
A
CQ
B
NC
Q9
D9
A
NC
K
BWS0
A
NC
NC
Q8
C
NC
NC
D10
VSS
A
A
A
VSS
NC
Q7
D8
D
NC
D11
Q10
VSS
VSS
VSS
VSS
VSS
NC
NC
D7
E
NC
NC
Q11
VDDQ
VSS
VSS
VSS
VDDQ
NC
D6
Q6
F
NC
Q12
D12
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
Q5
G
NC
D13
Q13
VDDQ
VDD
VSS
VDD
VDDQ
NC
NC
D5
H
DOFF
VREF
VDDQ
VDDQ
VDD
VSS
VDD
VDDQ
VDDQ
VREF
ZQ
J
NC
NC
D14
VDDQ
VDD
VSS
VDD
VDDQ
NC
Q4
D4
K
NC
NC
Q14
VDDQ
VDD
VSS
VDD
VDDQ
NC
D3
Q3
L
NC
Q15
D15
VDDQ
VSS
VSS
VSS
VDDQ
NC
NC
Q2
M
NC
NC
D16
VSS
VSS
VSS
VSS
VSS
NC
Q1
D2
N
NC
D17
Q16
VSS
A
A
A
VSS
NC
NC
D1
P
NC
NC
Q17
A
A
QVLD
A
A
NC
D0
Q0
R
TDO
TCK
A
A
A
ODT
A
A
A
TMS
TDI
CY7C2544KV18 (2M x 36)
1
2
3
4
5
6
7
8
9
10
11
A
CQ
NC/288M
A
WPS
BWS2
K
BWS1
RPS
A
NC/144M
CQ
B
Q27
Q18
D18
A
BWS3
K
BWS0
A
D17
Q17
Q8
C
D27
Q28
D19
VSS
A
A
A
VSS
D16
Q7
D8
D
D28
D20
Q19
VSS
VSS
VSS
VSS
VSS
Q16
D15
D7
E
Q29
D29
Q20
VDDQ
VSS
VSS
VSS
VDDQ
Q15
D6
Q6
F
Q30
Q21
D21
VDDQ
VDD
VSS
VDD
VDDQ
D14
Q14
Q5
G
D30
D22
Q22
VDDQ
VDD
VSS
VDD
VDDQ
Q13
D13
D5
H
DOFF
VREF
VDDQ
VDDQ
VDD
VSS
VDD
VDDQ
VDDQ
VREF
ZQ
J
D31
Q31
D23
VDDQ
VDD
VSS
VDD
VDDQ
D12
Q4
D4
K
Q32
D32
Q23
VDDQ
VDD
VSS
VDD
VDDQ
Q12
D3
Q3
L
Q33
Q24
D24
VDDQ
VSS
VSS
VSS
VDDQ
D11
Q11
Q2
M
D33
Q34
D25
VSS
VSS
VSS
VSS
VSS
D10
Q1
D2
N
D34
D26
Q25
VSS
A
A
A
VSS
Q10
D9
D1
P
Q35
D35
Q26
A
A
QVLD
A
A
Q9
D0
Q0
R
TDO
TCK
A
A
A
ODT
A
A
A
TMS
TDI
Document #: 001-15885 Rev. *F
Page 5 of 26
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CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Table 1. Pin Definitions
Pin Name
IO
Pin Description
D[x:0]
InputData Input Signals. Sampled on the rising edge of K and K clocks during valid write operations.
Synchronous CY7C2540KV18 − D[7:0]
CY7C2555KV18 − D[8:0]
CY7C2542KV18 − D[17:0]
CY7C2544KV18 − D[35:0]
WPS
InputWrite Port Select − Active LOW. Sampled on the rising edge of the K clock. When asserted active, a
Synchronous write operation is initiated. Deasserting deselects the write port. Deselecting the write port ignores D[x:0].
NWS0,
NWS1
InputNibble Write Select 0, 1 − Active LOW (CY7C2540KV18 Only). Sampled on the rising edge of the K
Synchronous and K clocks during write operations. Used to select which nibble is written into the device during the
current portion of the write operations. Nibbles not written remain unaltered.
NWS0 controls D[3:0] and NWS1 controls D[7:4].
All the Nibble Write Selects are sampled on the same edge as the data. Deselecting a Nibble Write Select
ignores the corresponding nibble of data and it is not written into the device.
BWS0,
BWS1,
BWS2,
BWS3
InputByte Write Select 0, 1, 2 and 3 − Active LOW. Sampled on the rising edge of the K and K clocks during
Synchronous write operations. Used to select which byte is written into the device during the current portion of the write
operations. Bytes not written remain unaltered.
CY7C2555KV18 − BWS0 controls D[8:0].
CY7C2542KV18 − BWS0 controls D[8:0] and BWS1 controls D[17:9].
CY7C2544KV18 − BWS0 controls D[8:0], BWS1 controls D[17:9], BWS2 controls D[26:18] and BWS3 controls
D[35:27].
All the Byte Write Selects are sampled on the same edge as the data. Deselecting a Byte Write Select
ignores the corresponding byte of data and it is not written into the device.
A
InputAddress Inputs. Sampled on the rising edge of the K (read address) and K (write address) clocks during
Synchronous active read and write operations. These address inputs are multiplexed for both read and write operations.
Internally, the device is organized as 8M x 8 (2 arrays each of 4M x 8) for CY7C2540KV18, 8M x 9
(2 arrays each of 4M x 9) for CY7C2555KV18, 4M x 18 (2 arrays each of 2M x 18) for CY7C2542KV18,
and 2M x 36 (2 arrays each of 1M x 36) for CY7C2544KV18. Therefore, only 22 address inputs are needed
to access the entire memory array of CY7C2540KV18 and CY7C2555KV18, 21 address inputs for
CY7C2542KV18, and 20 address inputs for CY7C2544KV18. These inputs are ignored when the appropriate port is deselected.
Q[x:0]
OutputData Output Signals. These pins drive out the requested data during a read operation. Valid data is
Synchronous driven out on the rising edge of the K and K clocks during read operations. When the read port is
deselected, Q[x:0] are automatically tri-stated.
CY7C2540KV18 − Q[7:0]
CY7C2555KV18 − Q[8:0]
CY7C2542KV18 − Q[17:0]
CY7C2544KV18 − Q[35:0]
RPS
InputRead Port Select − Active LOW. Sampled on the rising edge of positive input clock (K). When active, a
Synchronous read operation is initiated. Deasserting deselects the read port. When deselected, the pending access is
allowed 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 two sequential transfers.
QVLD
Valid output
indicator
Valid Output Indicator. The Q Valid indicates valid output data. QVLD is edge aligned with CQ and CQ.
ODT [3]
On-Die
Termination
input pin
On-Die Termination Input. This pin is used for On-Die termination of the input signals. ODT range
selection is made during power up initialization. A LOW on this pin selects a low range that follows RQ/3.33
for 175Ω < RQ < 350Ω (where RQ is the resistor tied to ZQ pin). A HIGH on this pin selects a high range
that follows RQ/1.66 for 175Ω < RQ < 250Ω (where RQ is the resistor tied to ZQ pin). When left floating,
a high range termination value is selected by default.
Note
3. On-Die Termination (ODT) feature is supported for D[x:0], BWS[x:0], and K/K inputs.
Document #: 001-15885 Rev. *F
Page 6 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Table 1. Pin Definitions (continued)
Pin Name
IO
Pin Description
K
Input Clock
Positive Input Clock Input. The rising edge of K is used to capture synchronous inputs to the device
and to drive out data through Q[x:0]. All accesses are initiated on the rising edge of K.
K
Input Clock
Negative Input Clock Input. K is used to capture synchronous inputs being presented to the device and
to drive out data through Q[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 timing for the echo clocks is shown in Switching Characteristics on page 23.
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 timing for the echo clocks is shown in the Switching Characteristics on page 23.
ZQ
Input
Output Impedance Matching Input. This input is used to tune the device outputs to the system data bus
impedance. CQ, CQ, and Q[x:0] output impedance are set to 0.2 x RQ, where RQ is a resistor connected
between ZQ and ground. Alternatively, connect this pin directly to VDDQ, which enables the minimum
impedance mode. This pin cannot be connected directly to GND or left unconnected.
DOFF
Input
PLL Turn Off − Active LOW. Connecting this pin to ground turns off the PLL inside the device. The timing
in the operation with the PLL turned off differs from those listed in this data sheet. For normal operation,
connect this pin to a pull up through a 10 KΩ or less pull up resistor. The device behaves in QDR I mode
when the PLL is turned off. In this mode, the device can be operated at a frequency of up to 167 MHz
with QDR I timing.
TDO
Output
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/144M
Input
Not Connected to the Die. Can be tied to any voltage level.
NC/288M
Input
Not Connected to the Die. Can be tied to any voltage level.
VREF
VDD
VSS
VDDQ
InputReference
TDO for JTAG.
Reference Voltage Input. Static input used to set the reference level for HSTL inputs, outputs, and AC
measurement points.
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.
Document #: 001-15885 Rev. *F
Page 7 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Functional Overview
The CY7C2540KV18, CY7C2555KV18, CY7C2542KV18, and
CY7C2544KV18 are synchronous pipelined Burst SRAMs
equipped with 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 flows out through the read port. These devices multiplex the
address inputs 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 and avoids any
possible data contention, thereby simplifying system design.
Each access consists of two 8-bit data transfers in the case of
CY7C2540KV18, two 9-bit data transfers in the case of
CY7C2555KV18, two 18-bit data transfers in the case of
CY7C2542KV18, and two 36-bit data transfers in the case of
CY7C2544KV18 in one clock cycle.
These devices operate with a read latency of two cycles when
DOFF pin is tied HIGH. When DOFF pin is set LOW or connected
to VSS then the device behaves in QDR I mode with a read
latency of one clock cycle.
Accesses for both ports are initiated on the rising edge of the
positive input clock (K). All synchronous input and output timing
are referenced from the rising edge of the input clocks (K and K).
All synchronous data inputs (D[x:0]) pass through input registers
controlled by the input clocks (K and K). All synchronous data
outputs (Q[x:0]) pass through output registers controlled by the
rising edge of the input clocks (K and K) as well.
All synchronous control (RPS, WPS, NWS[x:0], BWS[x:0]) inputs
pass through input registers controlled by the rising edge of the
input clocks (K and K).
CY7C2542KV18 is described in the following sections. The
same basic descriptions apply to CY7C2540KV18,
CY7C2555KV18, and CY7C2544KV18.
Read Operations
The CY7C2542KV18 is organized internally as two arrays of 2M
x 18. Accesses are completed in a burst of two 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 is latched on the rising edge of the K clock. The address
presented to the address inputs is stored in the read address
register. Following the next two K clock rise, the corresponding
lowest order 18-bit word of data is driven onto the Q[17:0] using
K as the output timing reference. On the subsequent rising edge
of K, the next 18-bit data word is driven onto the Q[17:0]. The
requested data is valid 0.45 ns from the rising edge of the input
clock (K and K).
When the read port is deselected, the CY7C2542KV18 first
completes the pending read transactions. Synchronous internal
circuitry automatically tri-states the outputs following the next
rising edge of the positive input clock (K). This enables for a
seamless transition between devices without the insertion of wait
states in a depth expanded memory.
Document #: 001-15885 Rev. *F
Write Operations
Write operations are initiated by asserting WPS active at the
rising edge of the positive input clock (K). On the same K clock
rise the data presented to D[17:0] is latched and stored into the
lower 18-bit write data register, provided BWS[1:0] are both
asserted active. On the subsequent rising edge of the negative
input clock (K), the address is latched and the information
presented to D[17:0] is also stored into the write data register,
provided BWS[1:0] are both asserted active. The 36 bits of data
are then written into the memory array at the specified location.
When deselected, the write port ignores all inputs after the
pending write operations have been completed.
Byte Write Operations
Byte write operations are supported by the CY7C2542KV18. A
write operation is initiated as described in the Write Operations
section. The bytes that are written are determined by BWS0 and
BWS1, which are sampled with each set of 18-bit data words.
Asserting the appropriate Byte Write Select input during the data
portion of a write latches the data being presented and writes it
into the device. Deasserting the Byte Write Select input during
the data portion of a write enables the data stored in the device
for that byte to remain unaltered. This feature can be used to
simplify read, modify, or write operations to a byte write
operation.
Concurrent Transactions
The read and write ports on the CY7C2542KV18 operate
completely independently of one another. As 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. The user can start reads and writes in the same clock cycle.
If the ports access the same location at the same time, the SRAM
delivers the most recent information 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 CY7C2542KV18 has a port select input for each port. This
enables 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
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 VSS to enable 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 175Ω and 350Ω, with VDDQ = 1.5V. The
output impedance is adjusted every 1024 cycles upon power up
to account for drifts in supply voltage and temperature.
Page 8 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
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. These are free-running clocks and are
synchronized to the input clock of the QDR II+. The timing for the
echo clocks is shown in Switching Characteristics on page 23.
RQ/3.33 for 175Ω < RQ < 350Ω (where RQ is the resistor tied to
ZQ pin). A HIGH on this pin selects a high range that follows
RQ/1.66 for 175Ω < RQ < 250Ω (where RQ is the resistor tied to
ZQ pin). When left floating, a high range termination value is
selected by default. For a detailed description on the ODT implementation, refer to the application note, On-Die Termination for
QDRII+/DDRII+ SRAMs.
PLL
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.
On-Die Termination (ODT)
These devices have an On-Die Termination feature for Data
inputs (D[x:0]), Byte Write Selects (BWS[x:0]), and Input Clocks (K
and K). The termination resistors are integrated within the chip.
The ODT range selection is enabled through ball R6 (ODT pin).
The ODT termination tracks value of RQ where RQ is the resistor
tied to the ZQ pin. ODT range selection is made during power up
initialization. A LOW on this pin selects a low range that follows
These chips use a PLL that is designed to function between 120
MHz and the specified maximum clock frequency. During power
up, when the DOFF is tied HIGH, the PLL is locked after 20 μs
of stable clock. The PLL can also be reset by slowing or stopping
the input clocks K and K for a minimum of 30 ns. However, it is
not necessary to reset the PLL to lock to the desired frequency.
The PLL automatically locks 20 μs after a stable clock is
presented. The PLL may be disabled by applying ground to the
DOFF pin. When the PLL is turned off, the device behaves in
QDR I mode with one cycle latency and a longer access time).
For information, refer to the application note, PLL Considerations
in QDRII/DDRII/QDRII+/DDRII+.
Application Example
Figure 1 shows two QDR II+ used in an application.
Figure 1. Application Example
Vt
R
DATA IN
DATA OUT
Address
ZQ
ODT
SRAM #1
CQ/CQ
Q
D
A RPS WPS BWS K K
RQ = 250 ohms
SRAM #2
RQ = 250 ohms
CQ/CQ
Q
RPS WPS BWS K K
D
A
R
R
BUS MASTER RPS
(CPU or ASIC) WPS
ZQ
ODT
Vt
Vt
BWS
CLKIN1/CLKIN1
CLKIN2/CLKIN2
Source K
Source K
ODT
R
R = 50ohms, Vt = VDDQ /2
Document #: 001-15885 Rev. *F
Page 9 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Table 2. Truth Table
The truth table for CY7C2540KV18, CY7C2555KV18, CY7C2542KV18, and CY7C2544KV18 follow. [4, 5, 6, 7, 8, 9]
Operation
K
RPS WPS
DQ
DQ
Write Cycle:
Load address on the rising edge of K;
input write data on K and K rising edges.
L-H
X
L
D(A) at K(t) ↑
D(A + 1) at K(t) ↑
Read Cycle: (2.0 cycle Latency)
Load address on the rising edge of K;
wait two cycles; read data on K and K rising edges.
L-H
L
X
Q(A) at K(t + 2) ↑
Q(A + 1) at K(t + 2) ↑
NOP: No Operation
L-H
H
H
D=X
Q = High Z
D=X
Q = High Z
Stopped
X
X
Previous State
Previous State
Standby: Clock Stopped
Table 3. Write Cycle Descriptions
The write cycle description table for CY7C2540KV18 and CY7C2542KV18 follow. [4, 10]
BWS0/ BWS1/
K
K
L
L–H
–
L
L
–
L
H
L–H
L
H
–
H
L
L–H
H
L
–
H
H
L–H
H
H
–
NWS0
NWS1
L
Comments
During the data portion of a write sequence:
CY7C2540KV18 − both nibbles (D[7:0]) are written into the device.
CY7C2542KV18 − both bytes (D[17:0]) are written into the device.
L-H During the data portion of a write sequence:
CY7C2540KV18 − both nibbles (D[7:0]) are written into the device.
CY7C2542KV18 − both bytes (D[17:0]) are written into the device.
–
During the data portion of a write sequence:
CY7C2540KV18 − only the lower nibble (D[3:0]) is written into the device, D[7:4] remains unaltered.
CY7C2542KV18 − only the lower byte (D[8:0]) is written into the device, D[17:9] remains unaltered.
L–H During the data portion of a write sequence:
CY7C2540KV18 − only the lower nibble (D[3:0]) is written into the device, D[7:4] remains unaltered.
CY7C2542KV18 − only the lower byte (D[8:0]) is written into the device, D[17:9] remains unaltered.
–
During the data portion of a write sequence:
CY7C2540KV18 − only the upper nibble (D[7:4]) is written into the device, D[3:0] remains unaltered.
CY7C2542KV18 − only the upper byte (D[17:9]) is written into the device, D[8:0] remains unaltered.
L–H During the data portion of a write sequence:
CY7C2540KV18 − only the upper nibble (D[7:4]) is written into the device, D[3:0] remains unaltered.
CY7C2542KV18 − only the upper byte (D[17:9]) is written into the device, D[8:0] remains unaltered.
–
No data is written into the devices during this portion of a write operation.
L–H No data is written into the devices during this portion of a write operation.
Notes
4. X = “Don't Care,” H = Logic HIGH, L = Logic LOW, ↑represents rising edge.
5. Device powers up deselected with the outputs in a tri-state condition.
6. “A” represents address location latched by the devices when transaction was initiated. A + 1 represents the internal address sequence in the burst.
7. “t” represents the cycle at which a Read/Write operation is started. t + 1, and t + 2 are the first, and second clock cycles respectively succeeding the “t” clock cycle.
8. Data inputs are registered at K and K rising edges. Data outputs are delivered on K and K rising edges as well.
9. Ensure that when clock is stopped K = K and C = C = HIGH. This is not essential, but permits most rapid restart by overcoming transmission line charging symmetrically.
10. Is based on a write cycle that was initiated in accordance with the Write Cycle Descriptions table. NWS0, NWS1, BWS0, BWS1, BWS2 and BWS3 can be altered on
different portions of a write cycle, as long as the setup and hold requirements are achieved.
Document #: 001-15885 Rev. *F
Page 10 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Table 4. Write Cycle Descriptions
The write cycle description table for CY7C2555KV18 follow. [4, 10]
BWS0
K
K
Comments
L
L–H
–
During the data portion of a write sequence, the single byte (D[8:0]) is written into the device.
L
–
L–H
During the data portion of a write sequence, the single byte (D[8:0]) is written into the device.
H
L–H
–
No data is written into the device during this portion of a write operation.
H
–
L–H
No data is written into the device during this portion of a write operation.
Table 5. Write Cycle Descriptions
The write cycle description table for CY7C2544KV18 follow. [4, 10]
BWS0
BWS1
BWS2
BWS3
K
K
Comments
L
L
L
L
L–H
–
During the data portion of a write sequence, all four bytes (D[35:0]) are written into
the device.
L
L
L
L
–
L
H
H
H
L–H
L
H
H
H
–
H
L
H
H
L–H
H
L
H
H
–
H
H
L
H
L–H
H
H
L
H
–
H
H
H
L
L–H
H
H
H
L
–
H
H
H
H
L–H
H
H
H
H
–
Document #: 001-15885 Rev. *F
L–H During the data portion of a write sequence, all four bytes (D[35:0]) are written into
the device.
–
During the data portion of a write sequence, only the lower byte (D[8:0]) is written
into the device. D[35:9] remains unaltered.
L–H During the data portion of a write sequence, only the lower byte (D[8:0]) is written
into the device. D[35:9] remains unaltered.
–
During the data portion of a write sequence, only the byte (D[17:9]) is written into
the device. D[8:0] and D[35:18] remains unaltered.
L–H During the data portion of a write sequence, only the byte (D[17:9]) is written into
the device. D[8:0] and D[35:18] remains unaltered.
–
During the data portion of a write sequence, only the byte (D[26:18]) is written into
the device. D[17:0] and D[35:27] remains unaltered.
L–H During the data portion of a write sequence, only the byte (D[26:18]) is written into
the device. D[17:0] and D[35:27] remains unaltered.
–
During the data portion of a write sequence, only the byte (D[35:27]) is written into
the device. D[26:0] remains unaltered.
L–H During the data portion of a write sequence, only the byte (D[35:27]) is written into
the device. D[26:0] remains unaltered.
–
No data is written into the device during this portion of a write operation.
L–H No data is written into the device during this portion of a write operation.
Page 11 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
IEEE 1149.1 Serial Boundary Scan (JTAG)
These SRAMs incorporate a serial boundary scan Test Access
Port (TAP) in the FBGA package. This part is fully compliant with
IEEE Standard #1149.1-2001. The TAP operates using JEDEC
standard 1.8V IO logic levels.
Disabling the JTAG Feature
It is possible to operate the SRAM without using the JTAG
feature. To disable the TAP controller, TCK must be tied LOW
(VSS) to prevent clocking of the device. TDI and TMS are internally pulled up and may be unconnected. They may alternatively
be connected to VDD through a pull up resistor. TDO must be left
unconnected. Upon power up, the device comes up in a reset
state, which does not interfere with the operation of the device.
Test Access Port—Test Clock
The test clock is used only with the TAP controller. All inputs are
captured on the rising edge of TCK. All outputs are driven from
the falling edge of TCK.
Test Mode Select (TMS)
The TMS input is used to give commands to the TAP controller
and is sampled on the rising edge of TCK. This pin may be left
unconnected if the TAP is not used. The pin is pulled up internally, resulting in a logic HIGH level.
Test Data-In (TDI)
The TDI pin is used to serially input information into the registers
and can be connected to the input of any of the registers. The
register between TDI and TDO is chosen by the instruction that
is loaded into the TAP instruction register. For information about
loading the instruction register, see the TAP Controller State
Diagram on page 14. TDI is internally pulled up and can be
unconnected if the TAP is unused in an application. TDI is
connected to the most significant bit (MSB) on any register.
Instruction Register
Three-bit instructions can be serially loaded into the instruction
register. This register is loaded when it is placed between the TDI
and TDO pins, as shown in TAP Controller Block Diagram on
page 15. Upon power up, the instruction register is loaded with
the IDCODE instruction. It is also loaded with the IDCODE
instruction if the controller is placed in a reset state, as described
in the previous section.
When the TAP controller is in the Capture-IR state, the two least
significant bits are loaded with a binary “01” pattern to allow for
fault isolation of the board level serial test path.
Bypass Register
To save time when serially shifting data through registers, it is
sometimes advantageous to skip certain chips. The bypass
register is a single-bit register that can be placed between TDI
and TDO pins. This enables shifting of data through the SRAM
with minimal delay. The bypass register is set LOW (VSS) when
the BYPASS instruction is executed.
Boundary Scan Register
The boundary scan register is connected to all of the input and
output pins on the SRAM. Several No Connect (NC) pins are also
included in the scan register to reserve pins for higher density
devices.
The boundary scan register is loaded with the contents of the
RAM input and output ring when the TAP controller is in the
Capture-DR state and is then placed between the TDI and TDO
pins when the controller is moved to the Shift-DR state. The
EXTEST, SAMPLE/PRELOAD, and SAMPLE Z instructions can
be used to capture the contents of the input and output ring.
The Boundary Scan Order on page 18 shows the order in which
the bits are connected. Each bit corresponds to one of the bumps
on the SRAM package. The MSB of the register is connected to
TDI, and the LSB is connected to TDO.
Test Data-Out (TDO)
Identification (ID) Register
The TDO output pin is used to serially clock data out from the
registers. The output is active, depending upon the current state
of the TAP state machine (see Instruction Codes on page 17).
The output changes on the falling edge of TCK. TDO is
connected to the least significant bit (LSB) of any register.
The ID register is loaded with a vendor-specific, 32-bit code
during the Capture-DR state when the IDCODE command is
loaded in the instruction register. The IDCODE is hardwired into
the SRAM and can be shifted out when the TAP controller is in
the Shift-DR state. The ID register has a vendor code and other
information described in Identification Register Definitions on
page 17.
Performing a TAP Reset
A Reset is performed by forcing TMS HIGH (VDD) for five rising
edges of TCK. This Reset does not affect the operation of the
SRAM and can be performed while the SRAM is operating. At
power up, the TAP is reset internally to ensure that TDO comes
up in a High Z state.
TAP Registers
Registers are connected between the TDI and TDO pins to scan
the data in and out of the SRAM test circuitry. Only one register
can be selected at a time through the instruction registers. Data
is serially loaded into the TDI pin on the rising edge of TCK. Data
is output on the TDO pin on the falling edge of TCK.
Document #: 001-15885 Rev. *F
TAP Instruction Set
Eight different instructions are possible with the three-bit
instruction register. All combinations are listed in Instruction
Codes on page 17. Three of these instructions are listed as
RESERVED and must not be used. The other five instructions
are described in this section in detail.
Instructions are loaded into the TAP controller during the Shift-IR
state when the instruction register is placed between TDI and
TDO. During this state, instructions are shifted through the
instruction register through the TDI and TDO pins. To execute
the instruction after it is shifted in, the TAP controller must be
moved into the Update-IR state.
Page 12 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
IDCODE
BYPASS
The IDCODE instruction loads a vendor-specific, 32-bit code into
the instruction register. It also places the instruction register
between the TDI and TDO pins and shifts the IDCODE out of the
device when the TAP controller enters the Shift-DR state. The
IDCODE instruction is loaded into the instruction register at
power up or whenever the TAP controller is supplied a
Test-Logic-Reset state.
When the BYPASS instruction is loaded in the instruction
register and the TAP is placed in a Shift-DR state, the bypass
register is placed between the TDI and TDO pins. The advantage
of the BYPASS instruction is that it shortens the boundary scan
path when multiple devices are connected together on a board.
SAMPLE Z
The SAMPLE Z instruction connects the boundary scan register
between the TDI and TDO pins when the TAP controller is in a
Shift-DR state. The SAMPLE Z command puts the output bus
into a High Z state until the next command is supplied during the
Update IR state.
SAMPLE/PRELOAD
SAMPLE/PRELOAD is a 1149.1 mandatory instruction. When
the SAMPLE/PRELOAD instructions are loaded into the
instruction register and the TAP controller is in the Capture-DR
state, a snapshot of data on the input and output pins is captured
in the boundary scan register.
The user must be aware that the TAP controller clock can only
operate at a frequency up to 20 MHz, while the SRAM clock
operates more than an order of magnitude faster. Because there
is a large difference in the clock frequencies, it is possible that
during the Capture-DR state, an input or output undergoes a
transition. The TAP may then try to capture a signal while in
transition (metastable state). This does not harm the device, but
there is no guarantee as to the value that is captured.
Repeatable results may not be possible.
To guarantee that the boundary scan register captures the
correct value of a signal, the SRAM signal must be stabilized
long enough to meet the TAP controller's capture setup plus hold
times (tCS and tCH). The SRAM clock input might not be captured
correctly if there is no way in a design to stop (or slow) the clock
during a SAMPLE/PRELOAD instruction. If this is an issue, it is
still possible to capture all other signals and simply ignore the
value of the CK and CK captured in the boundary scan register.
EXTEST
The EXTEST instruction drives the preloaded data out through
the system output pins. This instruction also connects the
boundary scan register for serial access between the TDI and
TDO in the Shift-DR controller state.
EXTEST OUTPUT BUS TRI-STATE
IEEE Standard 1149.1 mandates that the TAP controller be able
to put the output bus into a tri-state mode.
The boundary scan register has a special bit located at bit #108.
When this scan cell, called the “extest output bus tri-state,” is
latched into the preload register during the Update-DR state in
the TAP controller, it directly controls the state of the output
(Q-bus) pins, when the EXTEST is entered as the current
instruction. When HIGH, it enables the output buffers to drive the
output bus. When LOW, this bit places the output bus into a High
Z condition.
This bit can be set by entering the SAMPLE/PRELOAD or
EXTEST command, and then shifting the desired bit into that
cell, during the Shift-DR state. During Update-DR, the value
loaded into that shift-register cell latches into the preload
register. When the EXTEST instruction is entered, this bit directly
controls the output Q-bus pins. Note that this bit is pre-set LOW
to enable the output when the device is powered up, and also
when the TAP controller is in the Test-Logic-Reset state.
Reserved
These instructions are not implemented but are reserved for
future use. Do not use these instructions.
After the data is captured, it is possible to shift out the data by
putting the TAP into the Shift-DR state. This places the boundary
scan register between the TDI and TDO pins.
PRELOAD places an initial data pattern at the latched parallel
outputs of the boundary scan register cells before the selection
of another boundary scan test operation.
The shifting of data for the SAMPLE and PRELOAD phases can
occur concurrently when required, that is, while the data
captured is shifted out, the preloaded data can be shifted in.
Document #: 001-15885 Rev. *F
Page 13 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Figure 2. TAP Controller State Diagram
The state diagram for the TAP controller follows. [11]
1
TEST-LOGIC
RESET
0
0
TEST-LOGIC/
IDLE
1
SELECT
DR-SCAN
1
1
SELECT
IR-SCAN
0
0
1
1
CAPTURE-DR
CAPTURE-IR
0
0
SHIFT-DR
0
SHIFT-IR
1
1
EXIT1-DR
1
EXIT1-IR
0
0
PAUSE-IR
1
0
1
EXIT2-DR
0
EXIT2-IR
1
1
UPDATE-IR
UPDATE-DR
1
1
0
PAUSE-DR
0
0
0
1
0
Note
11. The 0/1 next to each state represents the value at TMS at the rising edge of TCK.
Document #: 001-15885 Rev. *F
Page 14 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
Figure 3. TAP Controller Block Diagram
0
Bypass Register
2
Selection
Circuitry
TDI
1
0
Selection
Circuitry
Instruction Register
31
30
29
.
.
2
1
0
1
0
TDO
Identification Register
108
.
.
.
.
2
Boundary Scan Register
TCK
TAP Controller
TMS
TAP Electrical Characteristics
Over the Operating Range [12, 13, 14]
Parameter
Description
Test Conditions
Min
Max
Unit
VOH1
Output HIGH Voltage
IOH = −2.0 mA
1.4
V
VOH2
Output HIGH Voltage
IOH = −100 μA
1.6
V
VOL1
Output LOW Voltage
IOL = 2.0 mA
0.4
V
VOL2
Output LOW Voltage
IOL = 100 μA
0.2
V
VIH
Input HIGH Voltage
VIL
Input LOW Voltage
IX
Input and Output Load Current
0.65VDD VDD + 0.3
GND ≤ VI ≤ VDD
V
–0.3
0.35VDD
V
–5
5
μA
Notes
12. These characteristics pertain to the TAP inputs (TMS, TCK, TDI and TDO). Parallel load levels are specified in the Electrical Characteristics table.
13. Overshoot: VIH(AC) < VDDQ + 0.35V (Pulse width less than tCYC/2), Undershoot: VIL(AC) > −0.3V (Pulse width less than tCYC/2).
14. All Voltage referenced to Ground.
Document #: 001-15885 Rev. *F
Page 15 of 26
[+] Feedback
CY7C2540KV18, CY7C2555KV18
CY7C2542KV18, CY7C2544KV18
TAP AC Switching Characteristics
Over the Operating Range [15, 16]
Parameter
Description
Min
Max
Unit
20
MHz
tTCYC
TCK Clock Cycle Time
tTF
TCK Clock Frequency
tTH
TCK Clock HIGH
20
ns
tTL
TCK Clock LOW
20
ns
tTMSS
TMS Setup to TCK Clock Rise
5
ns
tTDIS
TDI Setup to TCK Clock Rise
5
ns
tCS
Capture Setup to TCK Rise
5
ns
tTMSH
TMS Hold after TCK Clock Rise
5
ns
tTDIH
TDI Hold after Clock Rise
5
ns
tCH
Capture Hold after Clock Rise
5
ns
50
ns
Setup Times
Hold Times
Output Times
tTDOV
TCK Clock LOW to TDO Valid
tTDOX
TCK Clock LOW to TDO Invalid
10
0
ns
ns
TAP Timing and Test Conditions
Figure 4 shows the TAP timing and test conditions. [16]
Figure 4. TAP Timing and Test Conditions
0.9V
ALL INPUT PULSES
1.8V
50Ω
0.9V
TDO
0V
Z0 = 50Ω
(a)
CL = 20 pF
tTH
GND
tTL
Test Clock
TCK
tTCYC
tTMSH
tTMSS
Test Mode Select
TMS
tTDIS
tTDIH
Test Data In
TDI
Test Data Out
TDO
tTDOV
tTDOX
Notes
15. tCS and tCH refer to the setup and hold time requirements of latching data from the boundary scan register.
16. Test conditions are specified using the load in TAP AC Test Conditions. tR/tF = 1 ns.
Document #: 001-15885 Rev. *F
Page 16 of 26
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Table 6. Identification Register Definitions
Instruction Field
Value
CY7C2540KV18
CY7C2555KV18
CY7C2542KV18
CY7C2544KV18
000
000
000
000
Revision Number
(31:29)
Cypress Device ID
(28:12)
Cypress JEDEC ID
(11:1)
Description
Version number.
11010010100000100 11010010100001100 11010010100010100 11010010100100100 Defines the type of
SRAM.
00000110100
00000110100
00000110100
00000110100
1
1
1
1
ID Register
Presence (0)
Allows unique
identification of
SRAM vendor.
Indicates the
presence of an ID
register.
Table 7. Scan Register Sizes
Register Name
Bit Size
Instruction
3
Bypass
1
ID
32
Boundary Scan
109
Table 8. Instruction Codes
Instruction
Code
Description
EXTEST
000
Captures the input and output ring contents.
IDCODE
001
Loads the ID register with the vendor ID code and places the register between TDI and TDO.
This operation does not affect SRAM operation.
SAMPLE Z
010
Captures the input and output contents. Places the boundary scan register between TDI and
TDO. Forces all SRAM output drivers to a High Z state.
RESERVED
011
Do Not Use: This instruction is reserved for future use.
SAMPLE/PRELOAD
100
Captures the input and output contents. Places the boundary scan register between TDI and
TDO. Does not affect the SRAM operation.
RESERVED
101
Do Not Use: This instruction is reserved for future use.
RESERVED
110
Do Not Use: This instruction is reserved for future use.
BYPASS
111
Places the bypass register between TDI and TDO. This operation does not affect SRAM
operation.
Document #: 001-15885 Rev. *F
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Table 9. Boundary Scan Order
Bit #
Bump ID
Bit #
Bump ID
Bit #
Bump ID
Bit #
Bump ID
0
6R
28
10G
56
6A
84
1J
1
6P
29
9G
57
5B
85
2J
2
6N
30
11F
58
5A
86
3K
3
7P
31
11G
59
4A
87
3J
4
7N
32
9F
60
5C
88
2K
5
7R
33
10F
61
4B
89
1K
6
8R
34
11E
62
3A
90
2L
7
8P
35
10E
63
2A
91
3L
8
9R
36
10D
64
1A
92
1M
9
11P
37
9E
65
2B
93
1L
10
10P
38
10C
66
3B
94
3N
11
10N
39
11D
67
1C
95
3M
12
9P
40
9C
68
1B
96
1N
13
10M
41
9D
69
3D
97
2M
14
11N
42
11B
70
3C
98
3P
15
9M
43
11C
71
1D
99
2N
16
9N
44
9B
72
2C
100
2P
17
11L
45
10B
73
3E
101
1P
18
11M
46
11A
74
2D
102
3R
19
9L
47
10A
75
2E
103
4R
20
10L
48
9A
76
1E
104
4P
21
11K
49
8B
77
2F
105
5P
22
10K
50
7C
78
3F
106
5N
23
9J
51
6C
79
1G
107
5R
24
9K
52
8A
80
1F
108
Internal
25
10J
53
7A
81
3G
26
11J
54
7B
82
2G
27
11H
55
6B
83
1H
Document #: 001-15885 Rev. *F
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Power Up Sequence in QDR II+ SRAM
PLL Constraints
QDR II+ SRAMs must be powered up and initialized in a
predefined manner to prevent undefined operations.
■
PLL uses K clock as its synchronizing input. The input must
have low phase jitter, which is specified as tKC Var.
■
The PLL functions at frequencies down to 120 MHz.
■
If the input clock is unstable and the PLL is enabled, then the
PLL may lock onto an incorrect frequency, causing unstable
SRAM behavior. To avoid this, provide 20 μs of stable clock to
relock to the desired clock frequency.
Power Up Sequence
■
Apply power and drive DOFF either HIGH or LOW (All other
inputs can be HIGH or LOW).
❐ Apply VDD before VDDQ.
❐ Apply VDDQ before VREF or at the same time as VREF.
❐ Drive DOFF HIGH.
■
Provide stable DOFF (HIGH), power and clock (K, K) for 20 μs
to lock the PLL
~
~
Figure 5. Power Up Waveforms
K
K
~
~
Unstable Clock
> 20Ps Stable clock
Start Normal
Operation
Clock Start (Clock Starts after V DD / V DDQ Stable)
VDD / VDDQ
DOFF
Document #: 001-15885 Rev. *F
V DD / V DDQ Stable (< +/- 0.1V DC per 50ns )
Fix HIGH (or tie to VDDQ)
Page 19 of 26
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Maximum Ratings
Exceeding maximum ratings may impair the useful life of the
device. These user guidelines are not tested.
Storage Temperature ................................. –65°C to +150°C
Ambient Temperature with Power Applied.. –55°C to +125°C
Supply Voltage on VDD Relative to GND ........–0.5V to +2.9V
Supply Voltage on VDDQ Relative to GND.......–0.5V to +VDD
Neutron Soft Error Immunity
Parameter
Description
Test
Conditions
Typ
Max*
Unit
LSBU
Logical
Single-Bit
Upsets
25°C
197
216
FIT/
Mb
LMBU
Logical
Multi-Bit
Upsets
25°C
0
0.01
FIT/
Mb
SEL
Single Event
Latchup
85°C
0
0.1
FIT/
Dev
DC Applied to Outputs in High Z ........ –0.5V to VDDQ + 0.3V
DC Input Voltage [13].............................. –0.5V to VDD + 0.3V
Current into Outputs (LOW)......................................... 20 mA
Static Discharge Voltage (MIL-STD-883, M. 3015). > 2,001V
Latch-up Current.................................................... > 200 mA
Operating Range
Range
Commercial
Industrial
Ambient
Temperature (TA)
0°C to +70°C
–40°C to +85°C
VDD
[17]
1.8 ± 0.1V
VDDQ
[17]
1.4V to
VDD
* No LMBU or SEL events occurred during testing; this column represents a
statistical χ2, 95% confidence limit calculation. For more details refer to Application Note AN 54908 “Accelerated Neutron SER Testing and Calculation of
Terrestrial Failure Rates”
Electrical Characteristics
DC Electrical Characteristics
Over the Operating Range [14]
Parameter
VDD
VDDQ
VOH
VOL
VOH(LOW)
VOL(LOW)
VIH
VIL
IX
Description
Power Supply Voltage
IO Supply Voltage
Output HIGH Voltage
Output LOW Voltage
Output HIGH Voltage
Output LOW Voltage
Input HIGH Voltage
Input LOW Voltage
Input Leakage Current
Test Conditions
IOZ
VREF
Output Leakage Current
GND ≤ VI ≤ VDDQ, Output Disabled
Input Reference Voltage [20] Typical Value = 0.75V
Note 18
Note 19
IOH = −0.1 mA, Nominal Impedance
IOL = 0.1 mA, Nominal Impedance
GND ≤ VI ≤ VDDQ
Min
Typ
Max
Unit
1.7
1.8
1.9
V
1.4
1.5
VDD
V
VDDQ/2 – 0.12
VDDQ/2 + 0.12 V
VDDQ/2 – 0.12
VDDQ/2 + 0.12 V
VDDQ – 0.2
VDDQ
V
VSS
0.2
V
VREF + 0.1
VDDQ + 0.15
V
–0.15
VREF – 0.1
V
−2
2
μA
−2
0.68
0.75
2
0.95
μA
V
Notes
17. Power up: Assumes a linear ramp from 0V to VDD(min) within 200 ms. During this time VIH < VDD and VDDQ < VDD.
18. Output are impedance controlled. IOH = −(VDDQ/2)/(RQ/5) for values of 175 ohms
