Cypress CY7C026A-20AC 16k x 16/18 dual-port static ram Datasheet

25/0251
CY7C026A
CY7C036A
16K x 16/18 Dual-Port Static RAM
• Automatic power-down
• Expandable data bus to 32/36 bits or more using Master/Slave chip select when using more than one device
• On-chip arbitration logic
• Semaphores included to permit software handshaking
between ports
• INT flags for port-to-port communication
• Separate upper-byte and lower-byte control
• Pin select for Master or Slave
• Commercial and Industrial temperature ranges
• Available in 100-Pin TQFP
• Pin-compatible and functionally equivalent to IDT70261
Features
• True dual-ported memory cells which allow simultaneous access of the same memory location
• 16K x 16 organization (CY7C026A)
• 16K x 18 organization (CY7C036A)
• 0.35-micron CMOS for optimum speed/power
• High-speed access: 12[1]/15/20 ns
• Low operating power
— Active: ICC = 180 mA (typical)
— Standby: ISB3 = 0.05 mA (typical)
• Fully asynchronous operation
Logic Block Diagram
R/WL
UBL
R/WR
UBR
CEL
CER
LBL
LBR
OEL
OE R
[2]
I/O 8/9L–I/O 15/17L
[3]
8/9
8/9
8/9
I/O
Control
I/O 0L–I/O 7/8L
14
A0L–A13L
Address
Decode
8/9
I/O
Control
[3]
I/O0L–I/O7/8R
Address
Decode
True Dual-Ported
RAM Array
[2]
I/O8/9L–I/O 15/17R
14
14
A0R–A13R
14
A0L–A13L
CEL
OEL
R/WL
SEM L
A0R–A13R
CER
OE R
R/WR
SEM R
Interrupt
Semaphore
Arbitration
[4]
[4]
BUSYL
INTL
UBL
LBL
BUSYR
INT R
UBR
LB R
M/S
Notes:
1. See page 6 for Load Conditions.
2. I/O8–I/O15 for x16 devices; I/O9–I/O17 for x18 devices.
3. I/O0–I/O7 for x16 devices; I/O0–I/O8 for x18 devices.
4. BUSY is an output in master mode and an input in slave mode.
For the most recent information, visit the Cypress web site at www.cypress.com
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
March 3, 2000
CY7C026A
CY7C036A
Each port has independent control pins: Chip Enable (CE),
Read or Write Enable (R/W), and Output Enable (OE). Two
flags are provided on each port (BUSY and INT). BUSY signals that the port is trying to access the same location currently
being accessed by the other port. The Interrupt flag (INT) permits communication between ports or systems by means of a
mail box. The semaphores are used to pass a flag, or token,
from one port to the other to indicate that a shared resource is
in use. The semaphore logic is comprised of eight shared
latches. Only one side can control the latch (semaphore) at
any time. Control of a semaphore indicates that a shared resource is in use. An automatic power-down feature is controlled independently on each port by the chip enable pin.
Functional Description
The CY7C026A and CY7C036A are low-power CMOS 16K x
16/18 dual-port static RAMs. Various arbitration schemes are
included on the devices to handle situations when multiple processors access the same piece of data. Two ports are provided, permitting independent, asynchronous access for reads
and writes to any location in memory. The devices can be utilized as standalone 16/18-bit dual-port static RAMs or multiple
devices can be combined in order to function as a 32/36-bit or
wider master/slave dual-port static RAM. An M/S pin is provided for implementing 32/36-bit or wider memory applications
without the need for separate master and slave devices or additional discrete logic. Application areas include interprocessor/multiprocessor designs, communications status buffering,
and dual-port video/graphics memory.
The CY7C026A and CY7C036A are available in 100-pin Thin
Quad Plastic Flatpack (TQFP) packages.
Pin Configurations
A7L
A8L
A9L
A10L
A11L
A12L
A13L
LBL
UBL
CEL
SEML
R/WL
VCC
OEL
I/O0L
I/O1L
GND
I/O2L
I/O3L
I/O4L
I/O5L
I/O6L
I/O7L
I/O8L
I/O9L
100-Pin TQFP (Top View)
100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76
NC
1
75
NC
NC
2
74
NC
NC
3
73
NC
NC
4
72
A6L
I/O10L
5
71
A5L
I/O11L
6
70
A4L
I/O12L
7
69
A3L
I/O13L
8
68
A2L
GND
9
67
A1L
I/O14L
10
66
A0L
I/O15L
11
65
INTL
VCC
12
64
BUSYL
GND
13
63
GND
I/O0R
14
62
M/S
I/O1R
15
61
BUSYR
I/O2R
16
60
INTR
VCC
17
59
A0R
I/O3R
18
58
A1R
I/O4R
19
57
A2R
I/O5R
20
56
A3R
I/O6R
21
55
A4R
NC
22
54
A5R
NC
23
53
NC
NC
24
52
NC
NC
25
51
NC
CY7C026A (16K x 16)
2
A6R
A7R
A8R
A9R
A10R
A11R
A12R
A13R
LBR
UBR
CER
SEMR
GND
R/WR
OER
I/O15R
GND
I/O14R
I/O13R
I/O12R
I/O11R
I/O10R
I/O9R
I/O8R
I/O7R
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
CY7C026A
CY7C036A
Pin Configurations (continued)
A 7L
A 6L
A 8L
A 10L
A 9L
A 11L
LB L
A 12L
UB L
SEM L
CE L
R/W L
OE L
VCC
I/O 0L
I/O 1L
I/O 2L
GND
I/O 3L
I/O 4L
I/O 5L
I/O 6L
I/O 7L
I/O 9L
I/O 10L
100-Pin TQFP
Top View
100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76
67
66
65
64
63
62
CY7C036A (16K x 18)
14
61
60
59
15
16
17
18
19
20
21
BUSY R
INT R
A 0R
A 1R
57
56
55
54
53
A 2R
A 3R
A 4R
A 13R
NC
NC
NC
A 5R
A 6R
A 7R
A 9R
A 8R
A 10R
A 11R
LB R
A 12R
UB R
CE R
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
SEM R
24
25
R/W R
GND
NC
NC
A 5L
A 4L
A 3L
A 2L
A 1L
A 0L
INT L
BUSY L
GND
M/S
58
52
51
OE R
22
23
I/O 7R
I/O 17R
I/O 16R
I/O 4R
I/O 5R
I/O 6R
I/O 8R
68
GND
I/O 3R
5
6
7
8
9
10
11
12
13
I/O 15R
VCC
GND
I/O 0R
I/O 1R
I/O 2R
VCC
72
71
70
69
I/O 14R
I/O 15L
I/O 16L
3
4
NC
NC
A 13L
I/O 13R
GND
73
I/O 12R
I/O 12L
I/O 13L
I/O 14L
2
I/O 11R
I/O 11L
NC
74
I/O 10R
I/O 17L
75
1
I/O 9R
NC
NC
I/O 8L
Selection Guide
CY7C026A
CY7C036A
-12[1]
CY7C026A
CY7C036A
-15
CY7C026A
CY7C036A
-20
Maximum Access Time (ns)
12
15
20
Typical Operating Current (mA)
195
190
180
Typical Standby Current for ISB1 (mA) (Both Ports TTL Level)
55
50
45
0.05
0.05
0.05
Typical Standby Current for ISB3 (mA) (Both Ports CMOS Level)
3
CY7C026A
CY7C036A
Pin Definitions
Left Port
Right Port
Description
CEL
CER
Chip Enable
R/WL
R/WR
Read/Write Enable
OEL
OER
Output Enable
A0L–A13L
A0R–A13R
Address
I/O0L–I/O 17L
I/O0R–I/O 17R
Data Bus Input/Output
SEML
SEMR
Semaphore Enable
UBL
UBR
Upper Byte Select (I/O8–I/O15 for x16 devices; I/O9–I/O 17 for x18 devices)
LBL
LBR
Lower Byte Select (I/O0–I/O 7 for x16 devices; I/O 0–I/O8 for x18 devices)
INTL
INTR
Interrupt Flag
BUSYL
BUSYR
Busy Flag
M/S
Master or Slave Select
VCC
Power
GND
Ground
NC
No Connect
DC Input Voltage[5] ........................................–0.5V to + 7.0V
Maximum Ratings
Output Current into Outputs (LOW)............................. 20 mA
(Above which the useful life may be impaired. For user guidelines, not tested.)
Static Discharge Voltage .......................................... >2001V
Storage Temperature .................................–65°C to +150°C
Latch-Up Current .................................................... >200 mA
Ambient Temperature with
Power Applied .............................................–55°C to +125°C
Operating Range
Supply Voltage to Ground Potential ............... –0.3V to +7.0V
DC Voltage Applied to Outputs
in High Z State ............................................... –0.5V to +7.0V
Range
Ambient
Temperature
VCC
Commercial
0°C to +70°C
5V ± 10%
–40°C to +85°C
5V ± 10%
Industrial
Note:
5. Pulse width < 20 ns.
4
CY7C026A
CY7C036A
Electrical Characteristics Over the Operating Range
CY7C026A
CY7C036A
-12[1]
Parameter
Description
Min.
Typ.
VOH
Output HIGH Voltage (VCC=Min., IOH=
–4.0 mA)
VOL
Output LOW Voltage (VCC=Min., IOH=
+4.0 mA)
VIH
Input HIGH Voltage
VIL
Input LOW Voltage
IOZ
Output Leakage Current
ICC
Operating Current (VCC = Max., Com’l.
IOUT = 0 mA) Outputs Disabled
Indust.
195
Standby Current
(Both Ports TTL Level)
CEL & CER ≥ V IH, f = fMAX
55
ISB1
ISB2
ISB3
ISB4
-15
Max.
Min.
2.4
Typ.
Standby Current
(Both Ports CMOS Level)
CEL & CER ≥ V CC –0.2V, f = 0
Standby Current
(One Port CMOS Level)
CEL | CER ≥ VIH, f = fMAX[6]
75
Indust.
125
205
Indust.
Com’l.
0.05
0.5
Indust.
Com’l.
115
185
Indust.
10
190
285
215
305
50
70
65
95
120
180
135
205
0.05
0.5
0.05
0.5
110
160
125
175
Unit
V
0.4
V
V
0.8
–10
325
Max.
2.2
0.8
Com’l.
Typ.
0.4
2.2
10
Min.
2.4
0.4
–10
Com’l.
Max.
2.4
2.2
Standby Current
(One Port TTL Level)
CEL | CER ≥ VIH, f = fMAX
-20
–10
180
0.8
V
10
µA
275
mA
mA
45
65
mA
mA
110
160
mA
mA
0.05
0.5
mA
mA
100
140
mA
mA
Capacitance[7]
Parameter
Description
CIN
Input Capacitance
COUT
Output Capacitance
Test Conditions
TA = 25°C, f = 1 MHz,
VCC = 5.0V
Max.
Unit
10
pF
10
pF
Notes:
6. fMAX = 1/tRC = All inputs cycling at f = 1/tRC (except output enable). f = 0 means no address or control lines change. This applies only to inputs at CMOS level
standby ISB3.
7. Tested initially and after any design or process changes that may affect these parameters.
5
CY7C026A
CY7C036A
AC Test Loads and Waveforms
5V
5V
R1 = 893Ω
RTH = 250Ω
OUTPUT
OUTPUT
R1 = 893Ω
OUTPUT
C = 30 pF
C = 30 pF
R2 = 347Ω
C = 5 pF
R2 = 347Ω
VTH = 1.4V
(a) Normal Load (Load 1)
(c) Three-State Delay (Load 2)
(Used for tLZ, tHZ, tHZWE, & tLZWE
including scope and jig)
(b) Thévenin Equivalent (Load 1)
AC Test Loads (Applicable to -12 only)[8]
OUTPUT
Z0 = 50Ω
ALL INPUT PULSES
R = 50Ω
3.0V
C
10%
GND
90%
10%
90%
≤ 3 ns
≤ 3 ns
VTH = 1.4V
(a) Load 1 (-12 only)
1 .00
0.90
∆ (ns) for all -12 access times
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.1 0
0.00
10
15
20
25
Capacitance (pF)
(b) Load Derating Curve
Note:
8. Test Conditions: C = 10 pF.
6
30
35
CY7C026A
CY7C036A
Switching Characteristics Over the Operating Range[9]
CY7C026A
CY7C036A
-12[1]
Parameter
Description
Min.
-15
Max.
Min.
-20
Max.
Min.
Max.
Unit
READ CYCLE
tRC
Read Cycle Time
12
15
tAA
Address to Data Valid
tOHA
Output Hold From Address Change
tACE[10]
CE LOW to Data Valid
12
15
20
ns
tDOE
OE LOW to Data Valid
8
10
12
ns
tLZOE[11, 12, 13]
tHZOE[11, 12, 13]
tLZCE[11, 12, 13]
tHZCE[11, 12, 13]
tPU[13]
tPD[13]
tABE[10]
OE LOW to Low Z
12
3
15
3
3
OE HIGH to High Z
3
CE HIGH to High Z
CE LOW to Power-Up
0
20
10
ns
12
3
10
0
ns
ns
3
3
10
ns
3
3
10
CE LOW to Low Z
20
ns
ns
12
0
ns
ns
CE HIGH to Power-Down
12
15
20
ns
Byte Enable Access Time
12
15
20
ns
WRITE CYCLE
tWC
Write Cycle Time
12
15
20
ns
tSCE[10]
CE LOW to Write End
10
12
15
ns
tAW
Address Valid to Write End
10
12
15
ns
tHA
Address Hold From Write End
0
0
0
ns
tSA[10]
Address Set-Up to Write Start
0
0
0
ns
tPWE
Write Pulse Width
10
12
15
ns
tSD
Data Set-Up to Write End
10
10
15
ns
tHD[15]
tHZWE[12, 13]
tLZWE[12, 13]
tWDD[14]
tDDD[14]
Data Hold From Write End
0
0
0
ns
R/W LOW to High Z
10
R/W HIGH to Low Z
3
10
3
12
3
ns
ns
Write Pulse to Data Delay
25
30
45
ns
Write Data Valid to Read Data Valid
20
25
30
ns
Notes:
9. Test conditions assume signal transition time of 3 ns or less, timing reference levels of 1.5V, input pulse levels of 0 to 3.0V, and output loading of the specified
I OI/IOH and 30-pF load capacitance.
10. To access RAM, CE=L, UB=L, SEM=H. To access semaphore, CE=H and SEM=L. Either condition must be valid for the entire tSCE time.
11. At any given temperature and voltage condition for any given device, tHZCE is less than tLZCE and tHZOE is less than tLZOE.
12. Test conditions used are Load 3.
13. This parameter is guaranteed but not tested.
14. For information on port-to-port delay through RAM cells from writing port to reading port, refer to Read Timing with Busy waveform.
15. For 15 ns industrial parts tHD Min. is 0.5 ns.
7
CY7C026A
CY7C036A
Switching Characteristics Over the Operating Range[9] (continued)
CY7C026A
CY7C036A
-12[1]
Parameter
BUSY TIMING
Description
Min.
-15
Max.
Min.
-20
Max.
Min.
Max.
Unit
[16]
tBLA
BUSY LOW from Address Match
12
15
20
ns
tBHA
BUSY HIGH from Address Mismatch
12
15
20
ns
tBLC
BUSY LOW from CE LOW
12
15
20
ns
tBHC
BUSY HIGH from CE HIGH
12
15
17
ns
tPS
Port Set-Up for Priority
5
5
5
ns
tWB
R/W HIGH after BUSY (Slave)
0
0
0
ns
tWH
R/W HIGH after BUSY HIGH (Slave)
11
13
15
ns
tBDD[17]
BUSY HIGH to Data Valid
INTERRUPT TIMING
12
15
20
ns
[16]
tINS
INT Set Time
12
15
20
ns
tINR
INT Reset Time
12
15
20
ns
SEMAPHORE TIMING
tSOP
SEM Flag Update Pulse (OE or SEM)
10
10
10
ns
tSWRD
SEM Flag Write to Read Time
5
5
5
ns
tSPS
SEM Flag Contention Window
5
5
5
ns
tSAA
SEM Address Access Time
12
15
20
ns
Timing
Data Retention Mode
Data Retention Mode
The CY7C026A and CY7C036A are designed with battery
backup in mind. Data retention voltage and supply current are
guaranteed over temperature. The following rules ensure data
retention:
VCC
1. Chip Enable (CE) must be held HIGH during data retention, within VCC to VCC – 0.2V.
4.5V
VCC > 2.0V
4.5V
VCC to VCC – 0.2V
CE
tRC
V
IH
2. CE must be kept between VCC – 0.2V and 70% of VCC
during the power-up and power-down transitions.
Parameter
3. The RAM can begin operation >tRC after VCC reaches the
minimum operating voltage (4.5 volts).
ICC DR1
Notes:
16. Test conditions used are Load 2.
17. tBDD is a calculated parameter and is the greater of tWDD–tPWE (actual) or t DDD–tSD (actual).
18. CE = VCC, Vin = GND to VCC, TA = 25°C. This parameter is guaranteed but not tested.
8
Test Conditions[18]
@ VCCDR = 2V
Max.
Unit
1.5
mA
CY7C026A
CY7C036A
Switching Waveforms
Read Cycle No.1 (Either Port Address Access)[19, 20, 21]
tRC
ADDRESS
tOHA
DATA OUT
tAA
tOHA
PREVIOUS DATA VALID
DATA VALID
Read Cycle No.2 (Either Port CE/OE Access)[19, 22, 23]
tACE
CE and
LB or UB
tHZCE
tDOE
OE
tHZOE
tLZOE
DATA VALID
DATA OUT
tLZCE
tPU
tPD
ICC
CURRENT
ISB
Read Cycle No. 3 (Either Port)[19, 21, 22, 23]
tRC
ADDRESS
tAA
tOHA
UB or LB
tHZCE
tLZCE
tABE
CE
tHZCE
tACE
tLZCE
DATA OUT
Notes:
19. R/W is HIGH for read cycles.
20. Device is continuously selected CE = VIL and UB or LB = VIL . This waveform cannot be used for semaphore reads.
21. OE = VIL.
22. Address valid prior to or coincident with CE transition LOW.
23. To access RAM, CE = VIL, UB or LB = VIL, SEM = VIH. To access semaphore, CE = VIH, SEM = VIL.
9
CY7C026A
CY7C036A
Switching Waveforms (continued)
Write Cycle No. 1: R/W Controlled Timing[24, 25, 26, 27]
tWC
ADDRESS
tHZOE [30]
OE
tAW
CE
[28,29]
tPWE[27]
tSA
tHA
R/W
tHZWE[30]
DATA OUT
tLZWE
NOTE 31
NOTE 31
tSD
tHD
DATA IN
Write Cycle No. 2: CE Controlled Timing[24, 25, 26, 32]
tWC
ADDRESS
tAW
CE
[28,29]
tSA
tSCE
tHA
R/W
tSD
tHD
DATA IN
Notes:
24. R/W must be HIGH during all address transitions.
25. A write occurs during the overlap (tSCE or tPWE) of a LOW CE or SEM and a LOW UB or LB.
26. tHA is measured from the earlier of CE or R/W or (SEM or R/W) going HIGH at the end of write cycle.
27. If OE is LOW during a R/W controlled write cycle, the write pulse width must be the larger of tPWE or (tHZWE + t SD) to allow the I/O drivers to turn off and
data to be placed on the bus for the required tSD. If OE is HIGH during an R/W controlled write cycle, this requirement does not apply and the write pulse
can be as short as the specified tPWE.
28. To access RAM, CE = VIL, SEM = VIH.
29. To access upper byte, CE = VIL , UB = VIL, SEM = VIH.
To access lower byte, CE = VIL, LB = VIL, SEM = VIH.
30. Transition is measured ±500 mV from steady state with a 5-pF load (including scope and jig). This parameter is sampled and not 100% tested.
31. During this period, the I/O pins are in the output state, and input signals must not be applied.
32. If the CE or SEM LOW transition occurs simultaneously with or after the R/W LOW transition, the outputs remain in the high-impedance state.
10
CY7C026A
CY7C036A
Switching Waveforms (continued)
Semaphore Read After Write Timing, Either Side[33]
tSAA
A 0–A 2
VALID ADRESS
VALID ADRESS
tAW
tACE
tHA
SEM
tOHA
tSCE
tSOP
tSD
I/O 0
DATA IN VALID
tSA
tPWE
DATA OUT VALID
tHD
R/W
tSWRD
tDOE
tSOP
OE
WRITE CYCLE
READ CYCLE
Timing Diagram of Semaphore Contention[34, 35, 36]
A0L –A 2L
MATCH
R/WL
SEM L
tSPS
A 0R –A 2R
MATCH
R/WR
SEM R
Notes:
33. CE = HIGH for the duration of the above timing (both write and read cycle).
34. I/O0R = I/O0L = LOW (request semaphore); CER = CEL = HIGH.
35. Semaphores are reset (available to both ports) at cycle start.
36. If tSPS is violated, the semaphore will definitely be obtained by one side or the other, but which side will get the semaphore is unpredictable.
11
CY7C026A
CY7C036A
Switching Waveforms (continued)
Timing Diagram of Read with BUSY (M/S=HIGH)[37]
tWC
ADDRESSR
MATCH
tPWE
R/WR
tHD
tSD
DATA IN R
VALID
tPS
ADDRESSL
MATCH
tBLA
tBHA
BUSYL
tBDD
tDDD
DATA OUTL
VALID
tWDD
Write Timing with Busy Input (M/S=LOW)
tPWE
R/W
BUSY
tWB
tWH
Note:
37. CEL = CER = LOW.
12
CY7C026A
CY7C036A
Switching Waveforms (continued)
Busy Timing Diagram No. 1 (CE Arbitration)[38]
CELValid First:
ADDRESS L,R
ADDRESS MATCH
CEL
tPS
CER
tBLC
tBHC
BUSYR
CER Valid First:
ADDRESS L,R
ADDRESS MATCH
CER
tPS
CE L
tBLC
tBHC
BUSY L
Busy Timing Diagram No. 2 (Address Arbitration)[38]
Left Address Valid First:
tRC or tWC
ADDRESS L
ADDRESS MATCH
ADDRESS MISMATCH
tPS
ADDRESSR
tBLA
tBHA
BUSY R
Right Address Valid First:
tRC or tWC
ADDRESSR
ADDRESS MATCH
ADDRESS MISMATCH
tPS
ADDRESSL
tBLA
tBHA
BUSY L
Note:
38. If tPS is violated, the busy signal will be asserted on one side or the other, but there is no guarantee to which side BUSY will be asserted.
13
CY7C026A
CY7C036A
Switching Waveforms (continued)
Interrupt Timing Diagrams
Left Side Sets INTR:
tWC
ADDRESSL
WRITE 3FFF
tHA [39]
CE L
R/W L
INT R
tINS [40]
Right Side Clears INTR:
tRC
ADDRESSR
READ 3FFF
CE R
tINR [40]
R/WR
OE R
INTR
Right Side Sets INT L:
tWC
ADDRESSR
WRITE 3FFE
tHA[39]
CE R
R/W R
INT L
[40]
tINS
Left Side Clears INTL:
tRC
READ 3FFE
ADDRESSR
CE L
tINR[40]
R/W L
OE L
INT L
Notes:
39. tHA depends on which enable pin (CEL or R/WL) is deasserted first.
40. tINS or tINR depends on which enable pin (CEL or R/WL) is asserted last.
14
CY7C026A
CY7C036A
within tPS of each other, the busy logic will determine which
port has access. If tPS is violated, one port will definitely gain
permission to the location, but it is not predictable which port
will get that permission. BUSY will be asserted tBLA after an
address match or tBLC after CE is taken LOW.
Architecture
The CY7C026A and CY7C036A consist of an array of 16K
words of 16 and 18 bits each of dual-port RAM cells, I/O and
address lines, and control signals (CE, OE, R/W). These control pins permit independent access for reads or writes to any
location in memory. To handle simultaneous writes/reads to
the same location, a BUSY pin is provided on each port. Two
Interrupt (INT) pins can be utilized for port-to-port communication. Two Semaphore (SEM) control pins are used for allocating shared resources. With the M/S pin, the devices can function as a master (BUSY pins are outputs) or as a slave (BUSY
pins are inputs). The devices also have an automatic powerdown feature controlled by CE. Each port is provided with its
own Output Enable control (OE), which allows data to be read
from the device.
Master/Slave
Functional Description
A M/S pin is provided in order to expand the word width by
configuring the device as either a master or a slave. The BUSY
output of the master is connected to the BUSY input of the
slave. This will allow the device to interface to a master device
with no external components. Writing to slave devices must be
delayed until after the BUSY input has settled (tBLC or tBLA),
otherwise, the slave chip may begin a write cycle during a contention situation. When tied HIGH, the M/S pin allows the device to be used as a master and, therefore, the BUSY line is
an output. BUSY can then be used to send the arbitration outcome to a slave.
Write Operation
Semaphore Operation
Data must be set up for a duration of tSD before the rising edge
of R/W in order to guarantee a valid write. A write operation is
controlled by either the R/W pin (see Write Cycle No. 1 waveform) or the CE pin (see Write Cycle No. 2 waveform). Required inputs for non-contention operations are summarized in
Table 1.
The CY7C026A and CY7C036A provide eight semaphore
latches, which are separate from the dual-port memory locations. Semaphores are used to reserve resources that are
shared between the two ports. The state of the semaphore
indicates that a resource is in use. For example, if the left port
wants to request a given resource, it sets a latch by writing a
zero to a semaphore location. The left port then verifies its
success in setting the latch by reading it. After writing to the
semaphore, SEM or OE must be deasserted for tSOP before
attempting to read the semaphore. The semaphore value will
be available tSWRD + tDOE after the rising edge of the semaphore write. If the left port was successful (reads a zero), it
assumes control of the shared resource, otherwise (reads a
one) it assumes the right port has control and continues to poll
the semaphore. When the right side has relinquished control
of the semaphore (by writing a one), the left side will succeed
in gaining control of the semaphore. If the left side no longer
requires the semaphore, a one is written to cancel its request.
If a location is being written to by one port and the opposite
port attempts to read that location, a port-to-port flowthrough
delay must occur before the data is read on the output; otherwise the data read is not deterministic. Data will be valid on the
port tDDD after the data is presented on the other port.
Read Operation
When reading the device, the user must assert both the OE
and CE pins. Data will be available tACE after CE or tDOE after
OE is asserted. If the user wishes to access a semaphore flag,
then the SEM pin must be asserted instead of the CE pin, and
OE must also be asserted.
Semaphores are accessed by asserting SEM LOW. The SEM
pin functions as a chip select for the semaphore latches (CE
must remain HIGH during SEM LOW). A0–2 represents the
semaphore address. OE and R/W are used in the same manner as a normal memory access. When writing or reading a
semaphore, the other address pins have no effect.
Interrupts
The upper two memory locations may be used for message
passing. The highest memory location (3FFF) is the mailbox
for the right port and the second-highest memory location
(3FFE) is the mailbox for the left port. When one port writes to
the other port’s mailbox, an interrupt is generated to the owner.
The interrupt is reset when the owner reads the contents of the
mailbox. The message is user defined.
When writing to the semaphore, only I/O 0 is used. If a zero is
written to the left port of an available semaphore, a one will
appear at the same semaphore address on the right port. That
semaphore can now only be modified by the side showing zero
(the left port in this case). If the left port now relinquishes control by writing a one to the semaphore, the semaphore will be
set to one for both sides. However, if the right port had requested the semaphore (written a zero) while the left port had control, the right port would immediately own the semaphore as
soon as the left port released it. Table 3 shows sample semaphore operations.
Each port can read the other port’s mailbox without resetting
the interrupt. The active state of the busy signal (to a port)
prevents the port from setting the interrupt to the winning port.
Also, an active busy to a port prevents that port from reading
its own mailbox and, thus, resetting the interrupt to it.
If an application does not require message passing, do not
connect the interrupt pin to the processor’s interrupt request
input pin.
When reading a semaphore, all sixteen/eighteen data lines
output the semaphore value. The read value is latched in an
output register to prevent the semaphore from changing state
during a write from the other port. If both ports attempt to access the semaphore within tSPS of each other, the semaphore
will definitely be obtained by one side or the other, but there is
no guarantee which side will control the semaphore.
The operation of the interrupts and their interaction with Busy
are summarized in Table 2.
Busy
The CY7C026A and CY7C036A provide on-chip arbitration to
resolve simultaneous memory location access (contention). If
both ports’ CEs are asserted and an address match occurs
15
CY7C026A
CY7C036A
Table 1. Non-Contending Read/Write
Inputs
Outputs
CE
R/W
OE
UB
LB
SEM
H
X
X
X
X
H
High Z
I/O 9–I/O17
High Z
I/O0–I/O8
Deselected: Power-Down
Operation
X
X
X
H
H
H
High Z
High Z
Deselected: Power-Down
L
L
X
L
H
H
Data In
High Z
Write to Upper Byte Only
L
L
X
H
L
H
High Z
Data In
Write to Lower Byte Only
L
L
X
L
L
H
Data In
Data In
Write to Both Bytes
L
H
L
L
H
H
Data Out
High Z
Read Upper Byte Only
L
H
L
H
L
H
High Z
Data Out
Read Lower Byte Only
L
H
L
L
L
H
Data Out
Data Out
Read Both Bytes
X
X
H
X
X
X
High Z
High Z
Outputs Disabled
H
H
L
X
X
L
Data Out
Data Out
Read Data in Semaphore Flag
X
H
L
H
H
L
Data Out
Data Out
Read Data in Semaphore Flag
H
X
X
X
L
Data In
Data In
Write D IN0 into Semaphore Flag
X
X
H
H
L
Data In
Data In
Write D IN0 into Semaphore Flag
L
X
X
L
X
L
Not Allowed
L
X
X
X
L
L
Not Allowed
Table 2. Interrupt Operation Example (assumes BUSYL=BUSYR=HIGH)
Left Port
Function
Right Port
R/WL
CEL
OEL
A0L–13L
INTL
R/WR
CER
OE R
A0R–13R
INTR
Set Right INTR Flag
L
L
X
3FFF
X
X
X
X
X
L[42]
Reset Right INTR Flag
X
X
X
X
X
X
L
L
3FFF
H[41]
Set Left INTL Flag
X
X
X
X
L[41]
L
L
X
3FFE
X
[42]
X
X
X
X
X
Reset Left INTL Flag
X
L
L
3FFE
H
Table 3. Semaphore Operation Example
Function
I/O0–I/O17 Left I/O0–I/O17 Right
Status
No action
1
1
Semaphore free
Left port writes 0 to semaphore
0
1
Left Port has semaphore token
Right port writes 0 to semaphore
0
1
No change. Right side has no write access to semaphore
Left port writes 1 to semaphore
1
0
Right port obtains semaphore token
Left port writes 0 to semaphore
1
0
No change. Left port has no write access to semaphore
Right port writes 1 to semaphore
0
1
Left port obtains semaphore token
Left port writes 1 to semaphore
1
1
Semaphore free
Right port writes 0 to semaphore
1
0
Right port has semaphore token
Right port writes 1 to semaphore
1
1
Semaphore free
Left port writes 0 to semaphore
0
1
Left port has semaphore token
Left port writes 1 to semaphore
1
1
Semaphore free
Notes:
41. If BUSYL=L, then no change.
42. If BUSYR=L, then no change.
16
CY7C026A
CY7C036A
Ordering Information
16K x16 Asynchronous Dual-Port SRAM
Speed
(ns)
Package
Name
Ordering Code
Package Type
Operating
Range
12[1]
CY7C026A-12AC
A100
100-Pin Thin Quad Flat Pack
Commercial
15
CY7C026A-15AC
A100
100-Pin Thin Quad Flat Pack
Commercial
CY7C026A-15AI
A100
100-Pin Thin Quad Flat Pack
Industrial
CY7C026A-20AC
A100
100-Pin Thin Quad Flat Pack
Commercial
20
16K x18 Asynchronous Dual-Port SRAM
Speed
(ns)
Ordering Code
Package
Name
Package Type
Operating
Range
12[1]
CY7C036A-12AC
A100
100-Pin Thin Quad Flat Pack
Commercial
15
CY7C036A-15AC
A100
100-Pin Thin Quad Flat Pack
Commercial
CY7C036A-15AI
A100
100-Pin Thin Quad Flat Pack
Industrial
20
CY7C036A-20AC
A100
100-Pin Thin Quad Flat Pack
Commercial
Document #: 38-00832-A
Package Diagram
100-Pin Thin Plastic Quad Flat Pack (TQFP) A100
51-85048-B
© Cypress Semiconductor Corporation, 2000. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use
of any circuitry other than circuitry embodied in a Cypress Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor does not authorize
its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress
Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.
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