IDT IDT70V38L20PFI

HIGH-SPEED 3.3V
64K x 18 DUAL-PORT
STATIC RAM
Features
◆
◆
◆
◆
◆
True Dual-Ported memory cells which allow simultaneous
access of the same memory location
High-speed access
– Commercial: 15/20ns (max.)
– Industrial: 20ns (max.)
Low-power operation
– IDT70V38L
Active: 440mW (typ.)
Standby: 660µW (typ.)
Dual chip enables allow for depth expansion without
external logic
IDT70V38 easily expands data bus width to 36 bits or
more using the Master/Slave select when cascading more
than one device
◆
◆
◆
◆
◆
◆
◆
◆
◆
IDT70V38L
M/S = VIH for BUSY output flag on Master,
M/S = VIL for BUSY input on Slave
Busy and Interrupt Flags
On-chip port arbitration logic
Full on-chip hardware support of semaphore signaling
between ports
Fully asynchronous operation from either port
Separate upper-byte and lower-byte controls for multiplexed bus and bus matching compatibility
LVTTL-compatible, single 3.3V (±0.3V) power supply
Available in a 100-pin TQFP
Industrial temperature range (–40°C to +85°C) is available
for selected speeds
Functional Block Diagram
R/WL
UBL
R/WR
UBR
CE0L
CE1L
CE0R
CE1R
OEL
OER
LBL
LBR
I/O9-17R
I/O 9-17L
I/O
Control
I/O 0-8L
I/O
Control
I/O0-8R
BUSYL (1,2)
A15L
BUSYR
64Kx18
MEMORY
ARRAY
70V38
Address
Decoder
A0L
16
CE0L
CE1L
OEL
R/WL
.
A15R
A0R
16
ARBITRATION
INTERRUPT
SEMAPHORE
LOGIC
SEML
(2)
INT L
Address
Decoder
(1,2)
M/S
NOTES:
1. BUSY is an input as a Slave (M/S=VIL) and an output when it is a Master (M/S=VIH).
2. BUSY and INT are non-tri-state totem-pole outputs (push-pull).
(1)
CE0R
CE1R
OER
R/WR
SEMR
(2)
INTR
4850 drw 01
SEPTEMBER 2003
1
©2003 Integrated Device Technology, Inc.
DSC-4850/3
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Description
The IDT70V38 is a high-speed 64K x 18 Dual-Port Static RAM.
The IDT70V38 is designed to be used as a stand-alone 1152K-bit
Dual-Port RAM or as a combination MASTER/SLAVE Dual-Port RAM
for 36-bit-or-more word system. Using the IDT MASTER/SLAVE
Dual-Port RAM approach in 36-bit or wider memory system applications results in full-speed, error-free operation without the need for
additional discrete logic.
This device provides two independent ports with separate control,
address, and I/O pins that permit independent, asynchronous access
for reads or writes to any location in memory. An automatic power
down feature controlled by the chip enables (either CE0 or CE1)
permit the on-chip circuitry of each port to enter a very low standby
power mode.
Fabricated using IDT’s CMOS high-performance technology,
these devices typically operate on only 440mW of power.
The IDT70V38 is packaged in a 100-pin Thin Quad Flatpack
(TQFP).
A8L
A7L
A6L
A5L
A4L
A3L
A2L
A1L
A0L
INTL
BUSYL
GND
GND
Vcc
M/S
BUSYR
INTR
A0R
A1R
A2R
A3R
A4R
A5R
A6R
A7R
Pin Configurations(1,2,3)
INDEX
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
1
75
2
74
3
73
4
72
5
71
6
70
7
69
8
68
9
IDT70V38PF
PN100-1(4)
10
11
12
100-Pin TQFP
Top View(5)
13
14
67
66
65
64
63
62
15
61
16
60
17
59
18
58
19
57
56
20
22
55
54
23
53
21
52
51
25
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
24
I/O9L
I/O8L
Vcc
I/O7L
I/O6L
I/O5L
I/O4L
I/O3L
I/O2L
GND
I/O1L
I/O0L
GND
I/O0R
I/O1R
I/O2R
I/O3R
I/O4R
I/O5R
I/O6R
Vcc
I/O7R
I/O8R
I/O9R
I/O10R
A9L
A10L
A11L
A12L
A13L
A14L
A15L
LBL
UBL
CE0L
CE1L
SEML
R/WL
OEL
Vcc
GND
I/O17L
I/O16L
GND
I/O15L
I/O14L
I/O13L
I/O12L
I/O11L
I/O10L
NOTES:
1. All Vcc pins must be connected to power supply.
2. All GND pins must be connected to ground.
3. Package body is approximately 14mm x 14mm x 1.4mm.
4. This package code is used to reference the package diagram.
5. This text does not indicate orientation of the actual part-marking.
2
A8R
A9R
A10R
A11R
A12R
A13R
A14R
A15R
LBR
UBR
CE0R
CE1R
SEMR
R/WR
GND
OER
GND
I/O17R
GND
I/O16R
I/O15R
I/O14R
I/O13R
I/O12R
I/O11R
4850 drw 02
.
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Pin Names
Left Port
Right Port
Names
CE0L, CE1L
CE0R, CE1R
Chip Enables
R/WL
R/WR
Read/Write Enable
OEL
OER
Output Enable
A0L - A15L
A0R - A15R
Address
I/O0L - I/O17L
I/O0R - I/O17R
Data Input/Output
SEML
SEMR
Semaphore Enable
UBL
UBR
Upper Byte Select
LBL
LBR
Lower Byte Select
INTL
INTR
Interrupt Flag
BUSYL
BUSYR
Busy Flag
M/S
Master or Slave Select
VCC
Power
GND
Ground
4850 tbl 01
Absolute Maximum Ratings(1)
Symbol
Rating
Commercial
& Industrial
Unit
VTERM(2)
Terminal Voltage
with Respect
to GND
-0.5 to +4.6
V
TBIAS
Temperature
Under Bias
-55 to +125
o
TSTG
Storage
Temperature
IOUT
DC Output
Current
Recommended DC Operating
Conditions
Symbol
-65 to +150
o
50
C
V CC
Supply Voltage
GND
Ground
VIH
Input High Voltage
VIL
C
Parameter
Input Low Voltage
Min.
Typ.
Max.
Unit
3.0
3.3
3.6
V
0
0
0
2.0
____
(1)
-0.3
V
VCC+0.3
____
(2)
0.8
V
4850 tbl 04
NOTES:
1. VIL > -1.5V for pulse width less than 10ns.
2. VTERM must not exceed Vcc + 0.3V.
mA
V
4850 tbl 02
NOTES:
1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may
cause permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in
the operational sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect reliability.
2. VTERM must not exceed Vcc + 0.3V for more than 25% of the cycle time or 10ns
maximum, and is limited to < 20mA for the period of VTERM > Vcc + 0.3V.
Capacitance(1)
Symbol
CIN
COUT
Maximum Operating Temperature
and Supply Voltage
Grade
Commercial
Industrial
Ambient
Temperature(1)
GND
Vcc
0OC to +70OC
0V
3.3V + 0.3V
-40OC to +85OC
0V
3.3V + 0.3V
Parameter
Input Capacitance
Output Capacitance
(TA = +25°C, f = 1.0MHz)
Conditions(2)
Max.
Unit
V IN = 3dV
9
pF
VOUT = 3dV
10
pF
4850 tbl 05
NOTES:
1. This parameter is determined by device characterization but is not production tested.
2. 3dV represents the interpolated capacitance when the input and output signals
switch from 0V to 3V or from 3V to 0V.
4850 tbl 03
NOTE:
1. This is the parameter TA. This is the "instant on" case temperature.
3
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Truth Table I – Chip Enable(1,2)
CE
L
Mode
CE0
CE 1
VIL
VIH
< 0.2V
>VCC -0.2V
Port Selected (CMOS Active)
VIH
X
Port Deselected (TTL Inactive)
X
VIL
Port Deselected (TTL Inactive)
>VCC -0.2V
X(3)
Port Deselected (CMOS Inactive)
<0.2V
Port Deselected (CMOS Inactive)
H
(3)
X
Port Selected (TTL Active)
4850 tbl 06
NOTES:
1. Chip Enable references are shown above with the actual CE0 and CE1 levels; CE is a reference only.
2. 'H' = VIH and 'L' = VIL.
3. CMOS standby requires 'X' to be either < 0.2V or >VCC-0.2V.
Truth Table II – Non-Contention Read/Write Control
Inputs(1)
Outputs
CE(2)
R/W
OE
UB
LB
SEM
I/O9-17
I/O0-8
Mode
H
X
X
X
X
H
High-Z
High-Z
Deselected: Power-Down
X
X
X
H
H
H
High-Z
High-Z
Both Bytes Deselected
L
L
X
L
H
H
DATAIN
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
DATAIN
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
4850 tbl 07
NOTES:
1. A0L — A15L ≠ A0R — A15R
2. Refer to Truth Table I - Chip Enable.
Truth Table III – Semaphore Read/Write Control(1)
Inputs(1)
Outputs
CE(2)
R/W
OE
UB
LB
SEM
I/O9-17
I/O0-8
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
DATAIN
DATA IN
Write I/O0 into Semaphore Flag
X
↑
X
H
H
L
DATAIN
DATA IN
Write I/O0 into Semaphore Flag
L
X
X
L
X
L
______
______
Not Allowed
L
X
X
X
L
L
______
______
Not Allowed
Mode
NOTES:
1. There are eight semaphore flags written to I/O0 and read from all the I/Os (I/O0-I/O17). These eight semaphore flags are addressed by A0-A2.
2. Refer to Truth Table I - Chip Enable.
4
4850 tbl 08
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
DC Electrical Characteristics Over the Operating
Temperature and Supply Voltage Range (VCC = 3.3V ± 0.3V)
70V38L
Symbol
Parameter
Test Conditions
(1)
Min.
Max.
Unit
|ILI|
Input Leakage Current
VCC = 3.6V, VIN = 0V to V CC
___
5
µA
|ILO|
Output Leakage Current
CE(2) = VIH, VOUT = 0V to V CC
___
5
µA
VOL
Output Low Voltage
IOL = +4mA
___
0.4
V
VOH
Output High Voltage
IOH = -4mA
2.4
___
V
4850 tbl 09
NOTES:
1. At Vcc < 2.0V, input leakages are undefined.
2. Refer to Truth Table I - Chip Enable.
DC Electrical Characteristics Over the Operating
Temperature and Supply Voltage Range(5) (VCC = 3.3V ± 0.3V)
70V38L15
Com'l Only
Symbol
ICC
ISB1
ISB2
ISB3
ISB4
Parameter
Test Condition
Version
70V38L20
Com'l
& Ind
Typ.(1)
Max.
Typ.(1)
Max.
Unit
mA
Dynamic Operating
Current
(Both Ports Active)
CE = VIL, Outputs Disabled
SEM = VIH
f = fMAX(2)
COM'L
L
145
235
135
205
IND
L
___
___
135
220
Standby Current
(Both Ports - TTL Level
Inputs)
CEL = CER = VIH
SEMR = SEML = VIH
f = fMAX(2)
COM'L
L
40
70
35
55
IND
L
___
___
35
65
(4)
Standby Current
(One Port - TTL Level
Inputs)
CE"A" = VIL and CE"B" = VIH
Active Port Outputs Disabled,
f=fMAX(2), SEMR = SEML = VIH
COM'L
L
100
155
90
140
IND
L
___
___
90
150
Full Standby Current
(Both Ports - All CMOS
Level Inputs)
Both Ports CEL and CER > VCC - 0.2V,
VIN > VCC - 0.2V or V IN < 0.2V, f = 0(3)
SEMR = SEML > VCC - 0.2V
COM'L
L
0.2
3.0
0.2
3.0
IND
L
___
___
0.2
3.0
Full Standby Current
(One Port - All CMOS
Level Inputs)
CE"A" < 0.2V and CE"B" > VCC - 0.2V(4),
SEMR = SEML > VCC - 0.2V,
VIN > VCC - 0.2V or V IN < 0.2V,
Active Port Outputs Disabled , f = fMAX(2)
COM'L
L
95
150
90
135
IND
L
___
___
90
145
mA
mA
mA
mA
4850 tbl 10
NOTES:
1. VCC = 3.3V, TA = +25°C, and are not production tested. ICCDC = 90mA (Typ.)
2. At f = f MAX, address and control lines (except Output Enable) are cycling at the maximum frequency read cycle of 1/tRC, and using “AC Test Conditions" of input levels of GND
to 3V.
3. f = 0 means no address or control lines change.
4. Port "A" may be either left or right port. Port "B" is the opposite from port "A".
5. Refer to Truth Table I - Chip Enable.
5
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
AC Test Conditions
3.3V
Input Pulse Levels
3.3V
GND to 3.0V
Input Rise/Fall Times
590Ω
3ns Max.
Input Timing Reference Levels
1.5V
Output Reference Levels
1.5V
Output Load
DATAOUT
BUSY
INT
DATAOUT
30pF
435Ω
Figures 1 and 2
590Ω
435Ω
5pF*
4850 tbl 11
4850 drw 03
4850 drw 04
Figure 2. Output Test Load
(for tLZ , tHZ, t WZ, tOW)
* Including scope and jig.
Figure 1. AC Output Load
Waveform of Read Cycles(5)
tRC
ADDR
(4)
tAA
(4)
tACE
(6)
CE
tAOE
(4)
OE
tABE (4)
UB, LB
R/W
tLZ
tOH
(1)
DATAOUT
VALID DATA
(4)
tHZ
(2)
BUSYOUT
tBDD
(3,4)
4850 drw 05
Timing of Power-Up Power-Down
CE(6)
tPU
tPD
ICC
50%
ISB
50%
4850 drw 06
.
NOTES:
1. Timing depends on which signal is asserted last, OE, CE, LB or UB.
2. Timing depends on which signal is de-asserted first CE, OE, LB or UB.
3. tBDD delay is required only in cases where the opposite port is completing a write operation to the same address location. For simultaneous read operations BUSY has no
relation to valid output data.
4. Start of valid data depends on which timing becomes effective last tAOE, tACE, t AA or tBDD .
5. SEM = VIH.
6. Refer to Truth Table I - Chip Enable.
6
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
AC Electrical Characteristics Over the
Operating Temperature and Supply Voltage Range
70V38L15
Com'l Only
Symbol
Parameter
70V38L20
Com'l
& Ind
Min.
Max.
Min.
Max.
Unit
READ CYCLE
tRC
Read Cycle Time
15
____
20
____
ns
tAA
Address Access Time
____
15
____
20
ns
Chip Enable Access Time
(3)
____
15
____
20
ns
tABE
Byte Enable Access Time
(3)
____
15
____
20
ns
tAOE
Output Enable Access Time
____
10
____
12
ns
tOH
Output Hold from Address Change
3
____
3
____
ns
3
____
3
____
ns
____
10
____
10
ns
0
____
0
____
ns
____
15
____
20
ns
10
____
ns
____
20
tACE
Output Low-Z Time
tLZ
(1,2)
Output High-Z Time
tHZ
(1,2)
Chip Enab le to Power Up Time
tPU
(2)
(2)
tPD
Chip Disable to Power Down Time
tSOP
Semaphore Flag Update Pulse (OE or SEM)
10
____
tSAA
Semaphore Address Access Time
____
15
ns
4850 tbl 12
AC Electrical Characteristics Over the
Operating Temperature and Supply Voltage
70V38L15
Com'l Only
Symbol
Parameter
70V38L20
Com'l
& Ind
Min.
Max.
Min.
Max.
Unit
15
____
20
____
ns
tEW
Chip Enable to End-of-Write
(3)
12
____
15
____
ns
tAW
Address Valid to End-of-Write
12
____
15
____
ns
0
____
0
____
ns
ns
WRITE CYCLE
tWC
Write Cycle Time
(3)
tAS
Address Set-up Time
tWP
Write Pulse Width
12
____
15
____
tWR
Write Recovery Time
0
____
0
____
ns
tDW
Data Valid to End-of-Write
10
____
15
____
ns
____
10
____
10
ns
0
____
ns
10
ns
ns
tHZ
tDH
tWZ
Output High-Z Time
Data Hold Time
(1,2)
(4)
0
____
(1,2)
____
10
____
(1,2,4)
0
____
0
____
5
____
ns
5
____
ns
Write Enable to Output in High-Z
tOW
Output Active from End-of-Write
tSWRD
SEM Flag Write to Read Time
5
____
tSPS
SEM Flag Contention Window
5
____
4850 tbl 13
NOTES:
1. Transition is measured 0mV from Low or High-impedance voltage with Output Test Load (Figure 2).
2. This parameter is guaranted by device characterization, but is not production tested.
3. To access RAM, CE= VIL and SEM = VIH. To access semaphore, CE = VIH and SEM = VIL. Either condition must be valid for the entire tEW time.
4. The specification for tDH must be met by the device supplying write data to the RAM under all operating conditions. Although tDH and tOW values will vary over voltage and
temperature, the actual tDH will always be smaller than the actual tOW.
7
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Timing Waveform of Write Cycle No. 1, R/W Controlled Timing(1,5,8)
tWC
ADDRESS
tHZ
(7)
OE
tAW
(9,10)
CE or SEM
(9)
UB or LB
tAS (6)
tWP
tWR (3)
(2)
R/W
tWZ (7)
tOW
(4)
DATAOUT
(4)
tDW
tDH
DATAIN
4850 drw 07
Timing Waveform of Write Cycle No. 2, CE Controlled Timing(1,5)
tWC
ADDRESS
tAW
CE or SEM
(9,10)
(6)
tAS
tWR (3)
tEW (2)
UB or LB(9)
R/W
tDW
tDH
DATAIN
4850 drw 08
NOTES:
1. R/W or CE or UB and LB = VIH during all address transitions.
2. A write occurs during the overlap (tEW or t WP) of a CE = VIL and a R/W = VIL for memory array writing cycle.
3. tWR is measured from the earlier of CE or R/W (or SEM or R/W) going HIGH to the end of write cycle.
4. During this period, the I/O pins are in the output state and input signals must not be applied.
5. If the CE or SEM = VIL transition occurs simultaneously with or after the R/W = VIL transition, the outputs remain in the High-impedance state.
6. Timing depends on which enable signal is asserted last, CE or R/W.
7. This parameter is guaranteed by device characterization, but is not production tested. Transition is measured 0mV from steady state with the Output Test Load
(Figure 2).
8. If OE = VIL during R/W controlled write cycle, the write pulse width must be the larger of tWP or (tWZ + tDW) to allow the I/O drivers to turn off and data to be
placed on the bus for the required tDW . If OE = VIH during an R/W controlled write cycle, this requirement does not apply and the write pulse can be as short as the
specified tWP .
9. To access RAM, CE = VIL and SEM = VIH. To access semaphore, CE = VIH and SEM = VIL. tEW must be met for either condition.
10. Refer to Truth Table I - Chip Enable.
8
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Timing Waveform of Semaphore Read after Write Timing, Either Side(1)
tSAA
A0-A2
VALID ADDRESS
VALID ADDRESS
tAW
tWR
tACE
tEW
SEM
tOH
tSOP
tDW
I/O
DATA OUT(2)
VALID
DATAIN VALID
tAS
tWP
tDH
R/W
tSWRD
OE
tAOE
tSOP
Write Cycle
Read Cycle
4850 drw 09
NOTES:
1. CE = VIH or UB and LB = VIH for the duration of the above timing (both write and read cycle) (Refer to Chip Enable Truth Table).
2. "DATAOUT VALID" represents all I/O's (I/O 0 - I/O17 ) equal to the semaphore value.
Timing Waveform of Semaphore Write Contention(1,3,4)
A0"A"-A2"A"
(2)
SIDE
"A"
MATCH
R/W"A"
SEM"A"
tSPS
A0"B"-A2"B"
(2)
SIDE
"B"
MATCH
R/W"B"
SEM"B"
4850 drw 10
NOTES:
1. DOR = D OL = VIL, CEL = CER = VIH or both UB and LB = VIH (Refer to Chip Enable Truth Table).
2. All timing is the same for left and right ports. Port "A" may be either left or right port. "B" is the opposite from port "A".
3. This parameter is measured from R/W"A" or SEM "A" going HIGH to R/W"B" or SEM"B" going HIGH.
4. If tSPS is not satisfied, the semaphore will fall positively to one side or the other, but there is no guarantee which side will be granted the semaphore flag.
9
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
AC Electrical Characteristics Over the
Operating Temperature and Supply Voltage Range
70V38L15
Com'l Only
Symbol
Parameter
70V38L20
Com'l
& Ind
Min.
Max.
Min.
Max.
Unit
BUSY TIMING (M/S=VIH)
tBAA
BUSY Access Time from Address Match
____
15
____
20
ns
tBDA
BUSY Disable Time from Address Not Matched
____
15
____
20
ns
tBAC
BUSY Access Time from Chip Enable Low
____
15
____
20
ns
tBDC
BUSY Access Time from Chip Enable High
____
15
____
17
ns
tAPS
Arbitration Priority Set-up Time (2)
5
____
5
____
ns
____
15
____
17
ns
12
____
15
____
ns
tBDD
tWH
(3)
BUSY Disable to Valid Data
(5)
Write Hold After BUSY
BUSY TIMING (M/S=VIL)
tWB
BUSY Input to Write(4)
0
____
0
____
ns
tWH
Write Hold After BUSY(5)
12
____
15
____
ns
PORT-TO-PORT DELAY TIMING
tWDD
Write Pulse to Data Delay(1)
____
30
____
45
ns
tDDD
Write Data Valid to Read Data Delay (1)
____
25
____
30
ns
NOTES:
1. Port-to-port delay through RAM cells from writing port to reading port, refer to "Timing Waveform of Write with Port-to-Port Read and BUSY (M/S = VIH)".
2. To ensure that the earlier of the two ports wins.
3. tBDD is a calculated parameter and is the greater of 0, tWDD – tWP (actual), or tDDD – tDW (actual).
4. To ensure that the write cycle is inhibited on port "B" during contention on port "A".
5. To ensure that a write cycle is completed on port "B" after contention on port "A".
10
4850 tbl 14
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Timing Waveform of Write with Port-to-Port Read and BUSY (M/S = VIH)(2,4,5)
tWC
MATCH
ADDR"A"
tWP
R/W"A"
tDW
tDH
VALID
DATAIN "A"
tAPS
(1)
MATCH
ADDR"B"
tBAA
tBDA
tBDD
BUSY"B"
tWDD
DATAOUT "B"
VALID
tDDD (3)
4850drw 11
NOTES:
1. To ensure that the earlier of the two ports wins. tAPS is ignored for M/S = VIL (SLAVE).
2. CEL = CER = VIL, refer to Chip Enable Truth Table.
3. OE = VIL for the reading port.
4. If M/S = VIL (slave), BUSY is an input. Then for this example BUSY"A" = VIH and BUSY"B" input is shown above.
5. All timing is the same for left and right ports. Port "A" may be either the left or right port. Port "B" is the port opposite from port "A".
Timing Waveform of Write with BUSY (M/S = VIL)
tWP
R/W"A"
tWB(3)
BUSY"B"
R/W"B"
tWH (1)
(2)
4850 drw 12
NOTES:
1. tWH must be met for both BUSY input (SLAVE) and output (MASTER).
2. BUSY is asserted on port "B" blocking R/W"B", until BUSY"B" goes HIGH.
3. tWB is only for the 'slave' version.
11
.
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Waveform of BUSY Arbitration Controlled by CE Timing (M/S = VIH)(1,3)
ADDR"A"
and "B"
ADDRESSES MATCH
CE"A"
tAPS (2)
CE"B"
tBAC
tBDC
BUSY"B"
4850 drw 13
Waveform of BUSY Arbitration Cycle Controlled by Address Match
Timing (M/S = VIH)(1)
ADDR"A"
ADDRESS "N"
tAPS (2)
ADDR"B"
MATCHING ADDRESS "N"
tBAA
tBDA
BUSY"B"
4850 drw 14
NOTES:
1. All timing is the same for left and right ports. Port “A” may be either the left or right port. Port “B” is the port opposite from port “A”.
2. If tAPS is not satisfied, the BUSY signal will be asserted on one side or another but there is no guarantee on which side BUSY will be asserted.
3. Refer to Truth Table I - Chip Enable.
AC Electrical Characteristics Over the
Operating Temperature and Supply Voltage Range
70V38L15
Com'l Only
Symbol
Parameter
70V38L20
Com'l
& Ind
Min.
Max.
Min.
Max.
Unit
INTERRUPT TIMING
tAS
Address Set-up Time
0
____
0
____
ns
tWR
Write Recovery Time
0
____
0
____
ns
tINS
Interrupt Set Time
____
15
____
20
ns
tINR
Interrupt Reset Time
____
15
____
20
ns
4850 tbl 15
12
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Waveform of Interrupt Timing(1,5)
tWC
INTERRUPT SET ADDRESS
ADDR"A"
tAS
(2)
(3)
tWR
(4)
CE"A"
R/W"A"
(3)
tINS
INT"B"
4850 drw 15
tRC
ADDR"B"
INTERRUPT CLEAR ADDRESS
tAS
(2)
(3)
CE"B"
OE"B"
tINR (3)
INT"B"
4850 drw 16
NOTES:
1. All timing is the same for left and right ports. Port “A” may be either the left or right port. Port “B” is the port opposite from port “A”.
2. Refer to Interrupt Truth Table.
3. Timing depends on which enable signal (CE or R/W) is asserted last.
4. Timing depends on which enable signal (CE or R/W) is de-asserted first.
5. Refer to Truth Table I - Chip Enable.
Truth Table IV — Interrupt Flag(1,4,5)
Left Port
Right Port
R/WL
CEL
OEL
A15L-A0L
INTL
R/WR
CER
OER
A15R-A0R
INTR
L
L
X
FFFF
X
X
X
X
X
L(2)
X
X
X
X
X
L
X
X
L
X
X
FFFE
X
L
(3)
Function
Set Right INTR Flag
X
L
L
FFFF
H
(3)
L
L
X
FFFE
X
Set Left INTL Flag
(2)
X
X
X
X
X
Reset Left INTL Flag
H
Reset Right INTR Flag
4850 tbl 16
NOTES:
1. Assumes BUSYL = BUSYR =VIH.
2. If BUSYL = VIL, then no change.
3. If BUSYR = VIL, then no change.
4. INTL and INTR must be initialized at power-up.
5. Refer to Truth Table I - Chip Enable.
13
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Truth Table V —
Address BUSY Arbitration(4)
Inputs
Outputs
CEL
CER
AOL-A15L
AOR-A15R
BUSYL(1)
BUSYR(1)
Function
X
X
NO MATCH
H
H
Normal
H
X
MATCH
H
H
Normal
X
H
MATCH
H
H
Normal
L
L
MATCH
(2)
(2)
Write Inhibit(3)
4850 tbl 17
NOTES:
1. Pins BUSYL and BUSYR are both outputs when the part is configured as a master. Both are inputs when configured as a slave. BUSY outputs on the IDT70V38 are pushpull, not open drain outputs. On slaves the BUSY input internally inhibits writes.
2. "L" if the inputs to the opposite port were stable prior to the address and enable inputs of this port. "H" if the inputs to the opposite port became stable after the address and
enable inputs of this port. If tAPS is not met, either BUSY L or BUSYR = LOW will result. BUSYL and BUSYR outputs can not be LOW simultaneously.
3. Writes to the left port are internally ignored when BUSYL outputs are driving LOW regardless of actual logic level on the pin. Writes to the right port are internally ignored when
BUSYR outputs are driving LOW regardless of actual logic level on the pin.
4. Refer to Truth Table I - Chip Enable.
Truth Table VI — Example of Semaphore Procurement Sequence(1,2,3)
Functions
D0 - D17 Left
D0 - D17 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:
1. This table denotes a sequence of events for only one of the eight semaphores on the IDT70V38.
2. There are eight semaphore flags written to via I/O0 and read from all I/O's (I/O0-I/O17 ). These eight semaphores are addressed by A0 - A2.
3. CE = VIH, SEM = VIL to access the semaphores. Refer to Truth Table III - Semaphore Read/Write Control.
Functional Description
4850 tbl 18
flag (INTL) is asserted when the right port writes to memory location
FFFE (HEX), where a write is defined as CER = R/WR = VIL per the
Truth Table. The left port clears the interrupt through access of
address location FFFE when CEL = OEL = VIL, R/W is a "don't care".
Likewise, the right port interrupt flag (INTR) is asserted when the left
port writes to memory location FFFF (HEX) and to clear the interrupt
flag (INTR), the right port must read the memory location FFFF. The
message (18 bits) at FFFE or FFFF is user-defined since it is an
addressable SRAM location. If the interrupt function is not used,
address locations FFFE and FFFF are not used as mail boxes, but as
part of the random access memory. Refer to Truth Table IV for the
interrupt operation.
The IDT70V38 provides two ports with separate control, address
and I/O pins that permit independent access for reads or writes to any
location in memory. The IDT70V38 has an automatic power down
feature controlled by CE. The CE0 and CE1 control the on-chip power
down circuitry that permits the respective port to go into a standby
mode when not selected (CE = HIGH). When a port is enabled, access
to the entire memory array is permitted.
Interrupts
If the user chooses the interrupt function, a memory location (mail
box or message center) is assigned to each port. The left port interrupt
14
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Busy Logic
In a master/slave array, both address and chip enable must be valid
long enough for a BUSY flag to be output from the master before the
actual write pulse can be initiated with the R/W signal. Failure to
observe this timing can result in a glitched internal write inhibit signal
and corrupted data in the slave.
Busy Logic provides a hardware indication that both ports of the
RAM have accessed the same location at the same time. It also allows
one of the two accesses to proceed and signals the other side that the
RAM is “Busy”. The BUSY pin can then be used to stall the access until
the operation on the other side is completed. If a write operation has
been attempted from the side that receives a BUSY indication, the
write signal is gated internally to prevent the write from proceeding.
The use of BUSY logic is not required or desirable for all applications. In some cases it may be useful to logically OR the BUSY outputs
together and use any BUSY indication as an interrupt source to flag the
event of an illegal or illogical operation. If the write inhibit function of
BUSY logic is not desirable, the BUSY logic can be disabled by placing
the part in slave mode with the M/S pin. Once in slave mode the BUSY
pin operates solely as a write inhibit input pin. Normal operation can be
programmed by tying the BUSY pins HIGH. If desired, unintended
write operations can be prevented to a port by tying the BUSY pin for
that port LOW.
The BUSY outputs on the IDT 70V38 RAM in master mode, are
push-pull type outputs and do not require pull up resistors to operate.
If these RAMs are being expanded in depth, then the BUSY indication
for the resulting array requires the use of an external AND gate.
Semaphores
A16
CE0
MASTER
Dual Port RAM
BUSYL
BUSYR
CE0
SLAVE
Dual Port RAM
BUSYL
BUSYR
CE1
MASTER
Dual Port RAM
CE1
SLAVE
Dual Port RAM
BUSYL
BUSYL
BUSYR
BUSYR
4850 drw 17
.
Figure 3. Busy and chip enable routing for both width and depth expansion
with IDT70V38 RAMs.
Width Expansion with Busy Logic
Master/Slave Arrays
When expanding an IDT70V38 RAM array in width while using
BUSY logic, one master part is used to decide which side of the RAMs
array will receive a BUSY indication, and to output that indication. Any
number of slaves to be addressed in the same address range as the
master use the BUSY signal as a write inhibit signal. Thus on the
IDT70V38 RAM the BUSY pin is an output if the part is used as a
master (M/S pin = VIH), and the BUSY pin is an input if the part used
as a slave (M/S pin = VIL) as shown in Figure 3.
If two or more master parts were used when expanding in width, a
split decision could result with one master indicating BUSY on one side
of the array and another master indicating BUSY on one other side of
the array. This would inhibit the write operations from one port for part
of a word and inhibit the write operations from the other port for the
other part of the word.
The BUSY arbitration on a master is based on the chip enable and
address signals only. It ignores whether an access is a read or write.
The IDT70V38 is an extremely fast Dual-Port 64K x 18 CMOS
Static RAM with an additional 8 address locations dedicated to binary
semaphore flags. These flags allow either processor on the left or right
side of the Dual-Port RAM to claim a privilege over the other processor
for functions defined by the system designer’s software. As an example, the semaphore can be used by one processor to inhibit the
other from accessing a portion of the Dual-Port RAM or any other
shared resource.
The Dual-Port RAM features a fast access time, with both ports
being completely independent of each other. This means that the
activity on the left port in no way slows the access time of the right port.
Both ports are identical in function to standard CMOS Static RAM and
can be read from or written to at the same time with the only possible
conflict arising from the simultaneous writing of, or a simultaneous
READ/WRITE of, a non-semaphore location. Semaphores are protected against such ambiguous situations and may be used by the
system program to avoid any conflicts in the non-semaphore portion
of the Dual-Port RAM. These devices have an automatic power-down
feature controlled by CE, the Dual-Port RAM enable, and SEM, the
semaphore enable. The CE and SEM pins control on-chip power
down circuitry that permits the respective port to go into standby mode
when not selected. This is the condition which is shown in Truth Table
III where CE and SEM are both HIGH.
Systems which can best use the IDT70V38 contain multiple
processors or controllers and are typically very high-speed systems
which are software controlled or software intensive. These systems
can benefit from a performance increase offered by the IDT70V38s
hardware semaphores, which provide a lockout mechanism without
requiring complex programming.
Software handshaking between processors offers the maximum in
system flexibility by permitting shared resources to be allocated in
varying configurations. The IDT70V38 does not use its semaphore
flags to control any resources through hardware, thus allowing the
system designer total flexibility in system architecture.
An advantage of using semaphores rather than the more common
methods of hardware arbitration is that wait states are never incurred
in either processor. This can prove to be a major advantage in very
high-speed systems.
How the Semaphore Flags Work
The semaphore logic is a set of eight latches which are independent of the Dual-Port RAM. These latches can be used to pass a flag,
or token, from one port to the other to indicate that a shared resource
is in use. The semaphores provide a hardware assist for a use
assignment method called “Token Passing Allocation.” In this method,
the state of a semaphore latch is used as a token indicating that a
shared resource is in use. If the left processor wants to use this
resource, it requests the token by setting the latch. This processor then
verifies its success in setting the latch by reading it. If it was successful,
15
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
question. Meanwhile, if a processor on the right side attempts to write
a zero to the same semaphore flag it will fail, as will be verified by the
fact that a one will be read from that semaphore on the right side during
subsequent read. Had a sequence of READ/WRITE been used
instead, system contention problems could have occurred during the
gap between the read and write cycles.
It is important to note that a failed semaphore request must be
followed by either repeated reads or by writing a one into the same
location. The reason for this is easily understood by looking at the
simple logic diagram of the semaphore flag in Figure 4. Two semaphore request latches feed into a semaphore flag. Whichever latch is
first to present a zero to the semaphore flag will force its side of the
semaphore flag LOW and the other side HIGH. This condition will
it proceeds to assume control over the shared resource. If it was not
successful in setting the latch, it determines that the right side
processor has set the latch first, has the token and is using the shared
resource. The left processor can then either repeatedly request that
semaphore’s status or remove its request for that semaphore to
perform another task and occasionally attempt again to gain control of
the token via the set and test sequence. Once the right side has
relinquished the token, the left side should succeed in gaining control.
The semaphore flags are active LOW. A token is requested by
writing a zero into a semaphore latch and is released when the same
side writes a one to that latch.
The eight semaphore flags reside within the IDT70V38 in a
separate memory space from the Dual-Port RAM. This address space
is accessed by placing a low input on the SEM pin (which acts as a chip
select for the semaphore flags) and using the other control pins
(Address, CE, and R/W) as they would be used in accessing a
standard Static RAM. Each of the flags has a unique address which
can be accessed by either side through address pins A0 – A2. When
accessing the semaphores, none of the other address pins has any
effect.
When writing to a semaphore, only data pin D0 is used. If a low level
is written into an unused semaphore location, that flag will be set to a
zero on that side and a one on the other side (see Truth Table VI). That
semaphore can now only be modified by the side showing the zero.
When a one is written into the same location from the same side, the
flag will be set to a one for both sides (unless a semaphore request
from the other side is pending) and then can be written to by both sides.
The fact that the side which is able to write a zero into a semaphore
subsequently locks out writes from the other side is what makes
semaphore flags useful in interprocessor communications. (A thorough discussion on the use of this feature follows shortly.) A zero
written into the same location from the other side will be stored in the
semaphore request latch for that side until the semaphore is freed by
the first side.
When a semaphore flag is read, its value is spread into all data bits
so that a flag that is a one reads as a one in all data bits and a flag
containing a zero reads as all zeros. The read value is latched into one
side’s output register when that side's semaphore select (SEM) and
output enable (OE) signals go active. This serves to disallow the
semaphore from changing state in the middle of a read cycle due to a
write cycle from the other side. Because of this latch, a repeated read
of a semaphore in a test loop must cause either signal (SEM or OE) to
go inactive or the output will never change.
A sequence WRITE/READ must be used by the semaphore in
order to guarantee that no system level contention will occur. A
processor requests access to shared resources by attempting to write
a zero into a semaphore location. If the semaphore is already in use,
the semaphore request latch will contain a zero, yet the semaphore
flag will appear as one, a fact which the processor will verify by the
subsequent read (see Table VI). As an example, assume a processor
writes a zero to the left port at a free semaphore location. On a
subsequent read, the processor will verify that it has written successfully to that location and will assume control over the resource in
L PORT
R PORT
SEMAPHORE
REQUEST FLIP FLOP
D0
WRITE
D
Q
SEMAPHORE
REQUEST FLIP FLOP
Q
SEMAPHORE
READ
D
D0
WRITE
SEMAPHORE
READ
Figure 4. IDT70V38 Semaphore Logic
4850 drw 18
continue until a one is written to the same semaphore request latch.
Should the other side’s semaphore request latch have been written to
a zero in the meantime, the semaphore flag will flip over to the other
side as soon as a one is written into the first side’s request latch. The
second side’s flag will now stay LOW until its semaphore request latch
is written to a one. From this it is easy to understand that, if a
semaphore is requested and the processor which requested it no
longer needs the resource, the entire system can hang up until a one
is written into that semaphore request latch.
The critical case of semaphore timing is when both sides request
a single token by attempting to write a zero into it at the same time. The
semaphore logic is specially designed to resolve this problem. If
simultaneous requests are made, the logic guarantees that only one
side receives the token. If one side is earlier than the other in making
the request, the first side to make the request will receive the token. If
both requests arrive at the same time, the assignment will be arbitrarily
made to one port or the other.
One caution that should be noted when using semaphores is that
semaphores alone do not guarantee that access to a resource is
secure. As with any powerful programming technique, if semaphores
are misused or misinterpreted, a software error can easily happen.
Initialization of the semaphores is not automatic and must be
handled via the initialization program at power-up. Since any semaphore request flag which contains a zero must be reset to a one,
all semaphores on both sides should have a one written into them
at initialization from both sides to assure that they will be free
when needed.
16
IDT70V38L
High-Speed 3.3V 64K x 18 Dual-Port Static RAM
Industrial and Commercial Temperature Ranges
Ordering Information
IDT XXXXX
Device
Type
A
999
A
A
Power
Speed
Package
Process/
Temperature
Range
Blank
I(1)
Commercial (0°C to +70°C)
Industrial (-40°C to +85°C)
PF
100-pin TQFP (PN100-1)
15
20
Commercial Only
Commercial & Industrial
L
Low Power
70V38
1152K (64K x 18) Dual-Port RAM
Speed in nanoseconds
4850 drw 19
NOTE:
1. Contact your sales office for Industrial Temperature range in other speeds, packages and powers.
Datasheet Document History:
08/01/99:
01/02/02:
08/29/03:
Initial Public Offering
Page 1 & 17 Replaced IDT logo
Page 3 Increased storage temperature parameter
Clarified TA Parameter
Page 5 DC Electrical parameters–changed wording from "open" to "disabled"
Page 4-6, 8 & 12 - 14 Added Truth Table I - Chip Enable to note 5
Page 7 Corrected ±200mV to 0mV in notes
Page 5, 7, 10 & 12 Added Industrial Temperature range for 20ns to DC & AC Electrical Characteristics
Removed Preliminary status
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17
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