IDT7026L15JG IDT, Integrated Device Technology Inc, IDT7026L15JG Datasheet - Page 15

• Manufacturer Part Number: IDT7026L15JG
• Description: IC SRAM 256KBIT 15NS 84PLCC
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT7026L15JG

• Format - Memory: RAM
• Memory Type: SRAM - Dual Port, Asynchronous
• Memory Size: 256K (16K x 16)
• Speed: 15ns
• Interface: Parallel
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 84-PLCC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 7026L15JG; 800-1366; 800-1366-5; 800-1366

Truth Table IV —
Address BUSY Arbitration
NOTES:
1. Pins BUSY
2. LOW if the inputs to the opposite port were stable prior to the address and enable
3. Writes to the left port are internally ignored when BUSY
Functional Description
I/O pins that permit independent access for reads or writes to any location
in memory. The IDT7026 has an automatic power down feature controlled
by CE. The CE controls on-chip power down circuitry that permits the
respective port to go into a standby mode when not selected (CE = V
When a port is enabled, access to the entire memory array is permitted.
Busy Logic
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.
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.
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.
CE
IDT7026S/L
High-Speed 16K x 16 Dual-Port Static RAM
X
X
H
L
master. Both are inputs when configured as a slave. BUSY
IDT7026 are push pull, not open drain outputs. On slaves the BUSY
internally inhibits writes.
inputs of this port. HIGH if the inputs to the opposite port became stable after the
address and enable inputs of this port. If t
= LOW will result. BUSY
regardless of actual logic level on the pin. Writes to the right port are internally
ignored when BUSY
on the pin.
The IDT7026 provides two ports with separate control, address and
Busy Logic provides a hardware indication that both ports of the RAM
The use of BUSY logic is not required or desirable for all applications.
The BUSY outputs on the IDT 7026 RAM in master mode, are push-
L
CE
X
X
H
L
R
Inputs
L
and BUSY
NO MATCH
A
A
MATCH
MATCH
MATCH
OR
OL
R
-A
-A
outputs are driving LOW regardless of actual logic level
13L
13R
R
L
and BUSY
are both outputs when the part is configured as a
BUSY
(2)
H
H
H
R
outputs cannot be LOW simultaneously.
L
Outputs
(1)
APS
is not met, either BUSY
BUSY
(2)
H
H
H
R
(1)
L
outputs are driving LOW
Write Inhibit
X
Function
outputs on the
Normal
Normal
Normal
L
or BUSY
2939 tbl 16
X
(3)
input
IH
).
R
6.42
15
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.
address signals only. It ignores whether an access is a read or write. 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 either the R/W signal or the byte enables. Failure
to observe this timing can result in a glitched internal write inhibit signal and
corrupted data in the slave.
Semaphores
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.
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
Width Expansion with BUSY Logic
Master/Slave Arrays
logic, one master part is used to decide which side of the RAM 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 IDT7026 RAM the BUSY
pin is an output if the part is used as a master (M/S pin = V
pin is an input if the part used as a slave (M/S pin = V
Figure 3.
decision could result with one master indicating BUSY on one side of the
BUSY
Figure 3. Busy and chip enable routing for both width and depth
The BUSY arbitration on a master is based on the chip enable and
The IDT7026 is an extremely fast Dual-Port 16K x 16 CMOS Static
The Dual-Port RAM features a fast access time, and both ports are
When expanding an IDT7026 RAM array in width while using BUSY
If two or more master parts were used when expanding in width, a split
L
Military, Industrial and Commercial Temperature Ranges
MASTER
Dual Port
RAM
BUSY
MASTER
Dual Port
RAM
BUSY
L
L
expansion with IDT7026 RAMs.
BUSY
BUSY
CE
CE
R
R
SLAVE
Dual Port
RAM
BUSY
SLAVE
Dual Port
RAM
BUSY
L
L
BUSY
BUSY
CE
CE
IH
R
R
), and the BUSY
IL
) as shown in
BUSY
2939 drw 16
R
,