BiCMOS StaticRAM
IDT71216
240K (16K x 15-BIT)
CACHE-TAG RAM
For PowerPC and RISC Processors
Integrated Device Technology, Inc.
This high-speed MATCH signal, with tADM as fast as 8ns,
provides the fastest possible enabling of secondary cache
accesses.
FEATURES:
• 16K x 15 Configuration
– 12 TAG Bits
The three separate I/O status bits (VLD, DTY, and WT) can
be configured for either dedicated or generic functionality,
depending on the SFUNC input pin. With SFUNC LOW, the
status bits are defined and used internally by the device,
allowing easier determination of the validity and use of the
given Tag data. SFUNC HIGH releases the defined internal
status bit usage and control, allowing the user to configure the
status bit information to fit his system needs. A synchronous
RESET pin, when held LOW at a rising clock edge, will reset
all status bits in the array for easy invalidation of all Tag
addresses.
The IDT71216 also provides the option for Transfer Ac-
knowledge (TA) generation within the cache tag itself, based
upon MATCH, VLD bit, WT bit, and external inputs provided
by the user. This can significantly simplify cache controller
logic and minimize cache decision time. Match and Read
operations are both asynchronous in order to provide the
fastest access times possible, while Write operations are
synchronous for ease of system timing.
– 3 Separate I/O Status Bits (Valid, Dirty, Write Through)
• Match output uses Valid bit to qualify MATCH output
• High-Speed Address-to-Match comparison times
– 8/9/10/12ns over commercial temperature range
• TA circuitry included inside the Cache-Tag for highest
speed operation
• Asynchronous Read/Match operation with Synchronous
Write and Reset operation
• Separate WE for the TAG bits and the Status bits
• Separate OE for the TAG bits, the Status bits, and TA
• Synchronous RESET pin for invalidation of all Tag entries
• Dual Chip selects for easy depth expansion with no
performance degredation
• I/O pins both 5V TTL and 3.3V LVTTL compatible with
VCCQ pins
• PWRDN pin to place device in low-power mode
• Packaged in a 80-pin Thin Plastic Quad Flat Pack
(TQFP)
The IDT71216 uses a 5V power supply on Vcc, with
separate VCCQ pins provided for the outputs to offer compli-
ance with both 5.0V TTL and 3.3V LVTTL Logic levels. The
PWRDN pin offers a low-power standby mode to reduce
power consumption by 90%, providing significant system
power savings.
The IDT71216 is fabricated using IDT's high-performance,
high-reliability BiCMOS technology and is offered in a space-
saving 80-pin Thin Plastic Quad Flat Pack (TQFP) package.
DESCRIPTION:
The IDT71216 is a 245,760-bit Cache Tag StaticRAM,
organized 16K x 15 and designed to support PowerPC and
other RISC processors at bus speeds up to 66MHz. There are
twelve common I/O TAG bits, with the remaining three bits
usedasstatusbits. A12-bitcomparatorison-chiptoallowfast
comparison of the twelve stored TAG bits and the current Tag
input data. An active HIGH MATCH output is generated when
these two groups of data are the same for a given address.
PIN DESCRIPTIONS
CLK
TAH
TAOE
TAIN
TA
System Clock
Input
Input
Input
Input
Output
I/O
A0 – A13
CS1, CS2
WET
Address Inputs
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
TA Force High
Chip Selects
TA Output Enable
Additional TA Input
Transfer Acknowledge
Write Enable - Tag Bits
Write Enable - Status Bits
Output Enable - Tag Bits
Output Enable - Status Bits
Status Bit Reset
WES
OET
TAG0 – TAG11 Tag Data Input/Outputs
VLDOUT / S1OUT Valid Bit / S1 Bit Output
DTYOUT / S2OUT Dirty Bit / S2 Bit Output
OES
Output
Output
Output
Output
Pwr
RESET
PWRDN
SFUNC
TT1
Powerdown Mode Control Pin
Status Bit Function Control Pin
Read/Write Input from Processor
WTOUT / S3OUT
MATCH
VCC
Write Through Bit / S3 Bit Output
Match
+5V Power
Output Buffer Power
Ground
VLDIN / S1IN Valid Bit / S1 Bit Input
DTYIN / S2IN Dirty Bit / S2 Bit Input
VCCQ
VSS
QPwr
Gnd
WTIN / S3IN
Write Through Bit / S3 Bit Input
3067 tbl 01
The IDT logo is a registered trademark and CacheRAM is a trademark of Integrated Device Technology, Inc.
PowerPC is a trademark of International Business Machines, Inc.
COMMERCIAL TEMPERATURE RANGE
AUGUST 1996
1996 Integrated Device Technology, Inc.
DSC-3067/3
14.3
1
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