LH543620
FEATURES
•
Fast Cycle Times: 20/25/30 ns
•
Selectable 36/18/9-Bit Word Width for Both
Input Port and Output Port
•
Byte-Order-Reversal Function (i.e.,
‘Big-Endian’
£
‘Little-Endian’ Conversion)
•
16-mA-I
OL
Three-State Outputs
•
Automatic Byte Parity Checking
•
Selectable Byte Parity Generation
•
Five Status Flags: Full, Almost-Full,
Half-Full, Almost-Empty, and Empty
•
All FIFO Status Flags are Synchronous
(AE, HF, AF Through Programming of
Control Register)
•
Programmed Values may be entered from
either Port
•
Two Enable Control Signals for each Port
•
Mailbox Register with Synchronized Flags
•
Asynchronous Data-Bypass Function
•
‘Smart’ Data-Retransmit Function
•
Configurable for Paralleled FIFO Operation
(72-Bit Data Width)
•
Space-Saving PQFP and TQFP
Packages
1
1024
×
36 Synchronous FIFO
FUNCTIONAL DESCRIPTION
The LH543620 is a FIFO (First-In, First-Out) memory
device, based on fully-static CMOS RAM technology,
capable of containing up to 1024 36-bit words. It can
replace four or more nine-bit-wide FIFOs in many appli-
cations.
The input port and the output port operate inde-
pendently of each other. Write operations are performed
on the rising edge of the input clock CKI, and enabled by
two enabled signals ENI
1
, ENI
2
. Read operations are
performed on the rising edge of the output clock CKO and
enabled by two enabled signals ENO
1
, ENO
2
.
Five status flags are available to monitor the memory
array status: Full, Almost-Full, Half-Full, Almost-Empty,
and Empty. The Almost-Full and Almost-Empty flags are
initialized to a default offset of eight locations from their
respective boundaries, but they are each programmable
over the entire FIFO depth.
Both the input port and the output port may be set
independently to operate at three data-word widths: 36
bits, 18 bits, or 9 bits. This setting may be changed during
system operation. The LH543620 can perform Byte-Or-
der-Reversal on the four nine-bit bytes of each 36-bit data
word passing through it, thus accomplishing ‘Big Endian’
↔
‘Little Endian’ conversion.
When data is read out of the FIFO a byte-parity check
is performed. The parity flag is used to indicate that a
parity error was detected in one of the 9-bit bytes of the
output word.
Parity generation, when selected, creates the parity bit
of each 8-bit byte of the input word. The result is written
into the MSB-bit of each 9-bit byte, overwriting the pre-
vious contents of the bit. The default is odd parity. How-
ever, the FIFO may be programmed to use even parity.
The LH543620 has a data-bypass mode that connects
the output port to the input port asynchronously. A mailbox
facility with Synchronized Flags is provided from the input
port to the output port.
The LH543620’s ‘Smart-Retransmit’ capability sets the
internal-memory read pointer to any arbitrary memory
location. The ‘Smart-Retransmit’ capability includes a
Marking Function and a Programmable Offset to support
data communication and digital signal processing appli-
cations.
•
PQFP-to-PGA Package Conversion
2
1. This is a final data sheet; except that all references to the TQFP
package have Preliminary status.
2. For PQFP-to-PGA conversion for thru-hole board designs, Sharp
recommends ITT Pomona Electronics’ SMT/PGA Generic Con-
verter model #5853
®
. This converter maps the LH543620 132-
pin PQFP to a generic 13
×
13, 132-pin PGA (100-mil pitch). For
more information, contact Sharp or ITT Pomona Electronics at
1500 East Ninth Street, Pomona, CA 91766, (909) 469-2900.
1
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