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STDL130
5-160
Samsung ASIC
CAM_HDL
High-Density Single-Port Synchronous Binary CAM
Pin Descriptions
Name
I/O
Description
CK
Clock
Clock input. CSN, WEN, A[], DI[], CDI[], CMN[], VDI and CEN are latched into the RAM on
the rising edge of CK. If CSN and WEN are low and CEN and RN are high on the rising
edge of CK, the RAM is in write mode. If CSN is low and WEN is high and CEN and RN
are high on the rising edge of CK, the RAM is in read mode. If CSN and CEN are low and
RN is high on the rising edge of CK, the RAM is in compare mode.
CSN
Chip Enable
Chip Enable input. The chip enable is active-low and is latched into the RAM on the rising
edge of CK. When CSN is low and RN is high, the RAM is enabled for reading, writing or
comparing, depending on the state of WEN and CEN. When CSN is high and RN is high,
the RAM goes to the standby mode and is disabled for reading or writing or comparing.
DOUT[], VDO, HIT and CAO[] remains previous data output.
WEN
Read/Write
Enable
Read or write enable input. The read/write enable is latched into the RAM on the rising
edge of CK depending on the state of CEN. When CSN and WEN is low and CEN and RN
are high, data are written to the addressed location and DOUT[], VDO, HIT and CAO[]
remains stable. When CSN is low and WEN is high and CEN and RN are high, data from
the addressed word are present at DOUT[] and VDO, whereas HIT and CAO[] remains
stable.
OEN
Data Output
Enable
Data output enable input. The data output enable is asynchronously operated regardless
of any input. When OEN is high, DOUT[] and VDO are disabled and go to high-impedance
state.
CEN
Compare Enable
Compare enable input. The compare enable is latched into the RAM on the rising edge of
CK. When CSN and CEN is low and RN is high, the CAM match function is activated.
When CSN is low and CEN and RN are high, only read-write accesses are permitted.
AEN
Address Output
Enable
Address output enable input. The address output enable is asynchronously operated
regardless of any input. When AEN is high, CAO[] is disabled and goes to high-impedance
state.
CMN [ ]
Compare Mask
Input
Compare mask input bus. CMN[] defines the pattern which enables the CDI[] pattern to be
used for the CAM match function. If the CMN[] bit is low, the corresponding CDI[] bit will be
interpreted as a wild card.
A [ ]
Address
Address input bus. The address is latched into the RAM on the rising edge of CK.
DI [ ]
Data Input
Data input bus. Data are latched on the rising edge of CK. Data input is written into the
addressed location in write mode.
VDI
Valid Bit Input
Valid Bit Input. VDI overwrites the valid bit associated with the CAM entry with the state
selected by A[], during a normal write access cycle. Valid Bit Input are latched on the rising
edge of CK.
CDI [ ]
Compare Data
Input
Compare Data input bus. Compare-data are latched on the rising edge of CK and define
the data pattern to be matched with the CAM entries, in conjunction to CMN[].
RN
Reset Enable
Reset Enable. RN, if low, invalidates all the CAM entries by setting all the valid-bits, one
per entry,to low states,therefore all the entries are excluded from CAM match function so
no match can occur. A low state of RN inhibits all access, same as when CSN is in a high
state.
DOUT [ ]
Data Output
Data output bus. Data output is valid after the rising edge of CK while the RAM is in read
mode. Data output remains previous data output while the RAM is in write mode and
compare mode.
VDO
Valid Bit Output
Valid bit output. VDO, during a normal read access cycle, reads back the valid bit
associated with the A[] selected by CAM entry.
CAO [ ]
Address Output
Address output bus. CAO[] presents the address of the matched entry, in a single match
case. In a multiple-match case, CAO[] is the lowest one of all matched addresses by the
built-in priority address encoder.
HIT
Match Output
Match Output. HIT indicates one or more CAM entries matched the masked CDI[], if high.