CYNSE70128-83BGI Cypress Semiconductor Corp, CYNSE70128-83BGI Datasheet - Page 98

• Manufacturer Part Number: CYNSE70128-83BGI
• Manufacturer: Cypress Semiconductor Corp

Specifications of CYNSE70128-83BGI

• Operating Supply Voltage (min): 1.425V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Package Type: BGA
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Not Compliant

10.6.11 Mixed-Size Searches on Tables Configured to Different Widths Using a CYNSE70128 with CFG_L HIGH
This subsection will cover the mixed-size searches (×72, ×144, and ×288) with tables of different widths (×72, ×144, ×288)
with CFG_L set high. The previous subsection described searches on tables of different widths using table designation bits
in the data array. This can be wasteful of the bits in the data array. In order to avoid the waste of these bits and yet support
up to three tables of ×72, ×144, and ×288, the CMD[2] and CMD[9] (in CFG_L high mode) in cycle A of the command can
be used as shown in Table 10-34.
Table 10-34. Searches with CFG_L Set High
10.7
When NSEs are cascaded using multiple CYNSE70128s, the SADR, CE_L, and WE_L (three-state signals) are all tied together.
In order to eliminate external pull-up and pull downs, one device in a bank is designated as the default driver. For non-Search or
non-Learn cycles (see “Learn Command” on page 98) or search cycles with a global miss, the SADR, CE_L, and WE_L signals
are driven by the device with the LRAM bit set. It is important that only one device in a bank of NSEs that are cascaded have this
bit set. Failure to do so will cause contention on SADR, CE_L, WE_L and can potentially cause damage to the device(s).
Similarly, when NSEs using multiple CYNSE70128s are cascaded, SSF and SSV (also three-state signals) are tied together. In
order to eliminate external pull-up and pull downs, one device in a bank is designated as the default driver. For nonsearch cycles
or Search cycles with a global miss the SSF and SSV signals are driven by the device with the LDEV bit set. It is important that
only one device in a bank of NSEs that are cascaded together have this bit set. Failure to do so will cause contention on SSV
and SSF and can potentially cause damage to the device(s).
10.8
Bit[0] of each 72-bit data location specifies whether an entry in the database is occupied. If all the entries in a device are occupied,
the device asserts FULO signal to inform the downstream devices that it is full. The result of this communication between depth-
cascaded devices determines the global FULL signal for the entire table. The FULL signal in the last device determines the
fullness of the depth-cascaded table.
The device contains 16 pairs of internal, 72-bit-wide comparand registers that store the comparands as the device executes
searches. On a miss by the Search signalled to ASIC through the SSV and SSF signals (SSV = 1, SSF = 0), the host ASIC can
apply the Learn command to learn the entry from a comparand register to the next-free location (see “NFA Register” on page 19).
The NFA updates to the next-free location following each Write or Learn command.
In a depth-cascaded table, only a single device will learn the entry through the application of a Learn instruction. The determination
of which device is going to learn is based on the FULI and FULO signalling between the devices. The first non-full device learns
the entry by storing the contents of the specified comparand registers to the location(s) pointed to by NFA.
In a ×72-configured table the Learn command writes a single 72-bit location. In a ×144-configured table the Learn command
writes the next even and odd 72-bit locations. In 144-bit mode, bit[0] of the even and odd 72-bit locations is 0, which indicates
that they are cascaded empty, or 1, which indicates that they are occupied.
Document #: 38-02040 Rev. *F
LRAM and LDEV Description
Learn Command
CMD[9]
X
X
0
1
CMD[2]
Figure 10-72. Multiwidth Configurations Example
0
0
1
0
CFG = 10 10 01 01 00 00 00 00
32 K
8 K
4 K
Search 72-bit-configured partitions only.
Search 144-bit-configured partitions only.
Cycles A and B for searching 288-bit-configured partitions.
Cycles C and D for searching 288-bit-configured partitions.
72
144
288
Search
CYNSE70128
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