MU9C2480A-70DC(1998) データシートの表示（PDF） - Music Semiconductors
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MU9C2480A-70DC Datasheet PDF : 28 Pages
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MU9C2480A/L
PIN DESCRIPTIONS
All signals are implemented in CMOS technology with TTL levels. Signal names that start with a slash (“/”) are active LOW. Inputs
should never be left floating. The CAM architecture draws large currents during compare operations, mandating the use of good layout
and bypassing techniques. Refer to the Electrical Characteristics section for more information.
/E (Chip Enable, Input, TTL)
The /E input enables the device while LOW. The falling
edge registers the control signals /W, /CM, and /EC. The
rising edge locks the daisy chain, turns off the DQ pins,
and clocks the Destination and Source Segment counters.
The four cycle types enabled by /E shown in Table 2 on
page 2.
/W (Write Enable, Input, TTL)
The /W input selects the direction of data flow during a
device cycle. /W LOW selects a Write cycle and /W HIGH
selects a Read cycle.
/CM (Data/Command Select, Input, TTL)
The /CM input selects whether the input signals on
DQ15–0 are data or commands. /CM LOW selects Command
cycles and /CM HIGH selects Data cycles.
/EC (Enable Daisy Chain, Input, TTL)
The /EC signal performs two functions. The /EC input enables
the /MF output to show the results of a comparison, as shown
in Figure 6 on page 14. If /EC is LOW at the falling edge of /E
in a given cycle, the /MF output is enabled. Otherwise, the
/MF output is held HIGH. The /EC signal also enables the
/MF– /MI daisy chain, which serves to select the device with
G ND 7
DQ4 8
DQ5 9
V CC 10
V CC 11
TEST 2 12
G ND 13
G ND 14
D Q 6 15
D Q 7 16
V CC 17
44-pin PL CC
(Top V ie w )
39 /M A
38 /MI
37 /MF
36 G ND
35 /R ESET
34 V CC
33 V CC
32 TE S T1
31 /E
30 /W
29 G ND
Pinout Diagram
the highest-priority match in a string of LANCAMs. Tables 5a
and 5b on page 12 explain the effect of the /EC signal on a
device with or without a match in both Standard and Enhanced
modes. /EC must be HIGH during initialization.
DQ15–0 (Data Bus, I/O, TTL)
The DQ15–0 lines convey data, commands, and status to
and from the LANCAM. /W and /CM control the direction
and nature of the information that flows to or from the
device. When /E is HIGH, DQ15–0 go to Hi-Z.
/MF (Match Flag, Output, TTL)
The /MF output goes LOW when one or more valid matches
occur during a compare cycle. /MF becomes valid after /E
goes HIGH on the cycle that enables the daisy chain (on
the first cycle that /EC is registered LOW by the previous
falling edge of /E; see Figure 6 on page 14). In a daisy
chain, valid match(es) in higher priority devices are passed
from the /MI input to /MF. If the daisy chain is enabled but
the match flag is disabled in the Control register, the /MF
output only depends on the /MI input of the device
(/MF=/MI). /MF is HIGH if there is no match or when the
daisy chain is disabled (/E goes HIGH when /EC was HIGH
on the previous falling edge of /E). The System Match flag
is the /MF pin of the last device in the daisy chain. /MF will
be reset when the active configuration register set is changed.
/MI (Match Input, Input, TTL)
The /MI input prioritizes devices in vertically cascaded
systems. It is connected to the /MF output of the previous
device in the daisy chain. The /MI pin on the first device in
the chain must be tied HIGH.
/MA (Device Match Flag, Output, TTL)
The /MA output is LOW when one or more valid matches
occur during the current or the last previous compare cycle.
The /MA output is not qualified by /EC or /MI, and reflects
the match flag from that specific device’s Status register.
/MA will be reset when the active register set is changed.
/MM (Device Multiple Match Flag, Output, TTL)
The /MM output is LOW when more than one valid match
occurs during the current or the last previous compare cycle.
The /MM output is not qualified by /EC or /MI, and reflects
the multiple match flag from that specific device’s Status
register. /MM will be reset when the active register set is changed.
3
Rev. 1a
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