79R3041-25J(2008) View Datasheet(PDF) - Integrated Device Technology
Part Name
Description
MFG CO.
79R3041-25J Datasheet PDF : 34 Pages
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IDT79R3041 INTEGRATED RISController FOR LOW COST SYSTEMS
COMMERCIAL TEMPERATURE RANGE
• Programmable memory Port Widths: The R3041 allows
the kernel to partition the physical memory space into
various sub-regions, and to individually indicate the port
width of these sub-regions. Thus, the bus interface unit can
perform data packing and unpacking when communicating
with narrow memory sub-regions. For example, these fea-
tures, can be used to allow the R3041 to interface with
narrow 8-bit boot PROMs, or to implement 16-bit only
memory systems.
THERMAL CONSIDERATIONS
The RISController family utilizes special packaging tech-
niques to improve the thermal properties of high-speed pro-
cessors. Thus, all versions of the RISController family are
packaged in cavity down packaging.
The lowest cost members of the family use a standard
cavity down, injection molded PLCC package (the “J” pack-
age). This package is used for all speeds of the R3041 family.
Higher speed and higher performance members of the
RISController family utilize more advanced packaging tech-
niques to dissipate power while remaining both low-cost and
pin- and socket- compatible with the PLCC package. Thus,
these members of the RISController family are available in the
MQUAD package (the “MJ” package), which is an all alumi-
num package with the die attached to a normal copper lead-
frame mounted to the aluminum casing. The MQUAD pack-
age is pin and form compatible with the PLCC package. Thus,
designers can choose to utilize this package without changing
their PCB.
Airflow (ft/min)
ØCA
0 200 400 600 800 1000
"J" Package
29
26 21 18 16 15
TQFP
55
40 35 33 31
30
2905 tbl 02
Table 2. Thermal Resistance (ØCA) at Various Airflows
The members of the RISController family are guaranteed in
a case temperature range of 0°C to +85°C. The type of
package, speed (power) of the device, and airflow conditions,
affect the equivalent ambient conditions which meet this
specification.
The equivalent allowable ambient temperature, TA, can be
calculated using the thermal resistance from case to ambient
(ØCA) of the given package. The following equation relates
ambient and case temperature:
TA = TC - P * ØCA
where P is the maximum power consumption at hot tempera-
ture, calculated by using the maximum Icc specification for the
device.
Typical values for ØCA at various airflows are shown in
Table 2 for the PLCC package.
NOTES ON SYSTEM DESIGN
The R3041 has been designed to simplify the task of high-
speed system design. Thus, set-up and hold-time require-
ments have been kept to a minimum, allowing a wide variety
of system interface strategies.
To minimize these AC parameters, the R3041 employs
feedback from its SysClk output to the internal bus interface
unit. This allows the R3041 to reference input signals to the
reference clock seen by the external system. The SysClk
output is designed to provide relatively large AC drive to
minimize skew due to slow rise or fall times. A typical part will
have less than 2ns rise or fall (10% to 90% signal times) when
driving the test load.
Therefore, the system designer should use care when
designing for direct SysClk use. Total loading (due to devices
connected on the signal net and the routing of the net itself)
should be minimized to ensure the SysClk output has a
smooth and rapid transition. Long rise and/or fall times may
cause a degradation in the speed capability of an individual
device.
Similarly, the R3041 employs feedback on its ALE output to
ensure adequate address hold time to ALE. The system
designer should be careful when designing the ALE net to
minimize total loading and to minimize skew between ALE and
the A/D bus, which will ensure adequate address access latch
time.
IDT's field and factory applications groups can provide the
system designer with assistance for these and other design
issues.
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