參數(shù)資料
型號(hào)： NS32828
廠商： National Semiconductor Corporation
英文描述： 1 Megabit High Speed Dynamic RAM Controller/Drivers
中文描述： 1兆位動(dòng)態(tài)隨機(jī)存儲(chǔ)器的高速控制器/驅(qū)動(dòng)器
文件頁(yè)數(shù)： 16/26頁(yè)
文件大?。?/td> 481K
代理商： NS32828
Applications
(Continued)
TL/F/8649–24
FIGURE 7c. Typical Application of DP8428 Using Modes 5 and 1
The DP84XX2 family of inexpensive preprogrammed medi-
um Programmable Array Logic devices (PALs) have been
developed to provide an easy interface between various mi-
croprocessors and the DP84XX family of DRAM controller/
drivers. These PALs interface to all the necessary control
signals of the particular processor and the DP8429. The
PAL controls the operation of the DP8429 in modes 5 and 1,
while meeting all the critical timing considerations discussed
above. The refresh clock, RFCK, may be divided down from
the processor clock using an IC counter such as the
DM74LS393 or the DP84300 programmable refresh timer.
The DP84300 can provide RFCK periods ranging from 15.4
m
s to 15.6
m
s based on an input clock of 2 to 10 MHz.
Figure 8 shows a general block diagram for a system using
the DP8429 in modes 1 and 5. Figure 9 shows possible
timing diagrams for such a system (using WAIT to prohibit
access when refreshing). Although the DP84XX2 PALs are
offered as standard peripheral devices for the DP84XX
DRAM controller/drivers, the programming equations for
these devices are provided so the user may make minor
modifications for unique system requirements.
ADVANTAGES OF DP8429 OVER
A DISCRETE DYNAMIC RAM CONTROLLER
1) The DP8429 system solution takes up much less board
space because everything is on one chip (latches, re-
fresh counter, control logic, multiplexers, drivers, and in-
ternal delay lines).
2) Less effort is needed to design a memory system. The
DP8429 has automatic modes (1 and 5) which require a
minimum of external control logic. Also programmable ar-
ray logic devices (PALs) have been designed which allow
an easy interface to most popular microprocessors (Mo-
torola 68000 family, National Semiconductor 32032 fami-
ly, Intel 8086 family, and the Zilog Z8000 family).
3) Less skew in memory timing parameters because all crit-
ical components are on one chip (many discrete drivers
specify a minimum on-chip skew under worst-case condi-
tions, but this cannot be used if more then one driver is
needed, such as would be the case in driving a large
dynamic RAM array).
4) Our switching characteristics give the designer the critical
timing specifications based on TTL output levels (low
e
0.8V, high
e
2.4V) at a specified load capacitance. All
timing parameters are specified on the DP8429:
A) driving 88 DRAM’s over a temperature range of 0–70
degrees centigrade (no extra drivers are needed).
B) under worst-case driving conditions with all outputs
switching simultaneously (most discrete drivers on the
market specify worst-case conditions with only one
output switching at a time; this is not a true worst-case
condition!).
16
相關(guān)PDF資料
PDF描述
NS32829 1 Megabit High Speed Dynamic RAM Controller/Drivers
NS32FX16-15 FILM/M CAPACITANCE=0.001 VOLT=630
NS32FX16-20 Imaging/Signal Processor
NS32FX16-25 Imaging/Signal Processor
NS32FX164-20 Advanced Imaging/Communication Signal Processors(高級(jí)圖象/通訊信號(hào)處理器)
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
NS32828D-70 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DRAM Controller
NS32828D-70/A+ 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DRAM Controller
NS32828D-80 制造商:Texas Instruments 功能描述:
NS32828D-80/A+ 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DRAM Controller
NS32828V-70 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DRAM Controller
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